Nutritional Requirements in Preoperative, Postoperative and Parenteral Feeding of Infants and Children

NUTRITIONAL REQUIREMENTS IN PREOPERATIVE., POSTOPERATIVE AND PARENTERAL FEEDING OF INFANTS AND CIIILDREN JAMES L. DENNIS, M.D.

A major objective of preoperative and postoperative management is to provide optimum conditions for the repair, maintenance and growth of healthy tissues. It is no coincidence that. this objective closely resembles the accepted definition of nutrition, i.e. "the sum of the processes concerned with the growth, maintenance, and repair of the human body."16 Nutrients that must be supplied to the body from exogenous sources are considered essential. These include calories, protein, fat and vitamins, as well as water and minerals. Although· the body can synthesize carbohydrate, it is usually at the expense of tissue protein. For this reason, carbohydrates must be considered essential so far as the parenteral feeding of children is concerned. CALORIES

The essentiality of calories becomes apparent during the preoperative and postoperative periods, particularly in the growing child who is receiving parenteral feeding. It is impossible to maintain a positive nitrogen balance in the face of an inadequate caloric intake. The wisdom of the body is such that during starvation the body proteins are protected by the priority utilization of carbohydrate and fat for energy. When glycogen stores are depleted, there is a shift to the fat stores. Fortunately, fatty acids and ketone bodies derived from fat are readily used by most body tissues except the brain. The production of fatty acids and ketone bodies is approximately in balance with tissue utilization; hence the ketonemia of fasting is slight as com-

912

PREOPERATIVE, POSTOPERATIVE AND PARENTERAL FEEDING

pared to that found in uncontrolled diabetes mellitus, in which ketone production has no relation to tissue utilization. Caloric requirements vary greatly at various ages and under various conditions (see Table 2). Normally during childhood, about 50 per cent of the caloric expenditure will be for basal metabolism, 12 per cent for growth, 25 per cent for physical activity, 10 per cent for fecal loss, and 3 per cent for the specific dynamic action of protein. During preoperative, postoperative and parenteral fluid therapy, the total caloric expenditure will be less than the normal caloric intake, but higher than the basal metabolism. TABLE

2. Average Daily Caloric Requirements

AGE

Under 1 year ............... 1-5 years .................... 5-10 years .................. 10-15 years .................

. . . .

CALORIES

PER

PER METER SQUARE

PER POUND

KILOGRAM

SURFACE AREA

50 45-40 35-30 30-25

110 100

80-65 65-50

1000 1000 1000 1000

The provision of the total caloric requirements by parenteral infusion remains an ideal not yet attainable, limited by the amounts and concentrations of fluid that can be infused. It is, however, possible and essential that enough calories be supplied to prevent ketosis and to reduce the catabolism of protein to a minimum. Under unusual circumstances, e.g. severe depletion or prolonged intravenous feeding, it may become necessary to increase the caloric intake with infusions that provide an increased concentration of carbohydrate, emulsified fat, or alcohol. The clinical applications of these preparations are considered in the section appropriate to each. PROTEIN

Protein is the principal component of cell protoplasm and as such is essential for the repair and growth of body tissues. Proteins vary considerably in their nutritional values. The characteristics of any given protein depend on the kind, numbers and arrangement of the amino acids forming the protein molecule. Ingested proteins are hydrolyzed in the alimentary canal and made available for absorption as amino acids. Essential amino acids not only provide material for the maintenance of the body tissue, but also perform specific metabolic functions and are the sources of important specific compounds concerned with intermediary metabolism. There have been continuous efforts to define the minimal daily protein allowances, and such definitions have been repeatedly revised, usually downward. It is currently recommended that infants be allowed 2.7 Gm. of protein per kilogram per day,* probably more than minimal *Food and Nutrition Board, National Research Council.

JAMES L. DENNIS

913

need, but providing a margin of safety. Requirements vary according to age, being highest in the young infant, decreasing rapidly during the first year, and exhibiting a slight rise at puberty, then a decline to adult levels of 0.5 to 1 Gm. per kilogram per day. Butler et aJ.5 recommended 30 Gm. of protein per square meter of body surface area per day for all ages, but add a 10 per cent increment during the periods of rapid growth. With the increment factor, this dosage provides approximately 2 Gm. of protein per kilogram per day. In order to meet the nitrogen needs of the body, it is necessary to provide at least the minimum allowance and to accompany this with a simultaneous and adequate provision of calories. Otherwise much of the amino acid supply will be diverted from anabolic to energy purposes. During starvation or periods of severe dietary imbalance the endogenous catabolism of body proteins becomes inevitable. Thus, when appropriately stressed, all human beings become cannibals, feeding upon themselves. Clinical Considerations

