Efficacy of Polyethylene Skin Wrapping in Preventing Hypothermia in Preterm Neonates (<34 Weeks): A Parallel Group Non-blinded Randomized Control Trial

Efficacy of Polyethylene Skin Wrapping in Preventing Hypothermia in Preterm Neonates (<34 Weeks):... Abstract Objective The objective of this study was to determine the efficacy of polyethylene skin wrapping on thermoregulation in preterm neonates. Methods Total 151 neonates were enrolled in this randomized control trial. In the control group, neonates were transferred to the radiant warmer and covered with warm cloth after initial care. In the study group, neonates were transferred to the radiant warmer and placed in a food-grade polyethylene bag for 1 h. Axillary temperature of all neonates was recorded for first 24 h at frequent time intervals. Results Mean temperature reached to normal range earlier and remained significantly higher in the study group for most time intervals, and this difference persisted even at 24 h. Significantly less number of preterm newborns suffered from hypothermia in the study group as compared with the control group [50 (67.6%) vs. 67 (87%), p = 0.004]. Conclusions Polyethylene wraps achieved rapid, sustained thermal control and were effective in preventing hypothermia in preterm newborns. cloth wrap, newborn, plastic wrap, transport, temperature INTRODUCTION Low birth weight neonates are at risk of developing hypothermia, and it is well recognized that maintaining normothermia significantly reduces neonatal mortality [1]. A major risk period is just after the birth of the baby, when a temperature drop of about 2–3°C can occur in the first 30 min after birth if interventions to maintain temperature are not deployed [2, 3]. Neonatal hypothermia on admission to neonatal intensive care unit (NICU) is associated with late-onset sepsis and in-hospital mortality where the mortality risk because of hypothermia increases exponentially with drop in temperature [4–6]. Recent data show hypothermia prevalence of about 30–85% in diverse settings, and it is challenging [4, 7–10]. In addition to routine precautionary actions to be taken during birth, use of plastic bags has shown promising results to keep newborns warmer. In a Cochrane review, plastic wraps were found effective in preterm infants <28 weeks’ gestation, but only one study was evaluated and showed that plastic wraps were no better than routine care in preterm infants between 28 and 31 weeks [3]. A couple of randomized control trials (RCTs) [11–15] have analyzed preterm neonates <32 weeks; however, there are only few published studies for neonates >32 weeks [16–18]. These studies have shown effectiveness of plastic wrap in reducing neonatal hypothermia in first few hours after birth, but its effect on temperature control for longer duration was not studied. The current study further evaluates the effectiveness of polyethylene wrap in a broader subgroup of preterm infants (<34 weeks) for first 24 h after birth. The temperature difference was considered primary outcome measure and hypothermia episodes was considered secondary outcome. METHODS This is a parallel group non-blinded RCT with a 1:1 allocation ratio between August 2013 and December 2014. All preterm neonates <34 weeks delivered at this hospital were eligible to be included in this study. At the dedicated newborn care area in the delivery room and in the operation theater, the warmer was switched on at least 20 min before the expected time of delivery so as to keep the room temperature >25°C. Room temperature was recorded at the time of delivery. Neonates with life-threatening congenital anomalies identified antenatally or at birth were excluded. Informed consent of parents was obtained before the delivery. In the control group, the neonate was received in pre-warmed linen, transferred to the servo-controlled warmer, dried and then were wrapped in cloth. In the intervention group, the neonate was received in a pre-warmed towel, transferred to the servo-controlled warmer and placed in a food-grade polyethylene bag—Zip Lock for 1 h. The bag was prepared before delivery by making a hole on one end. We made a pragmatic decision to ensure that the bags were of the same size for all neonates, and the hole made was variable based on the expected head size. The zip of the bag was opened and the neonate was placed in it, so that the head came out of the hole and the entire body remained inside and the zip was closed. The head was then dried with linen. Additional holes were made in the bag for putting temperature probe, umbilical venous access and placement of saturation monitor if required. Neonates were transferred in the top open trolley from labor room to NICU (55 m) and operation theater to either NICU (110 m) or newborn care corner in the mother’s room (80 m). Axillary temperature was used to study the temperature difference, which was recorded using digital thermometer (at 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 min, 1, 1.5, 2, 3, 4, 5, 6, 12, 24 h) after initial resuscitation. Head was not covered in both groups for 1 h. This was because time to apply cap varies in both normal and cesarean deliveries after birth in routine practice, so it was necessary to make it comparable. World Health Organization’s definition of hypothermia (mild hypothermia or cold stress for 36.0–36.4°C; moderate hypothermia for 32.0–35.9°C; and severe hypothermia for temperature <32.0°C) was used [19]. In the study group, after 1 h, the polyethylene bag was removed and the newborn was wrapped in the cloth. Head was covered with the cap in both groups after 1 h of resuscitation. Skin-to-skin care was not practiced while the infants were in the study. Sample size Previous data revealed that the SD of temperature of neonates within 30 min after birth was 0.95°C [8]. Considering temperature difference of 0.5°C as clinically important, a sample of 58 neonates per group was required at 5% type I error to achieve a power of 80%. To enable subgroup analysis for 32–34 weeks preterm neonates (prevalence of hypothermia is about 75%), the sample size was increased to 75 in each group. Randomization was done using Web-based software by a statistician not involved in the study. Balanced randomization with variable block sizes of 2, 4 and 6 was used to ascertain nearly equal number of participants in both the groups. A total of 154 random allocations were done, but three allocations from the study group were rejected because of practical issues (investigator had to attend other emergencies). The random numbers generated were then stored in 154 opaque envelopes with serial numbers on the top of the envelope. Trial registration Our study is registered at ctri.nic.in (CTRI number: CTRI/2015/02/005520). Ethics Study received approval of the Institutional Human Research Ethics committee. Statistical analysis Intention to treat analysis was undertaken. Descriptive statistics [mean (SD), frequency (%)] were used to depict the characteristics of the study population. Subgroup analysis was also performed for neonates having gestational age of 32–34 weeks. RESULTS A total of 151 preterm neonates (74 in the study group and 77 in the control group) <34 weeks gestational age were randomized over a period of 16 months (Fig. 1). The baseline profile of the study participants is depicted in Table 1. Table 1 Profile of study participants Characteristics Study group Control group Overall (n = 74) (n = 77) Gender  Male 45 (60.8%) 45 (58.4%) 90 (59.6%)  Female 29 (39.2%) 32 (41.6%) 61 (40.4%) Mode of delivery  Caesarean 28 (37.8%) 42 (54.5%) 70 (46.4%)  Vaginal 46 (62. 