Pulsatile flow during cardiopulmonary bypass preserves postoperative microcirculatory perfusion irrespective of systemic hemodynamics

Abstract

<jats:p>The onset of nonpulsatile cardiopulmonary bypass is known to deteriorate microcirculatory perfusion, but it has never been investigated whether this may be prevented by restoration of pulsatility during extracorporeal circulation. We therefore investigated the distinct effects of nonpulsatile and pulsatile flow on microcirculatory perfusion during on-pump cardiac surgery. Patients undergoing coronary artery bypass graft surgery were randomized into a nonpulsatile ( n = 17) or pulsatile ( n = 16) cardiopulmonary bypass group. Sublingual mucosal microvascular perfusion was measured at distinct perioperative time intervals using sidestream dark field imaging, and quantified as the level of perfused small vessel density and microvascular flow index (vessel diameter &lt; 20 μm). Microcirculation measurements were paralleled by hemodynamic and free hemoglobin analyses. The pulse wave during pulsatile bypass estimated 58 ± 17% of the baseline blood pressure waveform. The observed reduction in perfused vessel density during aorta cross-clamping was only restored in the pulsatile flow group and increased from 15.5 ± 2.4 to 20.3 ± 3.7 mm/mm<jats:sup>2</jats:sup>upon intensive care admission ( P &lt; 0.01). The median postoperative microvascular flow index was higher in the pulsatile group [2.6 (2.5–2.9)] than in the nonpulsatile group [2.1 (1.7–2.5); P = 0.001]. Pulsatile flow was not associated with augmentation of free hemoglobin production and was paralleled by improved oxygen consumption from 70 ± 14 to 82 ± 16 ml·min<jats:sup>−1</jats:sup>·m<jats:sup>−2</jats:sup>( P = 0.01) at the end of aortic cross-clamping. In conclusion, pulsatile cardiopulmonary bypass preserves microcirculatory perfusion throughout the early postoperative period, irrespective of systemic hemodynamics. This observation is paralleled by an increase in oxygen consumption during pulsatile flow, which may hint toward decreased microcirculatory heterogeneity during extracorporeal circulation and preservation of microcirculatory perfusion throughout the perioperative period.</jats:p>

Changes in Microcirculatory Perfusion and Oxygenation During Cardiac Surgery With or Without Cardiopulmonary Bypass

“…Recently, this group has demonstrated that nonpulsatile CPB is associated with reduced microcirculatory perfusion, which was most notable after discontinuation of extracorporeal circulation. 68 These findings later were confirmed by a study by O 'Neil et al 69 In contrast, others found that short-term administration of pulsatile flow during CPB was not beneficial for microcirculatory perfusion 70 or cerebral oxygenation 71 when compared with a laminar flow conditions. However, the design of these studies was suboptimal due to administration of a combination of distinct flow modalities to individual patients.…”

An Assessment of Renal Function with Pulsatile Perfusion During Proximal Graft Using Cardiac Contraction in Coronary Artery Bypass Graft Surgery

“…Pulsatile CBP maintained renal function, decreased liver injury, decreased levels of endotoxins, and led to smaller demand for inotropic agents, and a lowering number of death postoperatively (5).…”

Myocardial Microcirculation and Mitochondrial Energetics in the Isolated Rat Heart

“…However, several studies did show an improvement in microvascular flow with pulsatile perfusion, for example [42]. One explanation for this discrepancy is that these patients [41] may have been too healthy to show pulsatile perfusion-related improvement in microcirculation.…”