Cerebral oximetry


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  • Initial Hypothermia surgery – 1952, Lewis and Lillehei.First open heart surgery on pump  Gibbon 1953, May 6th ASD ;on pumpWith increasing levels of skills, knowledge and experience,The outcomes in respect of mortality has increased.But one thing stay tall and true, that..
  • The incidence of cerebral complications after cardiac surgery is age-related.3,4 Neurocognitive decline occurs more frequently than stroke: 60% at 1 weekafter surgery, and 25 to 30% between 2 months and 1 year
  • Type I (cerebral death, non-fatal stroke, focal injury, stupor, encephalopathy, coma and new transient ischemic attack); Type II (deterioration in cognitive function, deficit in memory or seizures). The incidence of these complications varies according to type of surgery, co-morbidites and age. CNS complications are associated with increased mortality, length of hospitalization, and use of long-term facilities with substantial estimated cost per year. Multiple approaches have been utilized to address neurological complications, though definitive therapeutic strategies are lacking
  • Emboli- thrombus, Air bubbles, calcium/plaqueTUFO et al:- There was a three-fold increase in the occurrence of cerebral complications whenmean arterial pressure (MAP) fell below 40 mm Hg than if MAP was maintained above60 mm Hg. The decreased flow in patients with lower MAP leads to lower cerebral perfusion and this probably impedes clearance of micro-emboli from the brain, resulting in cerebral injury.
  • The ability to insure adequate cerebral perfusion is further complicated by the fact that nearly half of the patients presenting for cardiac surgery, have either intracranial or extracranial atherosclerotic disease
  • The ability to insure adequate cerebral perfusion is further complicated by the fact that nearly half of the patients presenting for cardiac surgery, have either intracranial or extracranial atherosclerotic disease.However, Isoelectricity caused by deep hypothermia or excessive dosage of volatile anesthetic agents renders EEG monitoring useless, and JvSO2measurements require the invasive placement of a jugular bulb catheter.
  • It was almost 25 years later that Jöbsis,in 1977, published a series of investigations in animals (and human volunteers) demonstrating that blood flow related changes in brain oxygenation could be monitored non-invasively.**
  • C is oxy- and deoxy- hemoglobin in the tissue. represents values for oxy and deoxy hemoglobin. The tissue is a mixture of scalp, skull, and brain. C is calculated from a standard curve in which a series of experiments were performed in human volunteers, patients, animals, or models with the device in which C was known and I was measured. Although L is unknown as light travels circuitously in the tissue, the probe can be constructed to make L a constant A light source will decrease in intensity when an absorbing substance mediates the light source pathway, and the more light absorbed by a substance, the more a substance is present.
  • Regional (Capillary) Oximetry (rSO2)• Noninvasive• Capillary (venous and arterial) sample• Measures the balance between O2 supply and demandbeneath the sensor• End-organ oxygenation and perfusion• Requires neither pulsatility nor blood flow
  • Objective #4: ValidationProven brain interrogationProven accuracyREP DIRECTION: THIS SLIDE IS A SERIES OF 3 “CLICKS”Let’s talk about how this technology was validated.Hongo: peer-review paperEmpirically validatedperformance of our technologyin human subjects, not just based on scientific theory.The study validated that our technology:Measures the brainSuppresses surface tissue (ensuring an oxygenation measure of deeper tissues)And does so reliably across test study subjects of different skin color INVOS™ technology uses two detectors, allowing light to be processed at two distances from the emitter; proximal and distalHere you see the “shallow” light path returning to the proximal detectorCLICK TO NEXT IMAGE
  • Objective #4: ValidationProven brain interrogationProven accuracyHere you see the “deep” light path returning to the distal detectorThe spacing of the light emitter to the detectors defines the depth and length traveled by the light paths.Deep and shallow signals alternate rapidly for separate measurementsThis permits separate processing of oxygen saturation data to “localize” the area of measurement; a concept known as spatial resolutionCLICK TO NEXT IMAGE
  • Objective #4: ValidationProven brain interrogationProven accuracyHere you can see the two light paths together and the unique paths that they travel through tissues.Again, this permits separate processing of oxygen saturation data to “localize” the area of measurement; a concept known as spatial resolution
  • Assumptions:-Length of the path remains fixed.Light to the proximal detector traverses through whole of the non brain tissue and not through any brain tissue.The beam of light scatter a very little during its courseThe beam is broad in the centre and thin at the sensor end.
