Intraoperative neuromonitor during cardiac surgery

1
Intra-operative neuro-monitor during cardiac
surgery

• Intern ???
• 2006.05.01

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CNS complication during cardiac surgery

• 6.1 of 2100 patients undergoing conventional
  CABG surgery evidence clinically apparent CNS
  injury postoperatively.
• Over 50 of patients with either extra-cranial or
  intracranial atherosclerotic disease (ECAD, ICAD)

-John M. Murkin ltPerioperative Multimodality
Neuromonitoring An Overviewgt Seminars in
Cardiothoracic and Vascular Anesthesia, Jun 2004
8 167 - 171.
3
Intra-operative neuro-monitor modality

• Mean arterial Pressure (MAP)
• Transcranial Doppler (TCD)
• Cerebral Oximetry
• Near-infrared Reflectance Spectroscopy (NIRS)
• Electroencephalogram (EEG)
• Bispectral Index (BIS) Monitor
• Auditory Evoked Potentials (AEP)

-John M. Murkin ltPerioperative Multimodality
Neuromonitoring An Overviewgt Seminars in
Cardiothoracic and Vascular Anesthesia, Jun 2004
8 167 - 171.
4
Mean arterial Pressure (MAP)

• In patients undergoing CABG
• MAP was maintained at gt 80 mmHg
• ?A lower incidence of morbidity, including stroke

-Gold JP.lt Improvement of outcomes after coronary
artery bypass. A randomized trial comparing
intraoperative high versus low mean arterial
pressure.gt Journal of Thoracic Cardiovascular
Surgery. 110(5)1302-11 discussion 1311-4, 1995
Nov.
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Transcranial Doppler (TCD)

• Ultrasound at frequencies of 2 MHz
• Trans-temporal route above the zygomatic arch
• ACA, MCA, PCA
• Trans-orbital approach
• Carotid artery
• Sub-occipital route through the foramen magnum
• BA, VA
• Limitation
• small or absent trans-temporal windows or thick
  calvaria
• to maintain the probe in the same position

-Nousheh Saidi et al. ltApplied Neuromonitoring in
Cardiac Surgery Patient Specific Managementgt
Seminars in Cardiothoracic and Vascular
Anesthesia, Mar 2005 9 17 - 23.
6
-Dennis D. Doblar ltIntraoperative Transcranial
Ultrasonic Monitoring for Cardiac and Vascular
Surgerygt Seminars in Cardiothoracic and Vascular
Anesthesia, Jun 2004 8 127 - 145.
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High-intensity transient signals (HITS) caused by
micro-emboli
-Dennis D. Doblar ltIntraoperative Transcranial
Ultrasonic Monitoring for Cardiac and Vascular
Surgerygt-Seminars in Cardiothoracic and Vascular
Anesthesia, Jun 2004 8 127 - 145.
8
Transcranial Doppler (TCD)

• Improvement and new-finding
• 1. Distinguish between solid and gaseous emboli

-Abu-Omar et al. ltSolid and gaseous cerebral
microembolization during off-pump, on-pump, and
open cardiac surgery procedures gt Journal of
Thoracic and Cardiovascular Surgery ,127( 6)
June, 2004 pp. 1759-1765
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• Improvement and new-finding
• 2. Leukocyte depletion filtration gtintra-aortic
  filter
• 3. Cerebral emboli and adverse cerebral outcome
  might be related to the presence of aortic
  atheromatous disease in CABG
• 4. Modification of perfusionist intervention
• 5. Postoperatively, detect cerebral emboli after
  carotid endarterectomy triggered dextran
  anticoagulation
• significant decrease in perioperative stroke

-Nousheh Saidi and John M. Murkin ltApplied
Neuromonitoring in Cardiac Surgery Patient
Specific ManagementgtSeminars in Cardiothoracic
and Vascular Anesthesia, Mar 2005 9 17 - 23.
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EEG

• Requirement of a dedicated technician for
  placement of the electrodes
• Subjective nature of interpretation
• Electrical signal interference

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Bi-spectral Index (BIS) Monitor

• EEG-based monitor with dimensionless

-Nousheh Saidi and John M. Murkin ltApplied
Neuromonitoring in Cardiac Surgery Patient
Specific Management gt Seminars in Cardiothoracic
and Vascular Anesthesia, Mar 2005 9 17 - 23.
12
BIS value

• Active BIS monitoring of cardiac surgery is
  likely to significantly decrease the risk of
  intra-operative awareness and recall.

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BIS

• Use in cardiac anesthesia
• Low BIS values may be related to cerebral
  ischemia
• May used to detect cerebral embolic
• Several case-report suggest that
• A change in the BIS values is specific not for
  cerebral infarction
• But a BIS decrease may be the first indication of
  a serious cerebral event

-Naureen Adam and Peter S. Sebel ltBIS Monitoring
Awareness and Catastrophic Eventsgt Seminars in
Cardiothoracic and Vascular Anesthesia, Mar 2004
8 9 - 12.
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Near-infrared Reflectance Spectroscopy (NIRS)

• Monitor rSO2
• Of the 98 patients receiving CABG, 54 in control
  group and 44 in intervention group
• Intervention
• increasing perfusion pressure, pump flow,FiO2,
  Hct (if lt20), PaCO2 to gt45mmHg
• decrease temperature (if gt37C)
• Control managed routinely
• Significant shorting of length of stay

