NIRS vs TCD for Cerebrovascular Autoregulation During Non-cardiac Surgery

Study Overview
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Brief Summary
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Postoperative neurocognitive disorders (NCD) are of high priority in perioperative management. The risk of suffering from NCD after surgery may be increased due to perioperative impairment of cerebrovascular autoregulation and thereby inadequate cerebral perfusion. Cerebrovascular autoregulation refers to the ability of cerebral arterioles to ensure constant cerebral blood flow independently of fluctuations in systemic blood pressure. Cerebrovascular autoregulation can be measured based on mean arterial pressure (MAP) and a surrogate for cerebral blood flow using the correlation method. Until today, measurement of cerebral blood flow velocity assessed with transcranial Doppler sonography (TCD) is most commonly used as a non-invasive surrogate for cerebral blood flow. Alternatively, cerebral oxygenation measured with near-infrared spectroscopy (NIRS) can be used as another surrogate. The study includes three substudies: To compare NIRS and TCD for the assessment of perioperative cerebrovascular autoregulation in patients undergoing major non-cardiac surgery with an increased risk of bleeding. To compare MAP for optimal cerebrovascular autoregulation before induction of general anesthesia with MAP for optimal cerebrovascular autoregulation during or after general anesthesia. To analyze the association between the time-weighted average MAP below the MAP for optimal cerebrovascular autoregulation and postoperative NCD.

Official Title
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Cerebrovascular Autoregulation During Major Non-cardiac Surgery - a Comparison Between Near Infrared Spectroscopy and Transcranial Doppler Sonography

Conditions
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Cerebrovascular Circulation

Intervention / Treatment
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* Other: Continuous assessment of cerebrovascular autoregulation with NIRS and TCD


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age ≥ 18 years Elective surgery with a minimum duration of 120 minutes General anesthesia expected blood loss > 500 ml Exclusion Criteria: Temporal bone window failure Cerebrovascular disease Cardiac surgery Neurosurgery

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 99 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Other: Continuous assessment of cerebrovascular autoregulation with NIRS and TCD|Continuous monitoring of MAP, cerebral oxygenation, and cerebral blood flow velocity before, during, and after surgery to calculate two cerebrovascular autoregulation indices Cox and Mx.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Equivalence of NIRS-based and TCD-based intraoperative measurement of cerebrovascular autoregulation | calculation of cerebral autoregulation indices based on near-infrared spectroscopy and transcranial Doppler sonography | continuous assessment during the entire surgical procedure | 
| optimal MAP during NIRS-based measurement of cerebrovascular autoregulation | MAP at lowest cerebral autoregulation index COx | 30 minutes before anesthesia induction (n=38)/ from surgical incision up to two hours after arrival in the post-anesthesia care unit (all patients) | 
| delirium and postoperative NCD after surgery (composite) | screening for postoperative delirium; neuropsychological testing for the assessment of cognitive function | postoperative days 1-4 (delirium), postoperative day 7 or before hospital discharge (NCD) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| optimal MAP during TCD-based measurement of cerebrovascular autoregulation | MAP at lowest cerebral autoregulation index (Mx) | from surgical incision until the end of surgical procedure | 
| postoperative delirium between day 1 and 4 after surgery | screening for postoperative delirium | postoperative day 1 to 4 | 
| delayed neurocognitive recovery at day 7 after surgery or before hospital discharge | neuropsychological assessment | postoperative day 7 or before hospital discharge | 
| NCD at 3 months after surgery | neuropsychological assessment | 3 months after surgery | 
| length of hospital stay |  | at discharge from hospital | 
| length of ICU stay |  | at discharge from ICU | 
| mortality at 3 months after surgery |  | 3 months after surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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postoperative neurocognitive disorders, postoperative delirium, near-infrared spectroscopy, transcranial Doppler sonography, non-cardiac surgery