Acidemia does not affect outcomes of patients with acute cardiogenic pulmonary edema treated with continuous positive airway pressure

INTRODUCTION A lack of data exists in the literature evaluating acidemia on admission as a favorable or negative prognostic factor in patients with acute cardiogenic pulmonary edema (ACPE) treated with non-invasive continuous positive airway pressure (CPAP). The objective of the present study was to investigate the impact of acidemia on admission on outcomes of ACPE patients treated with CPAP. METHODS This was a retrospective, observational study of consecutive patients admitted with a diagnosis of ACPE to the Emergency Department of IRCCS Fondazione Cà Granda Ospedale Maggiore Policlinico, Milan, Italy, between January 2003 and December 2006, treated with CPAP on admission. Two groups of patients were identified: subjects with acidemia (acidotic group), and those with a normal pH on admission (controls). The primary endpoint was clinical failure, defined as switch to bi-level ventilation, switch to endotracheal intubation or inhospital mortality. RESULTS Among the 378 patients enrolled, 290 (77%) were acidotic on admission. A total of 28 patients (9.7%) in the acidotic group and eight patients (9.1%) among controls experienced a clinical failure (odds ratio = 1.069, 95% confidence interval = 0.469 to 2.438, P = 0.875). Survival analysis indicates that, among acidotic patients, the time at which 50% of patients reached the 7.35 threshold was 173 minutes (95% confidence interval = 153 to 193). Neither acidemia (P = 0.205) nor the type of acidosis on admission (respiratory acidosis, P = 0.126; metabolic acidosis, P = 0.292; mixed acidosis, P = 0.397) affected clinical failure after adjustment for clinical and laboratory factors in a multivariable logistic regression model. CONCLUSIONS Neither acidemia nor the type of acidosis on admission should be considered risk factors for adverse outcomes in ACPE patients treated with CPAP.