The circulating plasma proteins perform important osmotic functions that affect the blood pressure and the exchange a.nd distribution of water, minerals and other nutrients. Acute deficiencies of plasma proteins associated with shock, bums, extensive surgery and massive bleeding must be promptly corrected by plasma or blood infusion as soon as possible. Chronic protein deficits lead to hypoproteinemia, but not before depletion of the body tissue protein. A low serum protein level always indicates the existence of a significant body protein deficit. This is an important preoperative consideration, for protein deficiency is accompanied by an increased tendency to shock during anesthesia and surgery, lowered resistance to infection, delayed wound healing, increased susceptibility to liver disease, and prolonged convalescence. If possible, protein deficits should be corrected before operation. The oral route is always preferable when the circumstances permit. Although infused plasma is unexcelled for the purpose of restoring the circulating protein and fluid volume, it has no immediate nutritional value (the half-life of the infused albumin and globulin is 21 to 30 days). On the other hand, the amino acids of infused protein hydrolysate solutions are made available for tissue synthesis almost immediately. The parenteral feeding of protein in the form of intravenous amino acid hydrolysates is sometimes necessary. Amigen, * a 5 per cent solution of amino acids and small peptides, is derived from the enzymic digestion of casein. Aminosolt 5 per cent is essentially the same, but its amino acids are derived from the hydrolysis of fibrin rather than

* Mead Johnson & Company, Evansville,

Indiana. t Abbott Laboratories, North Chicago, Illinois.

914

PREOPERATIVE, POSTOPERATIVE AND PARENTERAL FEEDING

casein. Both preparations are available alone or with added 5 per cent dextrose, with 10 per cent fructose, with 2.5 or 5 per cent alcohol, with various minerals, and with various combinations of these materials. Although it is necessary to protect endogenous protein synthesis by the simultaneous infusion of calories from other sources, it is important to recognize that any fortification of the 5 per cent amino acid solutions makes them hypertonic and hence increases their sclerosing tendencies. In projecting dosage, it should be recognized that the total available nitrogen of the protein hydrolysate solution is less than the nitrogen of the protein from which it was derived. One gram of hydrolysate is equivalent to only 0.75 Cm. of protein; hence a 5 per cent solution containing 50 Cm. of hydrolysate per liter provides 37.5 Cm. of protein and 175 calories per liter. From this, it is possible to determine dosages applicable to the varying age requirements for protein (see Table 3). TABLE

3. Protein Hydrolysate Dosages for Protein Requirements

5% PROTEIN HYDROLYSATE SOL. 40 60 70 80 100 1500

ml./kg./day ml./kg./day ml./kg./day ml./kg./day ml./kg./day ml./M.2/day

OM. PROTEIN

provides provides provides provides provides provides

1.5/kg./day 2.25/kg./day 2.72/kg./day 3.0/kg./day 3.75/kg./day 56.0/M.2/day

Intravenous administration of amino acid solutions is contraindicated in patients with significant impairment of renal, cardiovascular or hepatic mechanisms. Their use in infants under 10 kg. of body weight requires cautious deliberation. In the small infant the tendency to produce sclerosis of the injected vein is a deterrent to more extensive use, a problem amplified by the necessity for continuous infusion and the limited number of accessible veins. Surgical procedures are always followed by two to three days of negative nitrogen balance. This deficit period is not prevented by the infusion of amino acid solutions. FAT

The fundamental role of fat in infant nutrition is considered elsewhere in this issue (see p. 927). One gram of fat yields 9 calories; hence depot fat is an important source of concentrated energy reserve. Fat also provides the transport vehicle for the fat-soluble vitamins A, D, E and K. Some fat in the diet may improve body resistance to infection. Ingested fats are important to satiety and have inhibitory effects upon gastric secretion and mobility. Although fat can be readily synthesized from the acetate residues of protein and carbohydrate degradation, this is not true for

JAMES L. DENNIS

915

linoleic acid; hence this unsaturated fatty acid must be considered a dietary essential. Wiese and co-workers22 reported that minimal normal levels of the serum unsaturated fatty acids require a diet providing 1 to 2 per cent of the calories as linoleic acid. Both animals and human beings on prolonged, fat-deficient (linoleic acid-deficient) diets exhibit skin changes characterized by dryness, increased thickness, keratinization, desquamation and weeping. 9 The possibility, even probability, that such a deficiency could impair wound healing and invite secondary infection is an interesting consideration that is now being investigated. An important caloric-sparing action of linoleic acid has been demonstrated in infants. Adam et a1,1 found that when infants were on diets providing less than 0.1 per cent of the calories consumed in the form of linoleic acid, their total caloric consumption was well above 125 calories per kilogram; but when linoleic acid comprised at least 1 per cent of the calories consumed, the caloric consumption per kilogram per day was decreased, without any change in the rate of weight gain. These studies suggest that the intravenous infusion of an emulsion of unsaturated fat containing linoleic acid might provide caloric economy and hence protect the body protein during prolonged periods of postoperative fasting. The work of Hansen et aJ.9 suggests that the restoration of normal levels of serum linoleic acid might contribute to the growth and maintenance of healthy skin in the burned child as well as to wound healing. We have observed impaired wound healing in infants who have had pyloromyotomies after the protracted vomiting of pyloric stenosis. When measured, the serum fat levels have been low. These implications are subject to further investigation. The parenteral infusion of fat has awaited the development of a stabilized and safe emulsion for intravenous feeding. Kaplan et al,13 report a satisfactory clinical experience with Lipomul I. V. * given to infants and children and suggest that this oil-in-water emulsion can be safely administered to infants and children if the dosage is not excessive, i.e. 30 ml. per kilogram infused over a period of 6 hours. This amount is not to be administered more often than once every 48 hours, or before the separated serum from the patient has lost its milky appearance, or before chemical examination of the serum reveals the absence of elevated fat levels. Intravenous fat should be considered for (1) severely malnourished patients who are unable to take adequate food by mouth; (2) patients with malfunctioning gastrointestinal tracts-e.g. newborn infants with congenital obstructions and surgically created temporary fistulas, many of whom die from inanition -those who have lost considerable portions of their intestinal tracts or those requiring prolonged intubation; (3) extensive burns; (4) acute

