The Collection and Storage of Human Milk and Human Milk Banking

CHAPTER 21

The Collection and Storage of Human Milk and Human Milk Banking Breast milk expression has become a very common practice. Although it is associated with maternal employment, it is also associated with the desire to make it possible for someone else to feed the infant. Pumping to donate the milk was an uncommon reason, as was pumping for a hospitalized infant. The prevalence of breast milk expression was determined by reviewing the data from the 2005 to 2007 Infant Feeding Practices Study II by the Center for Food Safety and Applied Nutrition, of the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC).41 Of mothers whose infants were younger than 4½ months, 85% had expressed milk at some time since birth, 43% having done so occasionally and 25% on a regular schedule. The number was higher among first-time mothers and slowly declined as the infant became older (Figures 21-1 and 21-2). The human milk bank has entered another era. The interest in providing human milk for infants with special needs, especially premature infants, has increased, but the concerns regarding donor milk have also escalated. Regulatory bodies have decreed that donor milk must be pasteurized. Milk banks have recognized the need for donors to be carefully screened and women at high risk for certain infections eliminated. When there are risks associated with using even a mother’s own milk for a given baby, the risk/ benefit ratio is determined. Because of the effects of heating, cooling, freezing, and storing milk, some of the most valued and precious qualities are diminished or destroyed; feeding the milk fresh or

at least fresh frozen and not heated preserves most of the constituents. The value of the milk produced by women who deliver prematurely has been discussed in Chapter 15. There are no reported cases of infection acquired from milk provided by a milk bank in compliance with the standards prescribed by the Human Milk Banking Association of North America (HMBANA).

Historical Perspective When “wet nursing” was the immediate alternative feeding to replace a mother’s own milk and no safe ways were available to store milk of any species, no human milk banks existed.8 As pasteurization became available and formulas based on milk from other species increased in popularity, the pool of human milk diminished. “Wet nurses” were increasingly difficult to locate and often were not safe sources because of wet-nurse lifestyle, risk for infections, and poor nutrition. It had already been clearly demonstrated in the early twentieth century that infants who did not receive their mother’s milk had six times the risk for dying in the first year of life (see Chapter 1). The impetus behind milk banks at the turn of the twentieth century was actually the medical profession’s desire to remove the control of infant feeding from wet nurses and separate the product (human milk) from the producer. Pediatricians anxious to improve the prognosis for infants deprived of their own mother’s milk for medical and social reasons developed a means of storing human milk 689

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Percentage

PREVALENCE OF BREAST MILK EXPRESSION 70 60 50 40 30 20 10 0

1.5-4.5 mo (n = 1302) >4.5-6.5 mo (n = 843) >6.5-9.5 mo (n = 529)

Electric pump

Manual pump

Combination pumpa

Battery pump

By hand (no pump)

Method Figure 21-1.  Percentage of breastfeeding mothers who had successfully expressed milk, according to method of milk expression and infant age-group. The 1.5- to 4.5-month sample is based on breastfeeding mothers who responded about methods used to successfully express milk since their infant was born; the >4.5- to 6.5-month sample is based on mothers who responded in the previous 3 months; and the >6.5- to 9.5-month sample is based on mothers reporting about methods used in the previous 2 months. Samples are smaller than the total of those who had successfully expressed milk during a given period (1315, 845, and 653, respectively, for the successive age-groups) as a result of question nonresponse. Respondents could mark all answers that applied; therefore percentages in each age group do not sum to 100%. aCombination pumps were defined as both electric and battery operated. 100 90 80 Percent

70 60 50 40 30 20 10 0 1.5-4.5 (n = 1493)

>4.5-6.5 (n = 1090)

>6.5-8.5 (n = 891)

Age-group (mo) On a regular schedule Occasionally None Figure 21-2.  Breastfeeding mothers’ prevalence of breast milk expression in the previous 2 weeks, according to infant age-group.

for general use for sick infants. The first milk bank was opened in Vienna in 1900. The first one in the United States was established 10 years later at the Massachusetts Infant Asylum, where wet nurses had been the only sources of human milk.31 In 1919 the first human milk bank was founded in Germany in Magdeburg by Dr. Marie-Elise Kayser. In 1934 she wrote guidelines that were used throughout Europe for the creation and operation of milk banks.70 Early attempts at providing donor milk depended on casual screening of donors for tuberculosis, syphilis, and various acute contagious diseases.49 There was little investigation of human milk, but the dairy industry was rigorous in its attempt to store and

market bovine and other mammalian milks. This technology was applied on a small scale, but other human milk banks appeared after Denny and Talbot created the one in Boston. The American Academy of Pediatrics (AAP) established its first formal guidelines for human milk banks in 1943.11,12 Similar guidelines were provided in other countries. After World War II, milk banks were mandated on both sides of the Berlin Wall. In 1959 the Federal Republic of Germany (West Germany) had 24 milk banks and the German Democratic Republic had 62.69 The numbers gradually decreased. As technology advanced in newborn care and in infant nutrition, science replaced nature. The interest in human milk faded and with it the call for banked human milk in the 1960s and into the 1970s. Experience in Rochester with short-gut syndrome and malabsorption syndromes, however, resulted in the development of a registry of lactating women who donated fresh milk when needed. A milk bank was developed with donors providing frozen milk on a regular basis. By 1975, five large commercial milk banks were operating in Britain. Milk banks also sprang up across the United States. The system thrived with the establishment in 1985 of the Human Milk Banking Association of North America (HMBANA), which not only facilitated communications among banks, but also began to investigate processes, develop uniform policies, and most important, provide professional and public education.77 The threat of human immunodeficiency virus (HIV) and hepatitis, the return of tuberculosis, and drug abuse have cast a long shadow on milk banks in the United States, resulting in the closure of all but seven in North America and five in the United States (see Appendix H). In Europe, milk banking

The Collection and Storage of Human Milk and Human Milk Banking    

has been key in the nourishment of premature and other high-risk infants. The Sorrento Maternity Hospital has supplied 50,000 L of milk from 10,000 donors in 40 years and provided 700 L a year both locally and across Britain in the nineties.3 In 1994 the remaining 18 milk banks in unified Germany supplied about 15,000 L. Many developing countries, especially in Central and South America, are establishing milk banks as part of national efforts to promote breastfeeding.65 Studies done in nurseries in Guatemala have shown a marked decrease in mortality and morbidity rates by providing every infant with human milk, especially colostrum.13 The United Nations Children’s Fund (UNICEF) has encouraged and supported such efforts.82 The First International Congress on Human Milk Banking: A Vision of the Future was held in Brazil in 2000, sponsored by the Brazilian Association of Milk Banks. There are 154 milk banks in Brazil. Representatives from South America, France, United Kingdom, North America, and the Caribbean attended. All the milk banks heat and process the milk. Some screen the serum of donors but not all. None pay donors but some do provide pumps.76 Regulations vary by locale. A resurgence of milk banks in the United States occurred in the last 10 years stimulated in part by the recognition of the value of human milk for premature and especially very-low-birth-weight infants by neonatologists. Another stimulus was the establishment of a for-profit milk bank in California, approved and licensed by the State of California. This milk bank, supported by venture capitalists, studied the safest ways to process milk. They were able to measure the caloric value of the milk and provide milk of 20, 22, 24, and 28 calories per ounce. Their most important contribution has been the development of a supplement consisting only of human milk to be used to enhance the protein, calcium, and caloric content of a feeding of mother’s milk for a premature or other compromised infant.

Storing Human Milk It is often necessary to store milk for infants, especially in the hospital. The storage of human milk involves two types of milk: mother’s milk and donor milk. The distinction becomes important in how the milk is stored and prepared for an infant. It is also important because many states have developed codes for donor milk but fortunately have not regulated mother’s milk as yet. Certain guidelines are appropriate for each milk. Indications for use of such milk were alluded to in other chapters but are briefly summarized here.

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MOTHER’S MILK FOR A HEALTHY INFANT The conditions under which a mother collects and stores milk while at work are not always ideal. At home, at work, or at school, milk should be collected with clean equipment, stored in sterile containers (dishwasher cleaned and dried suffices), and handled with just-washed hands. The limits of temperature and time are an important consideration in the storage of milk. To assess microbial growth and stability of milk protein and lipid at varying temperatures and for varying lengths of time, Hamosh et al33 collected samples from 16 healthy women with healthy babies who were exclusively breastfed. Sampling was done early in lactation (1 month postpartum) and late in lactation (5 to 6 months postpartum). The milk pH decreased from 7.02 ± 0.20 to 5.16 ± 0.26 after 24 hours of storage at 38° C (100° F), and significant differences in pH occurred at all temperatures at 24 hours or longer. Proteolysis was minimal at 15° C (59° F) and 25° C (77° F) but became apparent at 38° C (100° F) at 24 hours. Lipolysis was marked in the first 24 hours at all temperatures compared with freshly expressed milk. Bacterial growth or normal flora was minimal at 15° C at 24 hours, low at 25° C at 8 hours, and higher at 38° C by 4 hours. The authors concluded that storage of human milk is safe at 15° C for 24 hours and 25° C room temperature for 4 hours and should not be stored at 38° C. Proteins appear to maintain their structure and function in short-term storage. The marked lipolysis appears to slow bacterial growth at the same time.33

PASTEURIZING BREAST MILK AT HOME Many women face the dilemma of discarding milk pumped when they had a Candida infection of the breast before it was diagnosed. Freezing does not destroy Candida. It has been suggested that milk could be “pasteurized” at home for use at home by the mother’s own infant. The following steps are those utilized by Nancy Powers, MD,* for her patients, recognizing that there is no control over the temperature. Mothers, however, who wish to salvage this milk must follow these steps: Pour all milk into a large saucepan, and place over medium heat on the stove. Using a candy thermometer, gradually bring the milk to a temperature of 145° F (62.5° C). Watch closely, and stir often, keeping milk at this temperature for 30 minutes. Milk can then be poured into appropriate storage containers. *Nancy G. Powers, MD, Medical Director of Lactation ­Services, Wesley Medical Center, Wichita, Kan.

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Label each container with the baby’s name and the date and time of pasteurization. Freeze the pasteurized milk in dishwasher-clean containers until ready for use. Do not boil the milk (boiling occurs at 212° F or 100° C). If performed correctly, this process will decrease nutritional and immunologic components by about 30%, but will destroy all microorganisms. See Protocol 8 in Appendix P for more ­information.

MOTHER’S MILK FOR A SICK INFANT The following situations are common scenarios for the use of mother’s own milk. 1. A mother plans to breastfeed the infant ultimately but needs to provide pumped milk until the infant can be put to the breast. 2. An infant requires the special nutritional benefits of human milk (as with those infants who are recovering from intestinal surgery) but cannot nurse at the breast. 3. An infant weighs 1500 g or less and has difficulty digesting and absorbing other milks and is usually fed by nasogastric tube. Appendix H lists guidelines for handling mother’s milk for hospital use.

DONOR MILK The following scenarios are common reasons for obtaining donor milk. 1. An infant is at risk for infection or necrotizing enterocolitis. Although effects are not clearly demonstrated with mature milk, fresh colostrum is held to be especially protective and may be collected from low-risk, carefully screened mothers. 2. An infant has a gastrointestinal anomaly or other reasons for intestinal tract surgery, especially short-gut syndrome. 3. A physician thinks an infant would benefit from the nourishment in human milk because of prematurity, especially if the infant weighs less than 1500 g. 4. A mother is temporarily unable to nourish a breastfed infant completely. It may be that the mother’s supply is inadequate when she first puts the infant to the breast after weeks of pumping or when the mother has been ill or hospitalized. Usually these infants are already at home. 5. Donor milk is an excellent transition from parenteral nutrition when mother’s milk is not available. It allows earlier weaning from parenteral solution—earlier than when formula is known to be tolerated.

