Determinants of prolonged mechanical ventilation in patients with chronic obstructive pulmonary diseases and acute hypercapnic respiratory failure

Abstract 

Background

The aim of the present study was to identify early risk factors for prolonged mechanical ventilation (PMV) in chronic obstructive pulmonary disease (COPD) patients admitted to respiratory intensive care units (RICU) for acute hypercapnic respiratory failure.

Methods

PMV was defined as invasive ventilation lasting longer than 7 days. Between January 1, 2000 and December 31, 2005, epidemiological and clinical data on RICU admission day were retrospectively analyzed for eligible patients. Univariate and multiple stepwise logistic regression analyses were used for statistical analysis.

Results

A total of 152 patients were eligible for evaluation during the 6-year study period and their mean age was 63±12 years. Fifty-one patients died before day 7 after the onset of MV (early death group). Of the remaining 101 patients who survived until day 7, 56 had been weaned successfully (non-PMV group) and 45 continued to receive MV (PMV group). Logistic regression analysis showed that age above 65 (OR=1.98, 95% CI=0.96–4.17, P=0.011), a pH of 7.30 or less measured 12 h after ventilation (OR=2.09, 95% CI=1.17–5.64, P=0.002), an APACHE II score above 20 (OR=3.25, 95% CI=1.58–7.10, P<0.001), development of non-respiratory organ failure (OR=4.67, 95% CI=1.54–9.71, P<0.001), and the presence of shock (OR=4.71, 95% CI=2.14–10.09, P<0.001) were independently associated with PMV. The presence of two factors predicted PMV with a sensitivity of 86% and a specificity of 94%.

Conclusion

Age, APACHE II score, refractory acidosis, presence of non-respiratory organ failure, and shock on RICU admission day were early determinants of PMV in patients with COPD and acute hypercapnic respiratory failure.

Keywords: Chronic obstructive pulmonary disease, Mechanical ventilation, Respiratory failure, Risk factors