- Email: [email protected]
Heat Loss Prevention (HeLP) in the delivery room: A randomized controlled trial of polyethylene occlusive skin wrapping in very preterm infants
HEAT LOSS PREVENTION (HELP) IN THE DELIVERY ROOM: A RANDOMIZED CONTROLLED TRIAL OF POLYETHYLENE OCCLUSIVE SKIN WRAPPING IN VERY PRETERM INFANTS SUNITA VOHRA, MD, MSC, ROBIN S. ROBERTS, MSC, BO ZHANG, MPH, MARIANNE JANES, MHSC, AND BARBARA SCHMIDT, MD, MSC
Objectives To determine if polyethylene occlusive skin wrapping of very preterm infants prevents heat loss after delivery better than conventional drying and to evaluate if any benefit is sustained after wrap removal. Study design This was a randomized controlled trial of infants <28 weeks’ gestation. The experimental group was wrapped from the neck down. Only the head was dried. Control infants were dried completely. Rectal temperatures were compared on admission to the neonatal intensive care unit immediately after wrap removal and 1 hour later. Results Of 55 infants randomly assigned (28 wrap, 27 control), 2 died in the delivery room and 53 completed the study. Wrapped infants had a higher mean rectal admission temperature, 36.5C (SD, 0.8C), compared with 35.6C (SD, 1.3C) in control infants (P = .002). One hour later, mean rectal temperatures were similar in both groups (36.6C, SD, 0.7C vs 36.4C, SD, 0.9C, P = .4). Size at birth was an important determinant of heat loss: Mean rectal admission temperature increased by 0.21C (95% CI, 0.04 to 0.4) with each 100-g increase in birth weight. Conclusions Polyethylene occlusive skin wrapping prevents rather than delays heat loss at delivery in very preterm infants. (J Pediatr 2004;145:750-3)
ery small and preterm infants need special thermal protection at birth.1,2 To reduce heat loss after delivery, it is recommended to rapidly dry the infant under a radiant warmer.3 Occlusive wrapping of the wet body in polyethylene is superior to conventional drying in reducing the postnatal fall of body temperature in very low birth weight infants.4 A subgroup analysis suggested that this beneficial effect of the wrap was limited to infants <28 weeks’ gestation.4 We conducted a randomized, controlled trial in very preterm infants to confirm these findings. We also measured body temperature 1 hour after admission to the Neonatal Intensive Care Unit (NICU) and wrap removal to evaluate whether polyethylene occlusive skin wrapping prevents or merely delays postnatal heat loss.
V
METHODS Setting and Participants The Heat Loss Prevention (HeLP) study was conducted at McMaster University Medical Center in Hamilton, Ontario, Canada, from February 1999 to March 2000. Infants <28 weeks’ gestation were potentially eligible if they were born in the study center. Infants whose delivery was not attended by the neonatal team were excluded from enrollment. The protocol also prescribed that infants were to be excluded if they had major congenital anomalies that were not covered by skin (eg, gastroschisis, meningomyelocele) or if they had blistering skin conditions. The Research Ethics Board of McMaster University and Hamilton Health Sciences approved this study. The Research Ethics Board allowed enrollment without prior informed consent from parents because of the emergent, unanticipated nature of most of these deliveries and because of the need to administer the skin wrap immediately after birth. The research intervention involved a very minimal risk
HeLP
750
Heat Loss Prevention study
NICU
Neonatal intensive care unit
See editorial, p 720.
