Non-invasive mechanical ventilation in severe chronic obstructive lung disease and acute respiratory failure: Short- and long-term prognosis

Abstract

Objective: To evaluate the short- and long-term prognosis of patients with chronic obstructive lung disease (COLD) who had non-invasive mechanical ventilation (NMV) for acute respiratory failure (ARF). Design: Retrospective study. Setting: Two respiratory intermediate intensive care units. Patients: Two groups of patients suffering from COLD and an ARF episode requiring mechanical ventilation. Group 1 (30 patients) was given NMV using face masks (aged 64 ± 9 years; pH = 7.28 ± 0.05; PaCO2 = 83 ± 18 mmHg; PaO2/ FIO2 = 141 ± 61). Group 2 (27 patients) was composed of control patients (aged = 65 ± 8 years; pH = 7.26 ± 0.05; PaCO2 = 75 ± 17 mmHg; PaO2/FIO2 = 167 ± 41) given MV using endotracheal intubation (EI) when clinical and functional conditions had further deteriorated because the medical therapy failed and NMV was not available at the time. Causes of ARF were in group 1 and 2 respectively; pneumonia in 8 (27%) and 11 (41%), acute exacerbation of COLD in 19 (63%) and 14 (52%) and pulmonary embolism in 3 (10%) and 2 (7%) patients. Measurements and results: Success rate, mortality during stay in ICU (at 3 months and at 1 year), and the need for rehospitalization during the year following ARF were measured in this study. Group 1 showed a success rate of 74%, only 8/30 patients needing EI and conventional MV. In group 2, the weaning success was 74% (20/27 patients). The mortality for group 1 was 20% in HCU, 23% at 3 months and 30% at 1 year; and 26% for group 2 in ICU, 48% at 3 months and 63% at 1 year. Within each group 1-year mortality was greater (p < 0.01) in patients with pneumonia. The number of new ICU admissions during the follow-up at 1 year was 0.12 versus 0.30 in groups 1 and 2 respectively (p < 0.05). Conclusion: For patients suffering from COLD who have undergone ARF, avoiding EI by early treatment with NMV is associated with better survival in comparison to patients bound to invasive MV. Pneumonia as a cause of ARF may worsen the prognosis in both groups of patients.