Microvascular Responsiveness to Pulsatile and Nonpulsatile Flow During Cardiopulmonary Bypass.

Background: Pulsatile perfusion may offer microcirculatory advantages over conventional nonpulsatile perfusion during cardiopulmonary bypass (CPB). Here, we present direct visual evidence of microvascular perfusion and vasoreactivity between perfusion modalities.

Methods: A prospective, randomized cohort study of 20 high-risk cardiac surgical patients undergoing pulsatile (n = 10) or nonpulsatile (n = 10) flow during CPB was conducted. Changes in sublingual mucosal microcirculation were assessed with orthogonal polarization spectral imaging along with near-infrared spectroscopic indices of thenar muscle tissue oxygen saturation (StO) and its recovery during a vascular occlusion test at the following time points: baseline (T), 30 minutes on CPB (T), 90 minutes on CPB (T), 1 hour after CPB (T), and 24 hours after CPB (T).

Results: On the basis of our scoring scale, a shift in microcirculatory blood flow occurred over time. The pulsatile group maintained normal perfusion characteristics, whereas the nonpulsatile group exhibited deterioration in perfusion during CPB (T: 74.0% ± 5.6% versus 57.6% ± 5.0%) and after CPB (T: 76.2% ± 2.7% versus 58.9% ± 5.2%, T: 85.7% ± 2.6% versus 69.8% ± 5.9%). Concurrently, no important differences were found between groups in baseline StO and consumption slope at all time points. Reperfusion slope was substantially different between groups 24 hours after CPB (T: 6.1% ± 0.6% versus 3.7% ± 0.5%), indicating improved microvascular responsiveness in the pulsatile group versus the nonpulsatile group.

Conclusions: Pulsatility generated by the roller pump during CPB improves microcirculatory blood flow and tissue oxygen saturation compared with nonpulsatile flow in high-risk cardiac surgical patients, which may reflect attenuation of the systemic inflammatory response and ischemia-reperfusion injury.