M. Bagherinasab et al.: J Extra Corpor Technol 2026, 58, 73--78 77
reaching 100 % of the target flow rate of the HLM. This observation can be attributed to the identical dilutional volume of the priming solution utilized in both groups, as demonstrated in Table 1. Similarly, the observed disparity in NIRS values between the left and right sides, while not statistically significant, may be attributed to two potential factors. Firstly, it is plausible that the blood entering the right cerebral vessels is somewhat more diluted, as these vessels are anatomically closer to the delivery cannula of the bypass [ 1 ]. Alternatively, the jet produced by the cannula may be directed towards the left carotid artery, influencing the distribution of blood flow [ 1 ].
Severe hemodilution impacts cerebral oxygenation, necessitating increased blood pump flow rates to ensure sufficient cerebral oxygen delivery during CPB [ 13 ]. As demonstrated in Table 3, there is no statistically significant difference in HCT levels prior to the initiation of CPB. Based on the findings of this study, it can be inferred that both the fast- and slow- initiation CPB protocols are safe methods for patients, as evidenced by the aggregated numerical results pertaining to brain tissue oxygenation.
The incidence of delirium was evaluated utilizing the CAM-ICU. The CAM-ICU is a concise diagnostic tool specifically designed for the identification of delirium. It is derived from the more extensive Confusion Assessment Method( CAM), which is frequently employed in geriatric populations [ 14 ]. Notably, the CAM-ICU is distinguished by its rapid administration and its ability to be utilized without necessitating verbal communication from the patient. This feature renders it particularly suitable for application in individuals undergoing invasive mechanical ventilation and orotracheal intubation [ 15 ]. As indicated in Table 4, patients categorized in the slow group exhibited a reduced incidence of delirium in comparison to those in the fast group. The absence of a statistically significant difference may be ascribed to the limited sample size of the study. Research indicates that HCT levels and oxygen delivery significantly influence the incidence of delirium postcardiac surgery [ 13, 14 ]. The diminished incidence of delirium noted in the slow group may be associated with lower hematocrit levels and partial pressure of oxygen( PaO 2) at the onset of cardiopulmonary bypass( CPB). To date, there appears to be a lack of studies examining the relationship between the speed to reach full CO during CPB initiation and the subsequent development of delirium.
The duration of mechanical ventilation did not exhibit a statistically significant difference between the study groups( P > 0.05). Patients in the Slow group demonstrated a reduced length of stay in the ICU, which may be linked to a decreased occurrence of delirium within this study. Previous research has recognized delirium as an independent risk factor associated with extended ICU stays following cardiac surgery [ 13, 14 ].
Conclusion
The results of this study indicate that, despite the absence of a significant difference in TOI and HCT between the study groups, patients classified in the slow group exhibited a not statistically significant trend for a lower incidence of delirium in comparison to those in the fast group.
Limitations
This study was conducted at a single center with a relatively small sample size, which may limit the generalizability of the results. The lack of blood pressure, PaCO 2, oxygen delivery( DO 2), and AUC-DO 2 i data also limits the mechanistic insight. Additionally, cerebral embolization, depth of anesthesia, and postoperative medications, which may influence delirium, were not evaluated.
Funding This research did not receive any specific funding. Conflicts of interest The author declared no conflict of interest.
Data availability statement
The research data associated with this article are included within the article.
Author contribution statement
Mostafa Bagherinasab and Ali Reza Moradi designed the study and supervised the project.
Ali Jabbari, Sahra Rezaee, and Amin Noori conducted the experiments and collected the data. Sahra Rezaee performed the statistical analysis. Mostafa Bagherinasab prepared the initial draft of the manuscript. Nathaniel Darban and Zachary Archer contributed to editing, critical revision, and final approval of the manuscript.
All authors discussed the results and approved the final version of the paper.
Ethics approval Ethical approval was not required.
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