* The Upjohn Co., Kalamazoo, Michigan. Each 100 m!. of Lipomul LV. provides cotton seed oil, 15 Gm. dextrose, anhydrous, 4 Gm.; lecithin, 1.2 Gm.; and oxyethyleneoxypropylene polymer, 0.3 Gm. Total calories 160, or 1.6 calories per milliliter.

916

PREOPERATIVE, POSTOPERATIVE AND PARENTERAL FEEDING

renal failure; to reduce catabolism and the accumulation of toxic catabolic products; and to reduce serum potassium level, presumably, by inducing the transfer of potassium into cells.3 Complications have attended the use of previously available parenteral fat emulsions and have been characterized by (1) febrile reactions (Kaplan reported less than 10 per cent incidence in infants and children given Lipomul I. V., and in none was it necessary to discontinue the infusion); (2) colloidal reactions (dyspnea, cyanosis, flushing shortly after starting infusion) did not occur when the infusion was given as described; (3) hematologic reactions (anemia, thrombocytopenia, leukopenia) did not occur in Kaplan's series; (4) liver damage, as evidenced by liver biopsy, did not occur. Although Lipomul I. V. appears to provide a relatively safe solution for the parenteral feeding of fat, its use in pediatrics is still limited to selected and unusual circumstances. CARBO HYDRATE

Carbohydrate is readily synthesized from protein and to a lesser extent from fat, and hence is not a dietary essential. During parenteral feeding, however, the protein-sparing action of exogenous carbohydrate becomes indispensable to the internal economy of the body. Although dextrose (glucose) is usually considered the physiologic sugar, the body actually makes use of many carbohydrates. Of these, only glucose and fructose (levulose) are commonly used in parenteral feeding. The intermediary metabolism of fructose differs from that of glucose. Some feel that fructose enjoys certain biochemical advantages over glucose, since a portion of the fructose can be immediately and completely catabolized to produce water and carbon dioxide, plus energy. The remaining fraction is rapidly converted to glucose. In spite of reported differences in tolerances, the observable clinical differences of these solutions are not striking (see Table 4). Whether glucose or fructose is used, the amount that can be infused is limited. Sclerosing effects upon the vein are increased with concenTABLE

4. Reported Differences in Body Tolerances Various Clinical Conditions 2 • 14. 17

CONDITION

GLUCOSE

Surgery ............. Diminished tolerance Fever ............... Diminished tolerance Starvation ........... Loss of tolerance Diabetes ............ Abnormal Cortisone therapy ........... Impaired tolerance Hepatic disease ............ Marked impairment

of Glucose and Fructose during FRUCTOSE

*

Unaltered tolerance Unaltered tolerance Unimpaired tolerance Normal Unimpaired tolerance Near normal

*Fructose is easily converted to glucose; hence differences in tolerance may have little clinical significance.

JAMES L. DENNIS

917

trations above 5 per cent; and concentrations of 10 per cent or greater may produce serum levels that exceed the renal threshold with spillage into the urine, thereby placing an increased demand on the water available for renal excretion. Total caloric needs cannot be met by the parenteral infusion of glucose or fructose (5 per cent solutions yield only 200 calories per liter) . The practical objective is to supply sufficient calories to reduce the catabolism of protein to a minimum. This objective is met when the daily infusion contains at least 50 Cm. per liter of glucose or if the infusion supplies at least 50 Cm. of glucose per square meter per 24 hours. Five per cent solutions meet these requirements. ALCOHOL

