Impact of transient decrease in mixed venous oxygen saturation on prognosis in off-pump coronary artery bypass surgery: a retrospective cohort study

Abstract

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Hemodynamic management during off-pump coronary artery bypass surgery: a narrative review of proper targets for safe execution and troubleshooting

“…All rights reserved. position, which renders diastolic filling against gravity, while the ventricles are already being restricted by the mechanical constraint of the stabilizers [9,12,13]. Thus, impaired bi-ventricular diastolic filling would be the primary hemodynamic consequence followed by systolic dysfunction induced by mechanical constraint, not to mention that systolic and diastolic functions are closely interrelated as well [11,15].…”

“…By being a low-pressure, more compliant chamber with thinner walls, the RV has been proposed to suffer a more severe compression and dysfunction by mechanical constraint compared to the LV [9,21]. To alleviate the RV compression against the pleura, vertical pleurotomy can be tried while its clinical benefit remains obscure [52].…”

“…Hemodynamic management strategies using inodilators and atrial pacing targeted at improving RV function are essentially the same as described above. Other things to consider are that the pulmonary artery pressure usually increases during mechanical heart displacement, especially during lateral wall grafting, due to the increased left atrial pressure and impaired diastolic filling [9,14]. Accordingly, possible rescue for RV dysfunction in conjunction with increased pulmonary artery pressure would include application of inhaled milrinone (possibly in combination with epoprostenol) [53], which would act more on the pulmonary vasculature to relieve the afterload of the RV in addition to the inherent inotropic action.…”

“…The target to maintain SvO2 above 60% has been advocated mainly based on the physiologic limit of oxygen extraction ratio, by which the tissue can still obtain adequate oxygen supply despite reduced cardiac output and oxygen delivery [58,59]. Recently, a single-center, retrospective analysis involving 1071 OPCAB patients showed that even a transient decrease in SvO2 < 60% during lateral wall grafting was associated with adverse outcome (odds ratio: 2.72, 95% confidence interval: 1.60-4.61, P < 0.001) along with well-known risk factors including advanced age, chronic kidney disease, E/e', and EuroSCORE II [9]. In contrast, MAP and cardiac index did not show any differences between the morbidity and non-morbidity groups, which were greater than 75 mmHg and 1.7 L/min/m 2 , respectively, during grafting in that study.…”

“…Recurrent ischemic attacks after OPCAB were mainly attributed to fewer number of grafts and poorer graft patency [5][6][7]. To achieve complete revascularization, successful grafting at the lateral wall as well as the posterior wall is often required during which, the hemodynamic deterioration due to mechanical heart displacement is most severe [8,9], and the expertise of the team becomes crucial [10].…”