High frequency positive pressure ventilation (HFPPV) in a newborn infant with ruptured lungs.

A 4.2-kg full-term male infant underwent treatment of acute respiratory distress as a result of gross bilateral pneumothoraces, pneumomediastinum and interstitial emphysema. When a trial of continuous positive airway pressure failed conventional intermittent positive pressure ventilation was instituted, but this also failed to achieve satisfactory ventilation at a respiratory frequency of 60 b.p.m. while producing peak airway pressures of 30 cmH2O. High frequency positive pressure ventilation was instituted with a Siemens 900C ventilator delivering a minute volume of 3 litre min-1 at a respiratory frequency of 72 b.p.m., while registering peak airway pressures in the range of 20-23 cm H2O. During the first 30 min of this regimen the patient's condition improved such that FIO2 was decreased to 0.6. Six hours later FIO2 was decreased to 0.55 and the inspired minute volume to 2.8 litre min-1 with a further decrease in peak airway pressure. The infant was maintained on high frequency positive pressure ventilation for a total of 42 h, and following weaning made an uneventful recovery. In another newborn infant, weight 1.9 kg, the measurement of airway pressure at the distal end of the tracheal tube and gas flow in the inspiratory limb of the respiratory circuit established that the tracheal peak airway pressure was 10 cm H2O less that the pressure registered on the ventilator. The 900C ventilator produced a pattern of high frequency low pressure ventilation, with sustained PEEP, which closely resembles the defined pattern of HFPPV.