From the Departments of Pediatrics and Clinical Epidemiology and Biostatistics, McMaster University, the Children’s Hospital of Hamilton Health Sciences, Hamilton, Ontario, Canada. Dr Vohra is now with the Department of Pediatrics, Stollery Children’s Hospital, University of Alberta, Edmonton, Alberta, Canada. Supported by the Neonatal Resuscitation Program of the American Academy of Pediatrics. Submitted for publication Mar 20, 2004; last revision received Jun 22, 2004; accepted Jul 16, 2004. Reprint requests: Dr Barbara Schmidt, HSC 3N11E, 1200 Main Street West, McMaster University, Hamilton, Ontario, Canada L8N 3Z5. E-mail: [email protected]. 0022-3476/$ - see front matter Copyright ª 2004 Elsevier Inc. All rights reserved. 10.1016/j.jpeds.2004.07.036
Table I. Baseline characteristics of infants and their mothers
Characteristics
Figure 1. Flow of participants through screening stage, enrollment, and completion of the study protocol.
to the study patients and was well accepted by the clinical staff. The parents of all study infants received a Parent Information Form after the initial stabilization of their baby that explained the study purpose and methods.
Interventions All infants were stabilized in the delivery room under radiant warmers (Air-Shields Model IICS 90). The radiant warmers were preheated by using a 5% dextrose intravenous bag as a ‘‘phantom’’ and set to manual control with maximum output. Infants in the control (nonwrap) group were dried completely, according to the International Guidelines for Neonatal Resuscitation.3 For infants in the wrap group, a polyethylene bag was opened under the radiant warmer, the infant was placed on the bag from the shoulders down, and the entire body was wrapped.4 Only the head was dried. The polyethylene bags measured 20 cm by 50 cm and were manufactured by Eastern Paper, a Division of EPC Industries Ltd. Oxygenation, bag-mask ventilation, endotracheal intubation, and chest compressions were initiated in the delivery room as appropriate; more extensive stabilization including vascular access was performed in the NICU, which was immediately adjacent to the delivery room suite. All infants were carried by one member of the neonatal team from the delivery room into the NICU and placed in a single walled incubator with 60% humidity (Ohmeda/Ohio Medical Care Plus). At this point, the wrap was removed in the experimental group.
Mothers Racial or ethnic background, n (%) White Black Asian Other or unknown Route of delivery, n (%) Vaginal, no forceps or vacuum Vaginal, with forceps or vacuum Caesarean Epidural/spinal, n (%) Antenatal steroid, n (%) Time of membranes rupture (h), mean ± SD Infants Birth weight (g), mean ± SD Gestational age (wk), mean ± SD Female sex, n (%) Multiple birth, n (%) Umbilical cord pH, mean ± SD Venous Arterial
Wrap group (n = 28)
25 (89) 2 (7)
Control group (n = 27)
1 (4)
20 (74) 3 (11) 2 (7) 2 (7)
10 (36) 1 (4) 17 (61) 18 (64) 26 (93) 38 ± 35
15 (56) 1 (4) 11 (41) 18 (67) 23 (85) 52 ± 89
858 ± 199 26 ± 1.5 14 (50) 13 (46)
825 ± 270 26 ± 1.4 13 (48) 5 (19)
7.26 ± 0.17 7.27 ± 0.12
7.33 ± 0.07 7.26 ± 0.08
Outcomes The primary outcome measure was rectal temperature taken on admission to the NICU (immediately after wrap removal in wrapped infants) and again 1 hour later. Rectal temperature was measured with a digital rectal thermometer (IVAC Temp Plus II electronic thermometers, ALARIS Medical Systems Inc, San Diego, Calif ). Death from all causes before discharge was the secondary outcome. APGAR scores, first blood gas analysis, and first serum glucose concentration after admission were also recorded.
Sample Size In the previous trial of this intervention, the subgroup of 18 infants <28 weeks’ gestation had a pooled SD of 0.9C.4 We considered a mean difference of this magnitude to be clinically important. To detect a mean difference of 0.9C in core temperature required the enrollment of 23 infants per treatment group, for an a of 0.05 (2-tailed) and 90% power. To allow for infants who failed to complete the study protocol because of death in the delivery room, we planned to recruit at least 50 patients.
