A Double-Walled Incubator Alters the Partition of Body Heat Loss of Premature Infants

Bell, Edward F.; Rios, Gladys R.

doi:10.1203/00006450-198302000-00011

Cited by 45 publications

(31 citation statements)

References 24 publications

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“…However, the difference might be explained by our use of a plexiglass study chamber which would have the effect of a radiant heat shield. A radiant heat shield does not reduce total heat loss when in a thermoneutral environment; rather it reduces radiant heat loss, necessitating a decrease in air temperature in order to increase convective heat loss and avoid increasing body temperature (27). Thus, the air temperature necessary to maintain a thermoneutral mean operative temperature is reduced with a radiant heat shield.…”

Section: Discussionmentioning

confidence: 99%

Anemia Blunts the Thermogenic Response to Environmental Cold Stress in Newborn Piglets

Mayfield

Shaul

et al. 1987

Pediatr Res

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ABSTRACT. We tested the hypothesis that isovolemic anemia blunts the thermogenic response to environmental cold stress in 3 to 4-day-old newborn piglets. Eight animals were studied in both thermoneutral(31.6-32.8" C) and cold (19.6-20.2' C) environments, before and after an isovolemic, partial volume exchange transfusion which reduced the hematocrit from 26 to 15 %. In the nonanemic phase of study, deep rectal temperatures declined but had plateaued by 30 minutes after onset of cold stress and remained within normal limits for newborn piglets. In the anemic phase of study, deep rectal temperature declined continuously throughout cold stress with true body core hypothermia (<3S0 C) observed at all measurement points beyond 15 min of cold stress. Baseline oxygen consumption did not differ between the two study phases (17.6 f 1.8 versus 16.7 f 2.1 ml/kg-'/min-', mean f SEM). However, during environmental cold stress, oxygen consumption increased by 64% over baseline in the nonanemic phase of study ( p < 0.05) whereas 21% increase over baseline was observed in the anemic phase ( p NS). We conclude that isovolemic anemia limited oxygen consumption and heat production during environmental cold stress, resulting in body core hypothermia. (Pediatr Res 21: 482-486,1987

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Section: Discussionmentioning

confidence: 99%

Anemia Blunts the Thermogenic Response to Environmental Cold Stress in Newborn Piglets

Mayfield

Shaul

et al. 1987

Pediatr Res

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“…continuous indirect calorimetry as previously described (18). V02 and VC02 were Oxygen and carbon dioxide concentrations were constantly recorded and compared periodically with ambient (inspired) air.…”

Section: Methodsmentioning

confidence: 99%

“…The mean concentrations of oxygen and carbon dioxide in the sample and ambient gases and the flow ?ate of gas through the system were used to calculate the mean V02, VC02, and RQ for each 30-min period, correcting for the difference between inspired and expired volumes when the RQ is not 1.0 (18,22). These values were corrected to standard temperature and pressure.…”

Section: Methodsmentioning

confidence: 99%

Estimation of 24-Hour Energy Expenditure from Shorter Measurement Periods in Premature Infants