  • First curve shows the normal distribution of jugular bulb saturations in healthy young volunteersrSO2 curve shows intuitive correlation with jugular bulb distribution with a similar slope shifted to the right due to the arterial component of the measurement
  • Site specific measure is MORE SENSITIVE than global measurement as it provides earlier indication of mechanical issues or worsening physiological condition.Cerebral Oximetry focuses on the frontal cortex region of the brain, which behaves as the watershed region and is more prone to ischemia than the rest as it is ACA-MCA borderzone circulation.
  • 5. Problem IdentificationPreventable complications associated with unrecognized ischemiaEarly recognition is possibleA normal systemic blood pressure does not always provide adequate cerebral perfusionThis patient is undergoing renal dialysis where low blood pressure is tolerated so that additional fluid can be pulled offHistory: Diabetes mellitus, diabetic nephropathy, MI, and hypertensionPre-dialysis SPECT image showed a right-sided reduction in CBFIn this example INVOS™ values demonstrate correlation between:Right sided rSO2desaturationLeft sided hemiparesisTIA symptomsMR angiography showed an occlusion of the right ICAT2 weighted MR imaging showed cerebral infarction in the right watershed zonePatient underwent a right STA-MCA anastomosis to prevent further ischemic attacksFollow up SPECT showed right side CBF improvementAfter surgery, rSO2s did not change during hypotensionThe patient experienced no further TIAs
  • This patient underwent a successful isolated AVR with a CPB time of 147 minutes. After weaning from CPB, the patient presented as hemodynamically stable, and protamine administration was started to reverse systemic anticoagulation. Post CPB rSO2 values were stable at 55 percent on the left and 58 percent on the right. Upon protamine exposure, right and left rSO2 values indicated severe desaturation, dropping to 15 percent bilaterally. Swan-Ganz catheter SvO2 and pulmonary artery pressures, finger SaO2saturation, and arterial blood pressure decompensation did not present values of patient compromise until approximately five minutes later. Upon complete hemodynamic collapse, the decision was made to re-heparinize and return to CPB for resuscitation. After patient stabilization, a second wean from CPB was initiated. The patient weaned successfully and a second slow exposure to protamine was initiated, resulting in a second pulmonary event and drop in rSO2. At this point, protamine was discontinued, the patient stabilized and an extremely slow infusion of protamine was completed for heparin reversal by the time of OR exit. Event Review This case demonstrates the INVOS™ System’s significant sensitivity to determine patient compromise, often prior to conventional monitoring modalities such as continuous cardiac output, pulmonary artery catheters, arterial blood pressure and pulse oximetry. The technology provided a First Alert in changes to cerebral blood flow and oxygen delivery by reflecting the patient’s hemodynamic responses in real time.
  • The differences in thickness of skull and the skin pigmentation do not modify the readings.
  • Cerebral oximetry

    1. 1. Introduction… Increased PeriOp Complications Broader Indications Cardiac Surgery Increased Age at presentation Comorbidities
    2. 2. Neurological Complaints are second only to Cardiac problems for increasing morbidity in the post op period
    3. 3. 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
    4. 4. 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
    5. 5. The big “WHY”… Brain Injury Systemic inflammatory response EmbolisationCerebral Hypoperfusion Major Minor Tissue Ischemia Neuro-degeneration CPP = MAP - ICT
    6. 6. The big “WHY”… Etiology :- Multifactorial. Off Pump Procedures:- Hypotension, Anemia low oxygen Saturation, Genetic factors, Anesthetic agents Previous neurological pathology On Pump Procedures:- Hypotension, Anemia low oxygen Saturation, Genetic factors, Anesthetic agents Previous neurological pathology Embolisation of gaseous and particulate emboli
    7. 7. Monitoring is required to detect in timely manner. Modalities include.. 1. Electroencephalographic monitoring (EEG), 2. Serial measurements of jugular bulb saturations (jvSO2) 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
    8. 8. 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
    9. 9. Principle: NIRS “Biological Spectroscopic Window” exists at the wavelength range 660-940 nm because only a few chromophores like Hb and HbO2 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.
