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A study of premature infants fed cold formulas
556
The Journal of PEDIATRICS
A study of premature infants fed cold formulaJ The desirability of feeding infants with formulas warmed to the body temperature has been investigated in premature infants by controlled observations in which warmed formulas were compared with those given directly on removal from a refrigerator. Comparisons of the response to warmed or cold feedings in premature infants showed no significant difference.; in sleep patterns, vocalization, motility, intake of food or fluid, weight gain, or the regurgitation of food. The body temperature taken after [ceding was found to vary +1.2 ~ F. from the temperature before the feeding in both the cold and the warm formula groups. Within this range the variability was found to be somewhat greater in the cold formula group. The average postprandial temperature in the warm formula group was the same as the preprandial temperature; in the cold formula group it was decreased by 0.2 ~ F. The experiences in this study fail to demonstrate that the traditional procedure of warming the feeding is in any way advantageous to the infant.
L. E m m e t t Holt, Jr., M.D., "x"E d w a r d A. Davies, M.D., Eileen G. Hasselmeyer, M.A., R.N., and Apo|lonia O. Adams, M.A., R.N. NEW YORK~ N. Y.
T ~ E use of cold formulas in infant feeding is not altogether new. For some years French pediatricians 1 have used iced feedings in the treatment of vomiting. A single report in the American literature 2 deals with the response of normal infants to cold formulas with the conclusion that such feedings are acceptable to infants and lead to no untoward results. If the traditional procedure of heating the feeding to the body temperature
From the Pediatric Service, Bellevue Hospital, and Department of Pediatrics, New York University School of Medicine, New York City. ~Departent of Pediatrics, Nezv York University School of Medicine, 550 1st Avenue, New York 16, N. Y.
is indeed superfluous and carries no advantage to the infant, the saving of labor in infant care would be enormous. However, before accepting that conclusion it seemed desirable that the subject be studied in further detail and in the most critical manner possible. T h e observations which we wish to report were carried out in the premature unit of Bellevue Hospital. It was thought that if any differences existed in the results of warmed and cold feedings in the case of full-term infants, these should be more conspicuous and more readily detected in premature infants. During the winter of 1958 to 1959 two studies were carried out on the
Volume 61 Number 4
Cold [ormulas /or premature re]ants
premature unit with a somewhat different design. In the first study, a group of premature infants were placed for a period of 4 weeks on warm formulas. This was immediately followed by a similar 4 week period in which cold fornmlas were given to all. In this study, particular attention was focused on the behavior of the infants receiving the warm and the cold feedings. The methodologies employed were developed by the Division of Nursing of the United State; Public Health Service? A team of observers, trained by the Division of Nursing, was made availabl% and with their aid detailed observations on sleep, vocalization, and motor behavior were made every 10 minutes around the clock for periods of about 15 seconds. Such observations were made on 261 patient days of warm feedings and 197 patient days of cold feedings. Since patients were being admitted and discharged from the unit during these two periods, it follows that for the most part the subjects on warm feedings were not the same as those who received the cold feedings. There were, however, 7 subjects who were studied on both feedings; they were observed for the last three days of the warm formula period and on the succeeding 3 days after the changeover period to cold formulas. The data on these subjects are recorded separately. Apart
557
from these seven subjects who were studied on both types of formulas, it was thought that more valid data would be obtained if the comparisons were made on infants of comparable age and weight. Therefore, a selection was made of infants in the medium age and weight group. This netted a group of 15 infants fed warm formulas who were compared to a group of 11 infants fed cold formulas. The composite characteristics of these two groups is given in Table I. A second study was carried out with a somewhat different emphasis and design. In this study alternate babies were placed on warm and cold feedings upon which they were maintained and detailed observations were made on feeding behavior and on the body temperature before and after feeding. Measurements were made also of the temperature of the formulas as actually fed to the infants. This study was continued for 91 days, data being collected on 17 infants fed warm formulas and 16 fed cold formulas. Composite data of the subjects of this study are shown in Table II. RESULTS
Sleep, vocal, and motor behavior. Data on the behavior of the infants from the first study is shown graphically in Fig. 1 together with the code employed in studying these
Table I. First study
Group Warm formula Cold formula
No. o[ babies 15 11
Total patient days studied 261 197
Average birth weight (grams) 1,530 1,570
Average age at onset o[ study (days) 17.4 17.9
Average weight at onset o[ study (grams I 1,740 1,753
No. o[ [eedings studied 2,458 2,114
Average birth weight (grams) 1,610 1,627
Average age at onset o[ study (days) 16.1 13.0
Average weight at onset of study (grams) 1,728 1,722
Duration of study (days I 17.4 17.9
Average daily weight gain (grams) 31.7 30.3
Duration o[ study (days 1 22.7 21.2
Average daily weight gain (grams) 30.~ 30.9
Table II. Second study
Group Warm formula Cold formula
No. o[ babies ~ 17 16
-X'Exduded f r o m this study were 2 additional infants who developed iatcrcucrent infections. formula and the other on cold formuIa.