Random Assignment Eligible infants were assigned to the polyethylene wrap group or the control group, according to a computergenerated, randomized sequence balanced in blocks of 4
Heat Loss Prevention (Help) in the Delivery Room: A Randomized Controlled Trial of Polyethylene Occlusive Skin Wrapping in Very Preterm Infants
751
Table II. Outcomes Wrap group (n = 27)
Control group (n = 26)
P value
36.5 ± 0.8 36.6 ± 0.7
35.6 ± 1.3 36.4 ± 0.9
0.002 0.4
7 (25.0)
8 (29.6)
0.8
6 2–6
6 3-6
0.6
7 6–8 7.32 ± 0.12 20.5 ± 4.0 2.5 ± 1.1
7 7-8 7.36 ± 0.12 19.5 ± 2.8 2.8 ± 1.8
0.9
Primary outcome, rectal temperature (C) At NICU admission, mean ± SD One hour after NICU admission, mean ± SD Secondary outcomes Death, n (%)* APGAR score at 1 min Median Interquartile range APGAR score at 5 min Median Interquartile range Blood gas pH, mean ± SD Bicarbonate (mmol/L), mean ± SD Glucose (mmol/L), mean ± SD
0.3 0.3 0.5
*Death rate was calculated on the basis of 28 infants in the wrap group and 27 infants in the control group.
subjects. The randomized allocation was concealed in double-enclosed, opaque, sealed, and sequentially numbered envelopes. In the delivery room, the next sequential randomization envelope was opened only if the infant was found to be eligible by the neonatal team. The assigned procedure (wrap or no-wrap) was then performed. Multiple eligible births were separately randomized.
Statistical Methods The mean temperature after NICU admission and 1 hour later were compared between the two groups by means of a 2-sided Wilcoxon rank sum test. Comparisons of mean temperature were also conducted after adjustment (by multiple linear regression) for imbalances in a number of potentially prognostic baseline variables. The mortality rates in both groups were compared by Fisher exact test.
RESULTS
in rectal temperature between the two groups (Table II). After adjustment for potentially important baseline variables, that is, early membrane rupture, delivery route, sex, birth weight, and gestational age, the mean temperature advantage in the wrap group on admission to the NICU remained essentially unchanged. Of these variables, only birth weight influenced the amount of heat loss in the delivery room (P = .02, Figure 2). The regression model suggested that the mean rectal temperature on admission to the NICU increased by 0.21C (95% CI, 0.04 to 0.4) with each 100-g increase in birth weight. Median APGAR scores, first mean blood pH, and first mean serum glucose concentrations were comparable in both groups (Table II). Two infants died in the delivery room and 13 infants died after admission to the NICU. Mortality rates before discharge were similar in wrapped and control infants (Table II). Median (min-max) age at death was 4 days (0 to11) in the wrap group and 5 days (0 to27) in control infants. Rectal temperature at NICU admission had been below 36.5C in 2 of 6 deaths in the wrap group, compared with 7 of 7 deaths in the control group.
Participant Flow Figure 1 summarizes the flow of participants through the screening stage, enrollment, and completion of the study protocol. One infant who was randomly assigned to the nowrap group was wrapped in error but analyzed according to the intended treatment. All patients were followed until death or discharge, whichever occurred first. Table I shows that the baseline characteristics of the infants and their mothers were similar in both groups.
Outcomes The mean rectal temperature on admission to the NICU was significantly higher in infants who were wrapped compared with infants who received standard care (Table II). One hour later, there was no significant difference 752
Vohra et al
Adverse Events The wrap procedure was well accepted by the neonatal staff and did not interfere with resuscitation in the delivery room. Two infants had a rectal temperature on admission above 37.5C (Figure 2). Both infants had been assigned to the wrap group.
