Mechanics of Respiration in Apneic Anesthetized Infants

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Abstract
The mechanics of respiration were studied during nitrous-oxide halothane anesthesia in 15 apneic infants (weight range, 2. 2-5 kg.) ventilated by a time-cycled constant flow ventilator. The dynamic lung-thorax compliance was 28+ 0. 3 ml/cm of water. The dynamic lung compliance was 33[plus or minus] 0. 3 ml/cm of water and the dynamic chest wall compliance was 22. 3[plus or minus]3. 5 ml. /cm. of water. The inspiratory airway resistance (including tissue viscous resistance) was 63. 9[plus or minus] 3. 7 cm of water/l/sec. The calculated inspiratory work was 6,499 [plus or minus] 567 g. cm/min. The elastic inspiratory work was 4, 697 [plus or minus]427 g. cm/minute. Seventy-two % of the total inspiratory work was done against elastic forces. The static total, lung and chest wall compliances were determined in the same infants and did not differ significantly from the corresponding dynamic values. Substituting the determined values for compliance and resistance in a simplified equation of motion for the lung thorax, it was found that the pressures required for inflation of the lung in anesthetized infants are in the same range as in adults.