Transcutaneous carbon dioxide monitoring as a predictive tool for all-cause 6-month mortality after acute pulmonary embolism

Abstract

Background: Pulmonary embolism (PE) frequently remains undiagnosed. The partial pressure of carbon dioxide (PaCO2), a surrogate of dead-space ventilation, is useful in the evaluation of the degree of pulmonary artery occlusion. At present, there is no knowledge about the prognostic role of PaCΟ2 variations during the first hours of an acute PE. Transcutaneous measurement of CO2 (PtcCO2) is a simple, non-invasive method that correlates well with PaCO2 levels, evaluated in this study for the first time in patients with PE. Purpose: To assess the correlation between PtcCO2 and PaCO2 levels in the acute phase of PE and the role of PtcCO2 in predicting 6-months mortality. Methods: This was a pilot study including 53 patients with acute PE who hospitalized in Respiratory Medicine Department at University Hospital of Larissa in central Greece during 15 months. PtcCO2 was constantly monitored for four hours after PE diagnosis with the TCM40 monitoring system (SmartCal). Simultaneous arterial blood gas measurements were performed. Each patient was prospectively recorded for six months via standard telephone calls. Results: PaCO2 and PtcCO2 values were well-correlated in the acute phase of PE. Decreased PtcCO2 levels in the first monitoring hour were associated with a higher risk of mortality. In the PE subgroup who died, the lower PtcCO2 level in the first hour of PE was a predictor of shorter survival time independently of gender, age, comorbidities, and smoking status. Conclusion: PtcCO2 measurement, especially in the first hour after PE, seemed to be a valid tool in predicting all-cause 6-month mortality. © 2019 European Federation of Internal Medicine