O n e of ~hese was on w a r m
558
October 1962
Holt et aI,
SLEEP
BEHAVIOR
,WARM FEEDINGS ( 261 PATIENT DAYS )
VOCAL
COLD FEEDINGS ( 197 PATIENT DAYS )
I00-
WARM FEEDINGS (261 PATIENT DAYS )
BEHAVIOR
MOTOR
COLD FEEDINGS (197 PATIENT DAYS )
BEHAVIOR
WARM FEEDINGS
COLD FEEDINGS ( 197 PATIENT DAYS
( 261 PATIENT DAYS )
5--
90807060-
co
5040-
Illllll
!!!!!!!
3020"
lllllll I
!!!!!!!
I0"
Illlkll
IIIIIIII
O"
R = HANDLED U = UNCERTAIN A = AWAKE S r APPARENTLY SLEEPING { EYES CLOSED)
SLEEP WARM FORMULA
ioo
_
!
BEHAVIOR COLD FORMULA
3 = CRYING 2 = WHIMPERING I= OCCASIONAL SOUND O= NO SOUND
VOCAL WARM FORMULA
3 = KICKING 2 = SLOW MOVEMENTS,STRETCHING I = OCCASIONAL MOVEMENT 0 = NO MOVEMENT
BEHAVIOR
MOTOR BEHAVIOR
COLD FORMULA
::::
Fig. 1. Sleep, vocal, and motor behavior of infants on warm and cold feedings.
WARM FORMULA
COLD FORMULA
3-
75
50 S
25
0 DAY OF TEST
DAY OF TEST"
DAY OF TEST
H = HANDLED U = UNCERTAIN A = AWAKE S = SLEEPING
3 = CRYING 2= WHIMPERING I= OCCASIONAL SOUND o = NO SOUND
3 = KICKING 2 = SLOW MOVEMENTS,STRETCHING I= OCCASIONAL MOVEMENT O=NO MOVEMENT
phenomena. The percentages shown in the different columns represent a total of 37,584 individual observations in the warm formula group and a total of 28,368 observations in the cold formula group. The difference between the two groups is not impressiv e . Statistical analyses of the figures show a significant difference at the 0.01 level in two particulars: In the cold feeding group there was a greater amount of handling and of bodily movement in the No. 2 category. We are inclined to attribute the greater percentage of wakefulness to the increased handling of the infants during the cold formula period which may have resulted from the lower census on the unit at this time, a factor which permitted more time for nursing procedures. In Fig. 2 are shown the composite data
Fig. 2. Sleep, vocal, and motor behavior of the seven infants during transition from w a r m to cold feedings.
