Non-invasive mechanical ventilation in acute respiratory failure due to chronic obstructive pulmonary disease: correlates for success.

BACKGROUND--Non-invasive mechanical ventilation is increasingly used in the treatment of acute respiratory failure in patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to identify simple parameters to predict the success of this technique. METHODS--Fifty nine episodes of acute respiratory failure in 47 patients with COPD treated with non-invasive mechanical ventilation were analysed, considering each one as successful (78\%) or unsuccessful (22\%) according to survival and to the need for endotracheal intubation. RESULTS--Pneumonia was the cause of acute respiratory failure in 38\% of the unsuccessful episodes but only in 9\% of the successful ones. Success with non-invasive mechanical ventilation was associated with less severely abnormal baseline clinical and functional parameters, and with less severe levels of acidosis assessed during an initial trial of non-invasive mechanical ventilation. CONCLUSIONS--The severity of the episode of acute respiratory failure as assessed by clinical and functional compromise, and the level of acidosis and hypercapnia during an initial trial of non-invasive mechanical ventilation, have an influence on the likelihood for success with non-invasive mechanical ventilation and may prove to be useful in deciding whether to continue with this treatment.