BrainProtect-guided, Real-time Cerebral Autoregulation Monitoring and Protection of Brain During Cardiac Surgery With Cardiopulmonary Bypass Requiring Heart-lung Machine

Based on a review of the current literature and consultations regarding currently known clinical practice standards the "BrainProtect" study will be the first multicenter trial of cardiac surgery using a heart-lung machine with modulated blood flow by rectangular pulses and also with real-time cerebrovascular autoregulation monitoring. The feasibility and safety of this approach have been previously validated in two of our clinical studies.

Postoperative cognitive dysfunction (POCD and POD) with incidences up to 70% and 42% respectively after cardiac surgery with cardiopulmonary bypass (CPB) are common postoperative complications that affect the participant's quality of life and increase the risk of death. Our previous trials confirm that POCD and POD are associated with impaired cerebral autoregulation (CA) after increased or decreased mean ABP values above or below the upper or lower participant specific limits during cardiac bypass surgery. The upper and lower limits of CA are individual and variable.

In most scientific studies, cerebral autoregulation impairments are identified retrospectively. Currently available real-time monitoring methods for CA status identification are too slow and lack the sensitivity required for timely interventions to correct autoregulatory impairment. The identification of start and finish time moments of ischemic and hyperemic transient events after impairment of CA in individual participant's brain is the way to immediately stop such events to restore optimal brain perfusion.

In order to make perioperative transient hyperemic and ischemic events as short as possible we proposed a novel mode of HLM operation with blood flow modulation by continuous automatic blood flow change from value f1 to value f2 and back to generate rectangular continuous blood flow pulsation. Such modulated blood flow is transformed into rectangularly modulated arterial blood pressure (ABP) with stabilized amplitude of ABP(t) rectangular pulsation in the participant's body. Each front of rectangular ABP(t) is an input signal for testing of CA transient response. Shape of CA transient response is an indicator of CA status - CA rectangular transient response which passively follow rectangular pulsation of ABP(t) indicates impaired CA and Exponential CA transient response shows intact CA. Novel non-invasive participant's brain monitoring technology Archimedes 02 records transient responses of CA in real-time. Timely mean ABP management by perfusionists after identification of a start moment of CA impairment restores optimal participant's brain and other organs' perfusion within seconds to protect the brain from cognitive impairment and delirium.

The BrainProtect System is a non-invasive physiological monitoring medical device designed to continuously assess cerebral autoregulation and intracranial pressure pulse waveforms through closed eyelids using high-sensitivity pressure sensors. The device processes acquired signals using validated algorithms to derive indices of cerebral autoregulation and intracranial compliance, providing real-time feedback to clinicians during surgical procedures.

Impairment of cerebral autoregulation is common during cardiac surgery with cardiopulmonary bypass due to fluctuations in arterial blood pressure, temperature, anesthesia, and non-pulsatile or modified blood flow. Numerous clinical studies have demonstrated an association between cerebral autoregulation disturbances and adverse neurological outcomes following cardiac surgery. However, routine intraoperative monitoring of cerebral autoregulation is not part of standard clinical practice, primarily due to the lack of practical, non-invasive, and continuous monitoring solutions.

The current standard of care during cardiac surgery with cardiopulmonary bypass includes monitoring of systemic hemodynamic parameters such as arterial blood pressure, heart rate, oxygen saturation, and cerebral oxygenation using near-infrared spectroscopy (when available). Management of cerebral perfusion is typically based on population-based blood pressure targets and institutional protocols rather than individualized cerebral autoregulation limits.

Direct monitoring of cerebral autoregulation or intracranial pressure dynamics is not routinely performed in this participant population. As a result, periods of cerebral hypoperfusion or hyperperfusion may remain undetected during surgery, potentially contributing to postoperative neurological complications.

For participants in Group I the BrainProtect System monitoring will be used. The anesthesiologist and perfusionist will have real-time access to CA monitoring data and, immediately after CA impairment event is detected he will see an alarm sign on the screen of CA monitor. Perfusionist will follow instruction on the screen of CA monitor to increase mean ABP in the case of transient ischemic event or to decrease mean ABP in the case of hyperemic event to restore optimal participant's brain perfusion in seconds and to stop the brain injury. Alarm sign will automatically switch off when brain ischemic or hyperemic event will be stopped.

Before and after the appearance of an alarm sign on the monitor in Group I, the perfusionist will follow the existing guidelines for ABP management. Perfusionist will manage mean ABP according a usual practice in their site even in the case when an alarm will not switch off after an adequate change of mean ABP value. For participants in Group II a standard mode of constant HLM blood flow will be used and brain CA monitoring will not be used.

