Is Off-pump cardiac surgery ready for goal-directed therapy?

The Editor,

With great interest, I have read the article by Kapoor et al. recently published.[1] Hemodynamic monitoring to improve the outcome on high-risk patient and intensive care patients has been the focus of research for many years. Recently, negative studies were published.[23] Many confounders exist because of the complexity of these patient groups. When “soft” end-points are used, as in this study, good definitions need to be available. The outcome advantage in the goal-directed group is presented without real definitions concerning ready for discharge, Intensive Care Unit (ICU) or home readiness.

Kern and Shoemaker have shown that hemodynamic intervention has only value as the complication rate in a population is high >20%.[4] Mortality and morbidity before the intervention study are not mentioned in this article. I miss the power calculation to establish the right amount of patients to be included in this study. Hence, what these differences really mean remains to be seen. It is important to differentiate between statistical significant and clinical relevant differences.

Hemodynamic monitoring during off-pump coronary artery bypass surgery is challenging, especially when an anastomosis is performed posterior of heart. Problems with the filling of the heart and cardiac arrhythmias are no exception. The hemodynamic measurement using the EV1000/FloTrac under these clinical instable conditions is almost impossible. Hence, what remains is a 4-h period where the patients are ventilated in the ICU in which the stroke volume variation (SVV) could have been used. However, ventilation mode, tidal volume, and other SVV limitations are not mentioned. Fluid boluses are given per 100 ml, is this amount clinical relevant? In this article, I miss the amount of fluid given during different stages of the operation/IC stay. The same concerns apply for the amount of inotropic or vasopressor support. Both fluids and isotopes being essential in goal-directed therapy.

Finally, the suggested “good” agreement of the first and second generation software was not confirmed in our meta-analysis of the FloTrac/Vigileo system. The percentage of error in the cardiac and postcardiac surgery studies referenced by the authors was above the suggested 30%.[5]

I would like to invite the authors to explain the findings of their study as I cannot explain them from the presented data.

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Conflicts of interest

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