Comparison of heated water-filled mattress and space-heated room with infant incubator in providing warmth to low birthweight newborns. Rewarming preterm infants on a heated, water filled mattress. Providing warmth for preterm babies by a heated, water filled mattress. Thermal responses and heart rates of low-birth-weight premature babies during daily care on a heated, water-filled mattress. A double-walled incubator alters the partition of body heat loss of premature infants. Minimal oxygen consumption in infants cared for under overhead radiant warmers compared with conventional incubators. Oxygen consumption and temperature control of premature infants in a double-wall incubator. Heat loss prevention for preterm infants in the delivery room. Relative efficacy of an incubator and an open warmer in producing thermoneutrality for the small premature infant.
Prevention of excessive heat loss is fundamental to survival of low birthweight (LBW) newborns. The use of infant incubators (INC) is beyond the resources of developing countries, and the space-heated room (SHR) has been the only feasible means of providing thermal protection to LBW newborns. Recently a thermostatically controlled, heated, water-filled mattress (HWM) has been developed as a potentially simpler and affordable alternative.
                In a neonatal care ward of a referral hospital in Addis Ababa, 62 < 1 week old newborns, weighing 1000-1999 g, who were well enough to breathe comfortably in room air and tolerate oral feeds, were randomly allocated to INC, HWM or SHR and followed for 3 weeks. The level of cold stress as assessed by core-to-skin temperature gradient and the rate of weight gain were the main outcome measures.
                The level of cold stress was lowest in the INC, intermediate in the HWM and highest in the SHR. Relative to the INC group, the HWM group exhibited a modest increase in the occurrence of clinically important hyperthermic or hypothermic deviations in core temperature (rate ratio (RR) = 2.3; 95% CI: 0.9, 5.6), and the SHR displayed a definite increase (RR = 4.0; 95% CI: 1.7, 9.3). During the first week, the rate of weight gain was highest in the INC group (3.6 g/kg/day), lowest in the SHR group (-2.3 g/kg/day, P < 0.05 versus INC) and intermediate in the HWM group (1.6 g/kg/day, P > 0.1 versus INC).
                Care in the SHR produced clinically significant thermal stresses and was associated with deficient early neonatal growth, but the use of HWM may constitute a feasible and clinically acceptable alternative in providing warmth to LBW newborns during the neonatal period. Sixty low birthweight infants (1000-2000 g) admitted to a neonatal care unit in Turkey were studied. Those not requiring intensive care were randomly assigned for treatment either in a cot on a heated, water filled mattress kept at 37 degrees C (n = 28) or in air heated incubators with a mean air temperature of 35 degrees C (n = 32). On admission 53 (88.3%) of the infants had body temperatures between 30 degrees and 36 degrees C. There was good correlation between axillary and rectal temperatures in the infants while they were hypothermic. Normal temperatures were achieved within the first day and remained within this range during the subsequent days after admission in all the infants treated on the heated, water filled mattress, whereas they were not achieved until three days later in the incubator group. The neonatal mortality among those treated on the heated, water filled mattress was 21%, and among those treated in the incubator 34%. The heated, water filled mattress provides a good alternative to skin to skin contact with the mother, and to the use of a complex and expensive incubator for rapidly attaining and maintaining normal temperatures in the low birthweight newborn. Seventeen healthy preterm babies had extra warmth provided in their cots by thermocontrolled, heated, water filled mattresses. As controls 17 babies of the same weight were nursed in air heated incubators. Both groups were studied for three weeks. No differences were found in minimal oxygen consumption (measured by indirect calorimetry), rectal and mean skin temperatures, or in daily weight gain. The babies were kept just as warm on the heated, water filled mattresses as in air heated incubators but the mattresses had the advantage of giving the mothers easy access to their babies. Body temperatures, heart rates and resting oxygen consumptions were examined during routine nursing care in 12 premature babies treated alternately in incubators or on a heated, water-filled mattress (HWM). The mean temperatures were significantly higher in the axilla (0.3 degree C; p less than or equal to 0.05) and the foot (1.4 degrees C; p less than 0.001) during HWM care. The degree of maximal fall in various body temperatures during routine nursing procedures was the same for both treatments, whereas the time taken for the foot temperature to fall was 13 min shorter during HWM care (p less than 0.001). The proportion of heart rates below 160 bpm when the babies were not disturbed was 7.4% greater during HWM treatment (p less than 0.01). The resting oxygen consumption in babies treated on HWM was slightly lower (6.2 +/- 0.4 vs 6.4 +/- 0.5 ml/kg/min; p less than 0.05). Treatment on the HWM seems to promote calm and comfort, since it reduces the amount of thermal stress and prolongs quiet resting periods. Partitional calorimetry was used to assess the influence of a double-walled incubator (Air-Shields C-86 Isolette) on the body heat loss of eight premature newborn infants (birth weights 1.44-1.89 kg, ages 6-19 days). Each infant was studied in the same incubator with and without the inner wall. Incubator heater output was regulated by servocontrol to maintain the abdominal skin temperature at 36.5 degrees C. Operative environmental temperature was the same (mean 33.0 degrees C) in both incubators. There were no differences in body temperatures, oxygen consumption, carbon dioxide production, respiratory quotient, or evaporative water and heat losses. The double-walled incubator reduced radiant heat loss but increased convective heat loss, so that the total rate of body heat loss was unchanged. Infants under radiant warmers have large increases in insensible water loss compared with infants in single wall incubators. To answer the question of whether or not a minimal rate of oxygen consumption could be achieved under overhead radiant warmers, we measured oxygen consumption, carbon dioxide production, and abdominal skin, cheek, rectal, thigh, and environmental temperature in ten healthy newborn infants in incubators and radiant warmers, using each infant as his/her own control. The minimal VO2 ranged from 4.41 to 8.87 and from 4.35 to 9.06 cc/kg/minute in the incubator and radiant warmer, respectively. The differences were clearly not significant (paired Student t-test, P greater than 0.60). There were no significant differences between the respiratory quotients, VCO2, or abdominal skin, check, rectal or environmental temperatures. These data support the hypothesis that a thermoneutral environment can be provided with a radiant warmer and imply that large increases in insensible water loss can occur without affecting minimal oxygen consumption. The effects of a double wall in a forced convection-heated incubator were studied on ten naked, nondistressed, premature infants by measuring their mean skin temperature, esophageal temperature, and oxygen consumption when they were in thermal steady state, with, and without, the double wall in place. The incubator air temperature was maintained within the recommended thermoneutral zone during the consecutive paired experiments. Ambient room temperature and relative humidity were constant and the infant's activity (quiet sleep) and postprandial state were the same in both conditions. Together with a significant rise in operative temperature (P less than .05) induced by the double wall (accounted for by a 0.9 C mean increased in incubator wall temperature nearest the baby), their mean skin temperature and esophageal temperatures increased (P less than .025), while a decrease in oxygen consumption occurred in nine of the ten infants (P less than .05). These findings suggest that the double wall reduced radiant and total heat loss from the baby by diminishing the temperature gradient between the skin and incubator surfaces and that metabolic heat production (oxygen consumption) was reduced when the double wall was in place. Preterm infants are prone to hypothermia immediately following birth. Among other factors, excessive evaporative heat loss and the relatively cool ambient temperature of the delivery room may be important contributors. Most infants <29 weeks gestation had temperatures <36.4 degrees C on admission to our neonatal unit (NICU). Therefore we conducted a randomized, controlled trial to evaluate the effect of placing these infants in polyurethane bags in the delivery room to prevent heat loss and reduce the occurrence of hypothermia on admission to the NICU.
                After parental consent was obtained, infants expected to be <29 weeks gestation were randomized to intervention or control groups just prior to their birth. Infants randomized to the intervention group were placed in polyurethane bags up to their necks immediately after delivery before being dried. They were then resuscitated per NRP guidelines, covered with warm blankets, and transported to the NICU, where the bags were removed and rectal temperatures were recorded. Control infants were resuscitated, covered with warm blankets, and transported without being placed in polyurethane bags. Delivery room temperatures were recorded so this potentially confounding variable could be assessed.
                Intervention patients were less likely than control patients to have temperature < 36.4 degrees C on admission , 44 vs 70% (p<0.01) and the intervention group had a higher mean admission temperature, 36.5 degrees C vs 36.0 degrees C (p<0.003). This effect remained significant (p<0.0001) when delivery room temperature was controlled in analysis. Warmer delivery room temperatures (>/=26 degrees C) were associated with higher admission temperatures in both intervention and control infants, but only the subgroup of intervention patients born in warmer delivery rooms had a mean admission temperature >36.4 degrees C.
                Placing infants <29 weeks gestation in polyurethane bags in the delivery room reduced the occurrence of hypothermia and increased their NICU admission temperatures. Maintaining warmer delivery rooms helped but was insufficient in preventing hypothermia in most of these vulnerable patients without the adjunctive use of the polyurethane bags. To determine which warming system more closely approximates a neutral thermal environment, the oxygen consumption of 16 premature babies, weighing less than 1,500 gm each, was measured in a convectively heated incubator and under an open radiant warmer. Both systems were controlled to maintain a skin temperature of 36 C. The oxygen consumption of the infants was significantly higher under the radiant warmer. This result is in agreement with published data for this group of premature infants.
Cot-nursing using a heated water-filled mattress has similar effects to incubator care with regard to temperature control and weight gain. Important clinical outcomes need to be investigated further using randomised controlled trials. This is especially the case in the situation of developing countries, where differences in these outcomes are likely to be encountered. As limited data is available on cot-nursing using a space-heated room, this method is not recommended as practice.