DISCUSSION We have confirmed that polyethylene occlusive skin wrapping of very preterm infants immediately after birth provides better thermal protection in the delivery room than conventional drying. Moreover, we have shown that wrapping The Journal of Pediatrics December 2004
Size at birth is an important determinant of admission temperature.4,5,7 In the current study, mean rectal temperature on admission to the NICU increased by 0.21C (95% CI, 0.04 to 0.4) with each 100-g increase in birth weight. It follows that the smallest and most immature infants are most in need of special thermal protection at birth and that this population of infants probably will benefit the most from polyethylene occlusive skin wrapping. Several recent reports suggest that clinicians have begun to use this method of thermal protection in very preterm and very low birth weight infants.5,8-11 Hypothermia immediately after birth in extremely preterm infants was associated with a reduced chance of survival in the EPICure study.7 In the HeLP trial, rates of survival to discharge from hospital were similar in both groups. This is in contrast to the previous randomized study in which all 5 deaths occurred in the nonwrap group.4 Of note, we did not design this trial with mortality as the primary outcome. Therefore, we were capable to detect only very large relative reductions in death risk. Given the observed pooled mortality rate of 27% in this trial, we would have needed to study more than 1200 infants to detect a 25% relative reduction in the risk of death.
REFERENCES
Figure 2. Relation between birth weight and admission temperature for infants in wrap (1) and control (o) groups.
prevents rather than just delays heat loss after very preterm birth. Wrapped infants maintained their core temperature after admission to the NICU and after wrap removal in a closed incubator. The HeLP study is the second randomized trial of this intervention. We previously reported that polyethylene occlusive skin wrapping at delivery reduces the postnatal fall of body temperature.4 A subgroup analysis of this trial suggested that the difference in mean rectal temperature on admission was 1.9C in infants <28 weeks’ gestation.4 In the present study, in which we included only infants <28 weeks’ gestation, wrapping increased the mean rectal temperature on admission to the NICU by 0.9C. The risk of overheating is a potential concern when using the polyethylene wrap.5 We were reassured to find in the HeLP study that only 2 of 27 infants in the wrap group (7%) had rectal temperatures on admission to the NICU that were above the normal range of 36.5 to 37.5C. However, great care should be taken to avoid hyperthermia, especially in those infants who are at risk of hypoxic-ischemic encephalopathy.6
1. Sinclair JC. Management of the thermal environment. In: Sinclair JC, Bracken MB, eds. Effective care of the newborn infant. New York: Oxford University Press; 1992. p. 40-58. 2. Hey E. Thermoregulation. In: Avery GB, Fletcher MA, MacDonald MG, eds. Neonatology: Pathophysiology and Management of the Newborn. 4th ed. Philadelphia: JB Lippincott Company; 1994. p. 357-65. 3. Niermeyer S, Kattwinkel J, Van Reempts P, Nadkarni V, Phillips B, Zideman D, et al. International Guidelines for Neonatal Resuscitation: an excerpt from the guidelines 2000 for cardiopulmonary resuscitation and emergency cardiovascular care: International Consensus on Science. Pediatrics 2000;106:E29. 4. Vohra S, Frent G, Campbell V, Abbott M, Whyte R. Effect of polyethylene occlusive skin wrapping on heat loss in very low birth weight infants at delivery: a randomized trial. J Pediatr 1999;134:547-51. 5. Newton T, Watkinson M. Preventing hypothermia at birth in preterm babies: at a cost of overheating some? Arch Dis Child Fetal Neonatal Ed 2003; 88:F256. 6. Gunn AJ, Bennet L. Is temperature important in delivery room resuscitation? Semin Neonatol 2001;6:241-9. 7. Costeloe K, Hennessy E, Gibson AT, Marlow N, Wilkinson AR, for the EPICure Study Group . The EPICure study: outcomes to discharge from hospital for infants born at the threshold of viability. Pediatrics 2000;106: 659-71. 8. Bjo¨rklund LJ, Hellstro¨m-Westas L. Reducing heat loss at birth in very preterm infants. J Pediatr 2000;137:739-40. 9. Lenclen R, Mazraani M, Jugie M, Couderc S, Hoenn E, Carbajal R, et al. Use of a polyethylene bag: a way to improve the thermal environment of the premature newborn at the delivery room. Arch Pediatr 2002;9:238-44. 10. Meyer MP. Swaddling and heat loss. Arch Dis Child Fetal Neonatal Ed 2003;88:F256. 11. Lyon AJ, Stenson B. Cold comfort for babies. Arch Dis Child Fetal Neonatal Ed 2004;89:F93-4.
