The Effect of Hypoxic and Normoxic Cerebral Oximetry Levels on Cognitive Functions After Carotid Endarterectomy
Condition: Cerebral Hypoxia; Carotid Stenosis; Cognitive Dysfunction
MeSH terms: Carotid Stenosis; Hypoxia, Brain; Hypoxia; Cognitive Dysfunction
Study type: Observational

Summary: 
      In this study, we investigated the effect of the capacity to cope with oxidative stress
      (oxidative stress response during and after clamping) in individuals with cerebral oximetry
      level between 40- 60 % and above 60 % and their effect on cognitive functions.

      Methods: In this retrospective study, patients who were scheduled for carotid endarterectomy,
      examined the MOCA tests before and after the operation and collected blood samples
      intraoperatively were included between January 2020-2021. The time periods specified below,
      blood samples were taken and serums were frozen at -80 celcius all this patients. Montreal
      cognitive function assessment test was applied before the operation, 24 hours and 7 days
      after the operation. Ten mililiters venous blood samples were collected to examine the status
      of basal neuron specific enolase, S100B, oxydative stress parameters (HAF-1 and DAF-1) at
      time intervals. Time intervals as follow:

      T1: Peripheral baseline measurements (blood will be taken from arterial blood sampling) +
      Cerebral Oxymeter levels + Montreal cognitive performance test + Modified Rankin Scale (mRS)
      T2: 1 minute before clamping (from peripheral and jugular vena blood sampling) + Cerebral
      Oxymeter levels T3: Before opening clamp(from peripheral and jugular vena blood sampling) +
      Cerebral Oxymeter levels T4: 24 hours after the procedure. (peripheral blood sampling) +
      Montreal cognitive performance test T5: 7 days after the operation. (peripheral blood
      sampling) + Montreal cognitive performance test + CO levels+ Modified Rankin Scale (mRS)
      Results: We found significantly positive corelation between cerebral oxymeter levels,
      oxydative stress parameters and cognitive performance tests in this six patient.
    

Detailed description: 
      In this retrospective study, patients who were scheduled for carotid endarterectomy, examined
      the MOCA (Montreal cognitive assesment )tests before and after the operation and collected
      blood samples intraoperatively were included between January 2020-2021. The time periods
      specified below, blood samples were taken and serums were frozen at -80 celcius all this
      patients. Montreal cognitive function assessment test was applied before the operation, 24
      hours and 7 days after the operation. Ten mililiters venous blood samples were collected to
      examine the status of basal neuron specific enolase, S100B, oxydative stress parameters
      (HAF-1 and DAF-1) at time intervals. Time intervals as follow:

      T1: Peripheral baseline measurements (blood will be taken from arterial blood sampling) +
      Cerebral Oxymeter levels + MoCA + Modified Rankin Scale (mRS) T2: 1 minute before clamping
      (from peripheral and jugular vena blood sampling) + Cerebral Oxymeter levels T3: Before
      opening clamp(from peripheral and jugular vena blood sampling) + Cerebral Oxymeter levels T4:
      24 hours after the procedure. (peripheral blood sampling) + MoCA test T5: 7 days after the
      operation. (peripheral blood sampling) + MoCA + CO levels+ Modified Rankin Scale The degree
      of stenosis was determined according to the North American Symptomatic Carotid Endarterectomy
      Trial (NASCET) criteria. Written informed consent form was obtained from the patients 1 day
      before the operation. Basal invasive arterial blood pressure, pulse oximetry, heart rate,
      cerebral perfusion pressure, cerebral oximetry levels records of all patients were taken as
      baseline values before the operation. During the operation, serum samples were taken and 5 ml
      blood samples were taken from the artery (peripheral) and 5 ml from the vena jugularis
      interna during the operation. Blood samples were immediately centrifuged at 15000 rpm for 15
      minutes and the supernatant was collected. The supernatant was immediately stored at -80 °C
      for further analysis of oxidative stress and other parameters. The parameters studied are:
      Human NSE(Neuron Specific Enolase) ELISA Kit, Neuron Specific Enolase ELISA Kit, Human S100B
      (S100 Calcium Binding Protein B) ELISA Kit, HIF-1α (Hypoxia Inducible Factor 1 Alpha) ELISA
      Kit, Human DAF(Decay Accelerating Factor) ELISA Kit.

      A. General anesthesia procedure: Anesthesia induction was performed with 1-2 mg/kg propofol,
      1 mcg/kg fentanyl, 0.5 mg/kg rocuronium. Anesthesia was maintained with remifentanil infusion
      (0.05-0.1 mcg/kg/min), 1-2% sevoflurane (1 MAC), and rocuronium. Mechanical ventilation
      parameters were adjusted to be within the limits of end-tidal carbon dioxide normocarby
      (35-45mm Hg) (mean 40 mmHg). To prevent the development of bradycardia, 1% lidocaine was
      applied to the internal, external and common carotid arteries by the surgical team. Following
      systemic intravenous (5000 IU) heparin administration, carotid arterial cross-clamp was
      placed with appropriate active clotting time (>200) B. Superficial and deep cervical
      blockade: It was done with 0.5% isobaric bupivacaine 15 ml + 2% prilocaine 5 ml.

      ΔrSO2 (%) = 100 x (rSO2preclamping - rSO2baseline) / rSO2baseline Baseline rSO2 value, rSO2
      measurement for each specific time point and %rSO2 change between them were continuously
      monitored by oximetry (Invos System 4100, Somonetics Corporation, Troy, MI, USA). The entire
      CEA surgical procedure was performed with the standardized technique in these 6 patients.

      In the analysis phase, the patients were evaluated in 2 groups. Group 1: Basal cerebral
      oximetry levels between 41-60% Group 2: Basal cerebral oximetry levels > 61%
    

Observational model: Case-Only
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        Patients who were scheduled for carotid endarterectomy, examined the MOCA (Montreal
        cognitive assesment )tests before and after the operation and collected blood samples
        intraoperatively .