Is Hypocapnia a Risk Factor for Non-invasive Ventilation Failure in Cardiogenic Acute Pulmonary Edema?

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 PaCO 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.