• BrainProtect System (Device): The BrainProtect System consists of the Archimedes 02 monitoring system, the BrainProtect Plug-in Modulator, and BrainProtect Software. The Archimedes 02 monitoring system is positioned on the participant's closed eyelids to enable non-invasive monitoring of intracranial pressure pulse waves and cerebral autoregulation-related signals. Following initiation of cardiopulmonary bypass and confirmation of stable extracorporeal circulation, the BrainProtect Plug-in Modulator is activated. Rectangular flow modulation is initiated and maintained during cardiopulmonary bypass unless clinically contraindicated. The perfusionist has real-time access to cerebral autoregulation monitoring data. When predefined algorithm-based criteria for impaired cerebral autoregulation are detected, a visual event is generated. Blood pressure management decisions are made by the perfusionist based on cerebral autoregulation status and standard clinical practice.
• Standard perioperative management (Procedure): Standard perioperative management during CABG with CPB will be performed. Conventional systemic hemodynamic monitoring will be used. Adjunctive cerebral oxygenation monitoring using near-infrared spectroscopy (NIRS) may be used if routinely applied at the site.

Primary outcomes

• Number of Participants With Postoperative Delirium and/or Postoperative Cognitive Dysfunction (Composite Neurological Outcome) [Up to postoperative Day 7]: Number (percentage) of participants with a positive binary composite outcome of postoperative delirium (POD) and/or postoperative cognitive dysfunction (POCD). Individual assessments are used only to classify participants as composite-positive or composite-negative. Individual test scores are not reported in this outcome measure. POD: ≥1 positive Confusion Assessment Method for the ICU (CAM-ICU) assessment on postoperative Days 1-4 (Feature 1 acute onset/fluctuating course and Feature 2 inattention, plus Feature 3 altered consciousness or Feature 4 disorganized thinking). POCD: decline from preoperative baseline (1-2 days before surgery) to postoperative Days 4-7 in ≥2 of 4 tests: Mini-Mental State Examination (≥3-point decrease), Hopkins Verbal Learning Test-Revised (≥20% decrease), Digit Symbol Substitution Test (≥20% decrease), Schulte Table test (≥20% increase in completion time). A participant is composite-positive if POD and/or POCD is present.

Secondary outcomes

• Incidence of Postoperative Delirium (POD) [Postoperative Days 1 to 7]: Incidence of postoperative delirium (POD), defined as at least one positive CAM-ICU assessment during the postoperative assessment period.
• Incidence of Postoperative Cognitive Dysfunction (POCD) [Baseline and postoperative Days 4 to 7]: Incidence of postoperative cognitive dysfunction (POCD), defined as a decline from baseline performance in at least two tests within the neuropsychological test battery consisting of MMSE, HVLT-R, DSST, and Schulte Table test.
• Odds ratio for the composite neurological outcome according to duration of the longest cerebral autoregulation impairment event [Intraoperative cerebral autoregulation monitoring during CPB and neurological outcome assessment up to postoperative Day 7]: The odds ratio for the composite neurological outcome according to the duration of the longest intraoperative cerebral autoregulation (CA) impairment event per participant will be estimated, to evaluate whether longer CA impairment events are associated with a higher risk of the composite outcome. CA impairment event duration will be measured in seconds using the BrainProtect System during CPB. The composite neurological outcome is binary (POD and/or POCD present vs absent). The odds ratio with confidence interval will be estimated using exploratory logistic regression. This analysis is supported by previous findings showing an association between longer single CA impairment events and postoperative neurological outcomes (Kasputyte et al., 2025)
• Odds ratio for Postoperative Delirium according to duration of the longest cerebral autoregulation impairment event [Intraoperative monitoring during CPB and POD assessment through postoperative Day 7]: The odds ratio for postoperative delirium (POD) according to the duration of the longest intraoperative cerebral autoregulation (CA) impairment event per participant will be estimated, to evaluate whether longer CA impairment events are associated with a higher risk of POD. CA impairment event duration will be measured in seconds using the BrainProtect System during CPB. POD is a binary outcome (present/absent) assessed daily on postoperative Days 1-4 using CAM-ICU; POD is present if ≥1 CAM-ICU assessment is positive. The odds ratio with confidence interval will be estimated using exploratory logistic regression. This analysis is supported by previous findings linking longer CA impairment duration with POD (Kasputyte et al., 2025).
• Odds Ratio for Postoperative Cognitive Dysfunction According to Duration of the Longest Cerebral Autoregulation Impairment Event [Intraoperative monitoring during CPB and POCD assessment at postoperative Days 4 to 7]: The odds ratio for postoperative cognitive dysfunction (POCD) according to the duration of the longest intraoperative cerebral autoregulation (CA) impairment event per participant will be estimated, to evaluate whether longer CA impairment events are associated with a higher risk of POCD. CA impairment duration will be measured in seconds using the BrainProtect System during CPB. POCD is a binary outcome (present/absent) based on change from preoperative baseline to postoperative Days 4-7 in MMSE, HVLT-R, DSST and Schulte Table tests; POCD is present if predefined decline criteria (Outcome Measure 1) are met in ≥2 tests. The odds ratio with confidence interval will be estimated using exploratory logistic regression. This analysis is supported by previous findings linking longer CA impairment duration with postoperative cognitive decline (Kasputyte et al., 2025).
• Hospital Readmission [Within 31 days after the index surgery]: Hospital readmission after discharge from the index hospitalisation and the reason for readmission.
• Length of Hospital Stay [From index surgery (Day 0) until discharge from the index hospitalization, assessed up to postoperative Day 31.]: Length of stay will be calculated for each participant as the number of days from the date of index surgery (Day 0) to the date of discharge from the index hospitalization, assessed up to postoperative Day 31.
• Incidence of Device-Related Adverse Events [From informed consent through end of study participation, up to Day 31]: Incidence of device-related adverse events.
• Incidence of Serious Adverse Events Related to the Investigational Device or Study Procedures [From informed consent through end of study participation, up to Day 31]: Incidence of serious adverse events related to the investigational device or study procedures.
• Occurrence of Unanticipated Serious Adverse Device Effects [From informed consent through end of study participation, up to Day 31]: Occurrence of any unanticipated serious adverse device effects (USADEs), if applicable.

