Chronic obstructive pulmonary disease admitted to an intensive care unit because of acute respiratory failure: How do severity of acidosis effect short and long term mortality?

Abstract

Aim: Effect of the severity of respiratory acidosis on short and long term survival in chronic obstructive pulmonary disease (COPD) patients is investigated in this study.

Methods: Retrospective, observational cohort study in a intensive care unit (ICU) of a chest diseases hospital from January-December 2014. Acute respiratory failure(ARF) and COPD patients were included to study. Patients were divided into two groups according to ICU admission arterial blood gas values; ph≤7.20 (group1) and pH:7.21-7.34(group 2).Patients characteristics, ICU parameters, ICU mortality, short (28 days ) and long term (12 months) mortality were recorded.

Results: 312 COPD patients were enrolled. Study groups were group 1 (n=69 ) and group 2 (n=243). Groups demographics were similar. Length of ICU stay and ICU mortality were similar in two groups.28 day mortality was %13.1 and %10.6 (p=0.35),1 year mortality 29.5% ve 36 % (p=0.35 ) in group 1 and 2 respectively. In cox regression analysis, hazard ratio of 1 year mortality was associated with presence of septic shock (HR:2.1,CI:1-4.5, p=0.039), presence of domiciliary noninvasive mechanical ventilation(DNIMV) before ICU(HR:2.5, CI:1-5.9, p=0.03), severe acidosis (HR:0.42,CI:0.5-3.03, P=0.51) and DNIMV prescription after ICU discharge(HR:0.4,CI:0.17-0.9, p=0.035).

Conclusions: Severity of acidosis (pH< 7.20) does not affect short and long term mortality. Septic shock during ICU and pre ICU presence of DNIMV found to be a risk factor for 1 year mortality therefore should be followed closely. Also prescription of DNIMVafter ICU discharge decreases long term mortality significantly.