obtained on the seven individual infants who were followed during the changeover period from warm to cold formulas, Here again no significant difference can be detected. Feeding behavior. Data on feeding were obtained from the second study in which 17 infants on warm formulas were compared with 16 infants on cold formulas. The observations on each infant were continued for at least a 10 day period. Feeding behavior was closely followed and recorded by the nurses on a check list. Such data were obtained on 2,380 warm feedings as compared with 2,060 cold feedings. The data are presented in Table III. The table fails to reveal any appreciable difference in feeding behavior. Food intake. The caloric intake of infants
Volume 61
Number 4
fed w a r m and cold formulas is shown in Fig. 3. T h e figures are most meaningful from the tenth to the thirty-first days where the sample is large enough for comparison, while above and below that range the smaller n u m b e r of observations makes the result less significant. Ninety-four per cent of the feedings were given by nipple, the remainder by gavage. Regurgitation. In the w a r m formula group 9 infants regurgitated 1 or more times as c o m p a r e d to 10 in the cold formula group. T h e number of episodes of regurgitation was 21 in the w a r m formula group as c o m p a r e d with 36 in the cold formula group. However, 16 of these 36 episodes occurred in a single infant who h a d a history of regurgitation since the fourth day of life. (He was placed on cold formula on the fifteenth day of life.) His frequency of regurgitation was the same on cold as on w a r m formula. Less than 1 per cent of the feedings in both groups were regurgitated, and it does not appear that valid conclusions can be drawn from the available data on this point. T e m p e r a t u r e of tile formula. Observations on the actual temperatures of the formulas as fed to infants were made in 50 cases in each group. This was done by preparing duplicate bottles which were handled identically and simultaneously in precisely the m a n n e r as the bottle given to the infant. At selected times before, during, and after the feeding the temperature of the formula in the duplicate bottle was recorded. All formulas were kept in a refrigerator, the temperature of which was maintained at 4 ~ C. T h e cold formulas were fed within a few minutes of being removed from the refrigerator. T h e w a r m formulas were heated by being placed in a hot water bath by the nurse; the temperature was tested in the usual way by allowing a drop to fall on the wrist. T h e temperature of the cold formulas at the onset of the feeding varied f r o m 7 ~ C. to 11 ~ C. and at the end of the feeding from 9 ~ to 17 ~ C. T h e w a r m e d formulas showed an unexpectedly wide range f r o m 34 ~ to 51 ~ C. at the start
Cold formulas for premature infants
559
of the feeding and from 30 ~ to 43 ~ C. a t the end. It thus appears that the usual technique for regulating the temperature of the warmed feeding does not prevent an undesirably w a r m feeding being given to the infant at times.
Temperature of the infant, before and after feeding. It might be anticipated that the introduction of a cold feeding into the stomach of an infant might result in a reduction in body temperature. Observations were made, therefore, of the axillary temperatures before and after feeding--2,458 observations being made on infants given WARM FORMULA GROUP l COLD FORMULA GROUP IE~
150"
I00"
,1 o 50.
O-
T
IO
i4
17
2(
24
28
31
r 9"I
8
35
AGE IN DAYS. NUMBERS OF SUBJECTS
'COLD A MI 6' I GO I 0--t I,~' I
f4
r
13 _
Fig. 3. Average daily caloric intake on selected days of life.
COLD FORMULA GROUP
I000-
WARM FORMULA GROUP O
0
800 -
600-
03 4 0 0 -
/
Z
~
/ i 200-
0
~
-112 " 4 1 0 - 0 ' , 8 - 0 ' , 6 - 0 1 4 - 0 1 2 A.C.-
0'.0
P.C. T E M P E R A T U R E
0.2
0,4
0,6
CHANGE
0,8
LO
1,2
(~
Fig. 4. Change in body temperature after feeding.
560
Holt et al.