Heat Loss Prevention (Help) in the Delivery Room: A Randomized Controlled Trial of Polyethylene Occlusive Skin Wrapping in Very Preterm Infants
753
Objectives To determine if polyethylene occlusive skin wrapping of very preterm infants prevents heat loss after delivery better than conventional drying and to evaluate if any benefit is sustained after wrap removal. Study design This was a randomized controlled trial of infants <28 weeks’ gestation. The experimental group was wrapped from the neck down. Only the head was dried. Control infants were dried completely. Rectal temperatures were compared on admission to the neonatal intensive care unit immediately after wrap removal and 1 hour later. Results Of 55 infants randomly assigned (28 wrap, 27 control), 2 died in the delivery room and 53 completed the study. Wrapped infants had a higher mean rectal admission temperature, 36.5C (SD, 0.8C), compared with 35.6C (SD, 1.3C) in control infants (P = .002). One hour later, mean rectal temperatures were similar in both groups (36.6C, SD, 0.7C vs 36.4C, SD, 0.9C, P = .4). Size at birth was an important determinant of heat loss: Mean rectal admission temperature increased by 0.21C (95% CI, 0.04 to 0.4) with each 100-g increase in birth weight. Conclusions Polyethylene occlusive skin wrapping prevents rather than delays heat loss at delivery in very preterm infants. (J Pediatr 2004;145:750-3)
ery small and preterm infants need special thermal protection at birth.1,2 To reduce heat loss after delivery, it is recommended to rapidly dry the infant under a radiant warmer.3 Occlusive wrapping of the wet body in polyethylene is superior to conventional drying in reducing the postnatal fall of body temperature in very low birth weight infants.4 A subgroup analysis suggested that this beneficial effect of the wrap was limited to infants <28 weeks’ gestation.4 We conducted a randomized, controlled trial in very preterm infants to confirm these findings. We also measured body temperature 1 hour after admission to the Neonatal Intensive Care Unit (NICU) and wrap removal to evaluate whether polyethylene occlusive skin wrapping prevents or merely delays postnatal heat loss.
V
METHODS Setting and Participants The Heat Loss Prevention (HeLP) study was conducted at McMaster University Medical Center in Hamilton, Ontario, Canada, from February 1999 to March 2000. Infants <28 weeks’ gestation were potentially eligible if they were born in the study center. Infants whose delivery was not attended by the neonatal team were excluded from enrollment. The protocol also prescribed that infants were to be excluded if they had major congenital anomalies that were not covered by skin (eg, gastroschisis, meningomyelocele) or if they had blistering skin conditions. The Research Ethics Board of McMaster University and Hamilton Health Sciences approved this study. The Research Ethics Board allowed enrollment without prior informed consent from parents because of the emergent, unanticipated nature of most of these deliveries and because of the need to administer the skin wrap immediately after birth. The research intervention involved a very minimal risk
HeLP
750
Heat Loss Prevention study
NICU
Neonatal intensive care unit
See editorial, p 720.
From the Departments of Pediatrics and Clinical Epidemiology and Biostatistics, McMaster University, the Children’s Hospital of Hamilton Health Sciences, Hamilton, Ontario, Canada. Dr Vohra is now with the Department of Pediatrics, Stollery Children’s Hospital, University of Alberta, Edmonton, Alberta, Canada. Supported by the Neonatal Resuscitation Program of the American Academy of Pediatrics. Submitted for publication Mar 20, 2004; last revision received Jun 22, 2004; accepted Jul 16, 2004. Reprint requests: Dr Barbara Schmidt, HSC 3N11E, 1200 Main Street West, McMaster University, Hamilton, Ontario, Canada L8N 3Z5. E-mail: [email protected]. 0022-3476/$ - see front matter Copyright ª 2004 Elsevier Inc. All rights reserved. 10.1016/j.jpeds.2004.07.036
Table I. Baseline characteristics of infants and their mothers
Characteristics
Figure 1. Flow of participants through screening stage, enrollment, and completion of the study protocol.
to the study patients and was well accepted by the clinical staff. The parents of all study infants received a Parent Information Form after the initial stabilization of their baby that explained the study purpose and methods.