2%) 35 (45.5%) 81 (53.6%) Gestation age (in weeks)  <29-6 d 6 (8.1%) 14 (18.2%) 20 (13.2%)  30 to 31–6 d 12 (16.2%) 14 (18.2%) 26 (17.2%)  32 to 34-0 d 56 (75.7%) 49 (63.6%) 105 (69.5%) Birth weight  <1500 g 28 (37.8) 27 (35.1%) 55 (36.4%)  ≥1500 g 46 (62.2) 50 (64.9%) 96 (63.6%) Birth weight  Mean (SD) 1657.70 (357.83) 1626.75 (425.42) 1641.92 (392.75) Admission  NICU 54 (73.0%) 50 (64.9%) 104 (68.9%)  Neonatal Intermediate Care (NIMC) 6 (8.1%) 12 (15.6%) 18 (11.9%)  Ward 14 (18.9%) 15 (19.5%) 29 (19.2%) Ventilator support required  Yes 42 (56.8%) 40 (51.9%) 82 (54.3%)  No 32 (43.2%) 37 (48.1%) 69 (45.7%) Characteristics Study group Control group Overall (n = 74) (n = 77) Gender  Male 45 (60.8%) 45 (58.4%) 90 (59.6%)  Female 29 (39.2%) 32 (41.6%) 61 (40.4%) Mode of delivery  Caesarean 28 (37.8%) 42 (54.5%) 70 (46.4%)  Vaginal 46 (62. 2%) 35 (45.5%) 81 (53.6%) Gestation age (in weeks)  <29-6 d 6 (8.1%) 14 (18.2%) 20 (13.2%)  30 to 31–6 d 12 (16.2%) 14 (18.2%) 26 (17.2%)  32 to 34-0 d 56 (75.7%) 49 (63.6%) 105 (69.5%) Birth weight  <1500 g 28 (37.8) 27 (35.1%) 55 (36.4%)  ≥1500 g 46 (62.2) 50 (64.9%) 96 (63.6%) Birth weight  Mean (SD) 1657.70 (357.83) 1626.75 (425.42) 1641.92 (392.75) Admission  NICU 54 (73.0%) 50 (64.9%) 104 (68.9%)  Neonatal Intermediate Care (NIMC) 6 (8.1%) 12 (15.6%) 18 (11.9%)  Ward 14 (18.9%) 15 (19.5%) 29 (19.2%) Ventilator support required  Yes 42 (56.8%) 40 (51.9%) 82 (54.3%)  No 32 (43.2%) 37 (48.1%) 69 (45.7%) Table 1 Profile of study participants Characteristics Study group Control group Overall (n = 74) (n = 77) Gender  Male 45 (60.8%) 45 (58.4%) 90 (59.6%)  Female 29 (39.2%) 32 (41.6%) 61 (40.4%) Mode of delivery  Caesarean 28 (37.8%) 42 (54.5%) 70 (46.4%)  Vaginal 46 (62. 2%) 35 (45.5%) 81 (53.6%) Gestation age (in weeks)  <29-6 d 6 (8.1%) 14 (18.2%) 20 (13.2%)  30 to 31–6 d 12 (16.2%) 14 (18.2%) 26 (17.2%)  32 to 34-0 d 56 (75.7%) 49 (63.6%) 105 (69.5%) Birth weight  <1500 g 28 (37.8) 27 (35.1%) 55 (36.4%)  ≥1500 g 46 (62.2) 50 (64.9%) 96 (63.6%) Birth weight  Mean (SD) 1657.70 (357.83) 1626.75 (425.42) 1641.92 (392.75) Admission  NICU 54 (73.0%) 50 (64.9%) 104 (68.9%)  Neonatal Intermediate Care (NIMC) 6 (8.1%) 12 (15.6%) 18 (11.9%)  Ward 14 (18.9%) 15 (19.5%) 29 (19.2%) Ventilator support required  Yes 42 (56.8%) 40 (51.9%) 82 (54.3%)  No 32 (43.2%) 37 (48.1%) 69 (45.7%) Characteristics Study group Control group Overall (n = 74) (n = 77) Gender  Male 45 (60.8%) 45 (58.4%) 90 (59.6%)  Female 29 (39.2%) 32 (41.6%) 61 (40.4%) Mode of delivery  Caesarean 28 (37.8%) 42 (54.5%) 70 (46.4%)  Vaginal 46 (62. 2%) 35 (45.5%) 81 (53.6%) Gestation age (in weeks)  <29-6 d 6 (8.1%) 14 (18.2%) 20 (13.2%)  30 to 31–6 d 12 (16.2%) 14 (18.2%) 26 (17.2%)  32 to 34-0 d 56 (75.7%) 49 (63.6%) 105 (69.5%) Birth weight  <1500 g 28 (37.8) 27 (35.1%) 55 (36.4%)  ≥1500 g 46 (62.2) 50 (64.9%) 96 (63.6%) Birth weight  Mean (SD) 1657.70 (357.83) 1626.75 (425.42) 1641.92 (392.75) Admission  NICU 54 (73.0%) 50 (64.9%) 104 (68.9%)  Neonatal Intermediate Care (NIMC) 6 (8.1%) 12 (15.6%) 18 (11.9%)  Ward 14 (18.9%) 15 (19.5%) 29 (19.2%) Ventilator support required  Yes 42 (56.8%) 40 (51.9%) 82 (54.3%)  No 32 (43.2%) 37 (48.1%) 69 (45.7%) Fig. 1. View largeDownload slide Flow of recruitment. Fig. 1. View largeDownload slide Flow of recruitment. The mean delivery room temperature was less during winter months (October–March) as compared with summer months (April–September). The hypothermia episodes/preterm were more frequent in winter months (Table 2). Table 2 Seasonal variations in delivery room temperature and hypothermia episodes Month Mean (SD) delivery room temperature Mild hypothermia episodes Moderate hypothermia episodes Total episodes/ preterms Average hypothermia episodes per preterm January 26.20 (1.03) 53 68 121/10 12.10 February 27.08 (0.79) 28 42 70/12 5.83 March 28.89 (1.76) 19 10 29/9 3.22 April 30.50 (4.34) 23 23 46/18 2.56 May 29.33 (2.54) 40 25 65/19 3.42 June 29.66 (2.03) 27 24 51/13 3.92 July 30.71 (2.57) 29 17 46/13 3.54 August 30.88 (5.27) 20 4 24/4 6.00 September 29.41 (3.43) 44 24 68/14 4.86 October 27.59 (1.95) 41 20 61/21 2.90 November 26.45 (0.69) 20 25 45/11 4.09 December 26.43 (1.13) 20 6 26/7 3.71 Total 28.67 (2.94) 364 288 652/151 4.32 Month Mean (SD) delivery room temperature Mild hypothermia episodes Moderate hypothermia episodes Total episodes/ preterms Average hypothermia episodes per preterm January 26.20 (1.03) 53 68 121/10 12.10 February 27.08 (0.79) 28 42 70/12 5.83 March 28.89 (1.76) 19 10 29/9 3.22 April 30.50 (4.34) 23 23 46/18 2.56 May 29.33 (2.54) 40 25 65/19 3.42 June 29.66 (2.03) 27 24 51/13 3.92 July 30.71 (2.57) 29 17 46/13 3.54 August 30.88 (5.27) 20 4 24/4 6.00 September 29.41 (3.43) 44 24 68/14 4.86 October 27.59 (1.95) 41 20 61/21 2.90 November 26.45 (0.69) 20 25 45/11 4.09 December 26.43 (1.13) 20 6 26/7 3.71 Total 28.67 (2.94) 364 288 652/151 4.32 Table 2 Seasonal variations in delivery room temperature and hypothermia episodes Month Mean (SD) delivery room temperature Mild hypothermia episodes Moderate hypothermia episodes Total episodes/ preterms Average hypothermia episodes per preterm January 26.20 (1.03) 53 68 121/10 12.10 February 27.08 (0.79) 28 42 70/12 5.83 March 28.89 (1.76) 19 10 29/9 3.22 April 30.50 (4.34) 23 23 46/18 2.56 May 29.33 (2.54) 40 25 65/19 3.42 June 29.66 (2.03) 27 24 51/13 3.92 July 30.71 (2.57) 29 17 46/13 3.54 August 30.88 (5.27) 20 4 24/4 6.00 September 29.41 (3.43) 44 24 68/14 4.86 October 27.59 (1.95) 41 20 61/21 2.90 November 26.45 (0.69) 20 25 45/11 4.09 December 26.43 (1.13) 20 6 26/7 3.71 Total 28.67 (2.94) 364 288 652/151 4.32 Month Mean (SD) delivery room temperature Mild hypothermia episodes Moderate hypothermia episodes Total episodes/ preterms Average hypothermia episodes per preterm January 26.20 (1.03) 53 68 121/10 12.10 February 27.08 (0.79) 28 42 70/12 5.83 March 28.89 (1.76) 19 10 29/9 3.22 April 30.50 (4.34) 23 23 46/18 2.56 May 29.33 (2.54) 40 25 65/19 3.42 June 29.66 (2.03) 27 24 51/13 3.92 July 30.71 (2.57) 29 17 46/13 3.54 August 30.88 (5.27) 20 4 24/4 6.00 September 29.41 (3.43) 44 24 68/14 4.86 October 27.59 (1.95) 41 20 61/21 2.90 November 26.45 (0.69) 20 25 45/11 4.09 December 26.43 (1.13) 20 6 26/7 3.71 Total 28.67 (2.94) 364 288 652/151 4.32 The mean temperature was significantly higher in the study group than the control group for most time intervals (p < 0.001) (Table 3). Average temperature in the study group increased by 0.3°C (35.9–36.19°C), whereas it decreased by 