Cerebral oximetry

1. Cerebral Oximetry And CARDIAC SURGERY

2. Introduction… Increased PeriOp Complications Broader Indications Cardiac Surgery Increased Age at presentation Comorbidities

3. Neurological Complaints are second only to Cardiac problems for increasing morbidity in the post op period

4. Adverse CNS Outcomes Age Incidence Of Stroke <64 yrs <1% 65-75 yrs 5% > 75 yrs 7-9% Neurocognitive decline may occur in 60% at 1 week to 25 to 30% between 2 months and 1 year

5. Adverse CNS Outcomes Type I Cerebral death Non-fatal stroke / TIA Focal injury Stupor Encephalopathy Coma Type II Deterioration in cognitive function Deficit in memory Seizures

6. The big “WHY”… Brain Injury Systemic inflammatory response Embolisation Cerebral Hypoperfusion Major Minor Tissue Ischemia Neuro -degeneration CPP = MAP - ICT

7. The big “WHY”… Etiology :- Multifactorial . Off Pump Procedures:- H ypotension, A nemia low oxygen S aturation, G enetic factors, A nesthetic agents P revious neurological pathology On Pump Procedures:- H ypotension, A nemia low oxygen S aturation, G enetic factors, A nesthetic agents P revious neurological pathology E mbolisation of gaseous and particulate emboli

8. Monitoring is required to detect in timely manner. Modalities include.. 1. Electroencephalographic monitoring ( EEG ), 2. Serial measurements of jugular bulb saturations ( jvSO 2 ) and 3. Cerebral oximetry based on near infrared spectroscopy (NIRS) Cerebral oximetry is non-invasive, user friendly and is not influenced by the depth of anesthesia. It can even be utilized as a monitor to detect ischemia in real-time during a circulatory arrest period. Prevention

9. History … ** Jobsis FF. Noninvasive, infrared monitoring of cerebral and myocardial oxygen sufficiencyand circulatory parameters. Science. 1977;198:1264–1267. * Chance B. (1954). Spectrophotometry of intracellular respiratory pigments. Science 120, 767–775.10.1126/science.120.3124.767 CHANCE 1954 Absorbtion of light in the NIR spectrum by chromatophores involved in mitochondrial respiratory chain JOBSIS 1977 “the relatively high degree of transparency of myocardial and brain tissue in the near-infrared (NIR) range enabled real-time non-invasive detection of tissue oxygen saturation using transillumination spectroscopy” 22 years

10. Principle: NIRS “ Biological Spectroscopic Window ” exists at the wavelength range 660-940 nm because only a few chromophores like Hb and HbO 2 strongly absorb light in this spectra range, allowing light to penetrate tissue to a great distance. Absorption of this light due to other biological compounds and tissues such as water, lipids, skin, and bone is lower in magnitude , and these biological compounds generally have a flat absorption spectra, * Silvay G, Weinreich A, Owitz S. et al. The cerebral function monitoring during open-heart surgery. Herz . 1978;3:270–275 McCormick PW, Stewart M, Ray P. et al. Measurement of regional cerebrovascular haemoglobin oxygen saturation in cats using optical spectroscopy. Neurological Res. 1991;13:65–70.

11. principle... NIRS relies on the Beer-Lambert law which describes a relationship between light behavior and concentration of a compound : Log (I/I o ) = L*C ; I and I o are intensities of light at detector and emmitter ; L is the path length; C is Conc of the absorbing compound.

12. For probe on the head, the thin extra-cerebral tissue does not interfere with brain monitoring. NIRS monitors a “weighted average” O 2 saturation of blood in small “gas-exchanging” vessels with approximately 75% of the signal originating from venules . Pulse Oximetry Cerebral Oximetry Pulsatility Pulsatile Non- Pulsatile Light transmission (usually) Transmission (usually) Reflectance Wavelength 660/940 nm 730/810 nm Arterial component Mainly arterial 25% Arterial:75% venous Oxygen saturation Hb (arterial) Cerebral venous saturation LED 1 Emitter/1 sensor 1 Emitter/2 sensor Limitation Diathermy Diathermy NIRS views the tissue circulation beneath the optical probe, somewhat similar to Pulse Oximetry . principle...