Interventions All infants were stabilized in the delivery room under radiant warmers (Air-Shields Model IICS 90). The radiant warmers were preheated by using a 5% dextrose intravenous bag as a ‘‘phantom’’ and set to manual control with maximum output. Infants in the control (nonwrap) group were dried completely, according to the International Guidelines for Neonatal Resuscitation.3 For infants in the wrap group, a polyethylene bag was opened under the radiant warmer, the infant was placed on the bag from the shoulders down, and the entire body was wrapped.4 Only the head was dried. The polyethylene bags measured 20 cm by 50 cm and were manufactured by Eastern Paper, a Division of EPC Industries Ltd. Oxygenation, bag-mask ventilation, endotracheal intubation, and chest compressions were initiated in the delivery room as appropriate; more extensive stabilization including vascular access was performed in the NICU, which was immediately adjacent to the delivery room suite. All infants were carried by one member of the neonatal team from the delivery room into the NICU and placed in a single walled incubator with 60% humidity (Ohmeda/Ohio Medical Care Plus). At this point, the wrap was removed in the experimental group.
Mothers Racial or ethnic background, n (%) White Black Asian Other or unknown Route of delivery, n (%) Vaginal, no forceps or vacuum Vaginal, with forceps or vacuum Caesarean Epidural/spinal, n (%) Antenatal steroid, n (%) Time of membranes rupture (h), mean ± SD Infants Birth weight (g), mean ± SD Gestational age (wk), mean ± SD Female sex, n (%) Multiple birth, n (%) Umbilical cord pH, mean ± SD Venous Arterial
Wrap group (n = 28)
25 (89) 2 (7)
Control group (n = 27)
1 (4)
20 (74) 3 (11) 2 (7) 2 (7)
10 (36) 1 (4) 17 (61) 18 (64) 26 (93) 38 ± 35
15 (56) 1 (4) 11 (41) 18 (67) 23 (85) 52 ± 89
858 ± 199 26 ± 1.5 14 (50) 13 (46)
825 ± 270 26 ± 1.4 13 (48) 5 (19)
7.26 ± 0.17 7.27 ± 0.12
7.33 ± 0.07 7.26 ± 0.08
Outcomes The primary outcome measure was rectal temperature taken on admission to the NICU (immediately after wrap removal in wrapped infants) and again 1 hour later. Rectal temperature was measured with a digital rectal thermometer (IVAC Temp Plus II electronic thermometers, ALARIS Medical Systems Inc, San Diego, Calif ). Death from all causes before discharge was the secondary outcome. APGAR scores, first blood gas analysis, and first serum glucose concentration after admission were also recorded.
Sample Size In the previous trial of this intervention, the subgroup of 18 infants <28 weeks’ gestation had a pooled SD of 0.9C.4 We considered a mean difference of this magnitude to be clinically important. To detect a mean difference of 0.9C in core temperature required the enrollment of 23 infants per treatment group, for an a of 0.05 (2-tailed) and 90% power. To allow for infants who failed to complete the study protocol because of death in the delivery room, we planned to recruit at least 50 patients.
