Physiologic Response of Ventilator-dependent Patients with Chronic Obstructive Pulmonary Disease to Proportional Assist Ventilation and Continuous Positive Airway Pressure

摘要

To investigate the physiologic effects of proportional assist ventilation (PAV) in difficult-to-wean, me- chanically ventilated patients with advanced COPD, we measured in eight ICU patients the breathing pattern, neuromuscular drive (P_0.1), lung mechanics, and inspiratory muscle effort (PTPdi and PTPpl) during both spontaneous breathing (SB) and ventilatory support with PAV, CPAP, and CPAP_PAV (in random sequence). PAV (volume assist [VA] and flow assist [FA] was set as follows: dynamic lung elastane and inspiratory pulmoanry resistance were measured during SB; then VA and FA were set to counterbalance the elastic and resistive loads exceeding the normal values, respectively, the in- spiratory muscles bearing a normal elastic and resistive workload.