Technique or Application

A comparative study of the effect of slow and rapid initiation of cardiopulmonary pump on tissue oxygenation index and ischemic complications

¹ Baqiyatallah University of Medical Sciences, 19395-5487, Tehran, Iran
² Student Research Committee, Faculty of Nursing, Tehran University of Medical Sciences, 1417935840 Tehran, Iran
³ Student Research Committee, Faculty of Nursing, Baqiyatallah University of Medical Sciences, 19395-5487 Tehran, Iran
⁴ Golestan University of Medical Science, 4918936316 Gorgan, Iran
⁵ College of Health Sciences, Cardiovascular Science Program, Glendale, Arizona 85308, USA

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 10 June 2025
Accepted: 2 September 2025

Abstract

Introduction: Although the use of the heart-lung machine (HLM) is routine in cardiac operating theaters, there is still a lack of evidence-based guidelines concerning the optimal speed to reach full flow during initiation to reduce critical episodes of cerebral ischemia. Therefore, we have designed a study to compare two distinct initiation times for the commencement of cardiopulmonary bypass (CPB). Methods: We conducted a randomized, monocentric, double-blind, prospective study to assess the impact of two different CPB initiation speeds – rapid initiation at 30 s and slow initiation at 180 s – on cerebral tissue oxygenation (TOI via NIRS), arterial oxygen pressure, hematocrit (HCT) variation, and the incidence of postoperative delirium. The target flow rate was set at 2.4 L/min/m², with adjustments made according to the patient’s body surface area. Results: The absolute values of the tissue oxygenation index (TOI) and HCT showed no differences between the study during the first 180 s following commencement of CPB. Patients in the fast group exhibited significantly lower arterial oxygen pressure at the initiation of the (P < 0.05). Additionally, patients in the fast group experienced a higher incidence of delirium in the second and third days following surgery. While clinically relevant, the elevated incidence of delirium fell short of being statistically significant, with post-operative days 2 and 3 having P-values of 0.06 and 0.08, respectively. Conclusion: The results of this study indicate that, despite the absence of a significant difference in TOI between the study groups, patients in the slow group exhibited a not statistically significant trend for a lower incidence of delirium, as defined by CAMICU-7, in comparison to those in the fast group.