Journal of Applied Physiology, Vol 79, Issue 3 801-804, Copyright © 1995 by American Physiological Society
Endotracheal intubation influences respiratory water loss during heat stress in young lambs
K. Hammarlund, T. Norsted, T. Riesenfeld and G. Sedin
Department of Paediatrics, Uppsala University, Sweden.
To study the effect of intubation on respiratory water loss (RWL) during
heat stress, 10 young nonsedated lambs were exposed to radiative heat
stress both when intubated and when not. RWL, oxygen consumption (VO2), and
carbon dioxide production were monitored continuously by using a
flow-through system with a mass spectrometer for gas analysis. When the
lambs were not intubated, heat stress caused RWL to increase by 218%,
whereas VO2 and body temperature remained unchanged. When the lambs were
intubated, heat stress caused RWL to increase by 131% and VO2 to increase
by 36%. On extubation during heat stress, RWL increased by 117 +/- 48%
(standard error of the estimate) of the preextubation value and body
temperature started to fall. This study shows that intubation reduces the
ability of the lamb to increase RWL and heat loss during heat stress in a
warm environment, possibly as an effect of exclusion of the nose and a
reduction in dead space. After extubation, RWL increases markedly, a
finding that might also be valid for intubated infants.