October i962
T a b l e I I I . F e e d i n g b e h a v i o r ' of p r e m a t u r e infants receiving w a r m and cold formulas
Warm formula (2,380 [eedings)
Cold [ormula (2,060 feedings)
Behavior be[ore [eeding Awake, crying Awake, quiet Beginning to wake Sleeping
3'8.4 12.6 14.4 34.6
41.5 13.3 11.2 33.9
Behavior alter feeding AsIeep before returned to crib Asleep within 2 minutes Awake, quiet Awake, crying
24.2 22.6 50.4 2.8
29.5 24.5 44.2 1.8
Interest in feeding (first hail of [eeding) Anxious Alert, interested Alert, disinterested Not alert, interested Apathetic
56.2 35.7 2.4 4.7 1.0
54.2 34.1 2'.8 7.9 0.9
Interest in feeding (second hall o[ [ceding) Anxious Alert, interested Alert, disinterested Not alert, interested Apathetic
47.3 40.0 4.4 6.3 2.0
43.1 36.6 6.3 11.0 3.0
Time required to Iced (minutes) 5 or less 6 to 10 11 to 15 16 to 2'0 21 to 25 over 25
1.4 33.6 48.9 14.6 1.3 0.3
1.3 31.6 45.4 1'8.9 2.2 0.5
Type of feeding Evaporated milk formula Olae Other
65.5 34.3 0.2
62.3 37.7 0
(%)
w a r m feedings a n d 2,114 observations on those given cold feedings. T h e results are presented g r a p h i c a l l y in Fig. 4. I t a p p e a r s t h a t with either type of feeding the temp e r a t u r e m a y fluctuate within a range of -+ 1.2 ~ F. f r o m the p r e p r a n d i a l figure. In the case of the w a r m e d feedings the freq u e n c y curve of elevated a n d r e d u c e d temp e r a t u r e s was a b o u t equal, the m e a n temp e r a t u r e being the same after the feeding as before. I n the case of the cold feedings the m e a n t e m p e r a t u r e was 0.2 ~ F. lower than t h a t before the feeding. T h e v a r i a b i l i t y of the t e m p e r a t u r e change was g r e a t e r in the cold feeding series t h a n in the w a r m
(%)
feeding series (t test ~ 2.6 for the w a r m e d feedings, 47.1 for the cold feedings, both tests being significant at the 0.01 level). I n neither group, however, d i d the v a r i a t i o n exceed 1.2 ~ F. SUMMARY
1. T h e desirability of feeding infants with formulas w a r m e d to the body t e m p e r a t u r e has been investigated in p r e m a t u r e infants. Controlled observations have been m a d e in which w a r m e d formulas were c o m p a r e d with those fed directly on r e m o v a l from a refrigerator. 2. Q u a n t i t a t i v e m e t h o d s have been devel-
Volume 61 Number 4
oped for assessing the behavior of premature infants--their motility, vocalization, sleep patterns, and feeding behavior. 3. Comparisons of warmed and cold feedings in premature infants showed negligible differences in 'their sleep patterns, vocalization, and motility. Significant differences in the intake of food or fluid, the weight gain, and in the regurgitation of food were not observed. 4. T h e body temperature taken after feeding was found to vary _+1.2~ F. from the temperature before the feeding in both the cold and the warm formula groups. Within this range the variability was found to be somewhat greater in the cold formula group. T h e average postprandial temperature in the w a r m formula group was the same as the preprandial temperature; in the cold formula group it was decreased by 0.2 ~ F. 5. The observations presented in this study were submitted to statistical analysis, significant differences between the w a r m and the cold feeding group being found only in
Cold [ormulas [or premature in[ants
561
the case of the body temperature as mentioned above. 6. T h e experiences in this study fail to demonstrate that the traditional procedure of warming the feeding is in any way advantageous to the infant.
We should like to express our indebtedness to the nursing staff of the Bellevue Premature Unit and to the team of observers from the Division of Nursing, United States Public Health Service, who made this study possible, Statistical analysis of the data was done by the Statistics and Analysis Branch of the Division of Nursing of the United States Public Health Service. REFERENCES
Woringer, Pierre (Strasbourg): Personal communication. Gibson, J. P.: Reaction of 150 infants to cold formulas, J. PEDIAT. 52: 404, 1958. Hasselmeyer, E. G.: Behavior patterns of premature infants, Public Health Service publication No. 840, Washington, D. C., 1961, United States Department of Health, Education, and Welfare.