6. Metabolic disorders, especially amino acid disorders, respond well because of the physiologic profile of human milk (decreased casein, tyrosine, and phenylalanine). In addition, human milk is protective against infection, which may be a serious complication of these disorders. 7. Pooled samples of donor milk are prepared as a dried preparation for addition to fresh mother’s milk to increase the calorie and nutrient value for high-risk premature infants whose requirements exceed those available with unsupplemented human milk. 8. An older infant or child has unique feeding difficulties, usually characterized by an inability to tolerate any oral nourishment except human milk (e.g., a child dying of HIV infection).

STRUCTURE OF A MILK BANK Most informal and casual milk banks operating in conjunction with a neonatal intensive care unit (NICU) have disappeared.64 NICUs may provide a deep freeze for storage of mother’s own milk for use by her infant. They store it for feeding of the infant and do not process it at all except to culture random samples for contamination. Most do not permit “donating” milk to other infants except by private arrangements between the two mothers with a physician’s approval. No feeding is given an infant in the hospital without a physician’s order. Smaller public milk banks have phased out since state legislation or local medical practice standards have mandated strict surveillance of samples and pasteurization. A few large, well-established banks continue to operate in the United States and around the world. A network of these milk banks meets and shares information through the HMBANA.2,77* Copies of the association’s guidelines for milk storage are available for a fee. HMBANA works closely with the FDA concerning FDA regulations for human tissues and fluids. Appendix H provides the 2003 guidelines. The Mother’s Milk Bank of the Institute for Medical Research in San Jose, California, was established in 1974. It has a full-time coordinator and a medical director, provides milk for hundreds of infants, and contributes to the fund of knowledge on human milk. Because the milk is provided to patients only by physician’s prescription, it is reimbursable by health insurance carriers of California. Mother’s Milk Bank has developed procedures and policies regarding milk collection, storage, and processing. This is described in detail by Asquith et al2 and documented with an extensive bibliography. The Mother’s Milk Bank has prepared and keeps current a comprehensive manual for the organization and *HMBNA, c/o Mother’s Milk Bank, Wakemed, 3000 New Bern Ave, Raleigh, NC 27610.

The Collection and Storage of Human Milk and Human Milk Banking    

operation of a modern human milk bank, which is available to health care facilities. It is also a member of HMBANA, which can provide the names and addresses of other centers (Figure 21-3). The state of New York passed an amendment to the public health law in 1980 in which it was declared policy that any and all infants requiring human breast milk be assured access to sufficient quantities of wholesome human breast milk donated by concerned lactating mothers on a continued and systematic basis (see Appendix L for entire law). New York State has regulations, which have the force of law, governing human milk banks. They address construction, medical direction, donor

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qualifications, milk collection and storage, maintenance of records, and milk distribution. They are available on the Internet in Part 52, Subpart 52-9, of Title 10 (Health) of the New York Code of Rules and Regulations, which can be accessed from the New York State Department of Health’s Public Web site at http://www.health.state.ny.us/ nysdoh/­phforum/ nycrr10.htm (see Appendix H for references). The recommendations for the expansion of the human-milk-banking system have not gone without challenge from neonatologists. They offer ­sincere concerns about the risk/benefit ratio because alteration during storage and contamination may detract from the value of the original product for a mother’s

Mother’s own milk

Milk from donors expressed daily

Expressed

Home freezer or refrigerator

Home refrigerator or freezer

Transport to hospital

Mother brings in Milk bank freezer Hospital refrigerator (MFBM) or freezer, cultured

Thawed if necessary (MFFBM)

Mother’s OWN baby without further treatment

Excess

Thawed, pooled

Pasteurized (62.5° F for 30 min)

Cultured

Store in ICN freezer or milk bank freezer

Processed breast milk (PBM)

Baby Figure 21-3.  Flow chart of process for the mother at home pumping for her hospitalized infant (left). The right column ­outlines the steps a donor takes when collecting mild for the bank. The mother described on the left can become a donor if she has an abundance of mild and is screened to be a donor. MFBM, mother’s frozen breast milk.

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own infant. They caution that the cavalier feeding of unsterile unsupplemented breast milk to premature infants may produce iatrogenic problems. Mothers who pump and save milk for their own infants should follow the instructions/guidelines for storing mother’s own milk (see Appendix Protocol #8).

QUALIFICATIONS OF DONORS A mother who is willing to donate milk should be healthy and fulfill the following qualifications (Box 21-1): 1. Normal pregnancy and delivery 2. Serologically negative for syphilis, hepatitis B surface antigen, cytomegalovirus (CMV), and HIV 3. No infection, acute or chronic (i.e., not at high risk) 4. Not taking medications, smoking, or using excessive alcohol 5. Capable of carrying out sterile technique 6. If donating for other infants, own child is healthy and without jaundice A directive from the Department of Health and Social Security in Great Britain mandated HIV testing for donors to milk banks, and it was observed that the list of 19 established milk banks dwindled to six.3 The Sorrento Maternity Hospital, however, in accordance with the directive of the Department of Health and Social Security, screened all donors for HIV antibodies. Only four mothers of 470  potential donors have refused to be tested, contrary to fears that the ruling would discourage donating.3 The donor should not be taking medications regularly, including certain oral contraceptives and any nonprescription medications, such as aspirin or acetaminophen. Her infant should be well and should not have had neonatal jaundice. If the mother is donating only for her own infant, the state of the infant’s health does not prevent her from donating. Any time the donor becomes ill, however, she should discard milk from the previous 24-hour period and not save milk until the illness is gone if the milk is to be donated.43 Discarding milk during maternal illness is the most difficult regulation to which a mother must adhere. The desire to contribute may overshadow the mother’s understanding of the risk it poses for an infant not her own receiving such milk. The one limiting factor in donating milk is that the woman must be lactating. Becoming a professional donor of milk today is highly unlikely. The amount of protein has been noted to be lower after 6 months of lactation in some women; thus after 6 months or, at most, 8 months postpartum it is advisable to evaluate a given mother’s contributions

BOX 21-1. Screening and Exclusion of Human Milk Donors Donor screening procedures 1. Donors answer questions on a verbal health history screening form. Primary health care providers for the prospective donor and her infant are asked for verification of health. 2. Donors are tested serologically for: a. HIV-1 and HIV-2 b. HTLV-I and HTLV-II c. Hepatitis B d. Hepatitis C e. Syphilis 3. Repeat donors are treated as new donors with each pregnancy. 4. Milk banks will cover the cost of the serologic screening if the tests are done by the milk bank. Reasons for excluding a donor • Receipt of a blood transfusion or blood products within last 12 months • Receipt of an organ or tissue transplant within last 12 months • Regular use of more than 2 ounces of hard liquor or its equivalent in a 24-hour period • Regular use of over-the-counter medications or systemic prescriptions (replacement hormones and some birth control hormones acceptable) • Use of megadose vitamins or pharmacologically active herbal preparations • Total vegetarians (vegans) who do not supplement their diet with vitamins • Use of illegal drugs • Use of tobacco products • Silicone breast implants • History of hepatitis, systemic disorders of any kind, or chronic infections (e.g., HIV, HTLV, TB) Modified from Arnold LD: How North American donor milk banks operate: results of a survey, Part 1, J Hum Lact 13:159, 1997. HIV, Human immunodeficiency virus; HTLV, human T-cell leukemia virus; TB, tuberculosis.

to confirm that protein and caloric content is sufficient. There is always the theoretical risk for a donor mixing her collections with cow milk. This can be tested for bovine protein. Prolacta Bio­ science can screen for a mother’s DNA if content is in question.

TECHNIQUE FOR COLLECTION Whether collecting for a mother’s own infant or for other uses, it is of prime importance to maintain cleanliness and minimize bacteria in the process of collection. The mother should be instructed in

The Collection and Storage of Human Milk and Human Milk Banking    

Figure 21-4.  Purse-sized electric pump. This type of breast pump is serviceable for women who are fully lactating.

washing her hands and her breasts before handling the equipment or pumping. The two major ways of collecting are letting the milk drip while the infant nurses on the other side and pumping or manually expressing the milk.28,30,72 Drip milk is acceptable for one’s own infant when it is used as an occasional tide-over feeding in the mother’s temporary absence; however, it is not appropriate for donor milk. Dripped milk has been found to have lower caloric value and a much higher incidence of contamination. Pumped milk has a higher fat content than dripped or manually expressed milk, and in most individuals the volume is also greater. Any equipment used, such as hand pumps, tubing, and collecting bottles, should be sterile. If an electric pump is used, the parts that come in contact with the milk should be sterile or disposable (Figure 21-4). Many hospitals own electric pumps, or one may be rented from a local medical equipment rental company. Some women can pump large volumes of fat-rich milk manually, and for them, manual expression would be acceptable on a case-by-case basis. The hospital or the bank should provide a program of education for the donors. Milk samples should be cultured initially to ensure proper technique and the absence of significant contamination. Then samples should be sent for culture on a random basis. Studies have shown that milk collected at home has a higher contamination rate than that collected while the same donor is hospitalized or with equipment maintained by the hospital.

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Collection at the hospital also avoids the transportation problem. Many hospitals use the 4-oz sterile water-nursing bottles packaged by formula companies for collections by discarding the water at the time of collection and then filling them with milk. This can be costly if the hospital is paying for feeding supplies. Other programs suggest the use of 50-mL plastic centrifuge tubes,* which are presterilized and have tight-fitting tops. These tubes have the advantage of more appropriate volume and easy measurability and sterility. Ideally the hospital or milk bank provides a uniform container. Soft plastic bags are not recommended. If a woman wants to donate a large amount of previously collected and frozen milk that suddenly becomes available (infant weans or dies), this milk is a valuable resource and can be handled separately with culturing and pasteurization if the milk bank has a protocol for accepting such milk.1-3 The efficacy of various methods of removing milk from the breast has been evaluated. Electric pumping was clearly more effective in raising the maternal prolactin levels and increasing the volume of milk when compared with hand pumping and manual expression.87 The study did not compare various brands of pumps. A hospital may own a breast pump that is 10 or 20 years old, however, which may not have safety features that are built into current models. Problems of contamination are a significant issue because old models may not protect against milk backing up into the motor or tubing normally thought to be free of milk and of potential contamination. Care must be taken to check each machine and follow directions for its proper use. Old vacuum extraction pumps should be discarded. The use of most of the modern electric pumps with their disposable tubing and collecting vessels makes mechanical pumping the most efficient and cleanest of the methods. In addition, the milking action of an electric pump produces more physiologic stimulus to the breast. Most electric pumps provide attachments for pumping both breasts simultaneously. With double pumping, overall production is increased, and time for pumping may be cut in half. Bank milk collected by manual expression is less likely to be contaminated than that collected by hand pumps, even when pumps are boiled or placed in an electric dishwasher.78 The rubber bulb of the hand pump, resembling a bicycle horn, retains milk and bacteria and should not be used. “Nesty cups,” which are placed inside the brassiere to collect milk drippings between feedings, have been associated with the greatest contamination and are *No. 253300, manufactured by Corning Glass Works.

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T A B L E 2 1 - 1 Effect of Container Type on Milk Constituents Constituent

Pyrex

Polypropylene

Polyethylene Bags

Polyethylene (Rigid)

Colostrum Mature milk Cells Fat-soluble vitamins Micronutrients Secretory IgA Difficult to handle

Constituents stable

When refrigerated

24 hours in all

Containers

Stick to glass No effect No effect — —

Maintain phagocytosis No effect No effect — —

Stable — — Stable —

Recommend for donor milk

Highly

No

Stable — — Lower Very Spill easily No

not recommended. Some women develop mastitis using small hand pumps.23 Donowitz et al15 reported contaminated breast milk as the source of Klebsiella bacteremia in a NICU. Unpasteurized human milk from a single donor fed through nasogastric and nasoduodenal tubes to sick newborns was found to be contaminated from the safety overflow bottle and tubing of the electric breast pump maintained in the NICU. This part of the tubing and equipment should be sterilized or disposed of between collections according to the manufacturer’s instructions. Strict attention to sterilization of equipment is imperative. Older electric pumps that do not have a built-in mechanism to prevent milk from getting into the permanent “works” should be discarded, and only pumps with disposable or cleanable parts and a safety valve should be used. The bacteriologic benefit to discarding the first 5 to 10 mL of milk pumped from the breast remains disputed.9 Some banks require that their donors follow instruction for discarding the first 5 to 10 mL of milk expressed at each pumping and each breast. When a donor is collecting for long-term storage, this may be appropriate. When a mother is collecting for her own baby and her volume is meager, discarding 10 mL may be counterproductive. This is particularly important initially, when early colostrum and milk are less in total volume but high in value to the infant. At home, later, when production is abundant and technique may be less stringent, discarding 2 to 3 mL might be appropriate. This will allow a clean collection without washing the breast before pumping, which is associated with sore nipples in some women.