Random Assignment Eligible infants were assigned to the polyethylene wrap group or the control group, according to a computergenerated, randomized sequence balanced in blocks of 4
Heat Loss Prevention (Help) in the Delivery Room: A Randomized Controlled Trial of Polyethylene Occlusive Skin Wrapping in Very Preterm Infants
751
Table II. Outcomes Wrap group (n = 27)
Control group (n = 26)
P value
36.5 ± 0.8 36.6 ± 0.7
35.6 ± 1.3 36.4 ± 0.9
0.002 0.4
7 (25.0)
8 (29.6)
0.8
6 2–6
6 3-6
0.6
7 6–8 7.32 ± 0.12 20.5 ± 4.0 2.5 ± 1.1
7 7-8 7.36 ± 0.12 19.5 ± 2.8 2.8 ± 1.8
0.9
Primary outcome, rectal temperature (C) At NICU admission, mean ± SD One hour after NICU admission, mean ± SD Secondary outcomes Death, n (%)* APGAR score at 1 min Median Interquartile range APGAR score at 5 min Median Interquartile range Blood gas pH, mean ± SD Bicarbonate (mmol/L), mean ± SD Glucose (mmol/L), mean ± SD
0.3 0.3 0.5
*Death rate was calculated on the basis of 28 infants in the wrap group and 27 infants in the control group.
subjects. The randomized allocation was concealed in double-enclosed, opaque, sealed, and sequentially numbered envelopes. In the delivery room, the next sequential randomization envelope was opened only if the infant was found to be eligible by the neonatal team. The assigned procedure (wrap or no-wrap) was then performed. Multiple eligible births were separately randomized.
Statistical Methods The mean temperature after NICU admission and 1 hour later were compared between the two groups by means of a 2-sided Wilcoxon rank sum test. Comparisons of mean temperature were also conducted after adjustment (by multiple linear regression) for imbalances in a number of potentially prognostic baseline variables. The mortality rates in both groups were compared by Fisher exact test.
RESULTS
in rectal temperature between the two groups (Table II). After adjustment for potentially important baseline variables, that is, early membrane rupture, delivery route, sex, birth weight, and gestational age, the mean temperature advantage in the wrap group on admission to the NICU remained essentially unchanged. Of these variables, only birth weight influenced the amount of heat loss in the delivery room (P = .02, Figure 2). The regression model suggested that the mean rectal temperature on admission to the NICU increased by 0.21C (95% CI, 0.04 to 0.4) with each 100-g increase in birth weight. Median APGAR scores, first mean blood pH, and first mean serum glucose concentrations were comparable in both groups (Table II). Two infants died in the delivery room and 13 infants died after admission to the NICU. Mortality rates before discharge were similar in wrapped and control infants (Table II). Median (min-max) age at death was 4 days (0 to11) in the wrap group and 5 days (0 to27) in control infants. Rectal temperature at NICU admission had been below 36.5C in 2 of 6 deaths in the wrap group, compared with 7 of 7 deaths in the control group.
Participant Flow Figure 1 summarizes the flow of participants through the screening stage, enrollment, and completion of the study protocol. One infant who was randomly assigned to the nowrap group was wrapped in error but analyzed according to the intended treatment. All patients were followed until death or discharge, whichever occurred first. Table I shows that the baseline characteristics of the infants and their mothers were similar in both groups.
Outcomes The mean rectal temperature on admission to the NICU was significantly higher in infants who were wrapped compared with infants who received standard care (Table II). One hour later, there was no significant difference 752
Vohra et al
Adverse Events The wrap procedure was well accepted by the neonatal staff and did not interfere with resuscitation in the delivery room. Two infants had a rectal temperature on admission above 37.5C (Figure 2). Both infants had been assigned to the wrap group.
DISCUSSION We have confirmed that polyethylene occlusive skin wrapping of very preterm infants immediately after birth provides better thermal protection in the delivery room than conventional drying. Moreover, we have shown that wrapping The Journal of Pediatrics December 2004
Size at birth is an important determinant of admission temperature.4,5,7 In the current study, mean rectal temperature on admission to the NICU increased by 0.21C (95% CI, 0.04 to 0.4) with each 100-g increase in birth weight. It follows that the smallest and most immature infants are most in need of special thermal protection at birth and that this population of infants probably will benefit the most from polyethylene occlusive skin wrapping. Several recent reports suggest that clinicians have begun to use this method of thermal protection in very preterm and very low birth weight infants.5,8-11 Hypothermia immediately after birth in extremely preterm infants was associated with a reduced chance of survival in the EPICure study.7 In the HeLP trial, rates of survival to discharge from hospital were similar in both groups. This is in contrast to the previous randomized study in which all 5 deaths occurred in the nonwrap group.4 Of note, we did not design this trial with mortality as the primary outcome. Therefore, we were capable to detect only very large relative reductions in death risk. Given the observed pooled mortality rate of 27% in this trial, we would have needed to study more than 1200 infants to detect a 25% relative reduction in the risk of death.
