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
better than conventional drying and to evaluate if any benefit is sustained after wrap removal.
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.
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, 36.5?C (SD, 0.8?C), compared with 35.6?C (SD, 1.3?C) in
control infants (P = .002). One hour later, mean rectal temperatures were similar in both groups (36.6?C, SD, 0.7?C vs 36.4?C,
SD, 0.9?C, P = .4). Size at birth was an important determinant of heat loss: Mean rectal admission temperature increased by
0.21?C (95% CI, 0.04 to 0.4) with each 100-g increase in birth weight.
Polyethylene occlusive skin wrapping prevents rather than delays heat loss at delivery in very preterm infants.
(J Pediatr 2004;145:750-3)
conventional drying in reducing the postnatal fall of body temperature in very low birth
weight infants.4A subgroup analysis suggested that this beneficial effect of the wrap was
limited to infants <28 weeks’ gestation.4We 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.
To determine if polyethylene occlusive skin wrapping of very preterm infants prevents heat loss after delivery
ery small and preterm infants need special thermal protection at birth.1,2To reduce
heat loss after delivery, it is recommended to rapidly dry the infant under a radiant
warmer.3Occlusive wrapping of the wet body in polyethylene is superior to
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
From the Departments of Pediatrics
and Clinical Epidemiology and Bio-
statistics, McMaster University, the
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 Resuscita-
tion Program of the American Aca-
demy 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,
Ontario, Canada L8N 3Z5.
0022-3476/$ - see front matter
See editorial, p 720.
HeLP Heat Loss Prevention studyNICU Neonatal intensive care unit
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.
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.3For 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.4Only 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 in-
tubation, 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
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
MedicalSystemsInc, SanDiego, Calif). Death fromall causes
before discharge was the secondary outcome. APGAR scores,
first blood gas analysis, and first serum glucose concentration
after admission were also recorded.
In the previous trial of this intervention, the subgroup of
18 infants <28 weeks’ gestation had a pooled SD of 0.9?C.4
We considered a mean difference of this magnitude to be
clinically important. To detect a mean difference of 0.9?C 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.
Eligible infants were assigned to the polyethylene
wrap group or the control group, according to a computer-
generated, randomized sequence balanced in blocks of 4
Figure 1. Flow of participants through screening stage, enrollment,
and completion of the study protocol.
Table I. Baseline characteristics of infants and their
(n = 28)
(n = 27)
Racial or ethnic background, n (%)
Other or unknown
Route of delivery, n (%)
Vaginal, no forceps or vacuum
Vaginal, with forceps or vacuum
Epidural/spinal, n (%)
Antenatal steroid, n (%)
Time of membranes rupture (h),
mean ± SD
Birth weight (g), mean ± SD
Gestational age (wk), mean ± SD
Female sex, n (%)
Multiple birth, n (%)
Umbilical cord pH, mean ± SD
2 (7) 1 (4)
38 ± 35
52 ± 89
858 ± 199
26 ± 1.5
825 ± 270
26 ± 1.4
7.26 ± 0.17
7.27 ± 0.12
7.33 ± 0.07
7.26 ± 0.08
Heat Loss Prevention (Help) in the Delivery Room: A Randomized Controlled
Trial of Polyethylene Occlusive Skin Wrapping in Very Preterm Infants751
subjects. The randomized allocation was concealed in
double-enclosed, opaque, sealed, and sequentially numbered
envelopes. In the delivery room, the next sequential random-
ization envelope was opened only if the infant was found to be
eligible by the neonatal team. Theassigned procedure(wrapor
no-wrap) was then performed. Multiple eligible births were
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 werealsoconductedafter adjustment(bymultiple
linear regression) for imbalances in a number of potentially
prognostic baseline variables. The mortality rates in both
groups were compared by Fisher exact test.
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 no-
wrap group waswrappedin error butanalyzed according tothe
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.
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
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 0.21?C
(95%CI,0.04 to0.4) with each 100-gincreasein 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 5days (0 to27) in control infants. Rectal
temperature at NICU admission had been below 36.5?C in 2
of 6 deaths in the wrap group, compared with 7 of 7 deaths in
the control group.
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 37.5?C (Figure 2). Both infants had been assigned to
the wrap group.
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
Table II. Outcomes
Wrap group (n = 27)Control group (n = 26)
Primary outcome, rectal temperature (?C)
At NICU admission, mean ± SD
One hour after NICU admission, mean ± SD
Death, n (%)*
APGAR score at 1 min
APGAR score at 5 min
Blood gas pH, mean ± SD
Bicarbonate (mmol/L), mean ± SD
Glucose (mmol/L), mean ± SD
36.5 ± 0.8
36.6 ± 0.7
35.6 ± 1.3
36.4 ± 0.9
7 (25.0)8 (29.6)0.8
2 – 63-6
6 – 8
7.32 ± 0.12
20.5 ± 4.0
2.5 ± 1.1
7.36 ± 0.12
19.5 ± 2.8
2.8 ± 1.8
*Death rate was calculated on the basis of 28 infants in the wrap group and 27 infants in the control group.
752Vohra et al The Journal of Pediatrics?December 2004
prevents rather than just delays heat loss after very preterm Download full-text
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 poly-
ethylene occlusive skin wrapping at delivery reduces the
postnatalfallofbodytemperature.4Asubgroup analysis ofthis
trial suggested that the difference in mean rectal temperature
on admission was 1.9?C in infants <28 weeks’ gestation.4In
the present study, in which we included only infants <28
weeks’ gestation, wrapping increased the mean rectal temper-
ature on admission to the NICU by 0.9?C.
The risk of overheating is a potential concern when
using the polyethylene wrap.5We 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 37.5?C. However, great
care should be taken to avoid hyperthermia, especially in those
infants who are at risk of hypoxic-ischemic encephalopathy.6
Size at birth is an important determinant of admission
temperature.4,5,7In the current study, mean rectal temperature
on admission to the NICU increased by 0.21?C (95% CI, 0.04
to 0.4)witheach 100-gincreasein birth weight. It followsthat
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.7In the HeLP trial, rates of
This is in contrast to the previous randomized study in which
all 5 deaths occurred in the nonwrap group.4Of 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
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excerpt from the guidelines 2000 for cardiopulmonary resuscitation and
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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
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Sinclair JC. Management of the thermal environment. In: Sinclair JC,
Figure 2. Relation between birth weight and admission temperature
for infants in wrap (1) and control (o) groups.
Heat Loss Prevention (Help) in the Delivery Room: A Randomized Controlled
Trial of Polyethylene Occlusive Skin Wrapping in Very Preterm Infants 753