COLLECTION AND STORAGE CONTAINERS Colostrum was reported by Goldblum et al30 to impart greater stability to its components than did mature milk. None of the cellular or humoral immunologic factors investigated was diminished when

Yes

colostrum was stored at 4° C (39° F) for 24 hours in any of the containers (Table 21-1). The effect of the container on the stability of the constituents of milk was investigated by Garza et al.27 Pyrex and polypropylene containers were found not to interact with water-soluble and fat-soluble nutrients such as vitamin A, zinc, iron, copper, sodium, and protein nitrogen. Polyethylene bags were found to spill easily, to be harder for mothers to fill without contamination, and to be difficult to handle in the nursery. The containers also leaked and punctured easily, resulting in 60% lower secretory immunoglobulin A (IgA) levels because of adherence to the material. It appears that rigid polypropylene plastic containers may have a significant advantage in maintaining the stability of all constituents in human milk collections and may be easier and safer to handle. Paxson and Cress59 have reported a significant difference in the survival of leukocytes when milk is collected and stored in plastic containers rather than glass because the cells apparently stick to the glass. The phagocytosis of these cells, however, is not affected by the container. The researchers further demonstrated that varying the osmolarity or protein concentration does not alter the number or the phagocytosis of the cells. Because they believe the main reason for feeding preterm infants human milk is for the protection against infection, they suggest nasogastric feedings instead of nasojejunal feeding (to maintain pH in the acid range; in the small bowel, the pH is 6.5 to 8). The milk is collected in sterile plastic containers and maintained in the refrigerator until it is fed to the infant, avoiding heating, freezing, and alkaline solutions (see Table 21-1).

STORAGE AND TESTING OF MILK SAMPLES Fresh refrigerated unsterilized mother’s milk can be used for 48 hours following collection. If the milk is to be used fresh chilled, it should be refrigerated

The Collection and Storage of Human Milk and Human Milk Banking     T A B L E 2 1 - 2 Positive Bacterial Cultures from

41 Breastfeeding Mothers

Bacterial Groups*

No. (%) of Cultures Skin and Nipple Milk

Staphylococcus epidermidis

77 (94)

29 (71)

Streptococcus

17 (21)

6 (15)

Propionibacterium

10 (12)

5 (12)

Staphylococcus aureus

4 (5)

Pseudomonas aeruginosa

2 (2)

— —

Klebsiella pneumoniae

1 (1)

2 (5)

*Two or more organisms were identified in several skin, nipple, and milk cultures. T A B L E 2 1 - 3 Positive Rate of Breast Milk Cultures

Over Time Cultures

0

Positive Negative Total

33 8 41

Time of Refrigeration (hr) 48 120 27 14 41

11 30 41

From Sosa R, Barness L: Bacterial growth in refrigerated human milk, Am J Dis Child 141:111, 1987.

at home and brought in promptly for use within 48 hours. If it is to be frozen, this should be done immediately at −18° C (0° F) (standard home freezer) or in the top of a refrigerator freezer. The milk stored in the latter should be deep frozen within 24 hours if it is to be stored any length of time. The milk kept at −18° C can be kept for 6 months. Freezing and thawing, which can occur in a freezer that is part of a refrigerator, significantly alters the energy content and predispose to separation of the fat layer. Therefore milk stored in the freezer compartment of a refrigerator-freezer with separate doors should be placed well back in the freezer (not in door) and stored only 1 month. In the hospital or at a bank, all samples should be labeled with name of donor, date, and time. Milk is stored in the freezer in such a way that the oldest milk is used first, and all milk of a single donor is kept together and used only for the infant of that mother. When a hospitalized mother is contributing fresh milk to her own infant, it is usually not cultured. Pumping is usually done with the help of the nursing staff, and colostrum seems to be more resistant to contamination.14 Once a mother has been discharged home and she is producing mature milk, however, random sample culturing of her milk samples every week or two is a mechanism for checking milk-expression technique.19 NICUs have found that random testing improves technique in general. Because using the fresh milk from the mother to feed a premature infant is becoming commonplace,

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it is important to be aware of the bacteria cultured from fresh samples during refrigeration.5 Samples pumped by hand pump and manually expressed were cultured at zero time and after 48 and 120 hours of refrigeration by Sosa and Barness.69 Although eight of 41 samples had no growth, the others had the same bacteria on skin and nipple as appeared in the milk (Table 21-2). Concentration was low and decreased over time (Table 21-3), which is attributed to the bacterial inhibitory factors present in milk and suggests that refrigeration of carefully collected breast milk is a safe method for more than 48 hours. Guidelines for collection and use of mother’s own milk appear in Appendix H and Appendix P, Protocol #8.

STANDARDS FOR RAW DONOR MILK The FDA and the CDC do not recommend use of donor milk without heat treatment.77 Rare children, however, require fresh donor milk and cannot tolerate the heat-treated product. For these infants, the guidelines should be carefully followed. These special donors must be meticulously screened and monitored for high-risk behaviors. Parents of the infant recipient should sign an informed consent. All raw donor milk should be screened microbiologically before use. No generally accepted microbiologic criteria exist for such milk except that no potential pathogens should be present.10 Such pathogens include Staphylococcus aureus, β-hemolytic streptococci, Pseudomonas species, Proteus species, and Streptococcus faecalis. Some milk that cannot be fed raw can be pasteurized.78 Other guidelines include the following77: 1. Each pool of milk shall have a sterile sample taken for bacteriologic screening. 2. Only milk from a specially certified donor with less than 104 colony-forming units per milliliter (CFU/mL) of normal skin flora (e.g., coagulase negative staphylococcus, diphtheroids, Staphylococcus epidermis, or Streptococcus viridans) will be acceptable to dispense raw. The presence of any pathogen is unacceptable.

STANDARDS FOR PASTEURIZATION OF DONOR MILK Milk suitable for pasteurization should meet the following minimum standards78: 1. A total aerobic count that does not exceed 1 × 106 CFU/mL 2. S. aureus that does not exceed 1 × 103 CFU/mL; risk for feeding heat-treated enterotoxins when S. aureus exceeds 1 × 106 CFU/mL

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   Breastfeeding: A Guide for the Medical Profession

3. Presence of organisms defined as being of fecal origin not exceeding 1 × 104 CFU/mL 4. Presence of organisms not part of normal flora not exceeding 1 × 107 CFU/mL 5. Presence of no unusual organisms such as Pseudomonas aeruginosa, spore-bearing aerobes, or spore-bearing anaerobes

HEAT TREATMENT When human milk was pasteurized at 73° C (163° F) for 30 minutes, minimal immunoglobulins A and G (IgA, IgG), lactoferrin, lysozyme, and C3 complement remained. When the temperature was kept at 62.5° C (144.5° F) for 30 minutes, there was a loss of 23.7% of the lysozyme, 56.8% of the lactoferrin, and 34% of the IgG, but no loss of IgA, according to work done by Evans et al.21 Similar studies of heat treatments of graded severity were carried out by Ford et al.22 The findings were similar. Pasteurization at 62° C for 30 minutes (Holder method) reduced IgA by 20% and destroyed IgM and lactoferrin. Lysozyme was stable at 62.5° C but destroyed at 100° C, as was lactoperoxidase and the ability to bind folic acid against bacterial uptake.55 Growth of Escherichia coli increased when introduced into heated milk. Vitamin B12–binding capacity declined progressively with increasing temperature of the heat treatment.25 The effects of the Holder method on antiinfective agents were reviewed by Orloff et al,57 who concluded that high temperatures destroyed much of the bacteriostatic effect of human milk, thus decreasing the benefit to infants. These data raise the question of whether any heat treatment might not increase the risk for enteric infection in infants. Ford et al22 suggest that for batch processing, however, 62.5° C for 30 minutes may be the method of choice. The alterations of the lymphocyte and antibody content after processing were of concern. Significant changes with heat, including a decrease in total lymphocyte count and in specific antibody titer to E. coli are noted. Welsh and May81 discuss antiinfective properties of breast milk and provide two tables to demonstrate the stability of the antibacterial and antiviral properties of human milk. Low-temperature short-time pasteurization of human milk was reported by Wills et al84 using the Oxford human milk pasteurizer. Heating at 56.0° C for 15 minutes destroyed more than 99% of the inoculated organisms, which included E. coli, S. aureus, and group B β-hemolytic streptococci. The remaining activity of antimicrobial proteins after different time/temperature treatments is shown in Tables 21-4 and 21-5.

High-temperature short-time (HTST) treatment (72° C or 87° C up to 15 seconds) of human milk inoculated with endogenous bacteria and CMV rendered the milk bacteria free in 5 seconds and CMV-free in 15 seconds.29 Folic acid and vitamins B1, B2, B6, and C were not affected. Bile salt-stimulated lipase was inactivated by these conditions. Lactoferrin and IgA and secretory IgA antibody activity were stable at 72° C (162° F) for 15 seconds. Lysozyme concentration and enzymatic activity were increased, ­suggesting that lysozyme may be sequestered in the milk. The HTST technique was thoroughly studied by Terpstra et al74 to determine its effect on the bioburden of human milk. HTST was effective in eliminating all bacteria and lipidenveloped viruses as well as at least one nonlipid envelope virus from spiked samples. Furthermore, HTST preserved IgA and other proteins T A B L E 2 1 - 4 Comparison of Effects of

Temperature on Vitamins, Fatty Acids, and Cultures Microbial Analysis of Frozen and Thawed Breast Milk

Vitamin Analysis of Frozen and Thawed Breast Milk Vitamin A Vitamin C (IE/100 (mg/100 mL) mL)

Conditions

CFU/mL

8° C for 4 hours 8° C for 24 hours 23° C for 4 hours 23° C for 8 hours Repeated ­freeze-thaw Control

8.6 × 101 3.5 × 101 1.0 × 102 3.7 × 102 1.1 × 102

100 100 105 100 100

2.2 1.7 1.6 1.0 1.5

1.1 × 102

100

2.2

CFU, Colony-forming units.

T A B L E 2 1 - 5 Ranking of Samples Fatty Acid C6 C8 Cl0 C12 C14 C16:1 C16 C18:2 C18:1

F F F C C C C C C

Highest Peaks C D C D D C D F D F F B D F B F F B

B B E B B D B D D

Lowest Peaks E A E A B A E A E A A E A E A E A E

Modified from Tables 2, 3, 4 from Rechtman DJ, Lee ML, Berg H: Effect of environmental conditions on unpasteurized donor human milk, Breastfeed Med 1:24, 2006 A = 8° C for 4 hours; B = 8° C for 24 hours; C = 23° C for 4 hours; D = 23° C for 8 hours; E = represented freezethaw; F = control.

