Non-invasive monitoring of hemodynamic changes during hemodialysis by the use of a newly developed admittance cardiograph.

Only a little information is available for the evaluation of the complex hemodynamic changes that occur during hemodialysis. Recently, we developed the transthoracic electrical admittance cardiograph for repeated measurements of cardiac output, and monitored hemodynamic changes during hemodialysis by the use of this device. We measured cardiovascular hemodynamic and autonomic parameters non-invasively during 210 min of hemodialysis in 19 chronic hemodialysis patients who for more than 2 months had no history of cardiovascular collapses during hemodialysis. Blood pressure was monitored every 10 min using a cuff-oscillometric device (TM-2425; A & D, Tokyo, Japan). Cardiac output was monitored on a beat-by-beat basis by a newly developed electrical admittance cardiograph (NICOVIEW PA1100; NEC, Tokyo, Japan). Electrocardiogram R-R intervals were also monitored by the TM-2425. Power spectral analysis of R-R intervals was performed to obtain the low-frequency (LF; 0.05-0.15 Hz) and the high-frequency (HF; 0.15-0.40 Hz) components based on an autoregressive model. Change in circulatory blood volume was also monitored by a CRIT-LINE (In-Line Diagnostics, Riverdale, UT, USA). Although blood volume declined significantly by 16.3 +/- 1.4% (mean +/- SE) during hemodialysis (P < 0.0001), mean blood pressure did not change significantly. Heart rate increased significantly from the initial values of 76.3 +/- 3.4-86.4 +/- 4.9 beats/min (P = 0.03). Cardiac output and stroke volume decreased significantly from 4.47 +/- 0.30 to 2.91 +/- 0.32 L/min (P < 0.0001), and from 57.0 +/- 3.7 to 33.9 +/- 3.1 mL (P < 0.0001), respectively. Total peripheral vascular resistance increased significantly from 1940 +/- 146 to 3117 +/- 280 dyne x s x cm(5) (P < 0.0001). The LF component did not show significant change, while the HF component decreased significantly (P = 0.007), and the LF/HF ratio increased significantly (P = 0.03). These results suggest that a reduction in parasympathetic nerve activity and sympathetic nerve activation and a marked increase in total peripheral vascular resistance are responsible for the maintenance of blood pressure during hemodialysis in chronic hemodialysis patients. The admittance cardiograph seems to be one of the best options for serial measurements of cardiac output.