Pancuronium bromide does not lower airway pressures during intermittent positive pressure ventilation in young cats

High intrapulmonary pressure is probably an important factor in the development of extra-alveolar air leaks and bronchopulmonary dysplasia during neonatal intermittent positive pressure ventilation (IPPV). Spontaneous breathing, which may be asynchronous with the ventilator as a result of hypoventilation or sometimes of the ventilatory pattern of the ventilator, can be prevented by neuromuscular blockade. During neuromuscular blockade with pancuronium bromide the central inspiratory (phrenic nerve activity) activity could be inhibited during IPPV at all ventilatory frequencies tested, but a lower arterial PCO2 and a higher pH were needed to achieve inhibition at a low frequency (15 bpm). In the present study it was observed that central inspiratory activity in cats was stimulated by intravenous injection of pancuronium bromide. In cats not subjected to neuromuscular blockade the inspiratory activity was inhibited during IPPV at all ventilatory frequencies studied. At the onset of inhibition of this activity, the arterial blood gases and pH in these animals were almost the same at all ventilatory frequencies. When ventilation was administered at a low frequency, higher peak intratracheal pressures were needed to obtain inhibition of central inspiratory activity than when high frequencies were used, both before and after neuromuscular blockade.