An Experimental, Simplified Method for Intradialytic Cardiac Output Measurement

Hypotension during hemodialysis (HD) is a frequent and troublesome treatment complication. A decrease in the cardiac output (CO) due to an imbalance in the rates of fluid ultrafiltration vs. tissue reabsorption is a major cause of such episodes; thus, routine repeated measurements of CO during HD sessions could be of use in preventing its occurrence. We tested an experimental method (EXP) for measuring CO during HD using hardware already supplied with current Gambro dialysis machines. In 12 HD patients, CO was measured twice during dialysis by injecting a small (2 mL) bolus of highly concentrated saline into the patient's bloodstream and measuring the subsequent increase in dialysate conductivity using the Diascan technology. CO was calculated with the Stewart-Hamilton method using the area under the conductivity curve, measured dialysate flow rate, and dialyzer clearance. Compared with ultrasound hemodilution measurements, the EXP showed no bias and limits of agreement of ±34.6%. The intradialytic trend correlated well between the two methods (r(2) = 0.63, concordance rate 100%). We propose that with further development and refining, reliable measurements of CO could be performed easily during routine HD treatment using this new methodology.