Ethyl alcohol may be used as an adjuvant to carbohydrate in providing calories during parenteral feeding. Alcohol yields 7 calories per gram. Alcohol is quickly and completely metabolized, its oxidation forming water equivalent to 95 per cent of the weight of the alcohol metabolized and leaving almost no solute residue for renal excretion. These features make intravenous administration of alcohol attractive for patients in renal failure when high caloric needs and restricted water intake pose a dilemma. Unfortunately, some of the caloric attributes of alcohol are offset by the stimulation of an increased rate of metabolism (heat loss). Other physiologic effects of alcohol, at times, might be useful during the preoperative and postoperative periods, e.g. the sedative, hypnotic, analgesic, vasodilator, antipyretic and antidiuretic effects. Alcohol i~ a powerful inhibitor to the release of pituitary antidiuretic hormone. 2o Knowledge of this effect might be used to advantage in conditions in which the antidiuretic hormone action is excessive; e.g. the stress of major surgery and severe infection. The numerous undesirable side effects of alcohol include venous sclerosis, vasodilatation (dangerous to a patient in impending shock), intoxication (if the rate of flow is too rapid), and peripheral nerve palsy ( if inadvertently injected in or near a peripheral nerve). Ethyl alcohol is contraindicated when there is suspected hepatic disease. The exact dose of infused alcohol is governed to some extent by the reaction of the patient. In general, alcohol should provide no more than 10 to 15 per cent of the calculated 24-hour caloric expenditure. The rate of administration and the concentration of the alcohol solution are important factors. In children a 2.5 per cent concentration delivering not more than 50 mg. per hour is desirable. Frequent evaluation of the patient is mandatory. VITAMINS

From the standpoint of preoperative and postoperative nutrition, vitamin supplements are probably unnecessary for acute conditions of only

918

PREOPERATIVE, POSTOPERATIVE AND PARENTERAL FEEDING

a few days' duration. Patients who come to surgery in a questionable state of nutrition and those who require prolonged parenteral feeding do require vitamin supplements. The water-soluble vitamins are not stored in the body and may be rapidly exhausted during fluid therapy. Vitamin B complex, a group of water-soluble vitamins, tend to be found together in nature and are essential to the nutrition of children. They provide prosthetic groups necessary to form one or more of the coenzymes and enzymes concerned with cellular respiration and with carbohydrate, protein and fat metabolism. B complex vitamins are available for parenteral injection. Recommended daily allowances for B vitamins include thiamine 1 mg., riboflavin 2 mg., and niacin 10 mg. Vitamin C (ascorbic acid) is necessary for the structure of the intercellular ground substance in which tissue cells are embedded and held together. There is good experimental evidence that vitamin C is important to wound healing and to normal protein metabolism. 12 Vitamin C may be added to parenteral feedings. At least 60 mg. per day is required. Vitamin K is essential to prothrombin production, hence of obvious importance in any surgical patient. Naturally occurring, vitamin K is a fat-soluble vitamin; but synthetic water-soluble preparations are available for parenteral injection. Vitamin K is recommended before and after operation for all patients who are jaundiced, who have bleeding tendencies, or who have had prolonged antibiotic therapy. In newborn infants the dose of vitamin K should not exceed 1 mg. Vitamins A and D do not appear to have such direct relations to the problems of surgical management, but in the chronically debilitated child their use should not be neglected. Recommended daily allowances for the growing child are vitamin A 5000 I.U., and vitamin D 400 to 800 I.U. MINERALS

Minerals are not created or destroyed in the body. Body mineral content depends on a balance between intake and output. For growth and repair the over-all balance must be positive. Sodium is the principal cation of the extracellular fluids, and the serum sodium is directly related to total body fluid osmolarity. Low serum sodium (hyponatremia) may reflect deficits due to inadequate intake, inordinate losses, dilution by relative increase in total body water, or to cellular potassium deficiency. Chronic hyponatremia is usually asymptomatic; and correction is directed at the underlying condition, e.g. sodium-losing nephropathy or chronic dietary deficit. Acute hyponatremia produces signs of water intoxication, e.g. apathy, confusion, convulsions, muscle weakness, muscle cramps, vascular collapse. Treatment of acute hyponatremia is directed toward the restoration of normal osmolarity by the correction of sodium deficits. The deficit may be estimated by the following formula: 18

JAMES L. DENNIS

919

140 - patient's serum sodium in mEq./L. X 0.6 body weight (kg.)