The Journal of PEDIATRICS
A study of premature infants fed cold formulaJ The desirability of feeding infants with formulas warmed to the body temperature has been investigated in premature infants by controlled observations in which warmed formulas were compared with those given directly on removal from a refrigerator. Comparisons of the response to warmed or cold feedings in premature infants showed no significant difference.; in sleep patterns, vocalization, motility, intake of food or fluid, weight gain, or the regurgitation of food. The body temperature taken after [ceding was found to vary +1.2 ~ F. from the temperature before the feeding in both the cold and the warm formula groups. Within this range the variability was found to be somewhat greater in the cold formula group. The average postprandial temperature in the warm formula group was the same as the preprandial temperature; in the cold formula group it was decreased by 0.2 ~ F. The experiences in this study fail to demonstrate that the traditional procedure of warming the feeding is in any way advantageous to the infant.
L. E m m e t t Holt, Jr., M.D., "x"E d w a r d A. Davies, M.D., Eileen G. Hasselmeyer, M.A., R.N., and Apo|lonia O. Adams, M.A., R.N. NEW YORK~ N. Y.
T ~ E use of cold formulas in infant feeding is not altogether new. For some years French pediatricians 1 have used iced feedings in the treatment of vomiting. A single report in the American literature 2 deals with the response of normal infants to cold formulas with the conclusion that such feedings are acceptable to infants and lead to no untoward results. If the traditional procedure of heating the feeding to the body temperature
From the Pediatric Service, Bellevue Hospital, and Department of Pediatrics, New York University School of Medicine, New York City. ~Departent of Pediatrics, Nezv York University School of Medicine, 550 1st Avenue, New York 16, N. Y.
is indeed superfluous and carries no advantage to the infant, the saving of labor in infant care would be enormous. However, before accepting that conclusion it seemed desirable that the subject be studied in further detail and in the most critical manner possible. T h e observations which we wish to report were carried out in the premature unit of Bellevue Hospital. It was thought that if any differences existed in the results of warmed and cold feedings in the case of full-term infants, these should be more conspicuous and more readily detected in premature infants. During the winter of 1958 to 1959 two studies were carried out on the
Volume 61 Number 4
Cold [ormulas /or premature re]ants
premature unit with a somewhat different design. In the first study, a group of premature infants were placed for a period of 4 weeks on warm formulas. This was immediately followed by a similar 4 week period in which cold fornmlas were given to all. In this study, particular attention was focused on the behavior of the infants receiving the warm and the cold feedings. The methodologies employed were developed by the Division of Nursing of the United State; Public Health Service? A team of observers, trained by the Division of Nursing, was made availabl% and with their aid detailed observations on sleep, vocalization, and motor behavior were made every 10 minutes around the clock for periods of about 15 seconds. Such observations were made on 261 patient days of warm feedings and 197 patient days of cold feedings. Since patients were being admitted and discharged from the unit during these two periods, it follows that for the most part the subjects on warm feedings were not the same as those who received the cold feedings. There were, however, 7 subjects who were studied on both feedings; they were observed for the last three days of the warm formula period and on the succeeding 3 days after the changeover period to cold formulas. The data on these subjects are recorded separately. Apart
557
from these seven subjects who were studied on both types of formulas, it was thought that more valid data would be obtained if the comparisons were made on infants of comparable age and weight. Therefore, a selection was made of infants in the medium age and weight group. This netted a group of 15 infants fed warm formulas who were compared to a group of 11 infants fed cold formulas. The composite characteristics of these two groups is given in Table I. A second study was carried out with a somewhat different emphasis and design. In this study alternate babies were placed on warm and cold feedings upon which they were maintained and detailed observations were made on feeding behavior and on the body temperature before and after feeding. Measurements were made also of the temperature of the formulas as actually fed to the infants. This study was continued for 91 days, data being collected on 17 infants fed warm formulas and 16 fed cold formulas. Composite data of the subjects of this study are shown in Table II. RESULTS
Sleep, vocal, and motor behavior. Data on the behavior of the infants from the first study is shown graphically in Fig. 1 together with the code employed in studying these
Table I. First study
Group Warm formula Cold formula
No. o[ babies 15 11
Total patient days studied 261 197
Average birth weight (grams) 1,530 1,570
Average age at onset o[ study (days) 17.4 17.9
Average weight at onset o[ study (grams I 1,740 1,753
No. o[ [eedings studied 2,458 2,114
Average birth weight (grams) 1,610 1,627
Average age at onset o[ study (days) 16.1 13.0
Average weight at onset of study (grams) 1,728 1,722
Duration of study (days I 17.4 17.9
Average daily weight gain (grams) 31.7 30.3
Duration o[ study (days 1 22.7 21.2
Average daily weight gain (grams) 30.~ 30.9
Table II. Second study
Group Warm formula Cold formula
No. o[ babies ~ 17 16
-X'Exduded f r o m this study were 2 additional infants who developed iatcrcucrent infections. formula and the other on cold formuIa.