The Collection and Storage of Human Milk and Human Milk Banking    

699

concentrations during pasteurization, at temperatures commonly used by donor milk banks, slightly decreased TGF-α concentrations but not milk TGF-β2, with little difference when temperature was increased to 71° C.50

important to immune defences. The authors suggest HTST is the method of choice for milk banks74 (Tables 21-6 and 21-7). The effect of temperature on transforming growth factor (TGF)-α and TGF-β2 human milk

T A B L E 2 1 - 6 Effect of High-Temperature Short-Time (HTST) Pasteurization on Selected Vitamins

in Human Milk Time (s) 0

Vitamin B1 (μg/mL) 72° C 87° C Vitamin B2 (μg/mL) 72° C 87° C Vitamin B6 (μg/mL) 72° C 87° C Folic acid (μg/mL) 72°C 87°C Vitamin C (μg/mL) 72°C 87°C

1

X ± SD

n

0.104 ± 0.013

9

0.084 ± 0.011* 0.724 ± 0.132

3 9

0.237 ± 0.081

0.106 ± 0.020

9.2 ± 2.4

X ± SD

3

15

n

X ± SD

n

X ± SD

n

0.098 ± 0.005

3

0.091 ± 0.008 0.095 ± 0.027

3 3

0.088 ± 0.009 ND

3

0.75 ± 0.08 0.66 ± 0.13†

3 3

0.70 ± 0.09 0.72 ± 0.22

3 3

0.56 ± 0.07 ND

3 3

0.27 ± 0.05 0.25 ± 0.07

3 3

0.26 ± 0.025 0.26 ± 0.02

3 3

0.22 ± 0.012 ND

3

0.089 ± 0.005‡ 0.088 ± 0.008

3* 3

0.065 ± 0.018 0.080 ± 0.023

3 3

0.101 ± 0.012 ND

3

3 3

21.5 ± 3.0* 22.5 ± 13.3

3 3

8.7 ± 1.7 ND

3

9

9

9 11.2 ± 1.2 16.0 ± 4.9*

From Goldblum RM, Dill CW, Albrecht TB et al: Rapid high-temperature treatment of human milk, J Pediatr 104:380, 1984. *p <0.07. †p <0.001. ‡p <0.04. T A B L E 2 1 - 7 Effect of High-Temperature Short-Time (HTST) Pasteurization on Immunologic Proteins

in Human Milk Time (s) 0

Lactoferrin (mg/mL) 72° C 87° C Lysozyme (μg/mL) 72° C 87° C Total IgA (mg/mL) 72° C 87° C sIgA Ab (reciprocal titer) 72° C 87° C

1

X ± SD

n

0.67 ± 0.10

8

15.0 ± 8.7

0.37 ± 0.08

10.0 ± 4.8

3

15 n

X ± SD

n

0.58 ± 0.2 0.50 ± 0.2

3 3

0.83 ± 0.05 0.47 ± 0.17

3 2

2 3

78.0 ± 16.0 59.0 ± 9.0

3† 3†

59.0 ± 7.0* 36.0 ± 7.7

3 2

0.37 ± 0.07 0.06 ± 0.04*

2 3

0.25 ± 0.06 0.04 ± 0.02

3 3†

0.3 ± 0.04 0.05 ± 0.03

3 2

10.2 ± 12.4 <1

2 3

10.6 ± 4.8 <1

2 2

15.0 ± 3.5 <1

3 2

X ± SD

n

0.95 ± 0.21 0.50 ± 0.02

2 3

86.0 ± 3.5* 86.0 ± 9.1*

X ± SD

8

8

7

From Goldblum RM, Dill CW, Albrecht TB, et al: Rapid high-temperature treatment of human milk, J Pediatr 104:380, 1984. n, Number of experiments; sIgA, secretory immunoglobulin A; SD, standard deviation. *p <0.01. †p <0.05.

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   Breastfeeding: A Guide for the Medical Profession

T A B L E 2 1 - 8 Diameter of Growth Inhibition Zone (mm) as Affected by Human Milk Fortifier (Bovine

Derived) and Human Milk—Derived Fortifier (Prolacta) Number of Replicates

E. sakazakii

E. coli

C. difficile

Shigella

29 30 29

23.6 ± 0.8 0.9 ± 4.5* 2.3 ± 0.7

22.2 ± 4.5 2.4 ± 6.9* 23.3 ± 0.7

22.9 ± 0.6 2.4 ± 6.9* 22.7 ± 0.5

22.8 ± 0.6 1.6 ± 5.9* 22.9 ± 0.5

Human milk (HM) HM + HM fortifier, bovine HM and Prolact + 4

*p <0.001 compared with HM or HM and Prolact + 4; p = NS HM compared with HM and Prolact + 4.

PASTEURIZATION Recommended pasteurization of human milk for banks follows these steps77: 1. All containers shall be tightly closed with new caps to prevent contamination of milk during heat treatment. 2. Heat processing a. Aliquots of milk shall be processed by completely submerging the containers in a wellagitated or shaking water bath preheated to a minimum of 63° C. b. A control bottle containing the same amount of milk or water as the most filled container of milk in the batch shall be fitted with a calibrated thermometer to register milk temperature during heat processing. The control bottle should follow the same process as the rest of the batch at all times. c. The thermometer shall be positioned such that approximately 25% of the milk volume is below the measuring point of the thermometer. d. The monitored aliquot shall be placed into the water bath after all other aliquots and shall be positioned centrally among the treated aliquots. e. After the temperature of the monitored control bottle has reached a minimum of 62.5° C, the heat treatment shall continue for 30 minutes. Milk shall not reach a core temperature higher than 63° C.

VIRUSES IN HUMAN MILK The dilemma of CMV is a significant one because the virus does pass into the milk. In a study of postpartum women, CMV was recovered from the genital tract in 10%, from the urine in 7%, from the saliva in 2%, and from the breast milk in 30%. CMV does persist after storage at 4° and −20° C (39° and −4° F) in some specimens.71 It is destroyed at 62.5° C after 30 minutes.16 Donor milk should be accepted only from CMV-negative mothers. Mothers who are seropositive may be

permitted to provide for their own infants because they continue to provide the antibody protection as well. Hepatitis virus also passes into milk, and donors should therefore be screened and be seronegative. The question of having seropositive women feed their own infants is discussed in Chapter 17. The acquired immunodeficiency syndrome (AIDS) virus has been identified in human milk.75,85 Most banks require that donors be HIV negative, but because seropositivity may take months to develop, some mechanism for excluding high-risk donors should be in place. On the other hand, some think that donors should not be screened. Holding all milk samples for several months may not be practical, and pasteurizing all milk may decrease the value of the nutrient. Some AIDS experts are concerned that the threat may seriously alter the future of milk banks.45 It has been demonstrated that heat treatment kills the virus when milk is inoculated experimentally.17 The virus associated with HIV and human T-cell leukemia virus (HTLV) were incubated at temperatures from 37° to 60° C, and the virus titer was determined over time by a microculture infectivity assay. It required 32 minutes at 60° C to reduce the virus titer.48 Using the HMBANA standard of 62.5° C for 30 minutes totally destroyed the viruses. No virus could be recovered after the process even with repeated subculturing. Human milk contains one or more components that inactivate HIV-1 but that are not toxic for the cells in which the virus replicates.57 These components are under study and are probably lipids (Table 21-8).

Lyophilization and Freezing The impact of lyophilization was similar to that of heating, showing a decrease in total lymphocyte count and in immunoglobulin concentration and specific antibody titer to E. coli. (Lyophilization is the creation of a stable preparation of a biologic substance by rapid freezing and dehydration of the frozen product under high-vacuum freeze drying.) This technique is being utilized to store the human milk fortifier produced by Prolacta Biologics ­(Monrovia, CA).

The Collection and Storage of Human Milk and Human Milk Banking    

701

T A B L E 2 1 - 9 Effect of Deep Freezing (3 mo) at −20° C and Lyophilization of Human Milk Proteins

(mg/dL milk) Deep-Frozen Milk

α1-Antitrypsin (16 samples) IgA (8 samples) IgG (16 samples) Lactoferrin (11 samples) Lysozymes (11 samples) C3 (16 samples)

Raw Milk (Mean ± SE)

Mean ± SE

Mean as % Raw

2.38 ± 0.3 9.55 ± 0.84 0.42 ± 0.05 332 ± 71.7 5.1 ± 1.26 1.35 ± 0.13

1.98 ± 0.2 9.25 ± 0.83 0.42 ± 0.04 338 ± 57.4 4.6 ± 0.67 1.26 ± 0.11

83.2 96.9 100 102 90.2 93.3

Lyophilized Milk p

Mean ± SE

Mean as % Raw

<0.05 >0.1 >0.1 >0.1 >0.1 >0.1

2.22 ± 0.3 9.33 ± 0.74 0.33 ± 0.04 363 ± 79 4.8 ± 1.19 1.27 ± 0.13

93.3 97.7 78.6 109.3 94.1 94.1

p >0.1 >0.1 <0.05 >0.1 >0.1 >0.1

From Evans TJ, Ryley HC, Neale LM, et al: Effect of storage and heat on antimicrobial proteins in human milk, Arch Dis Child 53:239, 1978.

90

HM + HMF

80

×107 CFU/mL

70 HM+ P+4

60 50 40

HM HM+HMF

30 20

HM

HM+ P+4

HM+HMF HM+HMF HM

HM+ P+4

HM+ P+4

HM

10 0 E. sakazakii

E. coli

C. difficile

Shigella

Figure 21-5.  Bacterial growth at 3.5 hours.

Freezing specimens up to 4 weeks showed no change in IgA or E. coli antibody titer, although the lymphocyte count was decreased. The technique involved freezing to −23° C (−9° F) and thawing at 1, 2, 3, and 4 weeks. Although cells were present after freezing, they showed no viability when tested with the trypan blue stain exclusion method. The storage of human milk at 4° C (39° F) for 48 hours caused a decrease in the concentration of milk macrophages and neutrophils but not of the lymphocytes, which also maintained their activity, according to Pittard and Bill.60 The loss of cells may be desirable if the graft-versus-host reaction in a premature infant who is possibly immunodeficient is of concern. Evans et al21 reported their results with 3-month storage at −20° C and of freeze drying and reconstitution (lyophilization). They found no significant change in lactoferrin, lysozyme, IgA, IgG, and C3 after 3-month freezing but a small loss of IgG after lyophilization (Table 21-9).

Exposure to Environmental Conditions Concern always exists when milk has been left out of the refrigerator or thawed and not used, and it has resulted in discarding many ounces of valuable milk. Rechtman et al63 tested three scenarios in the laboratory and the effect on the bioburden and nutritional content. Microbial analysis showed that breast milk that had been frozen at −20° C and then thawed did not develop microbial load approaching 104 CFU/mL, which is the acceptable limit for raw unpasteurized milk. Similar results were found when the milk was stored at 23°C (room temperature) for 8 hours or had undergone repeated freeze-thaw cycles (see Table 21-4 and Figure 21-5). The authors63 point out that human milk is robust. Milk left unrefrigerated for less than 8 hours or in a refrigerator for a day maintains its nutrient value. Analysis of vitamin content and free fatty acids showed only slight changes. Unpasteurized milk that has been accidently thawed and left

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   Breastfeeding: A Guide for the Medical Profession

T A B L E 2 1 - 1 0 Storage of Human Milk and Protein

T A B L E 2 1 - 1 1 Thermal Destruction of Milk

N Concentrations (mg N/dL)

Components (Follows First-Order Reaction Kinetics)

Storage Temperature Storage Time (hr) 4 24 48

37° C 187 ± 8* 183 ± 7*,† 189 ± 8*

4° C 181 ± 7* 178 ± 5*,† 178 ± 5*

D Value*at 60° C (s)

−72° C 186 ± 8†

From Garza C, Johnson CA, Harrist R, et al: Effects of methods of collection and storage on nutrients in human milk, Early Hum Dev 6:295, 1982. Mean ± 1 SEM (n = 11). *Effects from temperature significant when samples stored at 37° C and 4° C are compared (p <0.05; F = 9.3). †Comparison of storage temperature effects on samples stored only for 24 hr not significant (p >0.05; F = 1.4).

in the refrigerator remains safe and can be refrozen. Fresh milk can be safely added to frozen milk by the mother at home.