0.08°C (35.71–35.64) in the the control group during intra-hospital transfer within 5 min after resuscitation. Further good thermoregulation (36.5–37.4°C) was achieved within 10–15 min in the study group, whereas it took 30–35 min in the control group. Also, good thermoregulation was maintained even after removal of plastic bag at 1 h (Fig. 2). Similar trend was observed for preterm newborns in the gestational age group of 32–34 weeks (Fig. 3). Table 3 Mean (SD) axillary temperature at various time intervals Temperature Control group Study group p-value N = 77 N = 74 Mean (SD) Mean (SD) 0 min 35.71 (0.84) 35.90 (1.01) 0.228 5 min 35.64 (0.84) 36.19 (0.77) <0.001 10 min 35.80 (0.82) 36.45 (0.61) <0.001 15 min 36.07 (0.68) 36.59 (0.48) <0.001 20 min 36.27 (0.52) 36.70 (0.44) <0.001 25 min 36.38 (0.47) 36.77 (0.39) <0.001 30 min 36.47 (0.42) 36.85 (0.38) <0.001 35 min 36.55 (0.39) 36.88 (0.38) <0.001 40 min 36.62 (0.34) 36.91 (0.39) <0.001 45 min 36.65 (0.31) 36.94 (0.40) <0.001 50 min 36.73 (0.30) 36.97 (0.37) <0.001 55 min 36.77 (0.32) 36.98 (0.37) <0.001 1 h 36.80 (0.27) 37.01 (0.35) <0.001 1.5 h 36.82 (0.28) 36.96 (0.34) 0.006 2 h 36.88 (0.25) 37.03 (0.37) 0.007 3 h 36.86 (0.24) 37.00 (0.32) 0.004 4 h 36.89 (0.23) 37.05 (0.30) <0.001 5 h 36.91 (0.26) 37.07 (0.31) 0.001 6 h 36.90 (0.25) 37.06 (0.30) 0.001 12 h 36.91 (0.27) 37.11 (0.29) <0.001 24 h 36.97 (0.29) 37.17 (0.30) <0.001 Temperature Control group Study group p-value N = 77 N = 74 Mean (SD) Mean (SD) 0 min 35.71 (0.84) 35.90 (1.01) 0.228 5 min 35.64 (0.84) 36.19 (0.77) <0.001 10 min 35.80 (0.82) 36.45 (0.61) <0.001 15 min 36.07 (0.68) 36.59 (0.48) <0.001 20 min 36.27 (0.52) 36.70 (0.44) <0.001 25 min 36.38 (0.47) 36.77 (0.39) <0.001 30 min 36.47 (0.42) 36.85 (0.38) <0.001 35 min 36.55 (0.39) 36.88 (0.38) <0.001 40 min 36.62 (0.34) 36.91 (0.39) <0.001 45 min 36.65 (0.31) 36.94 (0.40) <0.001 50 min 36.73 (0.30) 36.97 (0.37) <0.001 55 min 36.77 (0.32) 36.98 (0.37) <0.001 1 h 36.80 (0.27) 37.01 (0.35) <0.001 1.5 h 36.82 (0.28) 36.96 (0.34) 0.006 2 h 36.88 (0.25) 37.03 (0.37) 0.007 3 h 36.86 (0.24) 37.00 (0.32) 0.004 4 h 36.89 (0.23) 37.05 (0.30) <0.001 5 h 36.91 (0.26) 37.07 (0.31) 0.001 6 h 36.90 (0.25) 37.06 (0.30) 0.001 12 h 36.91 (0.27) 37.11 (0.29) <0.001 24 h 36.97 (0.29) 37.17 (0.30) <0.001 Table 3 Mean (SD) axillary temperature at various time intervals Temperature Control group Study group p-value N = 77 N = 74 Mean (SD) Mean (SD) 0 min 35.71 (0.84) 35.90 (1.01) 0.228 5 min 35.64 (0.84) 36.19 (0.77) <0.001 10 min 35.80 (0.82) 36.45 (0.61) <0.001 15 min 36.07 (0.68) 36.59 (0.48) <0.001 20 min 36.27 (0.52) 36.70 (0.44) <0.001 25 min 36.38 (0.47) 36.77 (0.39) <0.001 30 min 36.47 (0.42) 36.85 (0.38) <0.001 35 min 36.55 (0.39) 36.88 (0.38) <0.001 40 min 36.62 (0.34) 36.91 (0.39) <0.001 45 min 36.65 (0.31) 36.94 (0.40) <0.001 50 min 36.73 (0.30) 36.97 (0.37) <0.001 55 min 36.77 (0.32) 36.98 (0.37) <0.001 1 h 36.80 (0.27) 37.01 (0.35) <0.001 1.5 h 36.82 (0.28) 36.96 (0.34) 0.006 2 h 36.88 (0.25) 37.03 (0.37) 0.007 3 h 36.86 (0.24) 37.00 (0.32) 0.004 4 h 36.89 (0.23) 37.05 (0.30) <0.001 5 h 36.91 (0.26) 37.07 (0.31) 0.001 6 h 36.90 (0.25) 37.06 (0.30) 0.001 12 h 36.91 (0.27) 37.11 (0.29) <0.001 24 h 36.97 (0.29) 37.17 (0.30) <0.001 Temperature Control group Study group p-value N = 77 N = 74 Mean (SD) Mean (SD) 0 min 35.71 (0.84) 35.90 (1.01) 0.228 5 min 35.64 (0.84) 36.19 (0.77) <0.001 10 min 35.80 (0.82) 36.45 (0.61) <0.001 15 min 36.07 (0.68) 36.59 (0.48) <0.001 20 min 36.27 (0.52) 36.70 (0.44) <0.001 25 min 36.38 (0.47) 36.77 (0.39) <0.001 30 min 36.47 (0.42) 36.85 (0.38) <0.001 35 min 36.55 (0.39) 36.88 (0.38) <0.001 40 min 36.62 (0.34) 36.91 (0.39) <0.001 45 min 36.65 (0.31) 36.94 (0.40) <0.001 50 min 36.73 (0.30) 36.97 (0.37) <0.001 55 min 36.77 (0.32) 36.98 (0.37) <0.001 1 h 36.80 (0.27) 37.01 (0.35) <0.001 1.5 h 36.82 (0.28) 36.96 (0.34) 0.006 2 h 36.88 (0.25) 37.03 (0.37) 0.007 3 h 36.86 (0.24) 37.00 (0.32) 0.004 4 h 36.89 (0.23) 37.05 (0.30) <0.001 5 h 36.91 (0.26) 37.07 (0.31) 0.001 6 h 36.90 (0.25) 37.06 (0.30) 0.001 12 h 36.91 (0.27) 37.11 (0.29) <0.001 24 h 36.97 (0.29) 37.17 (0.30) <0.001 Fig. 2. View largeDownload slide Comparison of thermoregulation across groups of preterm neonates over the first day (overall). Fig. 2. View largeDownload slide Comparison of thermoregulation across groups of preterm neonates over the first day (overall). Fig. 3. View largeDownload slide Comparison of thermoregulation of preterm neonates over the first day across groups (32–34 weeks). Fig. 3. View largeDownload slide Comparison of thermoregulation of preterm neonates over the first day across groups (32–34 weeks). Overall, significantly less number of preterm newborns suffered from hypothermia in the study group as compared with the control group [50 (67.6%) vs. 67 (87%), p = 0.004]. Mild hypothermia episodes were less than half in the study group (105) than in the control group (222), whereas moderate hypothermia episodes were almost 2.5 times more in the control group (208) as compared with the study (79) group. The mean (SD) mild hypothermia episodes per preterm [1.4 (1.9) vs. 2.9 (2.1), p < 0.001] as well as moderate hypothermia episodes [1.1 (1.8) vs. 2.7 (2.9), p < 0.001] were significantly less in the study group. A single episode of severe hyperthermia was noted in the study group where the birth weight of baby was 840 g. For 32–34 weeks subgroup, mild hypothermia episodes were about two-third in the study group (78) as compared with the control group (122), whereas moderate hypothermia episodes were less than two-third in the study (54) group as compared with the control (90) group. The mean (SD) mild hypothermia episodes per preterm [1.3 (1.9) vs. 2.5 (2.0), p = 0.001] as well as moderate hypothermia episodes [0.9 (1.49) vs. 1.8 (2.3), p = 0.014] were significantly less in the study group. DISCUSSION We assessed whether covering the preterm newborns (<34 weeks) with polyethylene bag for 1 h is more effective than conventional method of covering with cloth in keeping newborns warmer and reducing hypothermia episodes in first 24 h of life. The incidence of hypothermia remains high with conventional care of drying and wrapping the newborns in pre-warmed cloth [4, 7, 9, 11]. Any intervention to maintain normal temperature of newborn should either decrease heat loss or provide external heat [3]. Polyethylene wraps prevent hypothermia predominantly by reducing evaporative and convective heat loss, and newborn receives radiant heat through transparent polyethylene bag [20]. The Cochrane review concluded that plastic wraps keep the preterm infants warmer and reduce hypothermia episodes and recommended to include more number of infants and studies to further strengthen its use in clinical practice [3]. Despite differences in methodological designs, most studies have documented significantly higher temperature toward normal in plastic wrap group. Buffalo et al. [20] in their study on use of vinyl bag for extremely preterm neonates noticed a difference of 1.0°C for average admission temperature