13. In order to guarantee that only cerebral oxygen saturation is being measured most commercially available oximeters minimize extracerebral contamination by equipping the sensors with 2 light detectors located at fixed distances from the light source. By simply subtracting the measurements obtained from the brain detector from the scalp detector, extracerebral contamination can be minimized. principle...

14. Localized Area of Measurement LED Emitter Distal Detector Proximal Detector 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.

15. Localized Area of Measurement LED Emitter Distal Detector Proximal Detector 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.

16. Localized Area of Measurement LED Emitter Distal Detector Proximal Detector 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.

17. Healthy Volunteers Comparison to Jugular Bulb Kim M, Ward D, Cartwright C, Kolano J, Chlebowski S, Henson L. Estimation of jugular venous O2 saturation from cerebral oximetry or arterial O2 saturation during isocapnic hypoxia. J Clin Monit Comput . 2000;16(3):191-99.

18. Viz A Viz BP & SPO2 Jugular Venous Saturation Whole Brain Whole Body Cerebral Oximetry Focal Brain

19. Left Brain Right Brain TIA Systemic BP Compared to Cerebral Perfusion With normal left brain arteries, perfusion and rSO 2 are independent of blood pressure. With stenotic right brain arteries, perfusion, rSO 2 and function are pressure-dependent. Hypotension caused right hemisphere TIA. Blood pressure is an unreliable indicator of regional brain perfusion Kashiwazaki D, Kuroda S, Terasaka S, Iwasaki Y. Detection of hemodynamic transient ischemic attack during hemodialysis with near-infrared monitoring in a patient with internal carotid artery occlusion. Surg Neurol. 2007;68(3):292-4.

20. Unrecognized Ischemia in CABG Underlying data and case notes on file ISC-10092. 22 | Covidien Respiratory and Monitoring Solutions | May 14, 2014 | Confidential

21. rSO 2 may act as FIRST ALERT of impending dysfunction Contributor: David J. Rosinski, CCP Underlying data and case notes on file ISC-10088.

22. Options There are presently four non-invasive cerebral oximetry devices with FDA approval to measure and monitor cerebral tissue oxygen saturation during the perioperative period. INVOS cerebral oximeter ( Somanetics Corporation, Troy, MI; now Covidien , Boulder,CO ); since 1993 FORE-SIGHT absolute cerebral oximeter (CAS Medical Systems, Branford, CT); since, 2007 NONIN regional oximeter ( Nonin Medical Inc. Minnesota, MN);since 2009 CER-OX monitor ( Ornim Medical Systems) A fifth device, the NIRO series near-infrared spectrophotometer (Hamamatsu, Photonic. Hamamatsu, Japan), is available in the Japanese and European markets.

23. INVOS INVOS – In-vivo Optical Spectroscopy Non-invasive technology which acts as a “window” into body’s microvasculature Monitor site-specific adequacy of perfusion in the brain or body tissue directly beneath sensor. Provide real-time data regarding balance or imbalance of O2 supply and demand.

24. Depth How deep does it measures? Measures 2.5 – 3cm beneath the sensor. The differences in thickness of skull; and the skin pigmentation do not modify the readings.

25. Using INVOS in patients?

26. Most critical thing to do: Cause the baseline saturation values follow a bell shaped curve pattern, rSO2 baselines should be obtain prior to induction/supplemental O2/sedation. SET BASELINE Heringlake study (2011) showed preoperative cerebral rSO2 values ≤ 50 were an independent predictor of short & long term mortality in patients undergoing on-pump cardiac surgery

27. Normal Values Normal rSO2 values in healthy cerebral tissue are 58-82. In cardiac patients, the baseline rSO2 values were 65 +/- 9. A reduced Value may be found during CPB at: Initiation of CPB , secondary to Haemodilution . Rewarming after CPB, due to an imbalance in oxygen supply and demand. At other times due to inadequate bypass flow, hypocarbia, inadequate MAP, or anaemia.

