951 RESTING OXYGEN CONSUMPTION OF PREMATURE INFANTS COVERED WITH A THERMAL BLANKET DESIGNED TO REDUCE INSENSIBLE WATER LOSS

Premature infants in single wall incubators covered with “thermal blankets” (TB) made of plastic packing material have large reductions in insensible water loss (IWL) compared to naked infants. We postulated that such reductions in evaporative heat loss would not result in decreases in caloric expenditure if body temperature were maintained by a servo controlled heat source. Using an open circuit technique, we measured oxygen consumption (VO2), carbon dioxide production (VCO2), heart rate (HR), respiratory rate (RR), abdominal skin (Tabd), cheek, thigh, rectal, incubator air, wall, and room air temperature in 10 infants less than 36 weeks gestation and from 2 to 24 days of age both naked and covered with a plastic TB. Tabdwas maintained between 36.2 and 36.8 and rectal temperature between 36.8 and 37.2 °C. in each environment by manual or automatic servo control. A “resting state” was defined using a combination of subjective and objective criteria. The mean values of VO2during the “resting state” were 7.31 and 7.59 cc/kg/min. for naked and covered infants, respectively. Mean values of VCO2, respratory quotient, HR, RR, abdominal, cheek, thigh, and rectal temperatures were essentially identical in both environments. Operant temperatures, however, averaged 0.5 °C. lower when the infants were covered. These data support the hypothesis that decreases in IWL do not necessarily imply reductions in caloric requirements in infants where Tabdis maintained by servo control.