between the two groups. In the current study, we noticed around 0.4°C higher temperature between 15 and 25 min of admission to NICU in the plastic wrap group. Gathwala et al. [15], in their study in India, found the temperature at NICU admission better in the polyvinyl group. In a Malaysian study, mean admission temperature was in favor of the plastic wraps, but they used incubator for transport from the delivery room to the NICU and caps in all neonates after drying the head [18]. A study from Thailand with smaller sample size had similar results favoring plastic bags. In contrast to the current study, they did transport by an incubator, used caps and removed the bag immediately on admission to the NICU [11]. Two other recently published RCTs from Australia [12] and Turkey [13] have similar findings in neonates <30 and 32 weeks, respectively. Most of these studies compared the temperature difference for short time after admission to NICU. The current study further adds to the existing literature that benefits of using plastic wrap persist even at 24 h. Plastic wrap not only keeps the newborn of all gestational ages warmer but also reduces hypothermia incidence in diverse settings. Belches et al. [16] showed that term infants wrapped in the plastic bag had lower rates of hypothermia and higher axillary temperature at 1 h after birth. A study from Turkey also used incubators to place the neonates after wrapping them in plastic and found that very low birth weight newborns reached to normal temperature faster than no wrap group [21]. Many centers in the developed world introduced use of polyethylene bags below the gestation of 30 weeks and reported a drop in hypothermia rates of neonates at admission to the NICU even if the definitions applied of hypothermia have varied (36.0 or 36.5) [22–24]. In an Italian study, the group that wore only polyethylene caps or only polyethylene wraps had much lower incidence of hypothermia as compared with the drying and cloth-wrapped neonates. [25]. The current study supports these findings and favors use of plastic wrap as an effective modality in reducing hypothermia in preterm newborns. RCT in Zambia showed that polyethylene wrap increased the chance of normothermia in the plastic group [26]. The settings of the Zambia study were similar to current study, but the infants were dried before being placed in the polyethylene bag. Cardona et al. [18] compared routine care with polyethylene bag with or without drying the neonates before placing them in bags. Drying the neonate before placement within the bag had no difference to the time required (30 min) to achieve axillary temperature of 36.5°C. Total body wrapping (including the head and body) was comparable with only body wrapping with plastic bag with regard to achievement of axillary temperature on admission to the NICU in neonates <29 weeks [14]. Most studies, even those from low-resource settings, including the current study, are carried out in centers equipped with resources for thermoregulation (though not optimal) in premature babies. However, most deliveries in low-resource countries take place in settings with poor resources for thermal control of term or preterm neonates. The low-cost polyethylene bag lends itself to scalability with its ease of use and effectiveness proven across many settings. The current study thus supports the usage of plastic bags for improving thermoregulation in all preterm babies <34 weeks. We also stress on the need to do similar studies in term neonates and integrating quality improvement to improve neonatal thermoregulation in diverse settings. REFERENCES 1. Silverman WA , Fertig JW , Berger AP. The influence of the thermal environment upon the survival of newly born premature infants . Pediatrics 1958 ; 22 : 876 – 86 . Google Scholar PubMed 2. Dahm LS , James LS. Newborn temperature and calculated heat loss in the delivery room . Pediatrics 1972 ; 49 : 504 – 13 . Google Scholar PubMed 3. McCall EM , Alderdice F , Halliday HL , et al. Interventions to prevent hypothermia at birth in preterm and/or low birthweight infants . Cochrane Database Syst Rev 2010 ; 17 : CD004210 . 4. Laptook AR , Salhab W , Bhaskar B. Admission temperature of low birth weight infants: predictors and associated morbidities . Pediatrics 2007 ; 119 : e643 – 9 . Google Scholar CrossRef Search ADS PubMed 5. Mullany LC , Katz J , Khatry SK , et al. Risk of mortality associated with neonatal hypothermia in southern Nepal . Arch Pediatr Adolesc Med 2010 ; 164 : 650 – 6 . Google Scholar PubMed 6. Sodemann M , Nielsen J , Veirum J , et al. Hypothermia of newborns is associated with excess mortality in the first 2 months of life in Guinea-Bissau, West Africa . Trop Med Int Health 2008 ; 13 : 980 – 6 . Google Scholar CrossRef Search ADS PubMed 7. Miller SS , Lee HC , Gould JB. Hypothermia in very low birth weight infants: distribution, risk factors and outcomes . J Perinatol 2011 ; 31 : S49 – 56 . Google Scholar CrossRef Search ADS PubMed 8. Nimbalkar SM , Patel VK , Patel DV , et al. Effect of early skin-to-skin contact following normal delivery on incidence of hypothermia in neonates more than 1800 g: randomized control trial . J Perinatol 2014 ; 34 : 364 – 8 . Google Scholar CrossRef Search ADS PubMed 9. Darmstadt GL , Kumar V , Yadav R , et al. Introduction of community-based skin-to-skin care in rural Uttar Pradesh, India . J Perinatol 2006 ; 26 : 597 – 604 . Google Scholar CrossRef Search ADS PubMed 10. Lunze K , Bloom DE , Jamison DT , et al. The global burden of neonatal hypothermia: systematic review of a major challenge for newborn survival . BMC Med 2013 ; 11 : 24. Google Scholar CrossRef Search ADS PubMed 11. Chantaroj S , Techasatid W. Effect of polyethylene bag to prevent heat loss in preterm infants at birth: a randomized controlled trial . J Med Assoc Thai 2011 ; 94 : S32 – 7 . Google Scholar PubMed 12. Smith J , Usher K , Alcock G , Buettner P. Application of plastic wrap to improve temperatures in infants born less than 30 weeks gestation: a randomized controlled trial . Neonatal Netw 2013 ; 32 : 235 – 45 . Google Scholar CrossRef Search ADS PubMed 13. Caglar S , Gozen D , Ince Z. Heat loss prevention (help) after birth in preterm infants using vinyl isolation bag or polyethylene wrap . J Obstet Gynecol Neonatal Nurs 2014 ; 43 : 216 – 23 . Google Scholar CrossRef Search ADS PubMed 14. Doglioni N , Cavallin F , Mardegan V , et al. Total body polyethylene wraps for preventing hypothermia in preterm infants: a randomized trial . J Pediatr 2014 ; 165 : 261 – 6 . Google Scholar CrossRef Search ADS PubMed 15. Gathwala G , Singh G , Agrawal N. Safety and efficacy of vinyl bags in prevention of hypothermia of preterm neonates at birth . Indian J Public Health 2010 ; 54 : 24 – 6 . Google Scholar CrossRef Search ADS PubMed 16. Belsches TC , Tilly AE , Miller TR , et al. Randomized trial of plastic bags to prevent term neonatal hypothermia in a resource-poor setting . Pediatrics 2013 ; 132 : e656 – 61 . Google Scholar CrossRef Search ADS PubMed 17. Rohana J , Khairina W , Boo NY , et al. Reducing hypothermia in preterm infants with polyethylene wrap . Pediatr Int 2011 ; 53 : 468 – 74 . Google Scholar CrossRef Search ADS PubMed 18. Cardona Torres LM , Amador Licona N , Garcia Campos ML , et al. Polyethylene wrap for thermoregulation in the preterm infant: a randomized trial . Indian Pediatr 2012 ; 49 : 129 – 32 . Google Scholar CrossRef Search ADS PubMed 19. World Health Organization . Thermal Protection of the Newborn: A Practical Guide . Geneva : World Health Organization , 1997 . 