NUTRITIONAL CONSEQUENCES Initially the focus in processing human milk was the effect on its unique antiinfective properties,30, 36 but attention has been given to the nutritional consequences as well.66 Storage for 24 hours did not affect vitamin A, zinc, iron, copper, sodium, or protein nitrogen concentrations at 37° C.73,83 Ascorbic acid levels decreased greatly when stored at 37° and 4° C at 24 and 48 hours. (They remained stable for 4 hours.) Other investigators have found that ascorbic acid levels drop 40% with heating.27,73 Levels of unsaturated fatty acids apparently are also affected by heating and cold storage, but the data need clarification.53 It is anticipated that ­heating or freezing and thawing are capable of damaging membranes surrounding milk fat globules.66 The fat globule could then undergo fragmentation and allow greater access of milk lipases to triglycerides. The percentages of polyunsaturated fatty acids, linoleic (C18:2) and linolenate (C18:3), decreased after both heating and freezing, but monounsaturates and saturated fatty acids were unaffected.80 When milk is stored at −11° C for 48 hours, release of fatty acids progresses over time with an increase in the proportion of free C18:2, C20:4, and other long-chain polyenic acids. No measurable lipolysis occurred when milk was stored at −70° C. The higher the temperature and the longer the time, the greater is the accumulation of free fatty acids.42 Other investigators have confirmed this, concluding the lipoprotein lipase and bile salt–stimulated lipase remain fully active at −20° C but not −70° C with or without presence of serum. Berkow et al6 therefore recommend that milk be stored at −70° C. Other enzymes were not affected by freezing and storing

IgA Lactoferrin Thiamine Folic acid

104

4.9 × 2.4 × 103 7.7 × 105 1.9 × 104

Z Value† 5.5° C 4.7° C 28.4° C 6.4° C

Modified from Morgan JN, Toledo RT, Eitenmiller RR, et al: Thermal destruction of immunoglobulin A, lactoferrin, thiamin, and folic acid in human milk, J Food Sci 51:348, 1986. *90% degradation at 60° C in seconds. †Temperature change to alter degradation rate by a factor of 10.

except lactoperoxidase, which lost activity (Tables 21-10 and 21-11). Because the nourishment of low-birth-weight (LBW) infants has been the purpose of many milk banks, the ability of preterm infants to utilize treated bank milk is relative. Pasteurization at 62.5° C for 30 minutes was reported not to influence nitrogen absorption or retention in LBW infants.66 When raw, pasteurized, and boiled human milks were fed to very LBW (VLBW) (less than 1.3 kg) preterm infants in three separate consecutive weeks, fat absorption was reduced by one third in the heattreated group. There was a reduction in the amount of nitrogen retained in the heat-treated group as well, although the absorption was unaffected. The absorption and retention of calcium, phosphorus, and sodium were unaffected by heating or freezing. The mean weight gain was greater by one third when the infants were fed raw human milk.83 Pasteurization decreased vitamin B12 by approximately 50% and folate-binding capacity by 10%51 (see Table 21-11). Sterilization (100° C for 20 minutes), on the other hand, had similar effects on vitamin B12 binding and completely inactivated folate binding.73 Vitamins A, D, E, B2, and B6, choline, niacin, and pantothenic acid were barely affected by pasteurization, whereas thiamine was reduced up to 25%, biotin up to 10%, and vitamin C up to 35%.79 Refrigeration at 4° to 6° C for 72 hours allows little bacterial growth and causes no change in nutrients or infection-protective properties. Freezing does have some effect on both, and the milk can be kept for months, whereas heating has significant effect, and the milk still requires freezing for storage. Experience feeding donated raw milk to newborns has shown no ill effects if carefully monitored, according to Björksten et al.7 Quick freezing and frozen storage do not significantly affect levels of biotin, niacin, folic acid, vitamin E, and the fatsoluble vitamins. Photooxidation and absorption by

The Collection and Storage of Human Milk and Human Milk Banking    

the container or tubing are always a consideration. Vitamin C is reduced by both these processes.26 The effect of heating and freezing on the various constituents of human milk has been studied by a number of investigators. Their data should be considered before deciding how to store milk for special purposes.67 Routine analysis of the nutrient value of milk samples has been considered not practical, so gross screening by creamatocrit has been done by some banks and nurseries. A method of infrared analysis using a Milko-Scan 104 Infrared Analyzer (A/S Foss Electric, Hillerod, Denmark) has been described by Michaelsen et al.52 It is simpler and more rapid than previous methods. These investigators in Denmark found a linear correlation between infrared results and the standard reference methods of Kjeldahl for nitrogen (protein), Roese Gottlieb for fat, and bomb calorimetry for energy. These techniques were used on all incoming milk and on the outgoing pooled milk. All the milk from the same mother was thawed, pooled, and stirred vigorously on arrival at the bank. A 10-mL sample was taken and stored at −5° C until analysis. Samples were collected every 2 weeks and were analyzed up to 2 to 3 weeks after expression. For the 2554 collections of milk contributed by 224 women, the mean protein content was 9 g/L and the fat was 39 g/L. The greater the body mass index of the mother, the greater was the protein and fat content. The authors suggest that by selecting the milk with the highest protein content (12 g/L), a highprotein milk can be created with a higher energy content (725 kcal/L) for use in VLBW infants. Furthermore they recommend pooling milk from up to five mothers to decrease the variability in nutrient levels.52 The product available from Prolacta Bioscience is labeled by both caloric content and protein content. Neo20 contains 20 calories per ounce and 1.2 g of protein per 100 mL. Prolact20 also contains 20 cal/oz and 1.2 g protein/100 mL as well as essential minerals. They have also produced human milk fortifier (Prolacta+H2MF) that contains only human milk. Ross and Mead Johnson products called human milk fortifier (a misnomer) are made solely of bovine products. Nutritional constituents are provided on the label. This allows fortification of mother’s milk or donor milk to meet the growth needs of VLBW infants using a human milk product. At the Hvidovre Milk Bank in Copenhagen, monitoring of the macronutrients in donor milk is part of the bank’s quality assurance standards, and donors are discontinued if their milk protein content becomes less than 8 g/L. Their milk was viewed adequate for their own baby but not for high-risk infants, especially premature infants.

703

CREAMATOCRIT Testing milk for protein, fat, and carbohydrate has not been done by most banks. However Lucas et al46 have suggested a quick method of analysis. It involves standard hematocrit microtubes and a centrifuge. The percentage of cream, or “creamatocrit,” is read from the capillary tube. Fat and energy content have a linear relationship, as follows: Fat (g/L) = (Creamatocrit [%] - 0.59)/0.146 kcal/L = 290 + (66.8 ¥ Creamatocrit [%]) Accuracy is within 10%. The Research Institute for Health Sciences provides the following formula for calculating the fat and energy content of milk using the measurement of the creamatocrit (%)62: Fat (g/L) = (6.24 ¥ Creamatocrit [%]) - 3.08 [r = 0.98, 95% confidence limit = ± 4.39 g/L] kcal/dL = (5.57 ¥ Creamatocrit [%]) + 45.13 [r = 0.92, 95% confidence limit = ± 12.61 kcal/dL] Studies done comparing energy value calculated by creamatocrit with energy value from percentage of carbon, as measured by Manchester bomb calorimeter using pooled pasteurized milk samples, were somewhat inaccurate compared with data obtained by creamatocrit on fresh or fresh-frozen samples.68 The methodology was validated with further analysis by Lemons et al,44 who repeated the studies and confirmed actual measurements of total fat and caloric content. Because the protein and lactose content remains relatively constant over time, the variation in fat content is the primary constituent affecting caloric value of the milk. Neither freezing for up to 2 months nor pasteurization affected the creamatocrit. There was no evidence of fat globule degradation during storage that affected the test. Special cautions while performing this simple test should include the following: • Use a representative, well-mixed sample. • Complete a sample of pumping from at least one breast; do not take just a spot sample. • Use a well-mixed 24-hour sample. • Use a tube at least three fourths filled; seal one end. • Centrifuge for 15 minutes in standard table-top centrifuge. A new technology, the Creamatocrit Plus, has been reported by Meier et al.51 The device is a special centrifuge to spin and calculate the creamatocrit. It automatically calculates the fat and calorie

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   Breastfeeding: A Guide for the Medical Profession

content. This device has been in use in a research and in NICUs. Its accuracy was compared with the standard laboratory centrifuge with a hematocrit reader and the standard laboratory centrifuge with digital calipers utilizing 36 milk specimens from 12 women. The results varied less than 1% from each other. Laboratory measurements for lipids and calories were confirmatory.51

ULTRASONIC HOMOGENIZATION Pooling specimens of human milk may not result in a milk of uniform fat content after storage. The separation of fat during processing, storage, and administration by continuous nasogastric infusion, whether by gravity flow or continuous mechanical pump, results in significant loss of fat and variation in the milk received (47.4% of fat with slow infusion and 16.8% with fast infusion). Homogenization by ultrasonic treatment was studied by Martinez et al,47 who found that changes in fat concentration during infusion and loss of fat during administration, caused by the fat sticking to the container and tubes, were eliminated. Furthermore, the fat-soluble vitamins are preserved. Because 31% of iron, 15% of copper, 12% of zinc, 10% of calcium, and 2% of magnesium sulfate are in the fat fraction of both human and cow milk, preserving the fat is essential to maximizing nutrient intake from human milk, especially in compromised infants. Tube feedings have been noted to reduce vitamins B2, B6, A, and C in human milk. Ultrasonic homogenization was accomplished in this study by subjecting the milk to treatment in a Tekmar Sonic Disruptor TSD-P 250 (Tekmar Co., Cincinnati, OH). The homogenization time (2, 4, or 8 minutes) is a function of the volume of milk

and intensity of vibration. The procedure should be done with milk in an ice bath. It has not been tested to determine the amount of lipase, if any, that survives pasteurization and would be capable of digesting the fat after homogenizing.

MICROWAVE EFFECTS Milk should be thawed in the refrigerator, and each bottle should be used completely within 24 hours. Defrosting in the microwave oven may lead to separation of layers, and microwaves decrease vitamin C content. The greatest danger of microwaving is that the milk heats and the container does not, so an infant could be burned or the milk significantly overheated. The effects of microwave radiation on human milk have been much debated. The only nutritional effect identified has been the lowering of the vitamin C level. Lysozyme activity, total IgA, and specific IgA to E. coli serotypes 01, 04, and 06 were tested in 22 freshly frozen milk samples before and after heating for 30 seconds at lowpower and high-power settings of the microwave oven.61 Additional samples were tested at microwave low (20° to 25° C), medium (60° to 70° C), and high (98° C or higher) powers before the addition of E. coli suspension. Microwaving at high temperatures (72° to 98° C) greatly decreased all the tested antiinfective factors (Table 21-12). E. coli growth at 98° C or higher was 18 times that of untreated thawed human milk. Low temperatures did not affect total IgA or specifics IgA to E. coli serotypes 01 and 04 or specifics IgA to E. coli serotype 06. At only 20° to 25° C, the growth of E. coli was five times that of the untreated thawed milk.61

T A B L E 2 1 - 1 2 Impact of Microwaving on Antiinfective Factors in Human Milk* Lysozyme activity (μg/mL) Total IgA (mg/dL) Antigen-specific antigen to E. coli serotype 01 04 06

No.

Control

22

23.7 ± 4.0

19.2 ± 3.4

0.9 ± 0.72

73.3 ± 16.1

p <0.005 48.9 ± 15.8 NS†

p <0.0005 1.55 ± 1.54

91 ± 9.2‡ 90.3 ± 6.5‡ 79.8 ± 5.7‡

24.9 ± 10.0‡ 12.3 ± 3.7‡ 17.1 ± 3.6‡

p <0.005

p <0.0005

22

22 22 22

100% 100% 100%

Low Microwave

High Microwave

p <0.0005

From Quan R, Yang C, Rubinstein S, et al: Effects of microwave radiation on anti-infective factors in human milk, Pediatrics 89:667, 1992. IgA, Immunoglobulin A. *Results are mean ± SEM. All significant differences were also confirmed by the Fisher’s protected least significant ­difference test. †Not significant. ‡Percentage of control.

