Posthypercapnic
alkalosis (PHA) is frequently overlooked as a complication of
mechanical ventilation in patients with exacerbation of
chronic obstructive pulmonary disease (
COPD). The current study was conducted to determine the incidence, risk factors for development and effect on outcome of PHA. Eighty-four patients (62 +/- 11 years, range 42-78 years, M:F 58: 26) with exacerbation of
COPD with underlying chronic
hypercapnic respiratory failure requiring
mechanical ventilation were included in a retrospective fashion. PHA was defined as static or rising serum
bicarbonate levels, 72 hours or more after return of PaCO2 to baseline, with concurrent pH > 7.44. Development of PHA was noted in 17 patients (20.2%).
Corticosteroid use >or=10 days during the
hospital stay was an independent risk factor for development of PHA (Adjusted OR, 95% CI: 9.4, 1.6-55.3; P = 0.013). Development of PHA was associated with an increased incidence of
ventilator dependence (64.7% vs. 37.3%, OR, 95% CI: 3.1, 1.1-9.4, P = 0.04) and duration of ICU stay (14.7 +/- 6.7 vs. 9.5 +/- 5.9, P = 0.01) but no increase in hospital mortality (43.3% vs. 41.2%, P = NS). It is concluded that PHA is a common complication in patients with exacerbation of
COPD requiring
mechanical ventilation and is associated with increased incidence of
ventilator dependence and ICU stay.