20. Mathew B , Lakshminrusimha S , Cominsky K , et al. Vinyl bags prevent hypothermia at birth in preterm infants . Indian J Pediatr 2007 ; 74 : 249 – 53 . Google Scholar CrossRef Search ADS PubMed 21. Duman N , Utkutan S , Kumral A , et al. Polyethylene skin wrapping accelerates recovery from hypothermia in very low-birthweight infants . Pediatr Int 2006 ; 48 : 29 – 32 . Google Scholar CrossRef Search ADS PubMed 22. Singh A , Duckett J , Newton T , et al. Improving neonatal unit admission temperatures in preterm babies: exothermic mattresses, polythene bags or a traditional approach? J Perinatol 2010 ; 30 : 45 – 9 . Google Scholar CrossRef Search ADS PubMed 23. Carroll PD , Nankervis CA , Giannone PJ , et al. Use of polyethylene bags in extremely low birth weight infant resuscitation for the prevention of hypothermia . J Reprod Med 2010 ; 55 : 9 – 13 . Google Scholar PubMed 24. Ibrahim CP , Yoxall CW. Use of plastic bags to prevent hypothermia at birth in preterm infants–do they work at lower gestations? Acta Paediatr 2009 ; 98 : 256 – 60 . Google Scholar CrossRef Search ADS PubMed 25. Trevisanuto D , Doglioni N , Cavallin F , et al. Heat loss prevention in very preterm infants in delivery rooms: a prospective, randomized, controlled trial of polyethylene caps . J Pediatr 2010 ; 156 : 914 – 7 . Google Scholar CrossRef Search ADS PubMed 26. Leadford AE , Warren JB , Manasyan A , et al. Plastic bags for prevention of hypothermia in preterm and low birth weight infants . Pediatrics 2013 ; 132 : e128 – 34 . Google Scholar CrossRef Search ADS PubMed © The Author(s) [2018]. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Tropical Pediatrics Oxford University Press

Efficacy of Polyethylene Skin Wrapping in Preventing Hypothermia in Preterm Neonates (<34 Weeks): A Parallel Group Non-blinded Randomized Control Trial

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© The Author(s) [2018]. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com
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Abstract

Abstract Objective The objective of this study was to determine the efficacy of polyethylene skin wrapping on thermoregulation in preterm neonates. Methods Total 151 neonates were enrolled in this randomized control trial. In the control group, neonates were transferred to the radiant warmer and covered with warm cloth after initial care. In the study group, neonates were transferred to the radiant warmer and placed in a food-grade polyethylene bag for 1 h. Axillary temperature of all neonates was recorded for first 24 h at frequent time intervals. Results Mean temperature reached to normal range earlier and remained significantly higher in the study group for most time intervals, and this difference persisted even at 24 h. Significantly less number of preterm newborns suffered from hypothermia in the study group as compared with the control group [50 (67.6%) vs. 67 (87%), p = 0.004]. Conclusions Polyethylene wraps achieved rapid, sustained thermal control and were effective in preventing hypothermia in preterm newborns. cloth wrap, newborn, plastic wrap, transport, temperature INTRODUCTION Low birth weight neonates are at risk of developing hypothermia, and it is well recognized that maintaining normothermia significantly reduces neonatal mortality [1]. A major risk period is just after the birth of the baby, when a temperature drop of about 2–3°C can occur in the first 30 min after birth if interventions to maintain temperature are not deployed [2, 3]. Neonatal hypothermia on admission to neonatal intensive care unit (NICU) is associated with late-onset sepsis and in-hospital mortality where the mortality risk because of hypothermia increases exponentially with drop in temperature [4–6]. Recent data show hypothermia prevalence of about 30–85% in diverse settings, and it is challenging [4, 7–10]. In addition to routine precautionary actions to be taken during birth, use of plastic bags has shown promising results to keep newborns warmer. In a Cochrane review, plastic wraps were found effective in preterm infants <28 weeks’ gestation, but only one study was evaluated and showed that plastic wraps were no better than routine care in preterm infants between 28 and 31 weeks [3]. A couple of randomized control trials (RCTs) [11–15] have analyzed preterm neonates <32 weeks; however, there are only few published studies for neonates >32 weeks [16–18]. These studies have shown effectiveness of plastic wrap in reducing neonatal hypothermia in first few hours after birth, but its effect on temperature control for longer duration was not studied. The current study further evaluates the effectiveness of polyethylene wrap in a broader subgroup of preterm infants (<34 weeks) for first 24 h after birth. The temperature difference was considered primary outcome measure and hypothermia episodes was considered secondary outcome. METHODS This is a parallel group non-blinded RCT with a 1:1 allocation ratio between August 2013 and December 2014. All preterm neonates <34 weeks delivered at this hospital were eligible to be included in this study. At the dedicated newborn care area in the delivery room and in the operation theater, the warmer was switched on at least 20 min before the expected time of delivery so as to keep the room temperature >25°C. Room temperature was recorded at the time of delivery. Neonates with life-threatening congenital anomalies identified antenatally or at birth were excluded. Informed consent of parents was obtained before the delivery. In the control group, the neonate was received in pre-warmed linen, transferred to the servo-controlled warmer, dried and then were wrapped in cloth. In the intervention group, the neonate was received in a pre-warmed towel, transferred to the servo-controlled warmer and placed in a food-grade polyethylene bag—Zip Lock for 1 h. The bag was prepared before delivery by making a hole on one end. We made a pragmatic decision to ensure that the bags were of the same size for all neonates, and the hole made was variable based on the expected head size. The zip of the bag was opened and the neonate was placed in it, so that the head came out of the hole and the entire body remained inside and the zip was closed. The head was then dried with linen. Additional holes were made in the bag for putting temperature probe, umbilical venous access and placement of saturation monitor if required. Neonates were transferred in the top open trolley from labor room to NICU (55 m) and