Lithium dilution cardiac output measurements using a peripheral injection site comparison with central injection technique and thermodilution.
OBJECTIVE: The lithium dilution technique for the measurement of cardiac output by the central injection of lithium chloride was introduced by Linton et al. in 1993. In the present report, we compare lithium dilution cardiac output measurement (LD) by the peripheral injection of lithium chloride (pLD) and by central venous injection (cLD), cardiac output determined by electromagnetic flowmetry (EM), and conventional thermodilution cardiac output measurement (TD) on ten swine. METHODS: The animals were monitored with a pulmonary artery catheter, a femoral artery catheter, and an electromagnetic flowmeter placed around the ascending aorta. cLD, pLD, TD, and EM were determined at the baseline, then in a hyperdynamic state produced by dobutamine administration, at a second baseline, and finally in a hypodynamic state induced by propranolol during deep anesthesia. Data were analyzed by linear regression analysis and the comparison method described by Bland and Altman; bias and precision were calculated using the method of Sheiner and Beal. RESULTS: The correlation coefficient between pLD and EM (0.86) was significantly less than that between cLD and EM (0.96), however it was not significantly different from that between TD and EM (0.85). The precision value of pLD (0.14) was the same as that of TD (0.14). CONCLUSION: The results of the present study indicate that pLD is a reliable technique.