28. Normal Values A difference of +/- 9 scale units of right-left rSO2 values are acceptable Any values of > 10 scale units cause for further investigation Possible causes of asymmetry include: carotid / intracranial arterial stenosis infarction intracranial space-occupying lesion excessive frontal sinus fluid

29. Critical Values A Common intervention trigger is taken as: rSO2 <50 or 20% change from rSO2 baseline Critical threshold for intervention is taken as : rSO2 <45 or 25% change from rSO2 baseline

30. What to do… 1 Increase Inspired O2 to 100% 2 Check head and canula position to ensure adequate venous drainage. 3 If PaCO2 < 40 mmHg; increase PaCO2 to > 40mmHg. 4 If MAP < 50 mmHg ; increase MAP > 60 mmHg. 5 If Hematocrit < 20%; Transfuse Blood. 6 If none of the above interventions improve cerebral saturation, decrease cerebral Oxygen consumption by increasing depth of anaesthesi As stated by Murkin JM, Iglesias I, Bainbridgge D, Adams S, et al Brain Oxygenation in Diabetic Patients during Coronary Surgery: A Randomized prospective Blinded Study. Anesthesia and Analgesia. 2005;100:SCA1-116

31. INVOS Clinical Evidence

32. The INVOS ™ System is the clinical referenced standard in cerebral/somatic oximetry 800+ clinical references (600 peer reviewed) unique to INVOS ™ technology. Three prospective, randomized controlled trials. 800+ centers nationwide, including 90% and 80% of the top 10 adult and pediatric heart hospitals respectively ( U.S. News & World Report , 2010). Approximately 6,000 units worldwide. 250,000 procedures annually.

33. Improved Patient Outcomes Five centers studying 4,300 cardiac surgery patients showed that monitoring reduced post-op neuro complications, generating a 1.66 day weighted average reduction in length of stay Yao et al. Anesthesiology 2001;95:A152. Anesthesia & Analgesia 2001;92:SCA86 Iglesias et al. Heart Surgery Forum 2003;6:204 Ganzel et al. Presented at STS, January 28-30, 2002 Fort Lauderdale Alexander et al. Annals of Thoracic Surgery 2002;373-C Schmahl . Anesthesiology 2000;93:A399 0.0 0.5 1.0 1.5 2.0 2.5 3.0 LOS Reduction (days) 2.1 2.7 1.4 1.7 1.2 Univ of Louisville Hackensack Univ Med Ctr Weill Medical College, NY St. Luke’s Med Ctr, Milwaukee Univ Western Ontario

34. Improve Neuro Protection Neuro dysfunction is not always embolic: Detect and correct other factors Cerebral Oxygen Desaturation is Associated With Early Postoperative Neuropsychological Dysfunction in Patients Undergoing Cardiac Surgery Yao FS, Tseng CC, Ho CY, Levin SK, Illner P. Cerebral oxygen desaturation is associated with early postoperative neuropsychological dysfunction in patients undergoing cardiac surgery. J Cardiothorac Vasc Anesth . 2004;18(5):552-558.

35. Goldman’s Study Retrospective Control, Prospective Intervention, Cardiac Surgery Study n = 2,289, Utilized the STS Stroke definition Targeted rSO 2 at or near patient baseline values in the intervention group Anesthesia and surgical methods were similar for both groups Control Group (Retrospective) n = 1,245 No Interventions Intervention Group (Prospective) n = 1,034 Interventions per Protocol Goldman S, et al. Heart Surg Forum 2004;7:E376-E378.

