LUNG AND CHEST WALL COMPLIANCE OF APNEIC PARALYZED INFANTS*

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Abstract
Total respiratory compliance has been measured in 21 normal preoperative infants, paralyzed with large intramuscular doses of a neuromuscular blocking agent, succinylcholine chloride. The infant''s lungs were inflated with oxygen at five different pressures between 6.8 and 34.0 cm H2O, and the gas contained in the lungs at each pressure then was collected in a spirometer during passive expiration. The average total compliance values for each pressure ranged between 4.6 and 6.2 ml/cm H2O and depended upon the series order of airway pressures used. When high pressures were used initially, proceeding to low pressures, the compliances were greater than when low pressures were used initially, proceeding to high pressures. The total compliance averages at 6.8 cm H2O were 4.9-5.2 ml/cm H2O, which closely approximate the values found by other workers for the infant''s lung compliance alone. This implies that the infant''s thorax has little influence on pulmonary expansion. These data are of practical interest for the administration of anesthesia to infants and in the design of infant resuscitation apparatus.