The Collection and Storage of Human Milk and Human Milk Banking    

In the experimental laboratories, the microwaves are carefully controlled. In the home, they vary tremendously. Ovesen et al58 admitted that the temperature had to stay under 60° C (140° F). Above that, antibodies were decreased and at 77° C (170° F), they were totally destroyed. Vitamins B1 and E were apparently stable, but they did not test for vitamin C. It is very clear that IgA, secretory IgA, and lysozyme were affected by microwaving at 14° C to 25° C (i.e., lower temperatures). Time is important because even at 30% power the temperature will increase over time. Microwaving clearly interferes with the antiinfective properties of human milk: The higher the temperature, the greater the effect (Table 21-13) and is not appropriate for heating human milk.

SPECIALTY MILKS New technologies offer the potential for providing specialty milks. Simple homogenization would preserve the fat, as noted; however, because of the presence of active enzymes, once the fat membrane is ruptured by homogenization, the milk should be used promptly to prevent excessive fat breakdown. Lyophilization or freeze drying is an opportunity to concentrate the nutrients without increasing the volume. Adding a freeze-dried aliquot to liquid human milk would be preferable to using the commercial bovine-based products. Such a product is in clinical trial and in use in some nurseries. In Denmark, infrared analysis of milk donations is used to provide high-protein or high-fat pools of milk. In Canada and the United States, some banks identify donors with dairyfree diets for specific infants with bovine protein allergies.1-3

CONTAMINATION WITH COW MILK Donor milk is at risk for being contaminated with cow milk by the donor. The California Mother’s Milk Bank checks its contributions with a simple test directed at precipitating the casein. They mix 1 mL of donor milk with 1 mL of 8 N sulfuric acid and 8 mL of water, and let it sit at room temperature for 5 hours. If cow milk is present, it will ­precipitate.56 Human milk makes a floccular curd. A quicker more accurate method is to check the DNA of the sample to match the donor.

CHANGING FLAVORS OF STORED MILK Women have reported to the lactation study center that their fresh-frozen breast milk smells sour and even rancid and is rejected by their infant. Although a slightly soapy odor had sometimes been noted, it had never been reported to be harmful or to be

705

rejected by the infant. This soapy smell has been attributed to a change in the lipid structure associated with the freeze-thaw effects of the self-defrost cycle in the freezer-refrigerator. The cases reported to the center, however, have suggested true lipid breakdown is associated with the rancid smell. The speculation was that some women have more lipase activity than others, as noted in the study of lipase and hyperbilirubinemia. Some mothers reported that their milk began to smell as soon as it cooled, whether refrigerated or frozen. Others have noted that their stockpile of milk, meticulously stored in anticipation of returning to work, was rancid and rejected by their infants. When these mothers heated their milk to a scald (not boiling) immediately after collection and then quickly cooled and froze it, the effect was not apparent, and their infants accepted the heattreated milk. That process inactivated the lipase and halted the process of fat digestion. On the other hand, scalding rancid milk will not improve the flavor or smell.

FINANCIAL ASPECTS Established milk banks have various financial structures.3 Charges can include fees for equipment rental and for processing milk. Certainly a hospital should recover costs of collecting and processing. Precedent for this has been set in the United States. Because some states have passed legislation mandating the availability of human milk for all babies who need it, reimbursement and funds must be available for its proper handling. All banks have a minimal charge that partially covers the cost of processing, such as labor, equipment, and supplies. As with blood banks, the recipient is not charged for the milk itself. Third-party payers do reimburse for this, and Women, Infants, and Children (WIC) programs also provide this reimbursement in more and more states. T A B L E 2 1 - 1 3 Impact of Microwaving on

Escherichia coli Growth in Human Milk at 31⁄2 Hours* Control Low microwave Medium microwave High microwave

No.

Colony Count

10 10 10 10

8.4 ± 2.7 × 107 43.9 ± 11.4 × 107† 90.1 ± 24.1 × 107‡ 152 ± 43 × 107‡

From Quan R, Yang C, Rubinstein S, et al: Effects of ­microwave radiation on anti-infective factors in human milk, Pediatrics 89:667, 1992. *Results are mean ± SEM. All significant differences were also confirmed by the Fisher’s protected least significant difference test. †p = 0.005 compared with control. ‡p = 0.001 compared with control.

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The recommendations from the State of New York (see Appendix L) suggest that the monitoring of standards of a hospital-based bank be absorbed into existing hospital surveillance. Free-standing banks would be monitored by the state and local health departments. Economic analysis indicates that the primary costs would be administrative overhead costs. The human milk supply is considered a donated product. Also acknowledged are staff costs, minimal equipment costs, and laboratory costs, as well as costs to the state health department to administer the system. Much consideration is being given to limiting banks to hospital settings, where health professionals and equipment are readily available. The average processing fee charged by milk banks in the United States begins over $4.00 per ounce, although it does not totally cover costs.3 No infant is refused access for lack of funds, and milk banks cover their costs by various methods, including donations, subsidies, and grants. With proper physician orders and paperwork, most third-party payers cover the cost of banked human milk. The cost of milk from Prolacta Bioscience is higher, but it only covers costs of operation and preparation. They provide information about the milk (calories, protein, fat, etc.).

Breast-Pumping Equipment Breast pumps have assumed an undeserved prominence in breastfeeding management in the last decade. Stimulated by the need to return to work for some women but also by the promotion by lactation professionals the rise has persisted. Sadly lactation professionals may also sell or rent this equipment, thus setting up an egregious conflict of interest. Not all women need a pump. For thousands of years women breastfed successfully without a pump. For everyday problems like engorgement or a plugged duct, a mother can use her hands. Every mother should be trained how to manually express her breasts before she leaves the hospital. Even before a pump is applied, the breast should be massaged and milk gently expressed. This approach reduces trauma and enhances the let-down reflex. Breast pumps are medical devices. They have multiple roles, from relieving engorgement, stimulating and increasing milk production, collecting milk for a sick infant who cannot nurse, or providing donor milk to a milk bank. The FDA regulates breast pumps. It monitors the performance of medical devices by several pathways, including mandatory reporting programs and a passive surveillance system that receives reports on adverse events and product problems. FDA databases list FDA-cleared breast pumps, characterize

breast pump adverse events, and identify any FDAinitiated or manufacturer pump recalls. The medical device reporting regulation requires reporting of significant medical device-related adverse events by manufacturers, importers, and users. A significant event is device-related deaths, serious injury, and malfunction. All reports are entered into the Manufacturer and User Facility Device Experience database, dating to 1991. Two medical device epidemiologists at the FDA with an independent epidemiologist from the University of Michigan and a nurse consultant at the FDA who reviews postmarket adverse events have reported on the events listed in FDA databases. The FDA recorded 37 reports between 1992 and 2003; 81% were for electric or battery-powered pumps. Tables 21-14 and 21-15 record the pump type and adverse events. Most reports were for device malfunction, which means failure of the device to meet specifications. Table 21-16 is a brief summary of five incidents reported to the FDA. The patient problems were predominantly pain, soreness, discomfort, and tissue damage from the ­electric pump. The most common problems for the manual pump were tissue damage and infection. The authors point out the importance of reporting such events to the FDA so that the problems can be corrected. FDA toll free number is 1-888-463-6332. The website for MedWatch is http://www.fda.gov/ medwatch/index.html. As noted earlier, several types of breast-pumping devices have provoked questions of the sterility of milk collected. Additional issues need to be considered, including efficiency, ease of use, potential for breast trauma, availability, and cost. A good pump should be capable of completely emptying the breast and of stimulating production. It should be clean and easy to keep clean, contamination free, easy to use, and atraumatic.

HAND PUMPS The “bicycle horn” pump has been marketed in drugstores for years without instructions for use or cleaning. At the museum at the Corning Glass Works in Corning, New York, a glass and rubber hand pump made by Davol circa 1830 is on display next to glass baby bottles and pewter nipples. The current model is the same, except the glass has been replaced by plastic. The dangers of this pump are many but can be summarized by saying the milk is contaminated, a spray of milk can go directly into the bulb, the pump requires constant emptying, and it can be quite traumatic to the nipple, areola, and breast and predispose to mastitis.23 Modifications of the bicycle horn pump insert a removable collecting bottle in place of the well. The modification permits feeding the infant

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TABLE 21-14 Patient and Device Problems Reported to the Food and Drug Administration for Electric

and Manual Breast Pumps Problem*

Pump Type, No. (%) Electric/Battery (n = 30) Manual (n = 7)

Patient problem† Report had at least 1 patient problem code Pain, soreness, discomfort Medical care or intervention Tissue damage Erythema, fever, swelling Not able to continue breastfeeding Bruise, thrombus Healing impaired Infection

20 (66.7) 17 (56.7) 6 (20.0) 4 (13.4) 2 (6.7) 2 (6.7) 1 (3.4) 0 (0.0) 0 (0.0)

4 (57.1) 1 (14.3) 1 (14.3) 2 (28.6) 0 (0.0) 0 (0.0) 1 (14.3) 1 (14.3) 2 (28.6)

Device problem‡ Report had at least 1 device problem code Suction high Suction inadequate Device design or structure problem Device motor or pump failure Milk bled back into motor Device fluid leak Device instructions inadequate Device not sterile Device misassembled Tear, rip, or hole in device Device out of box failure

23 (76.7) 4 (13.4) 4 (13.4) 2 (6.7) 2 (6.7) 1 (3.4) 0 (0.0) 1 (3.4) 1 (3.4) 1 (3.4) 1 (3.4) 1 (3.4)

5 (71.4) 1 (14.3) 0 (0.0) 2 (28.6) — — 1 (14.3) 0 (0.0) 0 (0.0) 1 (14.3) 0 (0.0) 0 (0.0)

From Brown L, Bright R, Dwyer D, et al: Breast pump adverse events: reports to the food and drug administration, J Hum Lact 21:169, 2005. *Multiple problems may be coded in each report. Each report does not necessarily have a coded patient or device problem. †Patient problem when specified. For 6 reports, a patient problem was coded as “unknown” or “other.” ‡Device problem when specified. For 14 reports, a device problem was coded with such nonspecific information as “performance,” “malfunction,” “unknown,” or “other.”

directly from the collecting vessel by placing a nipple on it. Milk does not wash back over the breast, and pumping is not interrupted for emptying. The bulb still may harbor bacteria because it is difficult to clean. The limitations of the effect of creating a simple vacuum and applying a simple, rigid, sharpedged flange against the breast are still present. This pump is satisfactory for temporary use, but it takes time to become proficient in its use, and it may never create enough pressure to be effective. Another model (Nurture) with a special flexible silicone funnel overcomes these problems. The cylindric pumps are two all-plastic cylindric tubes that fit inside one another to create a vacuum. A rigid flange to accommodate the nipple and areola is at the top of the inner tube, which also has a gasket for tight fit at the other end. The outer tube collects the milk and is adapted for use as a feeding unit when a nipple is screwed on top. The mother creates the vacuum by pulling the outer tube and creates rhythm by alternately pushing the outer

tube in and out (Figure 21-6). It is simple, easy to clean, and the milk is usable directly from the collecting cylinder with a nipple attached. This pump is excellent in the hands of an experienced, dextrous mother. The product has several manufacturers, and models differ slightly. Some have a choice of flanges. The only precaution is that 220 mm Hg of negative pressure can be produced if the cylinder is drawn at least three quarters of the way out when empty or when there is fluid (pumped milk) in the cylinder. The pressure desired can be achieved by pulling out the cylinder only a fraction. Most cylinder pumps are marked by the manufacturer to indicate degree of a cycle. The Lloyd-B pump has a trigger handle adapted to a flange mechanism that empties into a collection jar the size of a baby-food jar (not a baby bottle). It does have a vacuum relief switch; however, the entire mechanism requires a certain dexterity and a rather large hand to operate. It is portable and also easily cleaned. No parts harbor bacteria.

