Right Heart Function in Critically Ill Patients at Risk for Acute Right Heart Failure: A Description of Right Ventricular-Pulmonary Arterial Coupling, Ejection Fraction and Pulmonary Artery Pulsatility Index

Abstract

The gold standard for right heart function is the assessment of right ventricular-pulmonary arterial coupling defined as the ratio of arterial to end-systolic elastance (Ea/Emax). This study demonstrates the use of the volumetric pulmonary artery (PA) catheter for estimation of Ea/Emax and describes trends of Ea/Emax, right ventricular ejection fraction (RVEF), and pulmonary artery pulsatility index (PAPi) during initial 48hours of resuscitation in the trauma surgical intensive care unit (ICU). Review of prospectively collected data for 32 mechanically ventilated adult trauma and emergency general surgery patients enrolled within 6hours of admission to the ICU. Haemodynamics, recorded every 12hours for 48hours, were compared among survivors and non-survivors to hospital discharge. Mean age was 49±20 years, 69% were male, and 84% were trauma patients. Estimated Ea/Emax was associated with pulmonary vascular resistance and inversely related to pulmonary arterial capacitance and PA catheter derived RVEF. Seven (7) trauma patients did not survive to hospital discharge. Non-survivors had higher estimated Ea/Emax, suggesting right ventricular-pulmonary arterial uncoupling, with a statistically significant difference at 48hours (2.3±1.7 vs 1.0±0.58, p=0.018). RVEF was significantly lower in non-survivors at study initiation and at 48hours. PAPi did not show a consistent trend. Estimation of Ea/Emax using volumetric PA catheter is feasible. Serial assessment of RVEF and Ea/Emax may help in early identification of right heart dysfunction in critically ill mechanically ventilated patients at risk for acute right heart failure.