THE EFFECTS OF INTERMITTENT POSITIVE PRESSURE VENTILATION ON LUNG FUNCTION IN HYALINE MEMBRANE DISEASE

Fifty-eight infants with hyaline membrane disease were admittedto an intensive care unit. Twenty of these developed respiratoryfailure despite bicarbonate and oxygen therapy. They were thentreated by intermittent positive pressure ventilation and 13of the 20 survived. The mechanism of IPPV was determined in12 of these by the measurement of lung function and blood-gastensions. Results indicated that a normal alveolar ventilationcould be produced in these infants by a 50 per cent increasein their original minute volume. An adequate tidal volume (20ml) could only be obtained by a high peak transpulmonary pressure(35 cm H²O) and this volume had to be delivered at a mean rateof 56 cycles per minute. A reduction in either transpulmonarypressure or the rate of cycling resulted in an inadequate alveolarventilation and a precipitious fall in Pa_o2. Assisted breathingappeared to be more effective than passive ventilation overa short period of time. Measurements were made within 4 minutesof paralyzing the respiratory muscles, and must therefore beaccepted with reserve.