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Cerebral Oximetry and Neuroprotection

Cerebral Oximetry and Neuroprotection. 10 th International Conference Heart Summits Lahore October 13 th 2017. Sean Bennett Consultant Cardiothoracic Anaesthetist and Intensivist King Abdulaziz Medical City, Jeddah. Aim is to….

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Cerebral Oximetry and Neuroprotection

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  1. Cerebral Oximetry and Neuroprotection 10th International Conference Heart Summits Lahore October 13th 2017 Sean Bennett Consultant Cardiothoracic Anaesthetist and Intensivist King Abdulaziz Medical City, Jeddah

  2. Aim is to…. • Understand neuroprotection. Should we insult the brain and try to limit the damage or keep the brain well oxygenated throughout? • Ischaemia is a time line to infarction • Does cerebral oximetry play a role in protecting the brain?

  3. Method • Demonstrate where physiology, that we control, effects the patient outcome. • And how we can use Near InfraRed Spectroscopy (NIRS) as a means of measuring the physiological changes. • Literature • Case histories

  4. We can… • Stop the supply of oxygen, completely (for short periods), partially (longer periods). • Reducing the flow or pressure • Cause embolic events, plaque, debris, bubbles, thrombus, etc.

  5. What do we do if…. • In response to bleeding……measure Hb • In response to ventilation…..SaO2/PaCO2 • In response to renal insuff...measure urine • In response to myocardial insult….ECG • In response to dysrhythmia…..K+ • In response to neuro insult…..??????

  6. We tend to mitigate the insult by: • Drugs, cooling, keeping the pressure up

  7. Review of the Technology Penetration of NIRS Light Longer wavelength infrared light penetrates better than visible light The human skull is easily penetrated by near-infrared light

  8. Empirically Validated in Human Subjects Distal Detector Proximal Detector LED Emitter Signal from surface tissues are subtracted out Hongo K, Kobayashi S, Okudera H, Hokama M, Nakagawa F. Noninvasive cerebral optical spectroscopy: Depth-resolved measurements of cerebral haemodynamics using indocyanine green. Neurol Res. 1995;17(2):89-93. 9 |

  9. Empirically Validated in Human Subjects Distal Detector Proximal Detector LED Emitter Signal from surface tissues are subtracted out Hongo K, Kobayashi S, Okudera H, Hokama M, Nakagawa F. Noninvasive cerebral optical spectroscopy: Depth-resolved measurements of cerebral haemodynamics using indocyanine green. Neurol Res. 1995;17(2):89-93. 10 |

  10. Combines SpO2 and SJO2 Cerebral Oximetry (rSO2) Clinical Characteristic Noninvasive • Does not require pulsatile flow Pulse (Arterial) Oximetry (SpO2)Clinical Characteristics Jugular (Venous) Oxygen (SjO2) Clinical Characteristics • Noninvasive • Requires pulsatility and flow Invasive • Venous sample Think more Mixed Venous O2 saturations for the brain

  11. The Current Situation: is the brain OK? • SV02 CO • CPP/MAP/PaCO2 and Sa02 • Serum lactate and urine output

  12. Calcified aorta: patient-outcomes One patient required AVR and CABG who intra-operatively was found to have a calcified aorta. What do you do?

  13. You can see strokes happening 40 20

  14. Cerebral Oximetry for Cardiac and Vascular SurgeryHarvey L. Edmonds Seminars in Cardiothoracic and Vascular Anesthesia, Vol 8, No 2 (June), 2004: pp 147–166 • The overwhelming consensus of studies is the use of cerebral oximetry during cardiac and vascular operations is associated with significant and cost-effective reductions in neurocognitive injury and hospital cost drivers. The risk of brain oxygen monitoring is nil.

  15. Cerebral Near-Infrared Spectroscopy Monitoring and Neurologic Outcomes in Adult Cardiac Surgery Patients: A Systematic Review Zheng, Sheinberg et al. Anesth Analg 2013;116:663–76

  16. Cerebral Near-Infrared Spectroscopy Monitoring and Neurologic Outcomes in Adult Cardiac Surgery Patients: A Systematic Review • 1st; are decrements in cerebral oximetry during cardiac surgery are associated with: • Stroke • postoperative cognitive dysfunction • delirium • 2nd; whether interventions aimed at correcting cerebral oximetry decrements improve neurologic outcomes.

  17. Cerebral Near-Infrared Spectroscopy Monitoring and Neurologic Outcomes in Adult Cardiac Surgery Patients: A Systematic Review • 13 case reports, 27 observational and 2 RCT using NIRS during cardiac surgery. • Stroke: No studies powered to show a difference. • Postoperative cognitive dysfunction: 6/9 studies reported worse POCD with acute falls in NIRS. • Delirium: older age, lower MMSE score, neurologic disease, low baseline rSO2, but not intraoperative rSO2 desaturation.

  18. Cerebral Near-Infrared Spectroscopy Monitoring and Neurologic Outcomes in Adult Cardiac Surgery Patients: A Systematic Review • Secondly whether interventions aimed at correcting cerebral oximetry decrements improve neurologic outcomes. • No evidence that changing the rSO2 values modified the outcomes.

  19. Cerebral Near-Infrared Spectroscopy Monitoring and Neurologic Outcomes in Adult Cardiac Surgery Patients: A Systematic Review Did they find anything positive? • 7/9 studies showed a reduction in ICU or hospital length of stay. • A correlation between pre-op low rSO2 and post-op outcome in general. But not modifiable • Mal-positioning of aortic cannula identifiable by NIRS.

