When exposed to heat stress lambs increase their heat loss by increasing respiratory water loss (RWL). We have shown that this also occurs in fullterm infants.To study the effect of intubation on RWL 10 young nonsedated lambs were exposed to radiative heat stress on two separate time it was. The lambs were awake when exposed to heat stress. Measurements of RWL, oxygen consumption (VO2) and carbon dioxide production (VCO2) were made continuously using a flowthrough system with a mass-spectrometer for gas analysis. The lamb was intubated using a short period of Halothane anaesthesia, and blockade of n. laryngeus superior.When the lambs were not intubated heat stress caused RWL to increase by 220%, while VO2 and body temperature (Tb) remained unchanged. When intubated heat stress caused RWL to increased by 150%, VO2 by 37% and Tb by 0.5 °C. on extubation RWL increased to very high values and body temperature started to fall.This study shows that intubation reduces the ability of the lamb to increase RWL and heat loss, possibly as an effect of the reduction in dead space and exclusion of the nose. This could also be the case for intubate infants.
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