O n e of ~hese was on w a r m
558
October 1962
Holt et aI,
SLEEP
BEHAVIOR
,WARM FEEDINGS ( 261 PATIENT DAYS )
VOCAL
COLD FEEDINGS ( 197 PATIENT DAYS )
I00-
WARM FEEDINGS (261 PATIENT DAYS )
BEHAVIOR
MOTOR
COLD FEEDINGS (197 PATIENT DAYS )
BEHAVIOR
WARM FEEDINGS
COLD FEEDINGS ( 197 PATIENT DAYS
( 261 PATIENT DAYS )
5--
90807060-
co
5040-
Illllll
!!!!!!!
3020"
lllllll I
!!!!!!!
I0"
Illlkll
IIIIIIII
O"
R = HANDLED U = UNCERTAIN A = AWAKE S r APPARENTLY SLEEPING { EYES CLOSED)
SLEEP WARM FORMULA
ioo
_
!
BEHAVIOR COLD FORMULA
3 = CRYING 2 = WHIMPERING I= OCCASIONAL SOUND O= NO SOUND
VOCAL WARM FORMULA
3 = KICKING 2 = SLOW MOVEMENTS,STRETCHING I = OCCASIONAL MOVEMENT 0 = NO MOVEMENT
BEHAVIOR
MOTOR BEHAVIOR
COLD FORMULA
::::
Fig. 1. Sleep, vocal, and motor behavior of infants on warm and cold feedings.
WARM FORMULA
COLD FORMULA
3-
75
50 S
25
0 DAY OF TEST
DAY OF TEST"
DAY OF TEST
H = HANDLED U = UNCERTAIN A = AWAKE S = SLEEPING
3 = CRYING 2= WHIMPERING I= OCCASIONAL SOUND o = NO SOUND
3 = KICKING 2 = SLOW MOVEMENTS,STRETCHING I= OCCASIONAL MOVEMENT O=NO MOVEMENT
phenomena. The percentages shown in the different columns represent a total of 37,584 individual observations in the warm formula group and a total of 28,368 observations in the cold formula group. The difference between the two groups is not impressiv e . Statistical analyses of the figures show a significant difference at the 0.01 level in two particulars: In the cold feeding group there was a greater amount of handling and of bodily movement in the No. 2 category. We are inclined to attribute the greater percentage of wakefulness to the increased handling of the infants during the cold formula period which may have resulted from the lower census on the unit at this time, a factor which permitted more time for nursing procedures. In Fig. 2 are shown the composite data
Fig. 2. Sleep, vocal, and motor behavior of the seven infants during transition from w a r m to cold feedings.