Other outcomes

• Correlation Coefficient Between Intracranial Pressure Pulse Waveforms Recorded During Intact and Impaired Cerebral Autoregulation [Intraoperative monitoring during the index surgical procedure]: Intracranial pressure (ICP) pulse waves will be recorded non-invasively by the BrainProtect System during cardiopulmonary bypass and classified according to cerebral autoregulation (CA) status as intact or impaired. For each participant, representative ICP pulse waveforms during intact and impaired CA periods will be compared as complete waveform shapes. Waveform morphology similarity will be quantified using a correlation coefficient (r), reported as a dimensionless value. Lower correlation will indicate greater change in ICP pulse-wave morphology between intact and impaired CA states.

Sex: All, ages: 18 Years to 69 Years

Inclusion Criteria:

1. Age 18-69 years.
2. Patient has provided written informed consent to participate in the study.
3. Qualification for the elective coronary artery bypass graft (CABG) surgery requiring CPB.

Exclusion Criteria:

1. Female subjects who are pregnant or breastfeeding.
2. Patients with an eye disease that may affect monitoring results, as determined by the Investigator.
3. Patient who had an orbital or eye injury.
4. Patients who have acute or chronic but currently exacerbated respiratory disease.
5. Patients with uncompensated cardiovascular diseases (II-III AV block or cardiogenic shock).
6. Patients with cognitive impairments which could be associated with POD were diagnosed prior to surgery.
7. Patients with a history of clinically significant neurological or cognitive disorders that may interfere with neurocognitive assessment, including dementia, Alzheimer's disease, Parkinson's disease, or recurrent or persistent delirium within the last 12 months.
8. Patients who are receiving psychotropic medications.
9. It is not possible to perform a qualitative neuropsychological assessment due to other factors (e.g., hearing or vision impairments).

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• Results publication: Kasputyte G, Kumpaitiene B, Svagzdiene M, Andrejaitiene J, Sirvinskas E, Hamarat Y, Chaleckas E, Putnynaite V, Bartusis L, Zakelis R, Petkus V, Ragauskas A, Lenkutis T, Benetis R. Delirium after coronary artery bypass grafting with cardiopulmonary bypass surgery: The value of cerebral autoregulation. Perfusion. 2026 May;41(4):462-469. doi: 10.1177/02676591251370076. Epub 2025 Aug 17. PMID 40820307
• Results publication: Kasputyte G, Putnynaite V, Chaleckas E, Bartusis L, Hamarat Y, Zakelis R, Svagzdiene M, Kumpaitiene B, Andrejaitiene J, Lenkutis T, Gelmanas A, Sirvinskas E, Petkus V, Ragauskas A, Benetis R. Novel mode of heart and lung machine for real-time identification of cerebral autoregulation impairments during cardiac surgery with cardiopulmonary bypass: a prospective observational study. Minerva Anestesiol. 2025 Oct;91(10):919-928. doi: 10.23736/S0375-9393.25.18890-1. Epub 2025 Sep 10. PMID 40928505