Effective systolic orifice area of the aortic valve: implications for Doppler echocardiographic cardiac output determinations

Reliability of a new ultrasonic cardiac output monitor in recipients of living donor liver transplantation

The ultrasonic cardiac output monitor (USCOM) is a new Doppler device for noninvasive hemodynamic monitoring. The aim of this prospective nonrandomized study was to test the feasibility, perioperative reliability, and clinical applicability of using USCOM as an alternative to pulmonary artery catheterization in recipients of living donor liver transplantation. Thirteen patients scheduled to receive living donor liver transplants were initially recruited. Three were subsequently excluded prior to the commencement of surgery because of technical difficulties in obtaining diagnostic-quality images with USCOM. Ten patients proceeded to be studied. Cardiac output measurements by thermodilution and USCOM were compared at 30-minute intervals throughout the procedure and at 10 specific procedural reference points during the surgery when hemodynamic changes were most likely to be observed. The data were analyzed with Lin's concordance coefficient and Bland-Altman analysis. Two hundred ninety paired cardiac output values were obtained from the 10 patients. The concordance between both methods was excellent in 8 patients and satisfactory in 2. Bland-Altman analysis of all data produced a mean bias of - 0.02 L/minute for USCOM, and the 95% limits of agreement were -1.06 to +1.10 L/minute. Further analysis of the 10 reference time points showed minimal bias and high levels of agreement between the methods. We conclude that USCOM provides an accurate and noninvasive method for cardiac output measurement during liver transplantation. It may therefore represent an alternative to pulmonary artery catheter placement with consequent reduction in patient's risk and morbidity associated with catheterization. Liver Transpl 14:1029-1037, 2008. (c) 2008 AASLD.