A Randomized Controlled Trial of Evaluating the Efficacy of Alternative Swaddles for Body Temperature Control of Newborns

Abstract

Background/Aim: The critical drop of body temperature in neonatal termed “hypothermia” increases risk of morbidity and mortality. In order to minimize hypothermia during delivery room to nursery transportation, we trialed for appropriate alternative means of aluminum coated fabric (ACF), cotton swaddle, and their combination. The aim of the present study was to compare the efficacy of aluminum coated fabric, cotton swaddle, and combined method to prevent neonatal hypothermia.

Patients and Methods: One hundred and seventy-four of eligible infants (birth weight more than 2,500 g) were randomized into three groups (55 infants in aluminum coated fabric, 60 in combined aluminum coated fabric with cotton swaddle, and 59 in cotton swaddle as a control). Rectal temperature was determined before swaddling and arriving at nursery.

Results: There was no significant difference in antenatal and perinatal factors. Normothermia was detected in 50, 52, and 55 infants and decrease body temperature from its baseline were evidenced in 25, 24, and 14 infants swaddling with aluminum coated fabric, combined aluminum coated fabric with cotton swaddle and cotton swaddle, respectively (p=0.425 and p=0.210). Interestingly, results indicated that the use of cotton swaddle, ACF, and their combination could reduce the number of hypothermic infants from 4, 3, and 6 to 0, 5, and 1, respectively, pointing that the use of cotton swaddle exhibited the maximum hypothermia recovery potential.

Conclusion: The cotton swaddle showed the dominant hypothermal control over ACF and combination of cotton swaddle and ACF. These findings may benefit the development of new strategies for hypothermia prevention in newborns.

Previous well-established studies have reported that effective thermoregulation during transfer of newborns from delivery room to the nursery can increase infant survival rates (1-4). The homeothermic mechanisms of newborn have limited capacity; hence, the core body temperature is frequently fluctuated as a result of altered environment temperature. Infants are very sensitive to the change of surrounding temperature that may cause hypothermia because they have a high surface area to volume ratio (5,6). The drop of temperature generates cold stress causing the body to response by activating thermogenesis via sympathetic nerve discontinue in the brown fat followed fatty acids oxidation or re-esterification (7,8). This heat producing process enhances the metabolic rate and oxygen consumption up to 3 folds. Such an increase in oxygen consumption can be critical in infants with respiratory distress (9), leading to hypoxia and neuronal damage. Besides, prolonged hypothermia may cause metabolic acidosis and increases the risk of mortality (5,10,11).

Statistically, approximately 25% of newborns suffer from hypothermia, mainly due to the loss of body heat during the delivery from the labor room or operating room to the neonatal ward (11,12). The proper and effective heat preserving means like the transport incubator are necessary (13). Although portable incubator keeps infant temperature stable, this way of transport is considerably expensive; thereby, limited in many hospitals. Therefore, this research aimed at investigating the alternative covering means that can prevent body temperature loss including cotton swaddle and aluminum coated fabric (ACF). We also observed the incidence of complications that arise during the infant wrap in ACF, cotton swaddle with ACF, and cotton swaddle alone, such as tachypnea, hypoglycemia, and sepsis. The information obtained from the present study may be beneficial for preventing hypothermia in newborn infants and suggested a new safe and simple way of management.

Patients and Methods

Study population. A randomized control trial was conducted during a 24-month period at Phramongkutklao Hospital, Bangkok, Thailand. Term infants with birth weight more than 2,500 g were recruited. The inclusion criteria were infants with an Apgar score at 5 min more than 7. Exclusion criteria included infants whose mother had a fever more than 38.0˚C or chorioamnionitis, congenital anomalies or dysmorphic features, including infants with imperforate anus. The sample size estimation was based on the data from Lunze K. et al. (11), according to which incidence of hypothermia is 15%. A sample size of 64 infants per group was calculated to achieve a power of 80% with a significance level at 0.05. Parents were given verbal and written information regarding the procedure. Patient data were collected and recorded in an electronic database using codes to maintain patient confidentiality and a security password was set to limit access to the data. This study was approved for ethical issues by the Institutional Review Board Royal Thai Army Department (code h013h/62). The study was registered in Thai Clinical Trials Registry (code TCTR20210317003).

