High venous to arterial CO2 gap is related to cardiovascular death in cardiogenic shock

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Venous to arterial CO2 gap (CO2gap) is calculated by subtracting partial pressure of arterial CO2 to central venous partial pressure of CO2 (ScvCO2). This marker has been studied in septic shock and indicates hypoperfusion when exceeds 6mmHg. Its kinetics and applicability in cardiogenic shock (CS) are unclear, being mixed/central venous saturation and lactate more commonly used. Purpose The objective of the study is to describe CO2gap kinetics in patients with CS. Secondary objective is to analyze if CO2gap is as marker of prognosis in CS. Methods Prospective observational study that included patients admitted for CS in the Acute Cardiovascular Care Unit of a tertiary hospital. Gasometric samples were obtained at admission, 6, 12, 24 and 48 hours from the onset of shock. In-hospital mortality was registered. Results We included 40 patients with CS during 1 year. Most patients were male (80%), average age was 68 years. There was a high incidence of cardiac arrest (58%), most frequent cause of CS was STEMI (45%), in-hospital mortality was 45%, most cases from non-cardiovascular causes (61%). Refractory shock was frequent (28%). Average lactate peak was 6.02 mmol / L. CO2gap kinetics consisted in a peak at admission (8.8mmHg), a valley 6h (7.7mmHg), new peak at 12h (8.5mmHg) and progressive decrease at at 24 (6.8mmHg) and 48h (5.7 mmHg). Significantly, higher CO2gap values at admission (10.97mmHg vs 8.16mmHg, p = 0.007) was predictor of cardiovascular mortality. Lactate values at 6, 12 and 48 hours were also predictors of cardiovascular mortality, as well as ScvO2 at admission. Conclusions Patients with CS present with high CO2gap values during first hours of admission. The kinetics of this marker consists in two peaks at admission and 12 hours from CS onset, a valley at 6 hours and a progressive decrease at 24 and 48 hours. Its determination at admission is associated with cardiovascular mortality. We suggest the potential benefit of combining this marker, along with lactate and ScvO2 values, to guide management of patients with CS. Abstract Figure. CO2 gap and cardiovascular mortality