Abstract
To determine whether cooling affects pulmonary perfusion in the newborn infant we measured effective pulmonary capillary flow (Qpc) at two different environmental temperatures. Seven healthy term infants 15 to 61 h of age were studied initially in a ‘cool’ environment (ambient temperature 29°C) and then in a ‘warm’ one (32.7°C). Qpc was measured using the infants plethysmograph and a 15-sec period of rebreathing nitrous oxide and oxygen, as previously described [Circulation Suppl. 21: 50, 1969]. The mean valu of two determinations at each temperature was compared. The infan's rectal, abdominal skin, and foot temperatures, and the plathysmograph and room temperatures were monitored. Heart rate was measured from an electrocardiogram.
The mean foot-rectal temperature gradient was 5.1°C in the ‘cool’ environment and 2.6°C in the ‘warm’ one. Abdominal-rectal gradients were 0.8°C and 0.1°C respectively. In each instance Qpe was lower in the ‘cool’ environment (mean 141 ml/kg/min-‘cool’; 192 ml/kg/min-‘warm’; p < 0.05). Heart rate was lower (121/min ‘cool’; 128/min ‘warm’) but this was not statistically significant. This reduction in effetive pulmonary capillary flow could be due to increased shunting (the method does not mesure shunted blood), to marked inequalities of ventilation and perfusion, or to a decrease in total pulmonary blood flow. Our results provide further evidence of the possible adverse effects of cooling the newly born infant.
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Brady, J., Rigatto, H. & Dumpit, F. Effect of Cooling on Effective Pulmonary Capillary Flow in Newborn Infants. Pediatr Res 4, 472 (1970). https://doi.org/10.1203/00006450-197009000-00152
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DOI: https://doi.org/10.1203/00006450-197009000-00152