Hypernatremia (serum sodium greater than 150 mEq. per liter) may result from excessive sodium intake, but in infants and children it frequently reflects primary water deficit without corresponding sodium loss. Clinical signs of hypernatremia include significant weight loss without usual signs of dehydration (in fact, the infant may display edema although severely dehydrated) and central nervous system symptoms of irritability and convulsions, lethargy and stupor. Treatment of hypernatremia is directed toward supplying enough water to permit renal excretion of excess sodium and to correct hydration. It is impossible to correct hypernatremia rapidly. In spite of the existing hypernatremia, it is necessary to provide some sodium if water retention and "intoxication" are to be avoided. Blacklidge4 recommends at least 0.11 to 0.2 per cent saline in 5 per cent glucose. Babies with hypernatremia nearly always have potassium deficits. Once renal flow is established, potassium should be included in the infusion. Potassium is essential to the integrity of the cell and represents the predominant intracellular ion. There is poor correlation between the serum potassium and the total body potassium. The serum levels may be normal or elevated in the presence of severe intracellular deficit. But low serum levels (3.5 mEq. per liter or less) or normal levels in a hemoconcentrated serum always indicate a significant potassium deficit. Potassium deficit may result from inadequate intake (potassiumfree infusion or starvation) or from excessive losses from the gastrointestinal tract (vomiting, diarrhea, suction, exchange resins), from wasting renal disease, and during the period of negative nitrogen balance that follows surgery. Acute potassium deficits provide a common complication in the postoperative period and produce abdominal distention, ileus, muscle paresis, and cardiac and electrocardiographic changes (flattened, inverted T waves). Chronic potassium deficits produce a specific renal tubular necrosis, extracellular metabolic alkalosis, and a paradoxical intracellular acidosis. In the treatment of potassium deficit the rate of correction is limited by the necessity to avoid high levels of potassium in the serum. This is no great disadvantage, since it takes two to four days to correct severe potassium deficiency. Potassium infusion is relatively safe if the infusion does not contain more than 40 mEq. per liter, is not delivered at a rate exceeding 0.5 mEq. per kilogram per hour, and if the total daily dose is no more than 3 mEq. per kilogram per day. Hyperkalemia (serum potassium above 6 mEq. per liter) may reflect hemoconcentration, an excess of infused potassium, renal failure or adrenal insufficiency. Hyperkalemia may produce electrocardiographic changes 7 (peaked T waves) and cause death from cardiac arrest. The treatment of potassium excess includes such measures as ion exchange resins by mouth, tube or rectum; gastric or renal dialysis; intravenous

920 TABLE

PREOPERATIVE, POSTOPERATIVE AND PARENTERAL FEEDING

5. Sodium, Potassium and Chloride Requirements per 24 Hours

CONDITION

NormaL .................. Abnormal (deficits): Vomiting ............... Diarrhea ................

STATE OF

SODIUM

CHLORIDE

POTASSIUM

DEHYDRATION

mEq./kg.

mEq./kg.

mEq./kg.

Normal

2

2

1.5

Severe Severe

8 8-10

10

7-9

8 10-12*

NORMAL MAINTENANCE

mEq./M2/Day Newborn and premature, first week of life .................. . Infant and child ..................... .

30 50

mEq./M"/Day

40 40

*Potassium deficits of this order cannot be replaced in less than 48-72 hours. Doses greater than 3 mEq./kg. and concentrations of more than 40 mEq./L. should not be attempted.

administration of calcium gluconate (caution!), or intravenous glucose covered with 0.5 unit of insulin per gram of glucose. Magnesium is relatively abundant in foodstuffs, and an average daily diet provides about 300 mg. The daily requirement for infants is said to be 150 mg. per day.8 Severe deficiency appears to be uncommon, but can produce symptoms that resemble those of hypocalcemic tetany. Iron is essential for normal hemoglobin formation. Deficits are common between three and nine months of age, especially in the premature. In premature infants a total daily intake of about 2 mg. per kilogram should be assured by the third month, gradually decreasing to about 1 mg. per kilogram by the end of the first year. In term infants a total intake of 1.5 mg. per kilogram per day should be assumed by 6 months, gradually decreasing to 1 mg. per kilogram by one year and 0.5 mg. by 18 months of age. 19 Iron deficiency anemia should be corrected before subjecting an infant or child to surgery. In an acute situation whole blood transfusion will be necessary. Infants with severe iron anemia tend to have hypervolemia, and the usual transfusion increment of 10 m!. per pound may produce sudden heart failure and pulmonary edema. A safe ruleof-thumb for such situations is 1 m!. per pound per gram of hemoglobin; e.g. with 3 Cm. of hemoglobin give 3 m!. per pound of whole blood, or packed blood cells. If the surgical procedure is elective, time should be taken to correct iron deficits and anemia with oral or intramuscular iron preparations. WATER

Physicians responsible for pediatric surgical management should have expert knowledge pertaining to the peculiarities of water metabolism