1986

Self Cite

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ABSTRACT. We performed continuous indirect calorimetry for 24 h on nine occasions in small premature infants. Oxygen consumption, carbon dioxide production, respiratory quotient, and energy expenditure were calculated for each 2-h period. The mean energy expenditure during the first 6 h was within 6.5% of the mean for the whole 24-h period in all but one case. The mean error in estimating total daily energy expenditure from 6-h measurements was 0.9%. Because positive and negative errors tend to offset each other, we also calculated the mean absolute error, which was 5.6%. The mean coefficient of variation in energy expenditure among the 2-h periods was 11.0%. The mean coefficients of variation in oxygen consumption, carbon dioxide production, and respiratory quotient were 12.8, 9.9, and 14.1%, respectively. Total daily energy expenditure of small premature infants can be estimated from measurements as short as 6 h with sufficient accuracy for most purposes. (Pediatr Res 20: [646][647][648][649] 1986) Abbreviations vOq, oxygen consumption vC02, carbon dioxide production RQ, respiratory quotient In order to learn more about growth of infants, it is important to understand how dietary energy is utilized. Ingested energy that is not excreted in the feces or urine is either expended for metabolism or stored in body tissues (l,2). By measuring energy intake, excretion, and expenditure it is possible to calculate the energy stored in the body during growth. Relating the energy stored to the rate of weight gain provides insight into the composition of new tissues during growth; fat contains a higher concentration of energy than nonfat tissues.Energy intake and excretion can be determined by collecting and analyzing aliquots of diet and excreta during balance studies of at least several days. Energy expenditure, however, is considerably more difficult to measure, and few attempts have been made to measure energy expenditure of infants for periods of 24 h or longer (3-6). More frequently, 24-h energy expenditure has been estimated from indirect calorimetry of shorter duration, usually periods of 6 h or less (7-1 3).In adults, 24-h energy expenditure cannot be accurately predicted from brief measurement periods due to the influences of Received November 26, 1985; accepted March 4, 1986. Correspondence and reprint requests to Edward F. Bell, M.D., Department of Pediatrics, University of Iowa, Iowa City, IA 52242.This work was supported by grants from the National Institutes of Health (HD16974, HD07578, RR00059) and the March of Dimes Birth Defects Foundation (6-356), and by a grant-in-aid from Gerber Products Company. activity, sleep, and meals on energy expenditure (14, 15). Moreover, it is not possible to perform calorimetric studies of adult subjects during their normal range of activities (14). On the other hand, premature newborn infants are fed frequently at regular intervals, sleep much ofthe time, and are relatively inactive when awake.For these reasons it is possible, although difficult, to perform continuous in...

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“…Several studies have examined the effects of double-wall incubators on the body heat loss of premature infants [12,13,14], and showed that double-wall incubators are capable of reducing the heat loss by radiation. However, references [12] and [13] have attained this conclusion by using indirect measurement techniques like the oxygen consumption of the nursed baby, or by calculations of the heat balance components using average values of the air and walls temperatures. Additionally, average values of the air velocity have been used in order to calculate convective heat losses and, in each case, the geometry of the incubator, interior walls and the baby have not been considered.…”

Section: Introductionmentioning

confidence: 99%

A combined study of heat and mass transfer in an infant incubator with an overhead screen

Ginalski

Nowak

Wrobel

2007

Medical Engineering & Physics

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The main objective of this study is to investigate the major physical processes taking place inside an infant incubator, before and after modifications have been made to its interior chamber. The modification involves the addition of an overhead screen to decrease radiation heat losses from the infant placed inside the incubator. The present study investigates the effect of these modifications on the convective heat flux from the infant's body to the surrounding environment inside the incubator. A combined analysis of airflow and heat transfer due to conduction, convection, radiation and evaporation has been performed, in order to calculate the temperature and velocity fields inside the incubator before and after the design modification. Due to the geometrical complexity of the model, Computer-Aided Design (CAD) applications were used to generate a computer-based model. All numerical calculations have been performed using the commercial Computational Fluid Dynamics (CFD) package FLUENT, together with in-house routines used for managing purposes and User-Defined Functions (UDFs) which extend the basic solver capabilities. Numerical calculations have been performed for three different air inlet temperatures: 32, 34 and 36ºC. The study shows a decrease of the radiative and convective heat losses when the overhead screen is present. The results obtained were numerically verified as well as compared with results available in the literature from investigations of dry heat losses from infant manikins.

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A Double-Walled Incubator Alters the Partition of Body Heat Loss of Premature Infants

Cited by 45 publications

References 24 publications

Anemia Blunts the Thermogenic Response to Environmental Cold Stress in Newborn Piglets

Anemia Blunts the Thermogenic Response to Environmental Cold Stress in Newborn Piglets

Estimation of 24-Hour Energy Expenditure from Shorter Measurement Periods in Premature Infants

A combined study of heat and mass transfer in an infant incubator with an overhead screen

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