A Comparison of the Effect of Pulsatile and Nonpulsatile Flow during Cardiopulmonary Bypass on Cerebral Oxygen Saturation in Adult Patients Undergoing Cardiac Surgery

Abstract Background: The physiological benefits of pulsatile flow (PF) versus non-pulsatile flow (NPF) during cardiopulmonary bypass (CPB) remain debated, particularly regarding cerebral oxygenation, metabolic homeostasis, and systemic perfusion in adult cardiac surgery. Methods: In this prospective interventional crossover trial conducted at a tertiary cardiac centre, 112 adults undergoing elective cardiac surgery with CPB (February 2019–March 2020) were studied. Following aortic cross-clamping, PF and NPF were each applied for 20 minutes in random sequence, with every patient serving as their own control. Cerebral regional oxygen saturation (rSO 2 ) was continuously measured using near-infrared spectroscopy. Secondary outcomes included mean arterial pressure (MAP), arterial PaO 2 , PaCO 2 , pH, serum lactate, and bicarbonate (HCO 3 − ). Comparisons between flow modes were performed using paired analyses. Results: Mean rSO 2 during NPF (55.62 ± 5.42) was significantly higher than during PF (54.70 ± 5.73; P < 0.05). Mean PaO 2 was also higher with NPF (259.81 ± 69.25 mmHg) compared with PF (244.75 ± 61.81 mmHg; P < 0.001). Serum lactate levels were significantly greater during NPF ( P < 0.001), whereas serum bicarbonate was significantly lower during NPF than PF ( P < 0.05). No significant differences were observed in MAP, arterial pH, or PaCO 2 between the two flow patterns ( P > 0.05). Conclusions: In adult patients undergoing CPB, NPF was associated with modestly higher cerebral rSO 2 and PaO 2 values but also higher lactate and lower bicarbonate levels compared with PF. MAP, pH, and PaCO 2 were comparable between strategies. These findings suggest measurable physiological differences between flow modalities; however, the clinical significance of these variations warrants further investigation. Trial registration: Clinical Trials Registry—India (CTRI/2019/01/017030).