Journal of Applied Physiology, Vol 70, Issue 5 1977-1982, Copyright © 1991 by American Physiological Society
Respiratory compliance during sedation, anesthesia, and paralysis in infants and young children
M. E. Fletcher, C. Stack, M. Ewart, C. J. Davies, S. Ridley, D. J. Hatch and J. Stocks
Respiratory and Anaesthetic Unit, Institute of Child Health, London, United Kingdom.
Although total respiratory compliance (Crs) has been shown to fall in
adults on induction of halothane anesthesia, no successful paired studies
have been reported in children. The multiple occlusion technique was used
to measure Crs in 17 infants and young children during sedated sleep (CrsS)
and shortly after, following induction of halothane anesthesia (CrsA). Crs
fell in all but one infant after induction of anesthesia, with a mean fall
of 34.7% (range 0-58%). This was accompanied by a reduction in tidal volume
and increase in frequency in every case. In 7 of the 17 children, who were
to be paralyzed for surgical purposes, Crs was also measured in this
anesthetized-paralyzed state. When tidal volume administered during manual
ventilation was similar to that observed during measurement of CrsA, Crs
during this low-volume ventilation was similar to CrsA. When tidal volume
was increased and Crs remeasured, there was a significant increase in every
case, with the high-volume Crs within 10% of CrsS in all but one child, in
whom there was a 31.4% increase with respect to CrsS. Changes in tidal
volume accounted for approximately 50% of the variability in each state.
These results demonstrate a highly significant fall in Crs in infants and
young children after induction of halothane anesthesia. In addition it
appears that this reduction in Crs can be reversed by paralyzing the child
and manually ventilating with tidal volumes approximating those seen during
sedation.