JAMES L. DENNIS

921

in infants and children. Water is the most labile of the essential nutrients. There is a constant loss from the body by vaporization from the skin and lungs (insensible loss, accounting for 40 to 50 per cent of normal output), urinary loss (40 to 50 per cent) and gastrointestinal loss (3 to 10 per cent). Water losses must be continuously replenished by ingested water, and food containing water. The term "water balance" means just that; i.e. water intake equals water output. The infant is distinguished by his susceptibility to water imbalance. Although water comprises approximately 70 to 75 per cent of the infant's body weight (in contrast to that of 60 to 65 per cent in the adult), he gets into difficulty easily and early. The daily exchange of water in the infant is equal to half of his extracellular fluid volume, whereas the corresponding exchange in the adult is equivalent to only about one sixth of his extracellular fluid. There are important reasons for these differences. The infant has a relatively greater body surface area per unit of body weight. Basal heat production and water expenditures per kilogram of body weight are more than double those of the adult. Increased metab91ism produces increased metabolic wastes, requiring extra water for renal solute excretion; the immature infant kidney requires 2 to 3 ml. of water to excrete each unit particle (milliosmol) of solute waste, whereas the adult kidney can perform the same task with only 0.7 ml. of water. The foregoing observations have important clinical implications. It is apparent that any of the following circumstances will quickly affect water balance in the infant and child: Primary water deficit occurs when a child is deprived of water or when a sick infant refuses to eat or drink, so that normal obligatory losses alone will seriously deplete extracellular fluids in one to two days. When abnormal losses become superimposed, critical dehydration and collapse can occur with explosive rapidity. Insensible water losses, due to increased vaporization from skin and lungs, may be large during fever, hot weather, respiratory disease, arid with metabolic acidosis. Significant losses from the gastrointestinal tract frequently occur with diarrhea, vomiting, and continuous gastric suction. Abnormal urinary water loss may follow the ingestion of increased solute loads and in chronic renal conditions. During the preoperative and postoperative periods it is imperative that nurses and physicians remain alert to the fact that in children water excess can develop as quickly as water deficit and that excess is nearly always iatrogenic. Once the infusion needle has been introduced into the vein, the greatest danger becomes that of fluid overload. METHODOLOGY

One cannot discuss pediatric fluid requirements without considering methodology. Daily requirements must be calculated, and the requirements vary with the age. Talbot,21 Butleri' and others have

922

PREOPERATIVE, POSTOPERATIVE AND PARENTERAL FEEDING

successfully promoted the body surface area as a flarameter for calculating fluid requirements. The system presents the advantage, at least in theory, of providing a single "dose" for all ages. Although surgeons, generalists and many pediatricians accepted surface area as a simple, single-dose method, it was not embraced with enthusiasm by many pediatricians who were comfortable with time-proved systems based on weight alone. Actually, surface area, too, is based on weight (the two-thirds power of body weight). What wc call surface area represents a mathemical convenience, an exponential factor that provides a straight-line, single-dose implement. From a clinical standpoint, surface area is practical. It is neither more nor less scientific than other methods, and it does not diminish the need for pediatric knowledge. Talbot21 has pointed out that all systems are relatively safe because of the wide margin between the minimal requirements and the maximal tolerances for water. It has not been sufficiently emphasized that in the infant this margin is very narrow indeed, particularly when there are added limitations of homeostasis produced by the stress of surgery, preoperative and postoperative medication, and blood loss.5 Those surgeons and generalists who see the "simplicity" of the surface area method as an excuse to bypass pediatric consultation need to be reminded that no system can predict or alter age group peculiarities. Anyone who assumes the responsibility for parenteral fluid therapy without expert knowledge of these peculiarities is inviting disaster. The surface area system is here, and the pursuit of the literature requires a knowledge of its application. Unfortunately, in the process of reading a single journal, it is confusing to encounter several different methods for calculating fluids. Each system presents its own semantics with requirements expressed in such terms as milliliters per 100 calories expended, milliliters per square meter of body surface area, milliliters per milliosmol of solute excreted, milliliters per kilogram of body weight; and, occasionally, someone will use such vulgar terms as cubic centimeters per pound. Actually, all systems are TABLE

6. Relations of Surface Area, * Kilograms and Pounds SQUARE METER

KILOGRAMS

POUNDS

2 3 5 6 10 15 20 30 40 50

4.4 6.6 11.0 13.2 22.0 33.0 44.0 66.0 88.0 110.0

SURFACE AREA

0.15 0.20 0.25 0.30 0.45 0.6 0.8 1.0 1.3 1.5

*Approximate equivalents. What we call surface area represents an exponential factor derived from weight. Surface area is approximately proportional to weight to the 0.7 power.

JAMES L. DENNIS

923

good, and there is a surprising correlation in the allowances prescribed (see Table 6). The important thing is to understand what one is doing, with concern for the individual child uppermost in mind. Water Deficits and Water Requirements

