It is encouraging to see trials in progress addressing hypothermia in resource poor settings. I compliment the team at Vellore for this study [1]. There are some points in the study which the authors might want to clarify for their readers.
The rectal temperatures in this study are mean temperatures over time. What is difficult to infer from the paper is the duration that their subjects were outside the target temperature range, and further what extremes of temperature were encountered below the target temperature of 33 degree C. This is very important for understanding the safety of this method. A study published by Hoque, et al comparing different methods of cooling shows that the target rectal temperature of between 33.5 +/- 0.5 was within target temperature( +/-0.5 degree C), for 81% in infants cooled using a mattress for cooling manually, and 74% in infants who were cooled with gloves. Mean overshoot was 0.3 degree C for servo controlled whole body cooling, 1.3 degrees C for whole body cooling using a manually controlled mattress [2]. The variation in the mean rectal temperature from target temperature during the period of cooling was 0.08 ± 0.04°C in this study, which betters the servo controlled device used in Hoque’s study. Considering this was possible with 1:3 nursing support using a passive cooling method is exceptional.

A further point to emphasize is that Western trials for therapeutic hypothermia have kept very strict criteria for recruitment. 11 of the 20 neonates were outborn who were recruited on criteria which don’t meet definite criteria for perinatal asphyxia such as in the TOBY trial [3]. It is mentioned there was significant acidosis among inborn babies at admission, not the outborn. This raises a slight question of the representativeness of the sample in this trial. Why were outborn neonates recruited at all? If these neonates had neonatal encephalopathy due to other causes they might not have shown the complications that moderately to severely asphyxiated neonates display when cooled?

The surface temperatures correlated with the rectal temperatures very well in this study, probably a reflection of the narrow range of environmental temperatures. A recent study using passive cooling as part of a strict protocol showed there is poor correlation between the two. Continuous rectal temperature monitoring remains the standard for monitoring during therapeutic hypothermia and should be the standard whether using active or passive cooling methods [4].

References

1. Thomas N, George K, Sridhar S, Kumar M, Kuruvilla KA, Jana AK. Whole body cooling in newborn infants with perinatal asphyxial encephalopathy in a low resource setting: A feasibility trial. Indian Pediatr. 2011;48:445-51.

2. Hoque N, Chakkarapani E, Liu X, Thoresen M. A comparison of cooling methods used in therapeutic hypothermia for perinatal asphyxia. Pediatrics. 2010;126:e124-30.

3. Azzopardi DV, Strohm B, Edwards AD, Dyet L, Halliday HL, Juszczak E, et al. TOBY Study Group. Moderate hypothermia to treat perinatal asphyxial encephalopathy. N Engl J Med. 2009;361:1349-58.

4. Kendall GS, Kapetanakis A, Ratnavel N, et al. Passive cooling for initiation of therapeutic hypothermia in neonatal encephalopathy. Arch Dis Child Fetal Neonatal. Ed 2010; 95:F408-12.