Short-term and long-term effects of nasal intermittent positive pressure ventilation in patients with obesity-hypoventilation syndrome

Objective: To assess the outcome of 54 patients with obesity-hypoventilation syndrome (OHS) who were treated with nasal intermittent positive-pressure ventilation (NIPPV). Design: Descriptive analysis of retrospectively collected clinical data. Materials and methods: From March 1995 to December 2002, OHS (defined as a body mass index [BMI] of > 30 kg/m(2), a daytime PaCO2 of >= 50 mm Hg, and a PaO2 of < 60 mm Hg in the absence of COPD) was diagnosed in 69 cases. Fifteen patients (21.7%) refused to be treated with NIPPV, and 20 patients were started on NIPPV therapy electively and 34 following an acute exacerbation. We employed daytime arterial blood gas values and overnight pulse oximetry to determine the initial NIPPV modes and settings. The outcome measures were survival, clinical status, and arterial blood gas levels. Results: Among the 54 study patients (18 women), the mean (+/- SD) age was 56 +/- 13 years. The mean BMI was 44 +/- 8.8 kg/m(2). Sleep apnea syndrome (apnea-hypopnea index, > 5) was present in 87% of the patients. At presentation, 22 of the 54 patients had experienced an acute hypercapnic respiratory failure (pH < 7.34). None of these patients required orotracheal intubation after NIPPV treatment. Initially, 2 patients were treated with volume-preset ventilation, 49 patients used pressure-preset equipment, and 3 patients employed continuous positive airway pressure (CPAP). Forty-seven patients required supplemental oxygen. At the end of the follow-up period (mean duration, 50 months), PaO2 had increased by 24 mm Hg from baseline (95% confidence interval [CI], 21 to 28 min Hg; p < 0.0001) and PacO(2) had decreased by 17 mm Hg (95% CI, 13 to 20 mm Hg; p < 0.0001). NIPPV therapy improved subjective sleepiness (mean Epworth sleepiness scale score decrease, 16 +/- 5 to 6 +/- 2; p < 0.001), and dyspnea decreased in all but four patients. During follow-up, three patients died (one of them due to the progression of respiratory failure). NIPPV therapy could be withdrawn in 5 patients who had achieved a sufficient weight loss, and the conditions of 16 patients could be maintained without respiratory failure by the use of simple therapy with CPAP. Conclusions: NIPPV therapy is effective in the treatment of patients with OHS, providing a significant improvement in clinical status and gas exchange.