The following outline discussion presents a clinical approach to the estimation of water deficits and water requirements during the preoperative and postoperative periods. The allowances include estimates to cover average existing deficits, current losses, and maintenance. For detailed discussions of specific fluid and electrolyte problems, see the January, 1959, issue of Pediatric Clinics of North America. 1. Mild dehydration a. Evaluation: Weight loss less than 5%; no gross physical signs of dehydration; urine output good; taking and retaining oral fluids b. Place of therapy: home, clinic or office c. Mode of therapy: oral; clear, hypotonic, balanced electrolyte fluids or liquid foods. If unable to take oral fluids, maintenance requirements must be given parenterally d. Estimated daily fluid requirements:* Under 1 year of age: 1-5 years of age: 50 mI./lb. (± 15), or 60 mI./lb. (± 15), or 100-125 mI./kg., or 130-170 mI./kg., or 1500 mI./M.2 1500 mI./M.2 6-10 years of age: 40 mI./lb. (± 15), or 75-100 mI./kg., or 1500 mI./M.2 2. Moderate dehydration a. Evaluation: weight loss, 5-10%; moderate fever; skin warm and dry; urine output diminished; urine dark, scanty; questionable ability to retain fluids b. Place of therapy: hospital, unless home and communication are clearly reliable c. Mode of therapy: Oral as tolerated, or LV.; balanced, hypotonic solutions. Other nutrients as indicated in discussion d. Estimated daily fluid requirement: 1-5 years of age: Under 1 year of age: 80 mI./lb. (± 15), or 60 mI./lb. (± 15), or 175-200 mI./kg., or 130-170 mI./kg., or 2400 mI./M.2 2400 ml./M.2 6-10 years of age: 50 mI./lb. (± 15), or II 0 mI./kg., or 2400 mI./M.2 3. Severe dehydration a. Evaluation: weight loss, 10% or more; hyperpyrexia or subnormal temperature; skin dry with loss of turgor; pinched facies; softness of eyeball; anuria; unable to take fluids; continuous abnormal losses b. Place of therapy: hospitalization is mandatory c. Mode of therapy: intravenous route is mandatory (peripheral circulatory im· impairment makes hypodermoclysis less than useless and may actually be dehydrating in effect). To restore circulation and treat shock, an initial infusion of a nonpotassium-containing hypotonic solution or a reconstituted plasma solution. Rate 15-30 mI./kg. or 360 ml./M.2 delivered over a period of 30-45 minutes. Then slow rate to meet calculated daily requirement with a balanced hypotonic solution. Other nutrients as indicated. Add potassium when renal flow established * Neonates and prematures: 100 mI./kg. or 1000 mI./M.2 These allowances provide for correction of average deficits, maintenance, and average current loss.

924

PREOPERATIVE, POSTOPERATIVE AND PARENTERAL FEEDING

d. Estimated daily fluid requirement: 1-5 years of age: Under 1 year of age: 100 ml./lb. (± 15), or 80 ml./lb. (± 15), or 175 ml./kg., or 220 ml./kg., or 3000 ml./M.2 3000 to 3400 ml./M.2 6-10 years of age: 60 ml./lb. (± 15), or 130 ml./kg., or 3000 ml./M.2 GUIDE TO PREOPERATIVE AND POSTOPERATIVE EVALUATION AND MANAGEMENT

I. Preoperative A. Base line information: 1. Evaluation of deficits a. Accurate history of nutritional intake and abnormal losses b. Physical examination: general appearance, accurate weight and estima· tion of weight loss. (Classify state of dehydration as mild, moderate or severe) c. Urine: quantity, specific gravity d. Laboratory: electrolyte panel, including CO 2 and pH, blood urea nitrogen, serum proteins, hematocrit, hemoglobin, erythrocyte and leukocyte counts 2. Correction of deficits a. Correct nutritional deficits before surgery if possible b. Moderate dehydration and oliguria may be corrected rather quickly by 0.3 normal saline in 5% glucose in water; dose, 360 ml./M.2 or 20-30 ml./kg. given over a period of 45-60 minutes; drip rate then slowed to cover maintenance requirement 3. Things to avoid a. Do not withhold fluids from a child for longer than 6-8 hours before operation b. Do not overhydrate; it is better for the patient to go to surgery a little on the "dry" side c. Do not give intravenous potassium until renal flow established

II. Operative A. Patient should go to surgery with a needle in the vein available for emergency purposes, but with flow reduced to least amount necessary to keep infusion apparatus open (0.2 normal saline in 5% dextrose in water) B. Avoid fluid and electrolyte overload during operation C. Carefully record intake and output

III. Postoperative A. First 24 hours 1. Only enough fluid to cover insensible losses (approximately 40% of normal requirements) plus replacement of measured losses in urine, gastric suction, etc., ml. for ml. and mEq. for mEq. 2. LV. maintenance fluid should be hypotonic, providinif no more than 0.2 normal saline in 5% dextrose in water 3. No intravenous potassium until urinary flow established 4. Things to remember a. Newborn ·infants do not retain water and sodium and lose potassium as do older children and adults 6 b. Morphine and narcotics depress metabolism and produce diminished urinary flow and diminished sodium loss c. Accurately record intake and output d. It is impossible to maintain positive nitrogen balance during the immediate postoperative period

