Changes in respiratory pattern during continuous positive airway pressure in infants after cardiac surgery

Spontaneous breathing trials are commonly used in adults to enable smooth weaning from mechanical ventilation. However, few investigations have examined spontaneous breathing tests in infants. We investigated how respiratory patterns of infants changed during continuous positive airway pressure (CPAP) and whether successful extubation followed CPAP.

Fifty-one consecutive post-cardiac surgery infants satisfied the following weaning criteria: stable hemodynamics, pH > 7.30, tidal volume > 5 ml.kg(-1), and respiratory rate < 50 breaths.min(-1) with pressure control of 10-16 cm H(2)O. We applied CPAP of 3 cm H(2)O for 30 min to these 51 infants. During CPAP, tidal volume, respiratory rate, and arterial blood gases were measured. CPAP was terminated if the patient showed a sustained increase or decrease in heart rate or blood pressure (>20%), a decrease in arterial oxygen saturation (>5%), agitation, or diaphoresis. After the completion of CPAP, tracheal extubation was performed. We considered extubation successful if no reintubation was required in the ensuing 48 h.

Although hemodynamic and ventilatory variables were unstable for the first 5 min, they stabilized after 10 min of CPAP. Fifty infants completed the CPAP trial safely. Of these, 46 (92%) underwent successful extubation after the CPAP trial. The failure group (4 infants) showed lower pH, higher arterial carbon dioxide tension, and more rapid shallow breathing during CPAP than the success group.

After cardiac surgery, when infants recovered stable hemodynamics and spontaneous breathing, the ventilatory pattern and hemodynamics became stable after 10 min of CPAP. Ninety-two percent of the patients were successfully extubated following a 30-min CPAP trial.