Right ventricular end-diastolic volume index as a predictor of preload status in patients on positive end-expiratory pressure

Objective: To evaluate the clinical utility of right ventricular end-diastolic volume index (RVEDVI) and pulmonary artery occlusion pressure (PAOP) as measures of preload status in patients with acute respiratory failure receiving treatment with positive end-expiratory pressure. Design: Prospective, cohort study. Setting: Surgical intensive care unit in a Level I trauma center/university hospital. Patients: Sixty-four critically ill surgical patients with acute respiratory failure. Interventions: All patients were treated for acute respiratory failure with titrated levels of positive end-expiratory pressure (PEEP) with the goal of increasing arterial oxygen saturation to greater than or equal to 0.92, reducing FlO(2) to <0.5, and reducing intrapulmonary shunt to less than or equal to 0.2. Serial determinations of RVEDVI, PAOP, and cardiac index (CI) were recorded. Measurements and Main Results: Two hundred-fifty sets of hemodynamic variables were measured in 64 patients. The level of PEEP ranged from 5 to 50 cm H2O (mean 12 +/- 9 [SD] cm H2O). At all levels of PEEP, CI correlated significantly better with RVEDVI than with PAOP. At levels of PEEP greater than or equal to 15 cm H2O, CI was inversely correlated with PAOP, but remained positively correlated with RVEDVI. Conclusions: CI correlates significantly better with RVEDVI than PAOP at all levels of PEEP up to 50 cm H2O. RVEDVI is a more reliable predictor of volume depletion and preload recruitable increases in CI, especially in patients receiving higher levels of PEEP where PAOP is difficult to interpret.