Evolution of patients with chronic obstructive pulmonary disease, obesity hypoventilation syndrome or congestive heart failure in a respiratory monitoring unit

OBJECTIVE: We compared the use of noninvasive ventilation (NIV) for hypercarnic acidosis with hypoxemia respiratory failure with respiratory acidosis in patients with chronic obstructive pulmonary disease (COPD), obesity hypoventilation syndrome (OHS), or congestive heart failure (CHF) in a respiratory medicine monitoring unit. The objective was to evaluate each diagnostic group's response to therapy in terms of clinical course and evolution of blood gases. PATIENTS AND METHODS: Prospective, 12-month study of 53 patients with hypercarnic acidosis with hypoxemia. Twenty-seven patients had COPD, 17 OHS, and 9 CHF. Severity was assessed based on initial arterial blood gas analysis. Clinical course was studied by blood gas analysis after conventional treatment and after NIV(1-3 hours and 12-24 hours). Mortality was recorded. All patients received bilevel positive airway pressure support in assist-control mode. RESULTS: No significant differences were observed between mean (SD) initial baseline pH findings in the 3 diagnostic groups: COPD, 7.28 (0.1); OHS, 7.29 (0.09); and CHF, 7.24 (0.07). (nonsignificant differences). After initial conventional treatment, PaCO2 worsened for COPD patients (P=.026) and PaO2 improved for CHF patients (P=.028). After 1 to 3 hours of NIV, pH (P=.002) and PaO2 (P=.041) improved for COPD patients, and pH (P=.03) and PaCO2 (P=.045) improved in OHS patients; no significant changes were observed in CHF patients. After 12 to 24 hours of NIV, the mean pH was 7.36 (0.04) for COPD patients, 7.36 (0.05) for OHS patients, and 7.25 (0.1) for CHF patients (not significant). The mortality rate was 11.1% for COPD, 0% for OHS, and 33.3% for CHS (not significant, P=.076). CONCLUSIONS: In this group of patients with similar initial arterial blood gas values, response to NIV was seen to be better in OHS and COPD than in CHF. That the start of NIV is usually preceded by a poor response to conventional COPD treatment suggests that delaying NIV should be reconsidered.