operation theater to either NICU (110 m) or newborn care corner in the mother’s room (80 m). Axillary temperature was used to study the temperature difference, which was recorded using digital thermometer (at 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 min, 1, 1.5, 2, 3, 4, 5, 6, 12, 24 h) after initial resuscitation. Head was not covered in both groups for 1 h. This was because time to apply cap varies in both normal and cesarean deliveries after birth in routine practice, so it was necessary to make it comparable. World Health Organization’s definition of hypothermia (mild hypothermia or cold stress for 36.0–36.4°C; moderate hypothermia for 32.0–35.9°C; and severe hypothermia for temperature <32.0°C) was used [19]. In the study group, after 1 h, the polyethylene bag was removed and the newborn was wrapped in the cloth. Head was covered with the cap in both groups after 1 h of resuscitation. Skin-to-skin care was not practiced while the infants were in the study. Sample size Previous data revealed that the SD of temperature of neonates within 30 min after birth was 0.95°C [8]. Considering temperature difference of 0.5°C as clinically important, a sample of 58 neonates per group was required at 5% type I error to achieve a power of 80%. To enable subgroup analysis for 32–34 weeks preterm neonates (prevalence of hypothermia is about 75%), the sample size was increased to 75 in each group. Randomization was done using Web-based software by a statistician not involved in the study. Balanced randomization with variable block sizes of 2, 4 and 6 was used to ascertain nearly equal number of participants in both the groups. A total of 154 random allocations were done, but three allocations from the study group were rejected because of practical issues (investigator had to attend other emergencies). The random numbers generated were then stored in 154 opaque envelopes with serial numbers on the top of the envelope. Trial registration Our study is registered at ctri.nic.in (CTRI number: CTRI/2015/02/005520). Ethics Study received approval of the Institutional Human Research Ethics committee. Statistical analysis Intention to treat analysis was undertaken. Descriptive statistics [mean (SD), frequency (%)] were used to depict the characteristics of the study population. Subgroup analysis was also performed for neonates having gestational age of 32–34 weeks. RESULTS A total of 151 preterm neonates (74 in the study group and 77 in the control group) <34 weeks gestational age were randomized over a period of 16 months (Fig. 1). The baseline profile of the study participants is depicted in Table 1. Table 1 Profile of study participants Characteristics Study group Control group Overall (n = 74) (n = 77) Gender  Male 45 (60.8%) 45 (58.4%) 90 (59.6%)  Female 29 (39.2%) 32 (41.6%) 61 (40.4%) Mode of delivery  Caesarean 28 (37.8%) 42 (54.5%) 70 (46.4%)  Vaginal 46 (62. 2%) 35 (45.5%) 81 (53.6%) Gestation age (in weeks)  <29-6 d 6 (8.1%) 14 (18.2%) 20 (13.2%)  30 to 31–6 d 12 (16.2%) 14 (18.2%) 26 (17.2%)  32 to 34-0 d 56 (75.7%) 49 (63.6%) 105 (69.5%) Birth weight  <1500 g 28 (37.8) 27 (35.1%) 55 (36.4%)  ≥1500 g 46 (62.2) 50 (64.9%) 96 (63.6%) Birth weight  Mean (SD) 1657.70 (357.83) 1626.75 (425.42) 1641.92 (392.75) Admission  NICU 54 (73.0%) 50 (64.9%) 104 (68.9%)  Neonatal Intermediate Care (NIMC) 6 (8.1%) 12 (15.6%) 18 (11.9%)  Ward 14 (18.9%) 15 (19.5%) 29 (19.2%) Ventilator support required  Yes 42 (56.8%) 40 (51.9%) 82 (54.3%)  No 32 (43.2%) 37 (48.1%) 69 (45.7%) Characteristics Study group Control group Overall (n = 74) (n = 77) Gender  Male 45 (60.8%) 45 (58.4%) 90 (59.6%)  Female 29 (39.2%) 32 (41.6%) 61 (40.4%) Mode of delivery  Caesarean 28 (37.8%) 42 (54.5%) 70 (46.4%)  Vaginal 46 (62. 2%) 35 (45.5%) 81 (53.6%) Gestation age (in weeks)  <29-6 d 6 (8.1%) 14 (18.2%) 20 (13.2%)  30 to 31–6 d 12 (16.2%) 14 (18.2%) 26 (17.2%)  32 to 34-0 d 56 (75.7%) 49 (63.6%) 105 (69.5%) Birth weight  <1500 g 28 (37.8) 27 (35.1%) 55 (36.4%)  ≥1500 g 46 (62.2) 50 (64.9%) 96 (63.6%) Birth weight  Mean (SD) 1657.70 (357.83) 1626.75 (425.42) 1641.92 (392.75) Admission  NICU 54 (73.0%) 50 (64.9%) 104 (68.9%)  Neonatal Intermediate Care (NIMC) 6 (8.1%) 12 (15.6%) 18 (11.9%)  Ward 14 (18.9%) 15 (19.5%) 29 (19.2%) Ventilator support required  Yes 42 (56.8%) 40 (51.9%) 82 (54.3%)  No 32 (43.2%) 37 (48.1%) 69 (45.7%) Table 1 Profile of study participants Characteristics Study group Control group Overall (n = 74) (n = 77) Gender  Male 45 (60.8%) 45 (58.4%) 90 (59.6%)  Female 29 (39.2%) 32 (41.6%) 61 (40.4%) Mode of delivery  Caesarean 28 (37.8%) 42 (54.5%) 70 (46.4%)  Vaginal 46 (62. 2%) 35 (45.5%) 81 (53.6%) Gestation age (in weeks)  <29-6 d 6 (8.1%) 14 (18.2%) 20 (13.2%)  30 to 31–6 d 12 (16.2%) 14 (18.2%) 26 (17.2%)  32 to 34-0 d 56 (75.7%) 49 (63.6%) 105 (69.5%) Birth weight  <1500 g 28 (37.8) 27 (35.1%) 55 (36.4%)  ≥1500 g 46 (62.2) 50 (64.9%) 96 (63.6%) Birth weight  Mean (SD) 1657.70 (357.83) 1626.75 (425.42) 1641.92 (392.75) Admission  NICU 54 (73.0%) 50 (64.9%) 104 (68.9%)  Neonatal Intermediate Care (NIMC) 6 (8.1%) 12 (15.6%) 18 (11.9%)  Ward 14 (18.9%) 15 (19.5%) 29 (19.2%) Ventilator support required  Yes 42 (56.8%) 40 (51.9%) 82 (54.3%)  No 32 (43.2%) 37 (48.1%) 69 (45.7%) Characteristics Study group Control group Overall (n = 74) (n = 77) Gender  Male 45 (60.8%) 45 (58.4%) 90 (59.6%)  Female 29 (39.2%) 32 (41.6%) 61 (40.4%) Mode of delivery  Caesarean 28 (37.8%) 42 (54.5%) 70 (46.4%)  Vaginal 46 (62. 2%) 35 (45.5%) 81 (53.6%) Gestation age (in weeks)  <29-6 d 6 (8.1%) 14 (18.2%) 20 (13.2%)  30 to 31–6 d 12 (16.2%) 14 (18.2%) 26 (17.2%)  32 to 34-0 d 56 (75.7%) 49 (63.6%) 105 (69.5%) Birth weight  <1500 g 28 (37.8) 27 (35.1%) 55 (36.4%)  ≥1500 g 46 (62.2) 50 (64.9%) 96 (63.6%) Birth weight  Mean (SD) 1657.70 (357.83) 1626.75 (425.42) 1641.92 (392.75) Admission  NICU 54 (73.0%) 50 (64.9%) 104 (68.9%)  Neonatal Intermediate Care (NIMC) 6 (8.1%) 12 (15.6%) 18 (11.9%)  Ward 14 (18.9%) 15 (19.5%) 29 (19.2%) Ventilator support required  Yes 42 (56.8%) 40 (51.9%) 82 (54.3%)  No 32 (43.2%) 37 (48.1%) 69 (45.7%) Fig. 1. View largeDownload slide Flow of recruitment. Fig. 1. View largeDownload slide Flow of recruitment. The mean delivery room temperature was less during winter months (October–March) as compared with summer months (April–September). The hypothermia episodes/preterm were more frequent in winter months (Table 2). Table 2 Seasonal variations in delivery room temperature and hypothermia episodes Month Mean (SD) delivery room temperature Mild hypothermia episodes Moderate hypothermia episodes Total episodes/ preterms Average hypothermia episodes per preterm January 26.20 (1.03) 53 68 121/10 12.10 February 27.08 (0.79) 28 42 70/12 5.83 March 28.89 (1.76) 19 10 29/9 3.22 April 30.50 (4.34) 23 23 46/18 2.56 May 29.33 (2.54) 40 25 65/19 3.42 June 29.66 (2.03) 27 24 51/13 3.92 July 30.71 (2.57) 29 17 46/13 3.54 August 30.88 (5.27) 20 4 24/4 6.00 September 29.41 (3.43) 44 24 68/14 4.86 October 27.59 (1.95) 41 20 61/21 2.90 November 26.45 (0.69) 20 25 45/11 4.09 December 