Continuous monitoring of mixed venous oxygen saturation as an indicator of pharmacologic intervention

This prospective study evaluated the ability of continuous SvO2 measurements to predict the onset and duration of action of the oral vasodilator, fenoldopam. Eight patients with New York Heart Association functional class 3 CHF received 100 mg fenoldopam in the fasted state. Serial hemodynamic parameters and SvO2 measurements were obtained at baseline and up to eight hours postdose. Although wide interpatient variability was observed, the SvO2-time response curve produced a similar trend as the CI-time response curve. The SvO2 may be a useful drug monitoring parameter in patients with NYHA class 3 CHF. Seriously ill patients may not have a good CI/SvO2 correlation. This is most likely due to an unstable oxygen consumption rate at the tissue level. Therefore, we recommend establishing the relationship between CI and SvO2 prior to its use as a drug monitoring parameter.