[Show abstract][Hide abstract] ABSTRACT: In closed incubators, radiative heat loss (R) which is assessed from the mean radiant temperature (Tr) accounts for 40-60% of the neonate's total heat loss. In the absence of a benchmark method to calculate Tr--often considered to be the same as the air incubator temperature-errors could have a considerable impact on the thermal management of neonates. We compared Tr using two conventional methods (measurement with a black-globe thermometer and a radiative "view factor" approach) and two methods based on nude thermal manikins (a simple, schematic design from Wheldon and a multisegment, anthropometric device developed in our laboratory). By taking the Tr estimations for each method, we calculated metabolic heat production values by partitional calorimetry and then compared them with the values calculated from V(O2) and V(CO2) measured in 13 preterm neonates. Comparisons between the calculated and measured metabolic heat production values showed that the two conventional methods and Wheldon's manikin underestimated R, whereas when using the anthropomorphic thermal manikin, the simulated versus clinical difference was not statistically significant. In conclusion, there is a need for a safety standard for measuring TR in a closed incubator. This standard should also make available estimating equations for all avenues of the neonate's heat exchange considering the metabolic heat production and the modifying influence of the thermal insulation provided by the diaper and by the mattress. Although thermal manikins appear to be particularly appropriate for measuring Tr, the current lack of standardized procedures limits their widespread use.
[Show abstract][Hide abstract] ABSTRACT: To evaluate the time taken for rewarming hypothermic neonates and to correlate the time taken for rewarming with severity of hypothermia (WHO classification), weight, gestational age and associated morbidity.
100 extramural neonates transported to the Referral neonatal unit of a teaching hospital, with weight more than 1000 grams and abdominal skin temperature less than 36.5 oC at admission were included in the study. Hypothermia was classified as per WHO recommendations. Clinical features including age, weight, gestational age, clinical diagnosis and vitals were recorded at the time of admission. Rewarming was done under a servo-controlled radiant warmer, in skin mode at set temperature of 37 oC. Skin and air temperatures measured by the thermistor probe were recorded at the time of admission and then at least every 15 minutes till skin temperature reached 36.5 oC. The neonates were monitored for oxygen saturation, blood glucose and capillary filling time and stabilized promptly.
The mean abdominal skin temperature was 34.9 +/- 1.4 oC. 72% of babies were moderately or severely hypothermic as per WHO classification. The duration of rewarming was 4.9 +/- 0.8 min, 17.5 +/- 9.5 min and 42+/-7.9 min for mild, moderate and severe hypothermia respectively (p=0.021). The difference in rate of rewarming between various grades of hypothermia was also significant. The duration of rewarming a baby did not differ significantly between the different weight and gestational age groups. When the rate of rewarming was expressed as rise in oC per Kg body weight per hour, it was higher in smaller and more premature babies. The rate of rewarming was slower in asphyxiated babies.
The duration of rewarming depends on the severity of hypothermia. When rewarmed under radiant warmer using servo mode, the duration of rewarming a baby is the same irrespective of weight and gestational age. Asphyxiated babies take longer time to rewarm.
The Indian Journal of Pediatrics 06/2006; 73(5):395-9. · 0.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An increasing body of evidence has revealed that interventions performed during resuscitation of extremely-low-gestational-age neonates (ELGANs) may have a direct influence on the immediate survival and also on long-term morbidity. It has been proposed that interventions in the delivery room and/or hypothermia could trigger changes constitutive of chronic lung disease. New approaches in the first minutes of life using more gentle parameters of intervention are being studied. Thus, titrating inspiratory fraction of oxygen, the use of non-invasive ventilation to reduce trauma to the lung, the use of polyethylene/polyurethane wrapping to avoid hypothermia and delaying cord clamping altogether constitute promising initiatives. The first minutes of life are a valuable window for intervention. However, whilst these practice changes make sense and there are emerging data to support them, further evidence including long-term follow up is needed to definitively change resuscitation procedures in ELGANs.
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