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IV. Common Errors A. Too much fluid and salt during and after operation B. Errors in interpretation: after abdominal surgery muscle "splinting" and morphine medication may produce shallow breathing with retention of C02 (respiratory acidosis). This must be differentiated from the elevated C02 of metabolic alkalosis due to a loss of gastric secretions (suction or vomiting). Differentiation by pH. Respiratory acidosis presents a lowered pH; metabolic alkalosis elevated pH C. Failure to replace potassium losses via gastric suction may produce ileus V. Alimentation Graduated restoration of oral fluid intake as soon as tolerated, but not before 12 to 24 hours VI. Each Day A. Current history 1. Interest in oral fluids, ability to retain 2. Skin turgor-loss of elasticity or edema 3. Responses of patient-alert, depressed, toxic 4. Review intake and output record 5. Accurate body weight. Weight loss indicates continued deficit; rapid weight gain, excess fluid retention 6. Electrolyte panel, plasma proteins, hematocrit, blood counts, urine, specific gravity B. Reclassify clinical state of dehydration as mild, moderate or severe C. Estimate 24-hour requirements for parenteral feeding on basis of classification VII. Prolonged Parenteral Feeding A. Provide daily requirements of vitamins B. Consider the possible need to fortify infusion with protein hydrolysates, emulsified fat or alcohol solutions (see appropriate sections, this article, for requirements, dosage and contraindications) REFERENCES

1. Adam, D. J., Hansen, A. E., and Wiese, H. F.: Essential Fatty Acids in Infant Nutrition. II. Effect of Linoleic Acid on Caloric Intake. J, Nutrition, 66: 555, 1958. 2. Albanese, A. A., and others: Effect of Age on the Utilization of Various Carbohydrates by Man. Metabolism, 3: No.2, March, 1954. 3. Becker, G. H., and Buxbaum, M.: Clinical and Chemical Evaluation of Intravenous Fat Emulsion, with Particular Reference to Changes of Serum Electrolytes. Metabolism, 6:766, 1957. 4. Blacklidge, V. Y.: Hypernatremia. California Med., 95:219,1961. 5. Butler, A. M., and Richie, R. H.: Simplification and Improvement in Estimating Drug Dosage and Fluid and Dietary Allowances for Patients of Varying Sizes. New England J, Med., 262 :903, 1960. 6. Colle, E., and Paulsen, E. P.: Response of Newborn Infant to Major Surgery. Pediatrics, 23: 106 3, 1959. 7. Darrow, D. C., and Pratt, E. L.: Fluid Therapy. J,A.M.A., 143:345, 1950. 8. Duckworth, J.. and Warnock, G. M.: Normal Requirements of Magnesium. Nutrit. Abst. 6 Rev., 12:167, 1942. 9. Hansen, A. E., and others: Essential Fatty Acids in Infant Nutrition. III. Clinical Manifestations of Linoleic Acid Deficiency. J, Nutrition, 66:565, 1958. 10. Holt, L. E., Jr., and Snyderman, S. E.: The Amino Acid Requirements of Infants. l.A.M.A., 175:100, 1961. 11. Holt, L. E., Jr., McIntosh, R., and Barnett, H. L.: Pediatrics. 13th ed. New York, Appleton-Century-Crofts, Inc., 1962. 12. Jackson, D. S.: Some Biochemical Aspects of Fibrinogenesis and Wound Healing. New England J, Med., 259:814, 1958.

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13. Kaplan, S. A., Strauss, J., and Yuceoglu, A. M.: Use of a Fat Emulsion Infused Intravenously in Infants and Children. Pediatrics, 25:645, 1960. 14. Moncrief, 1. A., Caldwater, K. B., and Elman, R.: Postoperative Loss of Sugar in Urine Following Intravenous Infusion of Fructose. A.M.A. Arch. Surg., 67:57,1953. 15. Nelson, W. E.: Textbook of Pediatrics. 7th ed. Philadelphia, W. B. Saunders Company, 1959. 16. New Practical Standard Dictionary of the English Language. New York, Funk and Wagnalls Co., 1956. 17. Papper, S., Saxon, L., Prout, T. E., and Alpert, H. C.: The Effects of Cortisone on the Fructose and Glucose Tolerance Tests of Men. J. Lab. 6 Clin. Med., 48:13, 1956. 18. Pickering, D. E., Fisher, D. A., and West, E. S.: Fluid and Electrolyte Therapy: A Unified Approach. Portland, Ore., Medical Research Foundation, 1959. 19. Schulman, 1.: Iron Requirements in Infancy. J.A.M.A., 175:118, 1961. 20. Strauss, M. B., Rosenbaum, 1. D., and Nelson, W. P., III: The Effect of Alcohol on the Renal Excretion of Water and Electrolyte. J. Clin. Invest., 29:1053, 1950. 21. Talbot, N. B., Richie, R. H., and Crawford, 1. D.: Metabolic Homeostasis. Cam· bridge, Harvard University Press, 1959. 22. Wiese, H. F., Hansen, A. E., and Adam, D. 1.: Essential Fatty Acids in Infant Nutrition. 1. Linoleic Acid Requirement in Terms of Serum Di-, Tri- and Tetraenoic Acid Levels. J. Nutrition, 66:345, 1958. University of Arkansas Medical Center Little Rock, Ark.