    10. 10. principle... • NIRS relies on the Beer- Lambert law which describes a relationship between light behavior and concentration of a compound: Log (I/Io) = L*C ; I and Io are intensities of light at detector and emmitter; L is the path length; C is Conc of the absorbing compound.
    11. 11. For probe on the head, the thin extra-cerebral tissue does not interfere with brain monitoring. NIRS monitors a “weighted average” O2 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 1Emitter/2 sensor Limitation Diathermy Diathermy NIRS views the tissue circulation beneath the optical probe, somewhat similar to Pulse Oximetry. principle...
    12. 12. • 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...
    13. 13. 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.
    14. 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. 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. 16. 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.
    17. 17. Viz A Viz BP & SPO2 Jugular Venous Saturation Whole Brain Whole Body Cerebral Oximetry Focal Brain
    18. 18. Left Brain Right Brain TIA Systemic BP Compared to Cerebral Perfusion • With normal left brain arteries, perfusion and rSO2 are independent of blood pressure. • With stenotic right brain arteries, perfusion, rSO2 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.
    19. 19. Unrecognized Ischemia in CABG Underlying data and case notes on file ISC-10092. 22 | Covidien Respiratory and Monitoring Solutions | May 14, 2014 | Confidential
    20. 20. rSO2 may act as FIRST ALERT of impending dysfunction Contributor: David J. Rosinski, CCP Underlying data and case notes on file ISC-10088.
    21. 21. 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. 1. INVOS cerebral oximeter (Somanetics Corporation, Troy, MI; now Covidien, Boulder,CO); since 1993 2. FORE-SIGHT absolute cerebral oximeter (CAS Medical Systems, Branford, CT); since, 2007 3. NONIN regional oximeter (Nonin Medical Inc. Minnesota, MN);since 2009 4. 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.
    22. 22. 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.
    23. 23. 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.
    24. 24. Using INVOS in patients?
    25. 25. 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
    26. 26. 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: 1. Initiation of CPB, secondary to Haemodilution. 2. Rewarming after CPB, due to an imbalance in oxygen supply and demand. 3. At other times due to inadequate bypass flow, hypocarbia, inadequate MAP, or anaemia.
    27. 27. 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
    28. 28. 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
    29. 29. 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
    30. 30. INVOS Clinical Evidence
    31. 31. 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.
    32. 32. 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 LOSReduction(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
    33. 33. 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.
    34. 34. Goldman’s Study • Retrospective Control, Prospective Intervention, Cardiac Surgery Study • n = 2,289, Utilized the STS Stroke definition • Targeted rSO2 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.
    35. 35. 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. . 2.01% 0.97% 0% 1% 1% 2% 2% 3% Permanent Stroke 10.60% 6.80% 0% 2% 4% 6% 8% 10% 12% Prolonged Ventilation (p < 0.044) (p < 0.002)
    36. 36. Leveling the Playing Field for Diabetics 30 69 201.6 9 30 132 0 50 100 150 200 250 Ventilation p=0.002 ICU Stay P=0.008 Hospital Stay P=0.013 Control, Diabetics, n=26 Interventions, Diabetics, n=30 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
    37. 37. Murkin JM, et al. Anesth Analg 2005;100:SCA101. “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
    38. 38. 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
    39. 39. Predicting Cognitive Decline • A risk score formula was created by multiplying the number of points < 50 rSO2 by time in seconds • Any combination of intra-op rSO2 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. rSO2 Value Points Below Desaturation Threshold (50% rSO2) 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
    40. 40. 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)
    41. 41. 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) 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. 42. Murkin JM, et al. Anesth Analg 2007;7(6):515 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
    43. 43. 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.
    44. 44. “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