36. Reduced Complications INVOS ™ System use on cardiac surgery patients reduced permanent stroke, pulmonary complications and length of hospital stay Statistically significant decreases were achieved despite the INVOS System group having a higher acuity than the control group (64.1% in NYHA class III and IV vs. only 30.7%) Goldman S, Sutter F, Ferdinand F, Trace C. Optimizing intraoperative cerebral oxygen delivery using noninvasive cerebral oximetry decreases the incidence of stroke for cardiac surgical patients. Heart Surg Forum . 2004;7(5):E376-381. . (p < 0.044) (p < 0.002)

37. Leveling the Playing Field for Diabetics Randomized Prospective Blinded Diabetic cardiac surgery patients monitored with the INVOS ™ System showed statistically significant improvements over unmonitored diabetic patients. Murkin JM, Iglesias I, Bainbridge D, et al. Brain oxygenation in diabetic patients during coronary surgery: A randomized prospective blinded study. Anesth Analg . 2005;100:SCA101. Hours

38. Murkin JM, et al. Anesth Analg 2005;100:SCA101. Study Findings “Clinical outcomes were improved to the point that there were no significant differences between diabetics and non-diabetics , essentially leveling the playing field for patients who traditionally have had poorer outcomes during cardiac surgery.” John M. Murkin , MD Bringing Diabetics in Sync with Non-Diabetics

39. Casati A, et al. Anesth Analg . 2005 Sep;101(3):740-7. “All cerebral desaturations occurred during the maintenance period of general anesthesia and the episodes were never associated with a concomitant reduction in arterial oxygen saturation.” Time spent below the rSO2 desaturation threshold correlated significantly with: MMSE decline (p = 0.01) Increased LOS (p = 0.007) High Risk General Surgery *MMSE – Mini-Mental State Examination LOS - Length of stay

40. Predicting Cognitive Decline A risk score formula was created by multiplying the number of points < 50 rSO 2 by time in seconds Any combination of intra-op rSO 2 value and time that resulted in > 3,000 %seconds was found to increase risk Slater JP, Guarino T, Stack J, et al. Cerebral oxygen desaturation predicts cognitive decline and longer hospital stay after cardiac surgery. Presented at: 42nd Annual Meeting of the Society of Thoracic Surgeons, January 29-31, 2007; San Diego, CA. rSO 2 Value Points Below Desaturation Threshold (50% rSO 2 ) Multiplied By Seconds Under Threshold Cognitive Decline Risk Score 45 5 X 600 (or 10 minutes) 3,000 %seconds 40 10 X 300 (or 5 minutes) 3,000 %seconds 35 15 X 200 (or 3.3 minutes) 3,000 %seconds

41. Predicting Cognitive Decline Slater JP Cerebral Oxygen Desaturation Predicts Cognitive Decline and Longer Hospital Stay After Cardiac Surgery Ann Thorac Surg 2009 Jan;(1) 87:36–45)

42. Patients with cerebral rSO2 oxygen desaturation score of >3000 % seconds: Had a significantly higher risk of post-op cognitive decline (p=0.024) Had a near three-fold increased risk of a prolonged hospital stay > 6 days (p=0.007) Study Findings Slater JP Cerebral Oxygen Desaturation Predicts Cognitive Decline and Longer Hospital Stay After Cardiac Surgery Ann Thorac Surg 2009 Jan;(1) 87:36–45)

43. Murkin JM, et al. Anesth Analg 2007;7(6):515 BRAIN as an INDEX ORGAN Hypothesis By using the brain as an index organ, interventions to optimize cerebral perfusion will have a similarly beneficial effect on systemic tissue perfusion and clinical outcomes

44. Standard deviation was also tighter, indicating fewer outlier patients Reduced ICU Stay Murkin JM, Adams SJ, Novick RJ, et al. Monitoring brain oxygen saturation during coronary bypass surgery: a randomized, prospective study. Anesth Analg . 2007;104(1):51-58.

45. “ While none of the interventions undertaken are outside the range of good clinical practice, it is clear that in the absence of feedback from a specific indicator of end organ compromise (e.g., cerebral desaturations ), the ability of the clinician to detect and optimize otherwise silent but potentially adverse perturbations in clinical variables remains limited .” Murkin JM, et al. Anesth Analg 2007;7(6):515 Monitoring Brain Oxygen Saturation During Coronary Bypass Surgery: A Randomized Prospective Study Conclusion