26.43 (1.13) 20 6 26/7 3.71 Total 28.67 (2.94) 364 288 652/151 4.32 Month Mean (SD) delivery room temperature Mild hypothermia episodes Moderate hypothermia episodes Total episodes/ preterms Average hypothermia episodes per preterm January 26.20 (1.03) 53 68 121/10 12.10 February 27.08 (0.79) 28 42 70/12 5.83 March 28.89 (1.76) 19 10 29/9 3.22 April 30.50 (4.34) 23 23 46/18 2.56 May 29.33 (2.54) 40 25 65/19 3.42 June 29.66 (2.03) 27 24 51/13 3.92 July 30.71 (2.57) 29 17 46/13 3.54 August 30.88 (5.27) 20 4 24/4 6.00 September 29.41 (3.43) 44 24 68/14 4.86 October 27.59 (1.95) 41 20 61/21 2.90 November 26.45 (0.69) 20 25 45/11 4.09 December 26.43 (1.13) 20 6 26/7 3.71 Total 28.67 (2.94) 364 288 652/151 4.32 Table 2 Seasonal variations in delivery room temperature and hypothermia episodes Month Mean (SD) delivery room temperature Mild hypothermia episodes Moderate hypothermia episodes Total episodes/ preterms Average hypothermia episodes per preterm January 26.20 (1.03) 53 68 121/10 12.10 February 27.08 (0.79) 28 42 70/12 5.83 March 28.89 (1.76) 19 10 29/9 3.22 April 30.50 (4.34) 23 23 46/18 2.56 May 29.33 (2.54) 40 25 65/19 3.42 June 29.66 (2.03) 27 24 51/13 3.92 July 30.71 (2.57) 29 17 46/13 3.54 August 30.88 (5.27) 20 4 24/4 6.00 September 29.41 (3.43) 44 24 68/14 4.86 October 27.59 (1.95) 41 20 61/21 2.90 November 26.45 (0.69) 20 25 45/11 4.09 December 26.43 (1.13) 20 6 26/7 3.71 Total 28.67 (2.94) 364 288 652/151 4.32 Month Mean (SD) delivery room temperature Mild hypothermia episodes Moderate hypothermia episodes Total episodes/ preterms Average hypothermia episodes per preterm January 26.20 (1.03) 53 68 121/10 12.10 February 27.08 (0.79) 28 42 70/12 5.83 March 28.89 (1.76) 19 10 29/9 3.22 April 30.50 (4.34) 23 23 46/18 2.56 May 29.33 (2.54) 40 25 65/19 3.42 June 29.66 (2.03) 27 24 51/13 3.92 July 30.71 (2.57) 29 17 46/13 3.54 August 30.88 (5.27) 20 4 24/4 6.00 September 29.41 (3.43) 44 24 68/14 4.86 October 27.59 (1.95) 41 20 61/21 2.90 November 26.45 (0.69) 20 25 45/11 4.09 December 26.43 (1.13) 20 6 26/7 3.71 Total 28.67 (2.94) 364 288 652/151 4.32 The mean temperature was significantly higher in the study group than the control group for most time intervals (p < 0.001) (Table 3). Average temperature in the study group increased by 0.3°C (35.9–36.19°C), whereas it decreased by 0.08°C (35.71–35.64) in the the control group during intra-hospital transfer within 5 min after resuscitation. Further good thermoregulation (36.5–37.4°C) was achieved within 10–15 min in the study group, whereas it took 30–35 min in the control group. Also, good thermoregulation was maintained even after removal of plastic bag at 1 h (Fig. 2). Similar trend was observed for preterm newborns in the gestational age group of 32–34 weeks (Fig. 3). Table 3 Mean (SD) axillary temperature at various time intervals Temperature Control group Study group p-value N = 77 N = 74 Mean (SD) Mean (SD) 0 min 35.71 (0.84) 35.90 (1.01) 0.228 5 min 35.64 (0.84) 36.19 (0.77) <0.001 10 min 35.80 (0.82) 36.45 (0.61) <0.001 15 min 36.07 (0.68) 36.59 (0.48) <0.001 20 min 36.27 (0.52) 36.70 (0.44) <0.001 25 min 36.38 (0.47) 36.77 (0.39) <0.001 30 min 36.47 (0.42) 36.85 (0.38) <0.001 35 min 36.55 (0.39) 36.88 (0.38) <0.001 40 min 36.62 (0.34) 36.91 (0.39) <0.001 45 min 36.65 (0.31) 36.94 (0.40) <0.001 50 min 36.73 (0.30) 36.97 (0.37) <0.001 55 min 36.77 (0.32) 36.98 (0.37) <0.001 1 h 36.80 (0.27) 37.01 (0.35) <0.001 1.5 h 36.82 (0.28) 36.96 (0.34) 0.006 2 h 36.88 (0.25) 37.03 (0.37) 0.007 3 h 36.86 (0.24) 37.00 (0.32) 0.004 4 h 36.89 (0.23) 37.05 (0.30) <0.001 5 h 36.91 (0.26) 37.07 (0.31) 0.001 6 h 36.90 (0.25) 37.06 (0.30) 0.001 12 h 36.91 (0.27) 37.11 (0.29) <0.001 24 h 36.97 (0.29) 37.17 (0.30) <0.001 Temperature Control group Study group p-value N = 77 N = 74 Mean (SD) Mean (SD) 0 min 35.71 (0.84) 35.90 (1.01) 0.228 5 min 35.64 (0.84) 36.19 (0.77) <0.001 10 min 35.80 (0.82) 36.45 (0.61) <0.001 15 min 36.07 (0.68) 36.59 (0.48) <0.001 20 min 36.27 (0.52) 36.70 (0.44) <0.001 25 min 36.38 (0.47) 36.77 (0.39) <0.001 30 min 36.47 (0.42) 36.85 (0.38) <0.001 35 min 36.55 (0.39) 36.88 (0.38) <0.001 40 min 36.62 (0.34) 36.91 (0.39) <0.001 45 min 36.65 (0.31) 36.94 (0.40) <0.001 50 min 36.73 (0.30) 36.97 (0.37) <0.001 55 min 36.77 (0.32) 36.98 (0.37) <0.001 1 h 36.80 (0.27) 37.01 (0.35) <0.001 1.5 h 36.82 (0.28) 36.96 (0.34) 0.006 2 h 36.88 (0.25) 37.03 (0.37) 0.007 3 h 36.86 (0.24) 37.00 (0.32) 0.004 4 h 36.89 (0.23) 37.05 (0.30) <0.001 5 h 36.91 (0.26) 37.07 (0.31) 0.001 6 h 36.90 (0.25) 37.06 (0.30) 0.001 12 h 36.91 (0.27) 37.11 (0.29) <0.001 24 h 36.97 (0.29) 37.17 (0.30) <0.001 Table 3 Mean (SD) axillary temperature at various time intervals Temperature Control group Study group p-value N = 77 N = 74 Mean (SD) Mean (SD) 0 min 35.71 (0.84) 35.90 (1.01) 0.228 5 min 35.64 (0.84) 36.19 (0.77) <0.001 10 min 35.80 (0.82) 36.45 (0.61) <0.001 15 min 36.07 (0.68) 36.59 (0.48) <0.001 20 min 36.27 (0.52) 36.70 (0.44) <0.001 25 min 36.38 (0.47) 36.77 (0.39) <0.001 30 min 36.47 (0.42) 36.85 (0.38) <0.001 35 min 36.55 (0.39) 36.88 (0.38) <0.001 40 min 36.62 (0.34) 36.91 (0.39) <0.001 45 min 36.65 (0.31) 36.94 (0.40) <0.001 50 min 36.73 (0.30) 36.97 (0.37) <0.001 55 min 36.77 (0.32) 36.98 (0.37) <0.001 1 h 36.80 (0.27) 37.01 (0.35) <0.001 1.5 h 36.82 (0.28) 36.96 (0.34) 0.006 2 h 36.88 (0.25) 37.03 (0.37) 0.007 3 h 36.86 (0.24) 37.00 (0.32) 0.004 4 h 36.89 (0.23) 37.05 (0.30) <0.001 5 h 36.91 (0.26) 37.07 (0.31) 0.001 6 h 36.90 (0.25) 37.06 (0.30) 0.001 12 h 36.91 (0.27) 37.11 (0.29) <0.001 24 h 36.97 (0.29) 37.17 (0.30) <0.001 Temperature Control group Study group p-value N = 77 N = 74 Mean (SD) Mean (SD) 0 min 35.71 (0.84) 35.90 (1.01) 0.228 5 min 35.64 (0.84) 36.19 (0.77) <0.001 10 min 35.80 (0.82) 36.45 (0.61) <0.001 15 min 36.07 (0.68) 36.59 (0.48) <0.001 20 min 36.27 (0.52) 36.70 (0.44) <0.001 25 min 36.38 (0.47) 36.77 (0.39) <0.001 30 min 36.47 (0.42) 36.85 (0.38) <0.001 35 min 36.55 (0.39) 36.88 (0.38) <0.001 40 min 36.62 (0.34) 36.91 (0.39) <0.001 45 min 36.65 (0.31) 36.94 (0.40) <0.001 50 min 36.73 (0.30) 36.97 (0.37) <0.001 55 min 36.77 (0.32) 36.98 (0.37) <0.001 1 h 36.80 (0.27) 37.01 (0.35) <0.001 1.5 h 36.82 (0.28) 36.96 (0.34) 0.006 2 h 36.88 (0.25) 37.03 (0.37) 0.007 3 h 36.86 (0.24) 37.00 (0.32) 0.004 4 h 36.89 (0.23) 37.05 (0.30) <0.001 5 h 36.91 (0.26) 37.07 (0.31) 0.001 6 h 36.90 (0.25) 37.06 (0.30) 0.001 12 h 36.91 (0.27) 37.11 (0.29) <0.001 24 h 36.97 (0.29) 37.17 (0.30) <0.001 Fig. 2. View largeDownload slide Comparison of thermoregulation across groups of preterm neonates over the first day (overall). Fig. 2. View largeDownload slide Comparison of thermoregulation across groups of preterm neonates over the first day (overall). Fig. 3. View largeDownload slide Comparison of thermoregulation of preterm neonates over the first day across groups (32–34 weeks). Fig. 3. View largeDownload slide Comparison of thermoregulation of preterm neonates over the first day across groups (32–34 weeks). Overall, significantly less number of preterm newborns suffered from hypothermia in the study