  20. Cerebral Near-Infrared Spectroscopy Monitoring and Neurologic Outcomes in Adult Cardiac Surgery Patients: A Systematic Review • hospital length of stay- so something improved. • A correlation between pre-op low rSO2 and post-op outcome, not modifiable-does this mean we shouldn’t monitor it and intervene? • Mal-positioning of aortic cannula identifiable by NIRS.- does ‘modifying this change outcome?

  21. Cerebral Near-Infrared Spectroscopy Monitoring and Neurologic Outcomes in Adult Cardiac Surgery Patients: A Systematic Review Why no stronger data? • Studies too few and too small. • Several different NIRS devices in use which are not be comparable. • Definition of ‘ischaemic levels’ not uniform or clear. • Most outcomes are time dependent.

  22. Slater JP, Cerebral oxygen desaturation predicts cognitive decline and longer hospital stay after cardiac surgery. Ann Thorac Surg. 2009; 87 (1):36-44 • Powered for neurological outcomes but no difference in the de-saturation episodes between the control group and the study group. He therefore re-analysed the groups retrospectively and showed improvement in early neurocognitive and LOS outcomes. But not late. • This meant that it was impossible to say if the low rSO2 was a modifiable risk factor.

  23. Predicting the Limits of Cerebral Autoregulation During Cardiopulmonary BypassJoshi et al.Anesth Analg 2012;114(3):503-10 Lower limits of autoregulation in 232 (7 no limit) patients using Cerebral Doppler and Correlating it with NIRS

  24. Predicting the Limits of Cerebral Autoregulation During Cardiopulmonary BypassJoshi et al.Anesth Analg 2012;114(3):503-10 Lower limits of autoregulation in 232 (7 no limit) patients using Cerebral Doppler and Correlating it with NIRS

  25. Predicting the Limits of Cerebral Autoregulation During Cardiopulmonary BypassJoshi et al.Anesth Analg 2012;114(3):503-10 • We cannot do cerebral Doppler but we can use NIRS • When NIRS falls below baseline then we are loosing autoregulation and closing the gap on MOM • In 66 year old patients MAP 66mmHg was lower limit of autoregulation

  26. How does the stroke occur? Watershed strokes after cardiac surgery: diagnosis, etiology, and outcome Gottesman RF. Stroke. 2006 Sep;37(9):2306-11 • Patients with a decrease in mean arterial pressure of at least 10 mm Hg (intraoperative compared with preoperative) were 4 times more likely to have bilateral watershed infarcts than other infarct patterns.

  27. Why dispute in cardiac, • Watershed strokes after cardiac surgery: diagnosis, etiology, and outcome Gottesman RF. Stroke. 2006;37(9):2306-11 • 98 patients with clinical stroke after cardiac surgery who underwent MRI with diffusion-weighted imaging. • Explores the relationships between; MAP and watershed infarcts; infarcts and outcome; MRI versus CT

  28. Why dispute in cardiac, • Watershed strokes after cardiac surgery: diagnosis, etiology, and outcome Gottesman RF. Stroke. 2006 Sep;37(9):2306-11 • Bilateral watershed infarcts were present on 48% of MRIs and 22% of CTs (P<0.0001). Perioperative stroke patients with bilateral watershed infarcts, compared with those with other infarct patterns, were 17.3 times more likely to die.

  29. In cardiac, trying to keep on track • Maintain a MAP that is right for the individual patient. Go figure. • Risk for impaired cerebral autoregulation during CPB and post-operative stroke. Ono, Joshi, Br J Anaesth 2012;109:391-8 • 20% of patients had impaired autoregulation and a 12% incidence of stroke compared with 2% in normo-regulated patients.

  30. Hypertensive 1 • Pre-anaesthesia MAP 144 • Initial fall. Good LV

  31. Hypertensive 1

  32. Hypertensive 1 What happens next?

  33. Patient on ICU moving all 4 limbs. Communicates. 2 hours post-op extubated. • One hour later not moving left hand. Weakness increases over 24 hours.

  34. Right temporal Cerebral infarction

  35. Next slice shows old lacuna infarctions

  36. This was the trace, what could have been done differently? • Better control preop • Higher BP throughout • Monitor bigger area • Did we avoid a bigger infarct. • Renal function was good • Monitor post-op?

  37. Cerebral oximetryand Bleeding BP40 BP 100 BP100 35 mins

  38. Hypertensive 2.1st BP over 200.

  39. Hypertensive 2.

  40. June 28 case 2015

  41. CVP slowly rising. Surgical move corrected rSO2.

  42. Next case-elective CABG

  43. On Adrenaline BP 120 –rSO2 low 30s. What next? Surgery just starting.

  44. Adrenaline, next – change the ventilation. What happens when we go on bypass? pCO2 5.2kPa pCO2 3.9kPa

  45. What happens when we go on bypass? pCO2 5.2kPa pCO2 3.9kPa

  46. CO2 or inotropes ET CO2 was 4.6kPa

  47. Next case Bilateral 70% carotid disease-symptomatic. For CABG Just after induction rSO2 below 40. Needed to adjust CO2, BP and on CPB Hb. 1 hour scale.

  48. Bilateral 70% carotid disease-symptomatic. For CABG Constant adjustment. Kept rSO2 up she made a quick and complete recovery.

  49. Bilateral 70% carotid disease-symptomatic. For CABG Constant adjustment. Kept rSO2 up she made a quick and complete recovery.

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