COMPARISON OF THE ACCURACY OF THE LITHIUM DILUTION TECHNIQUE WITH THETHERMODILUTION TECHNIQUE FOR MEASUREMENT OF CARDIAC-OUTPUT

A new indicator dilution technique for measurement of cardiac output i s described. Lithium chloride is injected via a central venous cathete r and its dilution curve measured in arterial blood using a lithium-se lective electrode. We assessed the lithium dilution cardiac output mea surement (LiDCO) and a conventional thermodilution cardiac output meas urement (ThDCO) by comparing the results of both with cardiac output d etermined by electromagnetic flowmetry (EMCO) under controlled laborat ory conditions in 10 swine. They were monitored with a pulmonary arter y catheter, femoral artery catheter and electromagnetic flowmeter plac ed around the ascending aorta. LiDCO, ThDCO and EMCO measurements were determined at baseline, in a hyperdynamic state produced by administr ation of dobutamine, at a second baseline and finally in a hypodynamic state induced by propranolol during deep anaesthesia. Data were analy sed by linear regression analysis and the comparison method described by Bland and Altman; bias and precision of both LiDCO and ThDCO compar ed with EMCO were calculated by the method of Sheiner and Beal. The co rrelation coefficient between LiDCO and EMCO (0.95) was higher than th at between ThDCO and EMCO (0.87). The precision value of LiDCO (0.04) was significantly less (i.e. better) than that of ThDCO (0.09). The re sults of this study indicated that LiDCO was more reliable compared wi th conventional ThDCO.