Data collection. Informed consent was obtained from parents. Infants who met the selection criteria were randomized into 3 groups by block randomization provided in sequentially numbered opaque envelopes. Infants in the intervention group received ACF wrapping, cotton swaddle together with ACF or only cotton swaddle. Ambient temperature was controlled to be steady at 27˚C during the experiment. Radiant warmer was opened at least 5 min before the infant was born. The infants were assessed by a neonatologist. They were monitored for heart rate and oxygen saturation by Masimo SET Radical Signal Extraction Pulse Oximeter (Irvine, CA, USA) before transferred to nursery. After initial resuscitation, rectal temperature of the infant was measured using a rectal thermometer for 3 min (while measuring temperature, the infants were taken out of the radiant warmer and placed in the crib to prevent measurement errors resulting from the radiant warmer). We performed the swaddling according to the randomized group and then, transferred the infant to the nursery by crib. Upon arrival in the nursery, the doctor immediately took the rectal body temperature using a rectal thermometer for 3 min again. In the event that the infant had a normal body temperature (36.5-37.5˚C), the nurse removed the ACF (for group 1 and group 3 infants) and put the infant to the warmer underneath the crib and observe symptoms. In the event that the infant had low body temperature (less than 36.5˚C), the infant was put into the infant incubator. The nurses operating in the nursery measured the infant's temperature periodically every 30 min until the infant's temperature had returned to normal. In the event that the infant was found to have a high body temperature (37.5˚C), the nurse removed the ACF (for group 1 and group 3 infants), loosened the covering fabric, and wiped the infant’s body. Then, its temperature was periodically measured every 30 min until the temperature return to normal. Clinical evaluation including respiratory distress was monitored.

General information including maternal pregnancy history, gestational and labor problems, delivery method, place of delivery, gestational age, birth weight, maternal temperature, Apgar score, and neonatal resuscitation in the delivery room or operating room were recorded. The temperature of the infant in the labor room, operating room, and nursery was determined. Time used for transferring infants from the labor room/operating room to the nursery was recorded. Neonatal complications after birth including respiratory distress, low capillary blood glucose, and sepsis were assessed.

Statistical analysis. Descriptive statistics are presented as the mean±standard deviation (SD) for continuous variables, and count and percentage for categorical data. Chi-square statistics was used to compare categorical data among the groups, while continuous data with normal distribution were analyzed with one-way ANOVA statistics. Finally, paired t-test analysis was used for the comparison of infant temperatures in delivery room and in nursery. Statistical analysis was carried out using SPSS Statistical Software (SPSS version 22; IBM, New York, NY, USA). p-Values of less than 0.05 were considered statistically significant.

Results

One hundred and eighty neonates met the inclusion criteria. Six infants were excluded due to the suspected maternal chorioamnionitis. One hundred and seventy-four of eligible infants were randomized into three experimental groups (55 in ACF, 60 in combined ACF with cotton swaddle, and 59 in cotton swaddle as a control) as shown in Figure 1.

Figure 1. CONSORT flow diagram. ACF: Aluminum coated fabric.

The maternal factors did not differ among the three groups in age, gestational diabetes mellitus, hypertension, premature rupture of membrane and chorioamnionitis. There were no differences in the general characteristics including sex, birth weight, resuscitation after birth, and Apgar score at 5 min, as shown in Table I.

Table I. Maternal and neonatal characteristics.

ACF, Aluminum coated fabric. *Using chi-square test; ^aResults presented as mean±SD; ^bUsing One-way ANOVA.

In the delivery room, newborns in the ACF, combined ACF with cotton swaddle, and plain cotton swaddle groups had a low body temperature (<36.5˚C) at a percentage of 5.5, 10, and 6.8%, respectively. These percentages did not significantly differ (p=0.674) among the 3 groups. The majority of infants were found to have normal temperature (36.5-37.5˚C).

