Is hypocapnia a risk factor for non-invasive ventilation failure in cardiogenic acute pulmonary edema?

Abstract

Introduction and purpose: The impact of hypocapnia in the prognosis of cardiogenic acute pulmonary edema (CAPE) has not been sufficiently studied. The aim of this study was to analyse whether hypocapnia is a risk factor for non-invasive ventilation (NIV) failure and hospital mortality, in CAPE patients CAPE.

Methods: Retrospective observational study of all patients with CAPE treated with NIV. Patients were classified in three groups according to PaCO₂ level (hypocapnic, eucapnic and hypercapnic). NIV failure was defined as the need for endotracheal intubation and/or death.

Results: 1138 patients were analysed, 390 (34.3%) of which had hypocapnia, 186 (16.3%) had normocapnia and 562 (49.4%) had hypercapnia. NIV failure was more frequent in hypocapnic (60 patients, 15.4%) than in eucapnic (16 pacientes, 8.6%) and hypercapnic group (562 pacientes, 10.7%), with statistical significance (p = 0.027), as well as hospital mortality, 73 (18.7%), 19(10.2%) and 83 (14.8%) respectively (p = 0.026). The predicted factors for NIV failure were the presence of do-not-intubate order, complications related to NIV, a lower left ventricular ejection fraction, higher SAPS II and SOFA score and a higher HACOR score at one hour of NIV initiation.

Conclusions: Hypocapnia in patients with CAPE is associated with NIV failure and a greater in-hospital mortality.

Keywords: Heart failure; Hospital mortality; Hypocapnia; Intensive care unit; Noninvasive ventilation.