Haemodynamic response during initiation of non-invasive positive pressure ventilation in COPD patients with acute ventilatory failure

The aim of this study was to check non-invasively the acute haemodynamic effects of non-invasive positive pressure ventilation (NPPV) initiation in patients with chronic obstructive pulmonary disease (COPD) and acute ventilatory failure (AVF). Nineteen consecutive COPD patients with AVF were evaluated clinically and echocardiographically during spontaneous breathing with O2 supplementation and during NPPV plus O2. NPPV was administered with a scheduled inspiratory pressure of 15 cmH2O and an expiratory pressure of 4 cmH2O, via facial mask. Arterial blood gas improved significantly (pH and PaCO2; P < 0.001) during NPPV administration in all patients; none had hypotension or acute arrhythmia. Doppler echocardiographic evaluation was feasible in most of the patients (16/18). With reference to baseline values, no significant changes in pulmonary artery pressures and cardiac output (CO) were observed by Doppler echocardiography in most patients. Only four patients (21%) showed a significant reduction (> 15%) of CO during NPPV. No correlation was found between decreased CO and baseline data, but three patients showing CO reduction had poor tolerance to mask ventilation and did not improve respiratory rate during NPPV. It was concluded that the initiation of NPPV by facial mask does not alter haemodynamics acutely in most COPD patients with AVF, but individual patients may experience reduction in CO in spite of adequate oxygen saturation levels. This suggests that caution should be used when applying pre-determined and fixed pressures during NPPV. Monitoring haemodynamics by Doppler echocardiography may be useful for early detection of haemodynamic alterations due to NPPV application in patients with AVF.