Indian Journal of Public Health, Volume 54, Issue 1, January-March, 2010

Safety and Efficacy of Vinyl Bags in Prevention of Hypothermia of Preterm Neonates at Birth

*Geeta Gathwala, Gurmeet Singh, Kunal, Nitika AgrawalDepartment of Pediatrics, Division of Neonatology, Pt. B.D.S. Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India

Incidence of hypothermia among preterm neonates born at or below 1500 gm varies from 31 to 78%1. VLBW i.e Very Low Birth Weight (<1500g) preterm infants are likely to become hypothermic despite the use of traditional techniques for decreasing heat loss2. For this reason the American heart association (AHA) and American Academy of pediatrics (AAP) guidelines for resuscitation 2005 recommended the use of additional warming techniques in these babies3. The present study therefore, was planned to evaluate the safety and efficacy of vinyl bags in prevention of hypothermia during resuscitation at birth in very low birth weight neonates.

This study was conducted in the Neonatal Services Division of the Department of Pediatrics, Pt. B.D. Sharma PGIMS, Rohtak from 1.8.07 to 31.10.08. Type of study was a randomized controlled clinical trial. Neonates who met the inclusion criteria of the study i.e inborn, gestational age ≤32 week, birth weight <1500 gms were randomized to either the study group (vinyl bag group)

or the control group (conventional care group) using a random number Table. An informed parental consent was obtained for all neonates enrolled in the study.

Ethical clearance was also obtained from the hospital authorirty. Neonates with congenital malformation, with skin blisters and those whose parents refused consent were excluded from the study. The neonates under vinyl group were put in vinyl bags upto neck and the head was covered with a cap after drying immediately following delivery and resuscitated under a radiant warmer. Auscultation was done over the bag and if umbilical access was required, a hole was made in the bag to provide access. In conventional drying group, neonates were resuscitated by conventional drying under radiant warmer. Neonates of both the groups were then shifted to NICU in a pre warmed transport incubator (HillMedHM NeoTR) set at temperature 35°C and put to open care warmer where axillary and rectal temperature were measured by thermometer immediately after removing the vinyl bag and after 1 hour. For recording axillary temperature, the clinical thermometer was placed high in the axilla, and the arm then held against the side of the baby for at least five minutes and for recording rectal temperature, the thermometer was placed in the rectum to a maximum depth of 2 cm, where it was held for at least

*Corresponding Author: Geeta Gathwala, Department of Pediatrics, Division of Neonatology, Pt. B.D.S. Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India E-mail: g_gathwala@hotmail.com

DOI: 10.4103/0019-557X.70543 PMID: 20859046

Summary

The present study was planned to evaluate the safety and efficacy of vinyl bags in prevention of hypothermia during resuscitation at birth in very low birth weight neonates. Sixty neonates of gestational age ≤32 weeks and birth weight ≤ 1500gm were randomised to either study group, or control group. Study group neonates were put in vinyl bags up to neck and the head was covered with a cap after drying immediately following delivery and resuscitated under radiant warmer. Control group neonates were resuscitated by conventional drying under radiant warmer. Mean axillary and rectal temperature recorded immediately after admission to NICU were significantly higher in the study group compared to control group. Temperature recorded after 1 hour of admission to NICU were however comparable between the two groups. As temperature maintenance in these VLBW neonates is of tremendous importance, it would make sense to recommend the use of vinyl bags during their resuscitation.

Key words: Hypothermia, preterm neonates, vinyl bags

Short Communication

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Indian Journal of Public Health, Volume 54, Issue 1, January-March, 2010

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three minutes4. To establish difference in the temperature of 0.5°C as a significant difference between these two groups (Vinyl bag group and conventional drying group) at a significant level of 0.05 and a power of 80%, required sample size was 32. In this study a total of 60 newborns (30 in each group) were enrolled. The data was analyzed using the unpaired student’s ̀ t’ – test, the Chi-square test and Fischer Exact test.

The study and control groups were comparable according to the gestational age, birth weight, apgar score and cord pH [Table 1]. Mean axillary and rectal temperature recorded immediately after admission to NICU were 36.06±0.38°C and 36.35±0.36°C in the study group and 35.34±0.37°C and 35.6±0.42°C in control group respectively. Both the temperatures were seen significantly higher in study than control group. Temperatures recorded after 1 hour of admission to NICU were however comparable between the two groups [Table 2]. Also noteworthy was that no neonate was found to be hyperthermic.

Study group neonates therefore had a significantly higher temperature recorded immediately after admission than

control group neonates but after 1 hour of admission, temperature recorded in both study group and control group were comparable. Similar observation was made by Mathew et al.5 among 27 premature neonates less than 28 weeks of gestation and reported that vinyl bags prevented hypothermia at birth. The average axillary temperature recorded at admission to NICU in vinyl bag group was significantly higher (35.9±0.13°C vs. 34.9±0.24°C) than the control group5.

Sunita et al.6 compared the effects of wrapping (with polythene) neonates of <31 weeks of gestation (n=62) by measuring rectal temperature at nursery admission. Wraps were removed on nursery admission. They reported that the use of occlusive wrapping resulted in significantly higher admission rectal temperature in infants <28 weeks compared to non wrapped group (36.94±0.56°C vs. 35.04 ±1.08°C respectively, P<0.001). No significant difference in temperature was seen in neonates 28 to 31 weeks of gestation. In the present study, the mean gestation was 29.93 weeks in the vinyl bag group and 29.46 weeks in the conventional care group and unlike the observations of Sunita et al.,6 the present study recorded significantly higher temperature at NICU admission in the vinyl bag group neonates compared to controls.