REFERENCES
Figure 2. Relation between birth weight and admission temperature for infants in wrap (1) and control (o) groups.
prevents rather than just delays heat loss after very preterm birth. Wrapped infants maintained their core temperature after admission to the NICU and after wrap removal in a closed incubator. The HeLP study is the second randomized trial of this intervention. We previously reported that polyethylene occlusive skin wrapping at delivery reduces the postnatal fall of body temperature.4 A subgroup analysis of this trial suggested that the difference in mean rectal temperature on admission was 1.9C in infants <28 weeks’ gestation.4 In the present study, in which we included only infants <28 weeks’ gestation, wrapping increased the mean rectal temperature on admission to the NICU by 0.9C. The risk of overheating is a potential concern when using the polyethylene wrap.5 We were reassured to find in the HeLP study that only 2 of 27 infants in the wrap group (7%) had rectal temperatures on admission to the NICU that were above the normal range of 36.5 to 37.5C. However, great care should be taken to avoid hyperthermia, especially in those infants who are at risk of hypoxic-ischemic encephalopathy.6
1. Sinclair JC. Management of the thermal environment. In: Sinclair JC, Bracken MB, eds. Effective care of the newborn infant. New York: Oxford University Press; 1992. p. 40-58. 2. Hey E. Thermoregulation. In: Avery GB, Fletcher MA, MacDonald MG, eds. Neonatology: Pathophysiology and Management of the Newborn. 4th ed. Philadelphia: JB Lippincott Company; 1994. p. 357-65. 3. Niermeyer S, Kattwinkel J, Van Reempts P, Nadkarni V, Phillips B, Zideman D, et al. International Guidelines for Neonatal Resuscitation: an excerpt from the guidelines 2000 for cardiopulmonary resuscitation and emergency cardiovascular care: International Consensus on Science. Pediatrics 2000;106:E29. 4. Vohra S, Frent G, Campbell V, Abbott M, Whyte R. Effect of polyethylene occlusive skin wrapping on heat loss in very low birth weight infants at delivery: a randomized trial. J Pediatr 1999;134:547-51. 5. Newton T, Watkinson M. Preventing hypothermia at birth in preterm babies: at a cost of overheating some? Arch Dis Child Fetal Neonatal Ed 2003; 88:F256. 6. Gunn AJ, Bennet L. Is temperature important in delivery room resuscitation? Semin Neonatol 2001;6:241-9. 7. Costeloe K, Hennessy E, Gibson AT, Marlow N, Wilkinson AR, for the EPICure Study Group . The EPICure study: outcomes to discharge from hospital for infants born at the threshold of viability. Pediatrics 2000;106: 659-71. 8. Bjo¨rklund LJ, Hellstro¨m-Westas L. Reducing heat loss at birth in very preterm infants. J Pediatr 2000;137:739-40. 9. Lenclen R, Mazraani M, Jugie M, Couderc S, Hoenn E, Carbajal R, et al. Use of a polyethylene bag: a way to improve the thermal environment of the premature newborn at the delivery room. Arch Pediatr 2002;9:238-44. 10. Meyer MP. Swaddling and heat loss. Arch Dis Child Fetal Neonatal Ed 2003;88:F256. 11. Lyon AJ, Stenson B. Cold comfort for babies. Arch Dis Child Fetal Neonatal Ed 2004;89:F93-4.
Heat Loss Prevention (Help) in the Delivery Room: A Randomized Controlled Trial of Polyethylene Occlusive Skin Wrapping in Very Preterm Infants
753