Pulse contour-derived cardiac output in hemodialysis patients

Reliable methods for cardiac output determination are essential for studying the pathophysiology of intradialytic hypotension. Use of the current gold standard, the Transonic monitor, requires an arteriovenous fistula. We wished to verify the accuracy of a method based on finger pulse contour analysis, namely the Finometer monitor (FNM) for further use on patients dialyzing on a central vascular catheter. Fifty simultaneous cardiac output measurements were obtained during hemodialysis sessions in 25 patients. The internal variability of the FNM measurements was assessed by comparing 24 pairs of immediately successive measurements. The variability of successive FNM measurements was small (bias 0.28%, SD +/- 6.1%; NS). The absolute cardiac output values reported by the FNM were unreliable (bias 20.1%, SD +/- 35.3%; P<0.001) as were the relative intradialytic changes (r(2)=0.01). Excluding participants from the analysis due to old age, high dialysis vintage or a suspicion of atherosclerosis did not improve the results. Our findings do not support the use of pulse contour analysis for measuring cardiac output in hemodialysis patients. Uremic vascular disease may be the cause of the observed inaccuracy.