obtained on the seven individual infants who were followed during the changeover period from warm to cold formulas, Here again no significant difference can be detected. Feeding behavior. Data on feeding were obtained from the second study in which 17 infants on warm formulas were compared with 16 infants on cold formulas. The observations on each infant were continued for at least a 10 day period. Feeding behavior was closely followed and recorded by the nurses on a check list. Such data were obtained on 2,380 warm feedings as compared with 2,060 cold feedings. The data are presented in Table III. The table fails to reveal any appreciable difference in feeding behavior. Food intake. The caloric intake of infants
Volume 61
Number 4
fed w a r m and cold formulas is shown in Fig. 3. T h e figures are most meaningful from the tenth to the thirty-first days where the sample is large enough for comparison, while above and below that range the smaller n u m b e r of observations makes the result less significant. Ninety-four per cent of the feedings were given by nipple, the remainder by gavage. Regurgitation. In the w a r m formula group 9 infants regurgitated 1 or more times as c o m p a r e d to 10 in the cold formula group. T h e number of episodes of regurgitation was 21 in the w a r m formula group as c o m p a r e d with 36 in the cold formula group. However, 16 of these 36 episodes occurred in a single infant who h a d a history of regurgitation since the fourth day of life. (He was placed on cold formula on the fifteenth day of life.) His frequency of regurgitation was the same on cold as on w a r m formula. Less than 1 per cent of the feedings in both groups were regurgitated, and it does not appear that valid conclusions can be drawn from the available data on this point. T e m p e r a t u r e of tile formula. Observations on the actual temperatures of the formulas as fed to infants were made in 50 cases in each group. This was done by preparing duplicate bottles which were handled identically and simultaneously in precisely the m a n n e r as the bottle given to the infant. At selected times before, during, and after the feeding the temperature of the formula in the duplicate bottle was recorded. All formulas were kept in a refrigerator, the temperature of which was maintained at 4 ~ C. T h e cold formulas were fed within a few minutes of being removed from the refrigerator. T h e w a r m formulas were heated by being placed in a hot water bath by the nurse; the temperature was tested in the usual way by allowing a drop to fall on the wrist. T h e temperature of the cold formulas at the onset of the feeding varied f r o m 7 ~ C. to 11 ~ C. and at the end of the feeding from 9 ~ to 17 ~ C. T h e w a r m e d formulas showed an unexpectedly wide range f r o m 34 ~ to 51 ~ C. at the start
Cold formulas for premature infants
559
of the feeding and from 30 ~ to 43 ~ C. a t the end. It thus appears that the usual technique for regulating the temperature of the warmed feeding does not prevent an undesirably w a r m feeding being given to the infant at times.
Temperature of the infant, before and after feeding. It might be anticipated that the introduction of a cold feeding into the stomach of an infant might result in a reduction in body temperature. Observations were made, therefore, of the axillary temperatures before and after feeding--2,458 observations being made on infants given WARM FORMULA GROUP l COLD FORMULA GROUP IE~
150"
I00"
,1 o 50.
O-
T
IO
i4
17
2(
24
28
31
r 9"I
8
35
AGE IN DAYS. NUMBERS OF SUBJECTS
'COLD A MI 6' I GO I 0--t I,~' I
f4
r
13 _
Fig. 3. Average daily caloric intake on selected days of life.
COLD FORMULA GROUP
I000-
WARM FORMULA GROUP O
0
800 -
600-
03 4 0 0 -
/
Z
~
/ i 200-
0
~
-112 " 4 1 0 - 0 ' , 8 - 0 ' , 6 - 0 1 4 - 0 1 2 A.C.-
0'.0
P.C. T E M P E R A T U R E
0.2
0,4
0,6
CHANGE
0,8
LO
1,2
(~
Fig. 4. Change in body temperature after feeding.
560
Holt et al.
