Novel mode of heart and lung machine for real-time identification of cerebral autoregulation impairments during cardiac surgery with cardiopulmonary bypass: prospective observational study.

Background: Postoperative cognitive dysfunction (POCD) occurs in 20% to 80% of patients following cardiac surgical interventions. The incidence of delirium is from 20% to 50%. Impaired cerebral autoregulation (CA) during cardiopulmonary bypass (CPB) contributes to these issues. We investigated a novel method for real-time monitoring of CA during CPB. The study aimed to obtain real-time CA impairment data to demonstrate the timely arterial blood pressure (ABP) management for immediate restoration of intact CA and, potentially, to reduce the incidences of POCD and delirium.

Methods: An observational pilot clinical trial involved 108 elective on-pump surgery patients of whom 78 were included in the final analysis. All patients were evaluated for cognitive function on the 7^th to 10^th postoperative day. A rectangular blood flow modulation technique was proposed and applied to facilitate real-time detection of CA status impairment by using CA(t) transient response analysis.

Results: A single CA impairment event lasting longer than 241 seconds was statistically significantly associated with POCD (P=0.0178), while impairments exceeding 262 seconds were related to delirium (P=0.0315). It was demonstrated that CA impairment events and patient-specific lower and upper limits of CA can be identified with sub-minute delays during cardiac surgery.

Conclusions: The study demonstrated the feasibility of a novel heart and lung machine operation mode with rectangular blood flow modulation. Precise personal ABP(t) management can be performed during CPB to restore patient-specific optimal brain perfusion with sub-minute time resolution and, potentially, to reduce incidences of POCD and delirium.