Sunita et al.7 in another study had shown higher mean rectal temperature of 36.5°C ±0.8°C in wrapped group compared to 35.6°C±1.8°C in control infants, however one hour later, mean rectal temperature was similar in both the groups (36.6°C± 0.7°C vs. 36.4°C ± 0.9°C, P=0.4). These observations are similar to the present study.

Kent et al.8 observed improved admission temperature in infants <31 weeks gestation by increasing the ambient temperature in operation theatre and wrapping premature infants in polythylene wrap. Ibrahim et al.9 and McCall et al.10 made similar observations.

The use of vinyl bag decreases heat loss by several

Table 1: Comparison of study and control groups

Study group (n=30)

Control group (n=30)

‘P ’ value

Maternal age in years (Mean ±SD)

20.93 ±2.99 20.43 ±2.06 >0.05

Booked no (%)Unbooked no (%)

12 (40)18 (60)

9 (30)21 (70) >0.05

Mode of delivery no (%)Vaginal VertexVaginal breechEmergency LSCS

25 (83.33)3 (10)

2 (6.67)

23 (76.67)6 (20)

1 (3.33)>0.05

Gestational age (weeks)Mean±SD

29.93±1.08 29.46±1.33 >0.05

Birth weight (kg)Mean±SD

1.12±0.19 1.11±0.23 >0.05

Apgar scoreAt 1 minuteAt 5 minute

6.13±1.357.76±1.13

5.66±1.787.63±0.92 >0.05

Cord pH 7.24±0.11 7.22±0.123 >0.05

Table 2: Temperature recorded at admission and at 1 hour after admission to NICU

Time of recording Temperature recorded in °CMean ± SD

‘P ’ value

Study group (n=30) Control group (n=30) p1-axillary

Axillary Rectal Axillary Rectal p2-rectal

Immediately after admission to NICU 36.06±0.38 36.35±0.36 35.340.37 35.60±0.42 p1-<0.01p2--<0.01

After 1 hour of admission to NICU 36.59±0.334 36.87±0.34 36.47±0.28 36.780.31 p1->0.05p2->0.05

Gathwala G, et al.: Safety and Efficacy of Vinyl Bags in Prevention of Hypothermia

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Indian Journal of Public Health, Volume 54, Issue 1, January-March, 2010

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mechanisms. There is decreased evaporative heat loss as evaporative water loss from skin surface that is not in contact with membrane contributes to high humidity in the air between membrane and skin. All areas of vinyl membrane and skin under membrane that face heat source are heated through radiation causing heat gain to the neonate. This barrier also prevents convective heat loss from cold drafts in the delivery room. Absence of drying also retains vernix caseosa which too decreases the evaporative heat loss5,11.

Considering the importance of temperature maintenance in the very small neonates, it could be concluded that it would make sense to recommend the use of vinyl bags during their resuscitation.

References

1. Bhatt DR, White R, Martin G, Marter LJ, Finer N, Goldsmith JP, et al. Transitional hypothermia in preterm newborn. J Perinatol 2007;27:545-7.

2. Costeloe K, Hennerry E, Gibson AT, Marlow N, Wilkinson A. The EPICure study: outcome at discharge from hospital for infants born at the threshold of viability. Pediatrics 2000; 106:659-71.

3. 2005 American Heart Association (AHA) Guidelines for Emergency Cardiovascular Care (ECC) of Pediatric and Neonatal Patients: National Resuscitation Guidelines. Pediatrics 2006;117:e1029-38.

4. Thermal protection of the newborn: a practical guide. Maternal and Newborn Health / Safe motherhood unit. Division of Reproductive Health (Technical support), Geneva: WHO; 1997. p. 14-7.

5. Mathew B, Lakshminrusimha S, Cominsky K, Schroder E, Carrion V. Vinyl Bags prevent hypothermia at birth in preterm infants. Indian J Pediatr 2007;74:249-53.

6. Vohra S, Frent G, Campbell V, Abbett M, Whyte R. Effect of polythylene occlusive skin wrapping on heat loss in very low birth weight infants at delivery: a randomized trial. J Pediatr 1999;134:549-51.

7. Vohra S, Rober RS, Zhang B, James M, Schmidt B. Heat loss prevention (He LP) in the delivery room. A randomized, controlled trial of polythylene occlusive skin wrapping in very preterm infant. J Pediatr 2004;145:750-3.

8. Alison K, Joniz W. Increasing ambient operating theatre temperature and wrapping in polythylene improves admission temperature in premature infants. J Paediatr Child Health 2008;44:325-31.

9. Ibrahim C, Yoxall C. Use of plastic bags to prevent hypothermia at birth in preterm infants – do they work at lower gestations. Acta Paediatr 2009;98:256-60.

10. McCall EM, Alderdice FA, Halliday HL, Jenkins JS, Vohra S. Interventions to prevent hypothermia at birth in preterm and/ or low birthweight infants. Cochrane Database Syst Rev 2008;23:CD004210.

11. Visscher MO, Narendarn V, Fickeni WL, La Ruffa AA, Meizen DJ, Allen K, et al. Vernix caseosa in neonatal adaptation. J Perinatol 2005;25:440-6.

Source of Support: Nil, Conflict of Interest: None declared.

Gathwala G, et al.: Safety and Efficacy of Vinyl Bags in Prevention of Hypothermia

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