Changes in the Mixed Venous Blood Oxygen Saturation during the Acute Phase of Myocardial Infarction and Administration of Dobutamine

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KOEDA, T., AMANO, K., ICHIKAWA, T., SUZUKI, T., ISHIKAWA, M., SATO, M., MIURA, S., SUZUKI, T. and KATO, M. Changes in the Mixed Venous Blood Oxygen Saturation during the Acute Phase of Myocardial Infarction and Administration of Dobutamine. Tohoku J. Exp. Med., 1990, 160 (1), 55-65-Clinical significance of the continuous monitoring of mixed venous oxygen satuation (SvO₂) by Catheter Oxymetry System was evaluated in 45 patients with acute myocardial infarction (AMI). Patients with AMI were classified into 4 groups acccording to Forrester's hemodynamic classification. The mean SvO₂ value for each group was 70.4±4.1% for subset I, 54.7±6.9% for subset II, 55.8±9.8 for subset III, and 47.0±8.0% for subset IV. Subsets II, III, and IV showed significantly low values compared to subset I (p<0.01). The relationship between PCW and SvO₂ level was expressed by the negative regression line y=-0.8x+73.8 (r=-0.64, p<0.01). The curve representing the relationship between CI and SvO₂ level was expressed by the equation y=53.8 logx+42.7 (r=0.68, p<0.01). The SvO₂ level of the 14 patients who showed a significantly low value of 56.9±8.2% before administration of 5μg/kg/min dobutamin, increased to a mean value of 66.8±7.9%, as well as the CI after 60min. However, PCW demonstrated no pronounced changes because of dobutamin administration. Since the SvO₂ level highly correlated to the cardiac pumping function in acute phase of myocardial infarction, polygraphic monitoring of SvO₂ was found to be a useful index for evaluating changes in the hemodynamics. It was also a very useful measure in evaluating the effects of dobutamin.