title: The effect of optimising cerebral tissue oxygen saturation on markers of neurological injury during coronary artery bypass graft surgery.
abstract: BACKGROUND
  Surgical revascularisation of the coronary arteries is a cornerstone of cardiothoracic surgery. Advanced age and the incidence of preoperative co-morbidity in patients presenting for coronary artery bypass graft surgery increases the potential for stroke and other perioperative outcomes. It is hypothesised that by using interventions during cardiac surgery to improve cerebral oxygenation, the risk of patients enduring adverse neurological outcomes would be reduced.
  
  
  METHODS
  Forty patients (mean age 55.3, standard deviation 9.74 and range from 39 to 72 years) undergoing on-pump coronary artery bypass graft surgery were recruited at Inkosi Albert Luthuli Central Hospital, South Africa. Patients were randomised into a control group (n=20) and interventional group (n=20). Intraoperative regional cerebral oxygen saturation (rSO2) monitoring with active display and Murkin treatment intervention protocol was administered for the interventional group. Arterial blood samples for the measurement of serum S100B were taken pre and postoperatively. An enzyme immunoassay (ELISA) was used for the quantitative and comparative measurement of human S100B concentrations for both groups. A prioritised intraoperative management protocol to maintain rSO2 values above 75% of the baseline threshold during cardiopulmonary bypass was followed.
  
  
  RESULTS
  There was a highly significant difference in the change in S100B concentrations post surgery between the interventional (37.3picograms per millilitre) and control groups (139.3pg/ml). The control group showed a significantly higher increase in S100B concentration over time than the intervention group (p<0.001). There was a significant difference in cerebral desaturation time (p<0.001) between the groups. The mean desaturation time for the control group was 63.85min as compared to 24.7min in the interventional group. Cerebral desaturation occurred predominantly during aortic cross clamping, distal anastomosis of coronary arteries and aortic cross clamp release. Predictors of cerebral oxygen desaturation included, partial pressure of carbon dioxide (pCO2), temperature, pump flow rate (LMP), mean arterial pressure (MAP), haematocrit, heart rate (HR) and patient oxygen saturation (SpO2).
  
  
  CONCLUSIONS
  Monitoring brain oxygen saturation during on-pump CABG together with an effective treatment protocol to deal with cerebral desaturation must be advocated.
authors.affiliation: Dept of Cardiothoracic Surgery, Inkosi Albert Luthuli Central Hospital, KZN, South Africa.
authors.forename: Yakeen
authors.initials: Y
authors.lastname: Harilall
authors.affiliation: Department of Biomedical and Clinical Technology, Durban University of Technology, South Africa. Electronic address: wnsr65@hotmail.com.
authors.forename: Jamila Kathoon
authors.initials: JK
authors.lastname: Adam
authors.affiliation: College of Health Sciences, University of Kwazulu Natal, South Africa; Department of Anaesthesia, Inkosi Albert Luthuli Central Hospital, South Africa.
authors.forename: Bruce McLure
authors.initials: BM
authors.lastname: Biccard
authors.affiliation: Dept of Cardiothoracic Surgery, Inkosi Albert Luthuli Central Hospital, KZN, South Africa.
authors.forename: Anu
authors.initials: A
authors.lastname: Reddi
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D001921:Brain / Q000378:metabolism / Q000503:physiopathology; D001026:Coronary Artery Bypass / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D009422:Nervous System Diseases / Q000097:blood / Q000503:physiopathology / Q000517:prevention & control; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D064568:S100 Calcium Binding Protein beta Subunit / Q000097:blood*
chemical_list: D015415:Biomarkers; D064568:S100 Calcium Binding Protein beta Subunit; C579160:S100B protein, human; D010100:Oxygen
keywords: CABG; Cerebral tissue oxygen saturation (rSO(2)); Coronary artery bypass graft surgery (CABG); HCT; HR; MAP; Murkin protocol; NIRS; Near infrared spectroscopy (NIRS); PcvCO(2); S100B; ScvO(2); Serum S100beta protein (S100B); SpO(2); central venous oxygen saturation; coronary artery bypass graft surgery; haematocrit; heart rate; left cerebral oxygen saturation; mean arterial pressure; near infrared spectroscopy; partial pressure of carbon dioxide; patient oxygen saturation; rSO(2); rSO(2)L; rSO(2)R; regional cerebral oxygen saturation; right cerebral oxygen saturation; serum S100beta protein