Right ventricular end-diastolic volume in the postoperative care of cardiac surgery patients - A marker of the hemodynamic response to a fluid challenge

Background: This study evaluated the right ventricular end-diastolic volume index (RVEDVI) as a marker of the hemodynamic response to a fluid challenge in the postoperative care of cardiac surgery patients. Methods and Results: Continuous RVEDVI and other hemodynamic parameters were analyzed during and after 17 fluid challenges with 480-500 ml colloids (5% albumin, fresh frozen plasma or 6% hydroxyethyl starch) given over 30-60min following cardiac surgery. Changes in stroke volume index (SVI) were assessed to indicate fluid responsiveness. Responders were defined as those who experienced a 10% or greater increase in SVI. Fluid challenges with simultaneous changing of vasoactive agents were excluded. Linear regression analysis between the percentage change in SVI and baseline RVEDVI revealed a statistically significant but weak correlation (r²=0.249; p=0.041). Although the baseline RVEDVI was higher in non-responders than in responders (112.4±6.1 vs 104.4±5.8ml/m²; p=0.05), there was a marked overlap of baseline RVEDVI values, which did not allow identification of the threshold value of RVEDVI discriminating responders. Conclusions: After cardiac surgery, RVEDVI reflected fluid responsiveness only to a limited degree. Patients should not be resuscitated to an absolute RVEDVI alone and empirical fluid challenge should still be required.