-John M. Murkin ltPerioperative Detection of Brain
Oxygenation and Clinical Outcomes in Cardiac
Surgerygt Seminars in Cardiothoracic and Vascular
Anesthesia, Mar 2004 8 13 - 14.
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Near-infrared Reflectance Spectroscopy (NIRS)

• Cerebral Oximetry
• Wavelength of 6501100nm
• Bi-hemispheric measure of cerebral regional
  oxygen saturation (rSO2) through the intact
  calvarium
• A positive predictive value between low rSO2 and
  adverse CNS outcomes

-John M. Murkin ltPerioperative Multimodality
Neuromonitoring An Overviewgt Seminars in
Cardiothoracic and Vascular Anesthesia, Jun 2004
8 167 - 171.
16
NIRS

• A randomized, blinded study of 198 CABG patients
• rSO2 monitoring is associated with s significant
  decrease in combined major morbidities
• Death
• Stroke
• Myocardiacl infarction
• Prolonged ventilatory support
• Renal failure

-Nousheh Saidi and John M. Murkin ltApplied
Neuromonitoring in Cardiac Surgery Patient
Specific Management gt Seminars in Cardiothoracic
and Vascular Anesthesia, Mar 2005 9 17 - 23.
17
-Dimitri Novitzky ltReducing the Risk of
Myocardial Revascularization Relevance of
Multimodal Brain Monitoringgt Seminars in
Cardiothoracic and Vascular Anesthesia, Jun 2005
9 131 - 137.
18
-Dimitri Novitzky ltReducing the Risk of
Myocardial Revascularization Relevance of
Multimodal Brain Monitoringgt Seminars in
Cardiothoracic and Vascular Anesthesia, Jun 2005
9 131 - 137.
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Auditory Evoked Potentials (AEP)

• Early AEP from the auditory nerve and the
  brainstem (BASEP)
• Middle-latency AEP from polystnaptic activity in
  the midbrain or diencephalic nuclei and the
  primary auditory cortex and adjacent areas

Rosendo A. RodriguezHuman Auditory Evoked
Potentials in the Assessment of Brain Function
During Major Cardiovascular SurgerySeminars in
Cardiothoracic and Vascular Anesthesia, Jun 2004
8 85 - 99.
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Auditory Evoked Potentials (AEP)

• AEP assess specific areas of
• Auditory nerve
• Brainstem
• Midbrain
• Auditor cortices
• In cardiac surgery
• Monitoring of cerebral hypothermia and the
  avoidance of excessive re-warming during CPB
• Assessment of the functional integrity of the CNS

-Rosendo A. Rodriguez ltHuman Auditory Evoked
Potentials in the Assessment of Brain Function
During Major Cardiovascular SurgerygtSeminars in
Cardiothoracic and Vascular Anesthesia, Jun 2004
8 85 - 99.
21
-Rosendo A. Rodriguez ltHuman Auditory Evoked
Potentials in the Assessment of Brain Function
During Major Cardiovascular Surgerygt Seminars in
Cardiothoracic and Vascular Anesthesia, Jun 2004
8 85 - 99.
22
Monitoring of Cerebral Hypothermia and re-warming

• Extra-cranial sites may not reflect the
  temperature of the core brain
• Hypothermia
• the latency of BAEP ?
• the amplitude of BAEP ?
• these effects are reversible during re-warming
• An objective indirect method for monitoring
  functional temperature changes in the core of the
  brain.

-Rosendo A. Rodriguez ltHuman Auditory Evoked
Potentials in the Assessment of Brain Function
During Major Cardiovascular Surgerygt Seminars in
Cardiothoracic and Vascular Anesthesia, Jun 2004
8 85 - 99.
23
Monitoring of Cerebral Hypothermia and rewarming
-Rosendo A. Rodriguez ltHuman Auditory Evoked
Potentials in the Assessment of Brain Function
During Major Cardiovascular SurgerygtSeminars in
Cardiothoracic and Vascular Anesthesia, Jun 2004
8 85 - 99.
24
Assessment of the functional integrity of the CNS

-Rosendo A. Rodriguez ltHuman Auditory Evoked
Potentials in the Assessment of Brain Function
During Major Cardiovascular Surgerygt Seminars in
Cardiothoracic and Vascular Anesthesia, Jun 2004
8 85 - 99.
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Neuro-monitor Limitation

• Highly regional
• miss significant localized cerebral ischemia
• Global in nature
• relatively to regional ischemia
• Multimodality CNS monitoring that incorporates
  different complementary technique is needed

-John M. Murkin ltPerioperative Multimodality
Neuromonitoring An Overviewgt Seminars in
Cardiothoracic and Vascular Anesthesia, Jun 2004
8 167 - 171.
26
Take home massage

• MAP
• greater than 80 mmHg
• TCD
• to detect macro- or microemboli
• Bispectral Index (BIS)
• To detect cerebral ischemia
• Cerebral Oximetry
• for cerebral regional oxygen saturation (rSO2)
• Auditory Evoked Potentials (AEP)
• Monitoring of cerebral hypothermia and re-warming
• Assessment of the functional integrity of the CNS

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Thank you for attention !!