Anatomic deadspace in infants and children.
Numa, Andrew H., Christopher J. L. Newth.
Division of Pediatric Critical Care, Children's Hospital Los
Angeles, University of Southern California, Los Angeles, California
90027
APStracts 3:0013A, 1996.
In adults, anatomic deadspace is 2.2 ml/kg. Because of the relatively
large head size of infants and children, we hypothesized that
extrathoracic and therefore total deadspace would be relatively
larger in pediatric subjects. Extra-thoracic deadspace was measured
in 40 patients aged 7 days to 14.2 years, who were intubated with
cuffed endotracheal tubes, by a "water displacement"
technique. Intrathoracic deadspace was measured by continuous
analysis of end-tidal and mixed expired PCO2, and minute ventilation
in 10 patients aged 18 days to 14.7 years. Extrathoracic deadspace
per kg decreased exponentially with increasing age, ranging from 2.3
ml/kg in early infancy, to 0.8 ml/kg in children older than 6 years.
Mean intrathoracic anatomic deadspace was 1.03 ml/kg, and was not
related to age. The following relationship between total anatomic
deadspace (DStotal) in ml/kg and age in years is derived: DStotal
(ml/kg) = 3.28 - 0.56 { Ln (1 + Age) } with r = 0.95 and p = 0.0001.
Anatomic deadspace is age-dependant and is greater than 3 ml/kg in
early infancy.
Received 10 July 1995; accepted in final form 12 December 1995.
APS Manuscript Number A742-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 22 January 96