After transfer to the nursery within a 5 min period, the body temperature of newborns was measured. In the nursery, 9.1, 1.7, and 0 % of infants in the ACF, combined ACF with cotton swaddle, and plain cotton swaddle group, respectively, had a low body temperature. However, the body temperature of infants was not significantly different among the three groups (p=0.09) or between any two groups (ACF vs. ACF and cotton swaddle combination: p=0.07; ACF vs. cotton swaddle: p=0.07; cotton swaddle vs. ACF and cotton swaddle combination: p=0.99). Most of the infants were normothermic. Notably, 1 (1.6%) infant in the plain cotton swaddle group was found to get fever (hyperthermia condition). Results showed that the use of cotton swaddle, ACF, and combination could reduce the number of hypothermic infants from 4, 3, and 6 to 0, 5, and 1, respectively (Table II).

Table II. Body temperature of infants as measured in delivery room (DR) and after transfer to the nursery.

¹Comparison of number of infants with low, normal, or high T at delivery room between the three groups; ²Comparison of number of infants with low, normal or high T at nursery between the three groups. T: Temperature; low T: <36.5˚C; normal T: 36.5-37.5˚C; high T: ≥37.5˚C.

Regarding the secondary outcomes, we monitored respiratory rate and complications and found that the percentage of infants that experienced intermittent tachypnea was 6.6 and 15.2%, in the combined ACF with cotton swaddle and plain cotton swaddle group, respectively, with a statistically significant difference (p=0.048). All three groups had one case of hypoglycemia, which accounted for 1.6, 1.6, and 1.8%; however, no postpartum infection was found in all groups as shown in Table III.

Table III. Secondary outcomes: complications observed in infants.

ACF, Aluminum coated fabric. *Using chi-square test.

Discussion

Hypothermia in babies after birth was one of the leading factors in developing complications after birth (5,14-16). Preventive means of hypothermia are of essential for improving survival rate afterbirth (10,17,18). Our study demonstrated the possible use of ACF, combined ACF with cotton swaddle and plain cotton swaddle for temperature control during transportation from delivery room to nursery in 174 infants. We found that the cotton swaddling during transfer from the delivery room to the nursery was the best way for prevention of infant hypothermia.

According to our study, 16 infants had postnatal complications, including tachypnea and hypoglycemia; however, they were all spontaneously recovered. Similar to the study by Nayeri et al. (19), the hypothermic infants with body temperature less than 36.5˚C had respiratory distress during the first 6 h after birth; however, such complication was found to be spontaneously resolved. The complications of hypothermia may be caused through the mechanism of cold stress response. Specifically, the cold stress induced by the decrease of body temperature can stimulate the activity of sympathetic nervous system. These stimulations cause the increase of heat production by enhancing the cellular metabolism. However, in most cases, the increase of energy production requires more oxygen consumption and increase the risk of hypoxia and acidosis (5,6).

Considering the possible ways to prevent the cold stress, factors that influence heat loss of infants involve evaporation, conduction, and convection (1,4,12,20,21), which depend on birth weight, ambient temperature, and proximity to their mothers (22-24). According to our study, the ACF, combined ACF with cotton swaddle and plain cotton swaddle were able to prevent the heat loss by inhibiting evaporation, conduction, and convection. Although ACF was expected to be the most efficiency in preventing evaporation, our results showed that the preventive effects of ACF and ACF plus cotton swaddle were comparable to the cotton swaddle alone. We hypothesized that the cotton swaddle may have more prominent effect in terms of conduction over ACF, while the convection of all groups was relatively comparable.

Although we found no superior effects of ACF and combined ACF and cotton swaddle in our experiment, the report of Buggy D et al. (25), indicated that the use of ACF reduced the low body temperature in infants and gradually increased the body temperature compared to conventional treatment. About limitations, there were few populations involved and more studies on the cost-effective use of ACF were required.

Conclusion

This study compared the efficacy of hypothermia prevention among ACF, cotton swaddle with ACF, and cotton swaddle. We found that swaddling the infant in cotton swaddle had the superior hypothermia control over the other wrapping methods.

Conflicts of Interest

No potential conflicts of interest were informed by the Authors.

Authors’ Contributions

PC and NS designed the study, KJ collected and analyzed the data. PC and NS wrote this manuscript. All Authors approved the final manuscript.

Acknowledgements

The Authors thank all members of the Department of Pediatrics, Phramongkutklao Hospital and Phramongkutklao College of Medicine. This work was supported by grants from Phramonkutklao College of Medicine, Royal Thai Army Medical Department.