A review of infants with idiopathic respiratory distress syndrome developing pneumomediastinum and pneumothorax reveals (1) an incidence of 20% in patients receiving CPAP with an 11% incidence in comparable infants not receiving this mode of therapy; (2) in the CAPA-treated group the occurrence was at a stage in the illness when the inspired oxygen concentration was being lowered and when ventilation was stable; (3) the inspired oxygen concentration in the CPAP group at the time of the PM and/or PT was 52% (± S.D. 15%) at a mean age of 33 hours (± S.D. 23 hr).
These observations suggest that distending airway pressure creates excessive alveolar distention as an underlying mechanism of the air leak. It is recommended that distending airway pressure be lowered prior to achieving an inspired oxygen concentration of 60%. A controlled study is in progress to delineate the optimum distending airway pressures at specific inspired oxygen concentrations in order to reduce the incidence of alveolar rupture to a minimum.