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T A B L E 2 1 - 1 5 Characteristics of Adverse Events

Reported to the Food and Drug Administration for Electric and Manual Breast Pumps Characteristic Adverse event type Malfunction Injury Other or not ­specified Reporter Health care ­professional* Patient or consumer Other† Not specified Event location Home Hospital Outpatient facility Not specified Patient age (yr) 15-20 21-30 31-40 Not specified

Electric/Battery Pump No. (%)

Manual Pump No. (%)

11 (36.7) 7 (23.3) 12 (40.0)

4 (57.1) 1 (14.3) 2 (28.6)

13 (43.4) 9 (30.0) 2 (6.7) 6 (20.0)

1 (14.3) 2 (28.6) 3 (42.8) 1 (14.3)

14 (46.7) 4 (13.3) 1 (3.4) 11 (36.7)

1 (14.3) 4 (57.2) 0 (0.0) 2 (28.6)

2 (6.7) 9 (30.0) 3 (10.0) 16 (53.3)

0 (0.0) 1 (14.3) 1 (14.3) 5 (71.4)

*Includes one physician, six nurses, three lactation consultants, and four health care professionals not otherwise specified. †Other includes risk manager, biomedical engineer, and caregiver.

ELECTRIC MECHANICAL PUMPS Battery-operated pumps are available, but they have all the disadvantages of most battery-operated devices and in most cases are not sufficiently powerful to stimulate the breast adequately. They are ineffective for women whose infants are not feeding at the breast, such as premature infants or those hospitalized in NICUs. These small hand pumps work for some fully lactating women and those who have no trouble with volume but need a pump that fits in their purse for use while at work or school. Small, purse-size electric pumps may be effective for the fully lactating woman (see Figure 21-4). They have an advantage over a manually powered hand pump in that the electric power frees one hand for the mother to stroke the breast and encourage let-down. If flow is going well, the hand is free to perform other tasks, such as read, hold a telephone, or write, not an insignificant advantage for a busy, working, breastfeeding woman. Most small electric models have a small hole in the flange base that must be closed with a finger to develop the suction, as in many hospital suctioning devices. This also gives the mother control over the pressure. By rhythmically opening and closing

Figure 21-6.  Cylindric pump in use.

the hole with the finger, the operator can simulate milking action that is effective in extracting milk. The manufacturers, unfortunately, do not always point this out. Hand-held mechanical devices may not be enough for a woman trying to build up a supply when the infant cannot stimulate the breast directly. A new mother may become discouraged at the low volume of her production and discontinue the process. Part of the management of a sick infant is to be sure that the mother’s milk production is also progressing. Most hospitals provide a lactation consultant for lactating women with babies in the NICU or have trained the unit’s nursing staff to provide assistance. NICUs in the United States should provide a room with electric pumps for the mothers of infants in the NICU to learn how to pump their milk and breastfeed their infants. This is a key resource for any NICU because appropriate nourishment is key for the survival of infants in NICUs. Full-size electric pumps are the most efficient because the motor applies the mechanical effort. The mother can concentrate on applying the cup to her breast, massaging the breast, and relaxing so that adequate let-down can take place. All electric pumps are not equal, and some guidance is needed to be sure that the mother understands the principles involved. Nursery staff should be familiar with the equipment. The pumps are no challenge to skilled nurses in the NICU, who are adept at handling much more complicated electronic ­equipment. A pump that cycles pressure instead of maintaining constant negative pressure will be less likely to

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T A B L E 2 1 - 1 6 Examples of Medical Device Reports Submitted to the United States Food and Drug

Administration and Retrieved from the Manufacturer and User Facility Device Experience Database Case

Event Reported

1

This was reported for a manual breast pump by a consumer in January 2003. The pump was applied to the engorged breast to relieve pain and pressure. The suction created on the nipple tissue was so great that it pulled a clot to the surface. The action tore approximately one fourth of the nipple off, resulting in bleeding and leaving the breast susceptible to infection. The infection was treated with antibiotics; however, the nipple did not heal for 7 weeks and made successful breastfeeding nearly impossible. This was reported for a manual breast pump by a health professional in January 1999. In late September 1998, in the NICU, a set of premature twins became ill. The organism, Pseudomonas aeruginosa, was isolated as the cause of their illness. Because this organism is easily spread and is life threatening to infants in a NICU, swift action was taken. These infants were placed in isolation, and more than 50 items in the NICU were cultured as the possible source of this organism. All these cultures were negative. The mother of the twins was aware of the seriousness of the situation and the actions we were taking to find the source. She reported that the tubing from her breast pump system always seemed to have liquid in it. She wondered if this could be the source. Immediately, the company (breast pump manufacturer) gave her another kit and sent her complete kit to the laboratory to be tested. The tubing, breast shield, and valve from the kit, in addition to her pumped breast milk, all grew P. aeruginosa. After another course of antibiotics and discontinuation of the previously pumped breast milk, the infection abated. In response to this incident, a committee composed of a neonatologist, infection control director, lactation consultant, and manager met to develop a strategy to prevent any further incidents. This group recommended that the manufacturer make changes to their breast pump system. This was reported by a consumer for an electric breast pump in December 2000. The unit got stuck on the breast, and the suction release did not work. This was reported for an electric breast pump in April 1999. When using this single-breast electric pump, the reporter experienced extreme pain. The suction was so much that even on the lowest setting, it hurt badly. The pump did not get enough milk, resulting in engorgement. This was reported by a lactation consultant for an electric pump in October 1997. The mother had been using the breast pump for 24 to 48 hours when she began experiencing skin breakdown on her nipples. The breakdown resulted in wounds with bleeding, pain, two cracks on her right nipple, and four cracks on her left nipple. The wounds had since scabbed over. The mother sought medical advice from the lactation consultant who advised her to switch to a different barrier on her nipples. The lactation consultant claims this particular breast pump has a history of causing tissue damage. The device squeezes and pulls on the nipples, which leads to tissue damage.

2

3 4

5

NICU, Neonatal intensive care unit.

cause petechiae or internal trauma to the breast. The ultimate effect of pressure also depends on the length of time the pressure is applied. Tissue cannot withstand sustained high pressure. Pressure sustained for 2 seconds or at a rate of 30 pumps per minute is considered maximum time or minimum rate.18 Negative pressures should have a governing mechanism to avoid excessive pressures. Mean sucking pressures of most normal full-term infants range from −50 to −155 mm Hg/in2, with a maximum of −220 mm Hg/in2. Manufacturers recommend about 200 mm Hg/in2 to initiate flow in most women. A careful study by Johnson38 of more than 1000 patients at the University of Texas using a variety of pumps has confirmed some facts about pumps. The amount of negative pressure possible and the control mechanisms were recorded (Tables 21-17 to 21-19). An increasing number of pumps on the market have similar designs, but each has its special nuances. A standard electric pump capable of cycling pressures to 220 mm Hg (2.5 to 8.5 psi/Hg) is usually required to stimulate production de novo,

that is, when an infant is unavailable to suckle directly as a small premature infant on a ventilator in the NICU. Breast pumps have been identified repeatedly as the source of infection.54 Improvement in design with a safety trap between the collecting vessel and the machine to prevent milk getting into the mechanism is important. In addition, all equipment that comes in contact with milk or the breast should be sterilizable or disposable. The well-designed electric pump properly used is the best system for stimulating lactation and increasing volume for hospitalized infants. In the hospital, as with all special equipment, it is advisable to select the best equipment to fill the needs of that hospital and then purchase more of the same model so that staff can learn how to use one model properly and can instruct the patient. Similarly, the equipment should be checked on a routine basis, cleaned, and bacteriologically tested. Accessory equipment (disposable) can be resterilized for the same patient but not for a second patient. Although attention is usually given to the pressure mechanisms, equally important is the cup or

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TABLE 21-17 Electric Pumping Devices Mechanical pump

Advantages

Medela

Comfortable Automatic cycling Adjustable vacuum Double or single pump

Disadvantages

Classic electric breast pump   Heavy duty for hospital use (available to rent)

Lactina Select electric breast pump Light, portable, economical

flange that is applied to the breast. The diameter and depth of the flare are fixed for the hand pumps, but a choice is offered for the standard electric pumps (Figure 21-7). The nipple should have room to be drawn out, and the flange should be adequate to transmit pressure or milking action to the collecting ampullae under the areola. The hand pumps are too small; however, bigger is not always better, and a mother may find that the smaller model of the two offered may be more suited physiologically to her anatomy. This feature does not correlate directly with overall size of the breast. The ideal range is 68- to 82-mm outer diameter and 35- to 40-mm depth of flare (see Figure 21-7).36 Silicone funnels adapt well to all sizes and shapes because of their flexibility. The relative efficacy of four methods of human milk expression was measured by Green et al.32 The

electric pump (Egnell) enabled mothers to pump significantly more milk with higher fat content in the 10-minute time allotted for the study than did the Lloyd-B, the Evenflo hand pump, or manual expression, all three of which were about equal in efficacy. To test the effect on milk ejection, an electric pump was programmed to cycle 45 to 125 times per minute with vacuums between 45 to 273 mm Hg. The time it took for milk to be ejected was determined by ultrasound of the opposite breast measuring the dilation of lactiferous ducts. Ejection occurred between 136 ± 12 to 104 ± 10 seconds. This compares with ejection time when the infant suckles at 56 ± 4 seconds. The vacuum affected the volume of milk but not the time of ejection.40 When this same research group investigated means of assessing milk injection and breast milk

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TABLE 21-18 Hand Pumping Devices Hand pump

Advantages

Disadvantages

Bicycle horn

Inexpensive Portable

Difficult to clean Bulb retains bacteria Works as vacum No instructions Can cause trauma Not appropriate for donor milk Milk washes back over nipple Requires constant emptyimg Not recommented

Evenflo

Inexpensive

Difficult to clean;   Bulb harbors bacteria even when boiled

White River

Pliable flange Can feed baby from collecting container Works well for less experienced mother with good let-down No milk contacts mechanism

flow, they measured milk flow rates while mother pumped milk with an electric pump at different settings. They determined the milk duct diameter by ultrasound in the other breast simultaneously. They reported a direct relationship between increases in duct diameter and increases in milk flow rates.62 To understand the ability of various pumps to stimulate lactation and enhance milk volume in the maintenance of lactation, Zinaman86 and ­Zinaman et al87 studied milk yield, prolactin levels, and oxytocin; 23 women exclusively breastfeeding were randomly assigned to use three different pumping methods serially, which were compared with the suckling effectiveness of their infants. Blood samples were collected every 10 minutes from a previously inserted intravenous line controlled with a heparin

lock. An electric pump (White River Concepts, Marietta, Ga), pulsatile on medium settings of 180 mm Hg and autocycled at 40 pumps per minute, was used with double setup. A manual pump (Medela) was cycled by the user at 40 times per minute; pressures of 220 mm Hg were used for 15 minutes on both breasts simultaneously. The battery-operated pump (Gentle Expressions, Lumiscope, Atlanta, Ga) achieved suction levels of 110 mm Hg and was cycled 6 to 10 times per minute by the subject, individually pumping each side for 15 minutes. Hand expression was performed by the Marmet method. Testing was done for 7 days, at 10 am, at least 21⁄2 hours after the infant’s last feeding. Blood was collected at −15, 0, 10, 20, 30, 40, 50, and 60 minutes. Serum prolactin and plasma oxytocin tests were

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TABLE 21-19 Hand Pumping Devices Hand pump

Advantages

Disadvantages

Cylindric Two all-plastic cylindric tubes fit inside one another to create vacuum; inner tube has flange at top and rubber or nylon gasket

Less expensive than electric Portable Can feed baby from collecting container Easily cleaned and sterilized

Requires some dexterity Works as vacuum with some rhythm Rigid flange Can achieve >220 mm Hg of pressure Must follow intructions

Lloyd Glass flange attached to collecting jar; trigger handle ­mechanism creates vacuum; has vacuum relief switch