group as compared with the control group [50 (67.6%) vs. 67 (87%), p = 0.004]. Mild hypothermia episodes were less than half in the study group (105) than in the control group (222), whereas moderate hypothermia episodes were almost 2.5 times more in the control group (208) as compared with the study (79) group. The mean (SD) mild hypothermia episodes per preterm [1.4 (1.9) vs. 2.9 (2.1), p < 0.001] as well as moderate hypothermia episodes [1.1 (1.8) vs. 2.7 (2.9), p < 0.001] were significantly less in the study group. A single episode of severe hyperthermia was noted in the study group where the birth weight of baby was 840 g. For 32–34 weeks subgroup, mild hypothermia episodes were about two-third in the study group (78) as compared with the control group (122), whereas moderate hypothermia episodes were less than two-third in the study (54) group as compared with the control (90) group. The mean (SD) mild hypothermia episodes per preterm [1.3 (1.9) vs. 2.5 (2.0), p = 0.001] as well as moderate hypothermia episodes [0.9 (1.49) vs. 1.8 (2.3), p = 0.014] were significantly less in the study group. DISCUSSION We assessed whether covering the preterm newborns (<34 weeks) with polyethylene bag for 1 h is more effective than conventional method of covering with cloth in keeping newborns warmer and reducing hypothermia episodes in first 24 h of life. The incidence of hypothermia remains high with conventional care of drying and wrapping the newborns in pre-warmed cloth [4, 7, 9, 11]. Any intervention to maintain normal temperature of newborn should either decrease heat loss or provide external heat [3]. Polyethylene wraps prevent hypothermia predominantly by reducing evaporative and convective heat loss, and newborn receives radiant heat through transparent polyethylene bag [20]. The Cochrane review concluded that plastic wraps keep the preterm infants warmer and reduce hypothermia episodes and recommended to include more number of infants and studies to further strengthen its use in clinical practice [3]. Despite differences in methodological designs, most studies have documented significantly higher temperature toward normal in plastic wrap group. Buffalo et al. [20] in their study on use of vinyl bag for extremely preterm neonates noticed a difference of 1.0°C for average admission temperature between the two groups. In the current study, we noticed around 0.4°C higher temperature between 15 and 25 min of admission to NICU in the plastic wrap group. Gathwala et al. [15], in their study in India, found the temperature at NICU admission better in the polyvinyl group. In a Malaysian study, mean admission temperature was in favor of the plastic wraps, but they used incubator for transport from the delivery room to the NICU and caps in all neonates after drying the head [18]. A study from Thailand with smaller sample size had similar results favoring plastic bags. In contrast to the current study, they did transport by an incubator, used caps and removed the bag immediately on admission to the NICU [11]. Two other recently published RCTs from Australia [12] and Turkey [13] have similar findings in neonates <30 and 32 weeks, respectively. Most of these studies compared the temperature difference for short time after admission to NICU. The current study further adds to the existing literature that benefits of using plastic wrap persist even at 24 h. Plastic wrap not only keeps the newborn of all gestational ages warmer but also reduces hypothermia incidence in diverse settings. Belches et al. [16] showed that term infants wrapped in the plastic bag had lower rates of hypothermia and higher axillary temperature at 1 h after birth. A study from Turkey also used incubators to place the neonates after wrapping them in plastic and found that very low birth weight newborns reached to normal temperature faster than no wrap group [21]. Many centers in the developed world introduced use of polyethylene bags below the gestation of 30 weeks and reported a drop in hypothermia rates of neonates at admission to the NICU even if the definitions applied of hypothermia have varied (36.0 or 36.5) [22–24]. In an Italian study, the group that wore only polyethylene caps or only polyethylene wraps had much lower incidence of hypothermia as compared with the drying and cloth-wrapped neonates. [25]. The current study supports these findings and favors use of plastic wrap as an effective modality in reducing hypothermia in preterm newborns. RCT in Zambia showed that polyethylene wrap increased the chance of normothermia in the plastic group [26]. The settings of the Zambia study were similar to current study, but the infants were dried before being placed in the polyethylene bag. Cardona et al. [18] compared routine care with polyethylene bag with or without drying the neonates before placing them in bags. Drying the neonate before placement within the bag had no difference to the time required (30 min) to achieve axillary temperature of 36.5°C. Total body wrapping (including the head and body) was comparable with only body wrapping with plastic bag with regard to achievement of axillary temperature on admission to the NICU in neonates <29 weeks [14]. Most studies, even those from low-resource settings, including the current study, are carried out in centers equipped with resources for thermoregulation (though not optimal) in premature babies. However, most deliveries in low-resource countries take place in settings with poor resources for thermal control of term or preterm neonates. The low-cost polyethylene bag lends itself to scalability with its ease of use and effectiveness proven across many settings. The current study thus supports the usage of plastic bags for improving thermoregulation in all preterm babies <34 weeks. We also stress on the need to do similar studies in term neonates and integrating quality improvement to improve neonatal thermoregulation in diverse settings. REFERENCES 1. Silverman WA , Fertig JW , Berger AP. The influence of the thermal environment upon the survival of newly born premature infants . Pediatrics 1958 ; 22 : 876 – 86 . Google Scholar PubMed 2. Dahm LS , James LS. Newborn temperature and calculated heat loss in the delivery room . Pediatrics 1972 ; 49 : 504 – 13 . Google Scholar PubMed 3. McCall EM , Alderdice F , Halliday HL , et al. Interventions to prevent hypothermia at birth in preterm and/or low birthweight infants . Cochrane Database Syst Rev 2010 ; 17 : CD004210 . 4. Laptook AR , Salhab W , Bhaskar B. Admission temperature of low birth weight infants: predictors and associated morbidities . Pediatrics 2007 ; 119 : e643 – 9 . Google Scholar CrossRef Search ADS PubMed 5. Mullany LC , Katz J , Khatry SK , et al. 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For permissions, please email: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

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Journal of Tropical PediatricsOxford University Press

Published: May 23, 2018

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