Oxygenator-related gaseous microemboli and postoperative delirium after on-pump coronary artery bypass grafting: a prospective cohort study

The increasing preference for off-pump coronary artery bypass grafting (CABG) reflects efforts to reduce complications associated with cardiopulmonary bypass (CPB). A lower incidence of postoperative delirium (POD) after off-pump procedures suggests that embolic load during CPB may contribute to postoperative neurocognitive impairment. Oxygenator design may influence the generation and transmission of gaseous microemboli (GME) during CPB. This study aimed to determine whether differences in oxygenator design affect the GME-handling characteristics of the CPB circuit and to evaluate the clinical implications of microembolic burden in patients undergoing on-pump CABG. In this prospective, non-interventional observational study, 102 adult patients undergoing first-time isolated on-pump CABG were included. Patients were supported with one of three contemporary membrane oxygenators (Capiox FX25, Inspire 8, or Inspire 8 F). Gaseous microemboli number and cumulative volume were continuously measured proximal and distal to the oxygenator using an ultrasonic microbubble counter. Postoperative delirium was assessed every 12 h during the first postoperative week using the Confusion Assessment Method for the ICU and the Richmond Agitation–Sedation Scale by assessors blinded to oxygenator type. Baseline characteristics, operative variables, and venous GME burden were comparable among groups. Use of the Capiox FX25 oxygenator was associated with significantly lower arterial GME volume and the greatest reduction in microembolic volume compared with both Inspire oxygenators. Inspire 8 demonstrated the lowest reduction in GME number. Postoperative delirium occurred in 29.4% of patients and was least frequent in the Capiox FX25 group. Oxygenator design significantly influences intraoperative gaseous microembolic burden and is associated with differences in postoperative delirium after on-pump CABG. Oxygenator selection may represent a modifiable intraoperative factor affecting postoperative neurocognitive outcomes. As this was a non-interventional, observational study with no deviation from standard clinical practice, registration in a public clinical trial registry was not required.