A total of 12 patients (10%) with respiratory acidosis, 11 patients (13%) with metabolic acidosis, four patients (6.2%) with mixed acidosis and eight controls (9.3%) experienced clinical failure (P = 0.613) (see Table Table3).3). The type of acidosis on admission did not affect clinical failure after www.selleckchem.com/products/CAL-101.html adjustment for age, history of acute myocardial infarction, hypocapnia, normotension and PaO2/FiO2 ratio in a multivariable logistic regression model (respiratory acidosis, P = 0.126; metabolic acidosis, P = 0.292; mixed acidosis P = 0.397).Table 3Clinical endpoints of the study population based on type of acidosis on admissionThe time course of both pH and PaCO2 values during CPAP treatment in the acidotic groups, based on diagnosis at admission, as well as in controls is depicted in Figure Figure4,4, after replacing the missing values according to the last observation carried forward technique and after adjustment for age, sex and systolic blood pressure.

An increase in pH values was detected in all groups of patients regardless of the type of acidosis, while a decrease in PaCO2 values was observed in mixed and respiratory acidosis patients.Figure 4Time course of pH and PaCO2 during continuous positive airways pressure treatment. Time course of pH and partial pressure of carbon dioxide in arterial blood (PaCO2) during continuous positive airways pressure treatment in the controls and in the acidotic …DiscussionThe present study indicates that acidemia on admission is not a risk factor for adverse outcomes in ACPE patients treated with CPAP.

Furthermore, not even the type of acidosis on admission – respiratory, metabolic or mixed – impacts clinical outcomes of ACPE patients treated with CPAP.Among our cohort of ACPE patients treated with CPAP, more than three-quarters were acidotic on admission. Our acidotic patients showed similar clinical and laboratory characteristics on admission in comparison with the 346 ACPE acidotic patients treated with CPAP enrolled in the randomized controlled trial by Gray and coworkers [10]. The present study, however, reported lower ACPE-related, late and inhospital mortality rates than those reported in that trial. Possible explanations could be found in the CPAP setting (ventilator with a low initial PEEP), as well as the length of treatment used in the study by Gray and colleagues.

In this last study the mean duration of CPAP treatment was 2 to 3 hours. We showed that, while CPAP treatment GSK-3 in acidotic ACPE patients did actually bring 50% of patients to a pH value above 7.35 within 3 (2.5 to 6) hours, the treatment nevertheless had to be protracted for at least 6 hours before the mean pH crossed the threshold of 7.35.We found that acidemia on admission is not a risk factor for failure in ACPE patients treated with CPAP.