Less expensive than electric Portable Can be cleaned No milk contacts mechamism

Handle difficult to sequeeze Hand becomes cramped Awkward Large breast and nipple may hit flange Transfer of milk to feeding unit ­neccessary

performed simultaneously on all samples, which had been previously separated and frozen. Prolactin levels were highest with the pulsatile electric pump compared with those of an infant’s suckling, actually exceeding levels created by infants. The hand pumps were similar to hand expression, with the battery-operated pump achieving the lowest levels (Figures 21-8 and 21-9). No difference was seen in the oxytocin response, although the levels increased before feeding when the baby fed but not when the breast was pumped (Table 21-20). The mean volumes obtained were similar, with the pulsatile electric pump reaching 175 mL in 60 minutes, the manual pump 125 mL in 60 minutes, the battery-operated pump 110 mL in 60 minutes, and hand expression 75 mL in 60 minutes. Marked differences were seen in the pumps’ ability to produce an acute and sustained response, and differences in time were required to achieve the ultimate volume (Figure 21-10). The differences were related to the method of pumping

(i.e., electric, battery operated, manual) and not to comparison of brands. The WIC branch of the Hawaii Department of Health studied whether an electric or a manual pump would increase breastfeeding duration for those women returning to work or school.35 Of 246 women, 76.8% of women who used the manual pump (76 of 107) and 72.3% of those using the electric pump (94 of 139) breastfed for 6 months. The manual pump only pumped one breast at a time so pumping took longer. The groups were matched for age, parity, ethnicity, and socioeconomic ­status. Contrary to most studies, the women with some college education breastfed a shorter period time. This study suggests manual pumps work well when one is also breastfeeding an infant in contrast to pumping for a hospitalized child.35 A study of two electric pumps utilized by healthy women with healthy babies intending to return to work or school were randomly assigned to use a novel (Embrace, Playtex, Westport, Conn)

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T A B L E 2 1 - 2 0 Oxytocin Results* Method

Mean net AUC

SEM

Infant White River Electric Medela Manual Hand expression Gentle Expressions Battery

224.7 174.1 218.5 140.5 186.7

75.4 41.3 157.5 66.5 67.6

From Zinaman M, Hughes V, Queenan JT, et al: Acute ­prolactin, oxytocin responses and milk yield to infant suckling and artificial methods of expression in lactating women, Pediatrics 89:437, 1992. *Levels of plasma oxytocin with breast stimulation ­calculated as mean net area under the curves (AUC) for each of the five methods for the 60-minute sampling ­session. No significant differences were noted.

Figure 21-7.  Measurement of nipple cups. (From Johnson CA: An evaluation of breast pumps currently available on the American market, Clin Pediatr (Phila) 22:40, 1983.) Figure 21-9.  Serum prolactin results, with breast stimulation calculated as mean net area under curves for each of five methods. Data given as mean ± SEM. (Modified from Zinaman MJ, Hughes V, Queenan JT, et al: Acute prolactin, oxytocin responses and milk yield to infant suckling and artificial methods of expression in lactating women, Pediatrics 89:437, 1992.)

Figure 21-8.  Mean human serum prolactin (hPRL) levels for each of five expression methods. Data given as mean ± SEM. (Modified from Zinaman MJ, Hughes V, Queenan JT, et al: Acute prolactin, oxytocin responses and milk yield to infant suckling and artificial methods of expression in lactating women, Pediatrics 89:437, 1992.)

Figure 21-10.  Mean milk volumes obtained with breast stimulation for four of the five expression methods (infant not included). Data given as mean ± SEM. (Modified from Zinaman MJ, Hughes V, Queenan JT, et al: Acute prolactin, oxytocin responses and milk yield to infant suckling and artificial methods of expression in lactating women, ­Pediatrics 89:437, 1992.)

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T A B L E 2 1 - 2 1 Expression and Pumping Methods Type

Action

Equipment

Availability

Hand expression

Hand action stimulates milk ejection reflex and compresses milk ducts Cooling creates a vacuum so that the milk flows from breast (higher pressure) to the jar (lower pressure); suction pressure may be difficult to control Negative pressure created by hand; arm action of the pump causes milk to flow from breast to pump; suction pressure may be difficult to control; some brands designed to reduce arm/hand fatigue; some work on a “draw and hold” principle rather than an even in-out action Negative pressure at pump causes milk to flow from breast to pump; adjustable suction pressure and cycling time in some brands; some work on a “draw and hold” principle rather than even in-out action

None

Universal

Suitable glass jar, hot water, cold water, cloth

Widespread

Pump Cleaning supplies Most pumps have at least 3 parts One-handed pumps available and 2 pumps can be used for double pumping Pump Batteries: New batteries may be needed after 2-4 hours use; some have AC adapters available Cleaning supplies Most pumps have at least 4 parts Most are hand-held so weight of pump plus milk may be a concern Pump Electricity supply Cleaning supplies Most pumps have many parts Two collection sets can be used for double pumping for most brands Electricity supply or other power source Cleaning supplies Most pumps have 10 or more parts Two collection sets can be used

Depends on market demand/distribution

Hot jar (base cooled with cold cloth)

Manual pump: Compressing a bulb, pulling on two connected cylinders, or squeezing and releasing a handle

Battery pump: Power provided by battery, manner of creating pressure may vary

Small pump: Electric, diaphragm

Negative pressure created by pump action of the pump causes milk to flow from breast to pump; adjustable suction pressure and cycling time in some brands

Large electric: Piston pump, rotary vane pump, diaphragm pump; power may be provided by car battery or by foot treadle

Negative pressure created by action of the pump causes milk to flow from breast to pump; suction pressure may be difficult to control; some brands designed to reduce arm/hand fatigue; Some work on a “draw and hold” principle rather than an even in-out action

Depends on market demand /distribution

Depends on market demand/­ distribution

Depends on market demand/distribution; larger pumps generally purchased by hospitals or rental companies for loan to mothers

From Becker GE, McCormick FM, Renfrew MJ: Methods of milk expression for lactating women, Cochrane Database Syst Rev 8(4):CD006170, 2008. Note: Some brands of pumps have a flexible breast cup that compresses the breast and some have a choice of sizes of breast cup. Multiuser pumps require high-quality cleaning procedures and frequent servicing. There is no one type of pump that is suitable for all mothers and all circumstances. To obtain quantities of milk by any method requires an effective milk ejection reflex.

or a standard (pump-­in-style, Medela, Baar, Switzerland) electric pump. Milk extraction was greater with the standard pump; 24-hour production did not differ. However, women were equally likely to select either of the two pumps.37 The universal availability of a double collecting system so both breasts are “pumped” simultaneously greatly enhances production and saves time. Tables 21-21 and 21-22 provide data on expression and pump methods and logistical model ­factors. Breast pump efficiency was studied by Hartmann et al,34 utilizing a procedure for objective

determination of breast pump efficiency by measuring milk removal from one breast in a 5-minute period in 30 women using an electric breast pump (vacuum pattern of Medela Classic). They compared these data with breastfeeding characteristics. They determined each woman’s breastfeeding characteristics by collecting milk samples before and after each feed from each breast by either manual breast pump (Medela AG) or hand expression, by test weighing the infant, measuring degree of fullness, and direct measurement of breast volume, techniques standardized in their laboratory.

The Collection and Storage of Human Milk and Human Milk Banking    

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T A B L E 2 1 - 2 2 Logistic Model Factors and Adjusted Odds Ratios (95% Confidence Intervals) Associated

With Regular Milk Expression Compared With Occasional Milk Expression Among Breastfeeding Mothers Who Expressed Milk in the Previous 2 Weeks According to Infant Age-Group Characteristic Mother’s education Some college vs. high school or less College graduate vs. high school or less Household income 185%-350% vs. <185% poverty level >350% vs. <185% poverty level Region Northwest vs. West Midwest vs. West South vs. West Infant delivery Vaginal birth with pain medication vs. without pain medication Cesarean delivery vs. vaginal birth without pain medication Infant gestation, ≥37 vs. 35 to <37 wk Breastfed other infant, yes vs. no† Prenatal intent to breastfeed, ≥12 vs. <12 mo Employed in previous 4 wk, yes vs. no Embarrassed to breastfeed in public, yes vs. no Type of breast pump device used most often‡ Combination of electric/battery vs. electric pump Manual pump vs. electric pump Age of first breast pump use (wk)

1.5 to 4.5 mo (N = 853)

>4.5 to 6.5 mo (N = 558)

>6.5 to 9.5 mo (N = 362)

0.53 (0.30-0.92)* 0.76 (0.44-1.32)

1.43 (0.64-3.21) 2.07(0.93-4.57)*

0.95 (0.32-2.78) 1.37 (0.48-3.09)

1.23 (0.82-1.84) 1.82 (1.15-2.87)*

1.52 (0.91- 2.52) 1.50 (0.84- 2.67)

2.10 (1.04-4.22)* 2.48 (1.16-5.27)

1.24 (0.75-2.09) 1.36 (0.88-2.11) 1.73 (1.12-2.66)*

1.30 (0.70-2.41) 1.22 (0.72-2.06) 1.49 (0.87-2 .55)

0.78 (0.35-1.70) 0.64 (0.32-1.25) 1.05 (0.53-2.10)

0.95 (0.60-1.50) 1.10 (0.67-1.82)

0.97 (0.56- 1.69) 0.72 (0.39-1.32)

0. 69(0.35-1.35) 0.52 (0.25-1.11)

0.37 (0.16-0.81)* 0.64 (0.45-0.90)* 0.72 (0.45-1.14) 3.99 (2.86-5.56)* 1.34 (0.97-1.85)*

1.58 (0.56-4.52) 0.49 (0.31-0.76)* 0.49 (0.30-0.81)* 4.02 (2.68- 6.04)* 0.87 (0.59-1.09)

0.55 (0.14-2.17) 0.71 (0.40-1.27) 0.58 (0.32-1.06)* 5.94 (3.47-10.17) * 1.11 (0.66-1.87)

0.66 (0.43-1.02) 0.51 (0.35-0.75)* 0.91 (0.84-0.98)*

0.55 (0.33-0.92)* 0.39 (0.23-0.65)* 1.02 (0.96-1.09)

0.87 (0.42-1.82) 0.31 (0.16-0.59)* 1.02 (0.96-1.09)

From Labiner-Wolfe J, Fein SB, Shealy KR et al. Prevalence of breast milk expression and associated factors, Pediatrics 122: S63-S68, 2008. Analysis was limited to those with complete data on the relevant questions. *Indicates statistical significance at the p <0.05 level. †Includes mothers with no other children and mothers with other children whom they did not breastfeed. ‡Hand expression was not a response option on the question that asked about the type of pump device used most often.

The authors concluded that pump efficiency can be measured if maternal characteristics and the amount of milk in the breast available to be expressed are known. The proportion of available milk expressed varied greatly between mothers. Investigators in this same laboratory looked at the impact of vacuum on volume of milk expressed. They looked at 23 mothers (two were expressing milk only and not feeding the infant) who expressed their milk for 15 minutes set at their own maximum comfort levels and then at lesser vacuum levels. The mother’s comfort level maximum produced more milk than at lesser pressures. Milk flow was greatest at the onset and cream level was highest at the end of the 15 minutes at maximum comfort level.39 Milk output from the right and left breasts was compared in mothers who were exclusively pumping and had not fed their infants at the breast.20 It was reported that differences between right and left breasts are common, with the right often more productive. The difference was not related to handedness but was consistent through the day and over time.

Methods of milk expression for lactating women were reviewed for the Cochrane Collaboration by Becker et al.4 They found 12 studies that met ­criteria, of which six could be utilized, involving 397 mothers. Compared with hand expression, a study found that a greater volume of milk could be collected utilizing an electric pump (or a foot-pedal pump.) The later two were comparable. Providing a relaxing tape to be played while pumping resulted in a greater volume of milk. Pumping both breasts simultaneously took less time but no difference in total volume was found. There was no difference in milk contamination, breastfeeding at hospital discharge, fat content of milk, or serum prolactin by method of pumping. No data was reported on maternal satisfaction, adverse effects, or economic advantages.4 A complete assessment of all the pumps readily available on the market and details about other equipment for breastfeeding are provided in the Breastfeeding Product Guide by Kittie Frantz24 and at respective company websites.

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   Breastfeeding: A Guide for the Medical Profession

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