October i962
T a b l e I I I . F e e d i n g b e h a v i o r ' of p r e m a t u r e infants receiving w a r m and cold formulas
Warm formula (2,380 [eedings)
Cold [ormula (2,060 feedings)
Behavior be[ore [eeding Awake, crying Awake, quiet Beginning to wake Sleeping
3'8.4 12.6 14.4 34.6
41.5 13.3 11.2 33.9
Behavior alter feeding AsIeep before returned to crib Asleep within 2 minutes Awake, quiet Awake, crying
24.2 22.6 50.4 2.8
29.5 24.5 44.2 1.8
Interest in feeding (first hail of [eeding) Anxious Alert, interested Alert, disinterested Not alert, interested Apathetic
56.2 35.7 2.4 4.7 1.0
54.2 34.1 2'.8 7.9 0.9
Interest in feeding (second hall o[ [ceding) Anxious Alert, interested Alert, disinterested Not alert, interested Apathetic
47.3 40.0 4.4 6.3 2.0
43.1 36.6 6.3 11.0 3.0
Time required to Iced (minutes) 5 or less 6 to 10 11 to 15 16 to 2'0 21 to 25 over 25
1.4 33.6 48.9 14.6 1.3 0.3
1.3 31.6 45.4 1'8.9 2.2 0.5
Type of feeding Evaporated milk formula Olae Other
65.5 34.3 0.2
62.3 37.7 0
(%)
w a r m feedings a n d 2,114 observations on those given cold feedings. T h e results are presented g r a p h i c a l l y in Fig. 4. I t a p p e a r s t h a t with either type of feeding the temp e r a t u r e m a y fluctuate within a range of -+ 1.2 ~ F. f r o m the p r e p r a n d i a l figure. In the case of the w a r m e d feedings the freq u e n c y curve of elevated a n d r e d u c e d temp e r a t u r e s was a b o u t equal, the m e a n temp e r a t u r e being the same after the feeding as before. I n the case of the cold feedings the m e a n t e m p e r a t u r e was 0.2 ~ F. lower than t h a t before the feeding. T h e v a r i a b i l i t y of the t e m p e r a t u r e change was g r e a t e r in the cold feeding series t h a n in the w a r m
(%)
feeding series (t test ~ 2.6 for the w a r m e d feedings, 47.1 for the cold feedings, both tests being significant at the 0.01 level). I n neither group, however, d i d the v a r i a t i o n exceed 1.2 ~ F. SUMMARY
1. T h e desirability of feeding infants with formulas w a r m e d to the body t e m p e r a t u r e has been investigated in p r e m a t u r e infants. Controlled observations have been m a d e in which w a r m e d formulas were c o m p a r e d with those fed directly on r e m o v a l from a refrigerator. 2. Q u a n t i t a t i v e m e t h o d s have been devel-
Volume 61 Number 4
oped for assessing the behavior of premature infants--their motility, vocalization, sleep patterns, and feeding behavior. 3. Comparisons of warmed and cold feedings in premature infants showed negligible differences in 'their sleep patterns, vocalization, and motility. Significant differences in the intake of food or fluid, the weight gain, and in the regurgitation of food were not observed. 4. T h e body temperature taken after feeding was found to vary _+1.2~ F. from the temperature before the feeding in both the cold and the warm formula groups. Within this range the variability was found to be somewhat greater in the cold formula group. T h e average postprandial temperature in the w a r m formula group was the same as the preprandial temperature; in the cold formula group it was decreased by 0.2 ~ F. 5. The observations presented in this study were submitted to statistical analysis, significant differences between the w a r m and the cold feeding group being found only in
Cold [ormulas [or premature in[ants
561
the case of the body temperature as mentioned above. 6. T h e experiences in this study fail to demonstrate that the traditional procedure of warming the feeding is in any way advantageous to the infant.
We should like to express our indebtedness to the nursing staff of the Bellevue Premature Unit and to the team of observers from the Division of Nursing, United States Public Health Service, who made this study possible, Statistical analysis of the data was done by the Statistics and Analysis Branch of the Division of Nursing of the United States Public Health Service. REFERENCES
Woringer, Pierre (Strasbourg): Personal communication. Gibson, J. P.: Reaction of 150 infants to cold formulas, J. PEDIAT. 52: 404, 1958. Hasselmeyer, E. G.: Behavior patterns of premature infants, Public Health Service publication No. 840, Washington, D. C., 1961, United States Department of Health, Education, and Welfare.