Assessment of Cerebral Blood Flow Asymmetry in Cardiac Surgery Patients Undergoing Hypothermic Circulatory Arrest

Study Overview
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Brief Summary
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Cerebral oxygen desaturation during cardiac surgery measured using near infrared spectroscopy (NIRS) derived cerebral oximetry has been associated with significant postoperative morbidity. If significant desaturation occurs during this period, it may represent an ideal opportunity to further optimize the postoperative care of these patients.

Detailed Description
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Selective antegrade cerebral perfusion (SACP) is a commonly used technique for maintaining cerebral blood flow (CBF) during the use of hypothermic cardiac arrest (HCA) for aortic arch reconstruction. However, even with an intact Circle of Willis, asymmetric CBF is a common occurrence during HCA when SACP is used. The investigators have previously shown that ultrasound guided extrinsic compression of the left carotid artery can increase left cerebral oxygen saturation, and improved symmetry of CBF; however, this has not been investigated formally. In this study, the investigators will firstly formally assess the incidence and severity of asymmetrical cerebral flow between the left and right hemispheres in patients undergoing aortic arch repair (n=20). CBF will be assessed indirectly through regional cerebral oxygen saturation (rSO2) measured via near-infrared spectroscopy-derived cerebral oximetry. In addition, a number of clinical outcome parameters (up to 30 days post-op) will be evaluated. The investigators expect that significant left-side cerebral hypoperfusion will consistently be observed in patients undergoing aortic arch repair using SACP.

Official Title
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A Prospective Study of Cerebral Oximetry to Assess Symmetry of Cerebral Blood Flow and Clinical Outcomes in Cardiac Surgery Patients Undergoing Hypothermic Circulatory Arrest

Conditions
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Cerebral Desaturation, Cerebral Ischemia

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Informed consent Age 18 years or older Surgery requiring cardio pulmonary bypass Ascending aorta or arch repair surgery Surgery requiring hypothermic circulatory arrest Exclusion Criteria: Off-pump cardiac surgery Skin condition preventing the use of cerebral oximetry pads

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of asymmetrical cerebral desaturation | Cerebral desaturation defined as a greater than 10% difference in cerebral saturation comparing one hemisphere to the other based on a baseline reading taken in the minute preceding the onset of HCA to the end of the hypothermic period. | Duration of hypothermic circulatory arrest between surgical induction and ICU admission | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Severity of asymmetrical cerebral desaturation | Area of the curve (AUC) and time under the curve (TUC) for all saturation events less than pre-induction baseline as well as for 10%, 15% and 25%, relative reductions under the baseline rSO2 will also be determined. In addition, the AUC and TUC for rSO2 less than an absolute rSO2 of 50% will also be determined. | Duration of hypothermic circulatory arrest between surgical induction and ICU admission | 
| Severity of asymmetrical cerebral desaturation | Time under the curve (TUC) for all saturation events less than pre-induction baseline as well as for 10%, 15% and 25%, relative reductions under the baseline rSO2 will also be determined. In addition, the AUC and TUC for rSO2 less than an absolute rSO2 of 50% will also be determined. | Duration of hypothermic circulatory arrest between surgical induction and ICU admission | 
| All cause mortality | All cause mortality | Surgical induction to 30 day postoperative | 
| Neurologic injury | Any neurologic injury, including: stroke, delirium, seizures, coma | Surgical induction to 30 day postoperative | 
| Renal injury | Renal injury defined as a 50% decrease in estimated glomerular filtration rate (GFR) and/or need for dialysis | Surgical induction to 30 day postoperative | 
| Serious infection | Serious infection including: mediastinitis, cellulitis, pneumonia, urinary tract infection | Surgical induction to 30 day postoperative | 
| Gastrointestinal morbidity | Gastrointestinal (GI) morbidity defined as GI bleed, bowel perforation and/or ischemia | Surgical induction to 30 day postoperative | 
| In-hospital mortality | In hospital mortality | Surgical induction to hospital discharge or 30 days postoperative, whichever comes first | 
| Hospital length of stay | The length of time (in days) that the patient remained in the hospital after surgery | Surgical induction to hospital discharge or 30 days postoperative, whichever comes first | 
| ICU length of stay | length of stay in the intensive care unit | ICU admission to ICU discharge or 30 days postoperative, whichever comes first | 
| Intubation time | Duration of time that the patient was intubation from the start of surgery | Time of surgical intubation to time of extubation | 
| Transfusions | The need for transfusions, including: red blood cells, platelets, plasma and cryoprecipitate | Surgical induction to hospital discharge or 30 days postoperative, whichever comes first | 
| Renal function | Greatest percent change in creatinine and 25% and 50% increase in creatinine | Preoperative to hospital discharge or 30 days postoperative, whichever comes first | 
| Hemostatic support | Requirement of vasopressors, intra-aortic balloon pumps (IABPs) and inotropes (0-12 hours, 12-24 hours and >24 hours post-operative | ICU admission to hospital discharge or 30 days postoperative, whichever comes first | 
| Atrial fibrillation | Atrial fibrillation | ICU admission to hospital discharge or 30 days postoperative, whichever comes first | 
| Myocardial infarction | Myocardial infarction as defined by: | ICU admission to hospital discharge or 30 days postoperative, whichever comes first | 
| Atrial and/or ventricular arrhythmia | Atrial and/or ventricular arrhythmia, requiring electrical or pharmacologic intervention | ICU admission to hospital discharge or 30 days postoperative, whichever comes first | 
| Nausea and vomiting | Excess nausea and vomiting, requiring more than one drug therapy | ICU admission to hospital discharge or 30 days postoperative, whichever comes first | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Near-infrared spectroscopy-derived cerebral oximetry