CNS monitoring Standard for monitoring during anesthesia Standard for monitoring during anesthesia Clinician monitoring (inspection, palpation and auscultation) Monitoring devices do not replace clinical observation! Respiratory system monitoring (oxygenation, ventilation) Circulatory system monitoring (BP, ECG, etc.) Temperature monitoring To assess the integrity of brain, brainstem, spinal cord, cranial nerves, peripheral nerves Important during spinal surgeries, intracranial surgeries, cardiovascular surgery, otolaryngology surgeries, interventional neuroradiology surgeries EEG Records electrical activity in the brain Can detect ischemia and seizure activity Assess the impact of anesthetic agents in the brain

1. CNS Monitoring

2. Importance of monitoring
• To detect early warning of adverse changes or trends and allow
intervention before irreversible damage occurs
• To assess depth of anesthesia and titrate administration of
anesthetic agents
• To detect and correct equipment malfunction

3. Standard for monitoring during
anesthesia
• Pulse oximeter, ECG, non invasive blood pressure device,
temperature monitor
• Measurement of end tidal CO2
• Inspired O2
• The use of low oxygen concentration and ventilator disconnect
alarms
• Continuous presence of qualified anesthesia personnel

4. Monitoring modalities
• Clinician monitoring (inspection, palpation and auscultation)
Monitoring devices do not replace clinical observation!
• Respiratory system monitoring (oxygenation, ventilation)
• Circulatory system monitoring (BP, ECG, etc.)
• Temperature monitoring

5. Neuromonitoring
• To assess the integrity of brain, brainstem, spinal cord, cranial
nerves, peripheral nerves
• Important during spinal surgeries, intracranial surgeries,
cardiovascular surgery, otolaryngology surgeries, interventional
neuroradiology surgeries

7. EEG
• Records electrical activity in the brain
• Can detect ischemia and seizure activity
• Assess the impact of anesthetic agents in the brain

8. Uses of EEG
• During carotid endarterectomy to assess cerebral perfusion
• During intracranial surgery to evaluate the cortex for ischemia
• To identify epileptogenic focus for resection during craniotomy
• In comatose, critically ill patients
• To assess depth of anesthesia
• To monitor seizure activity

10. BIS – bispectral index monitor
• Modified EEG
• The bispectral index (BIS) monitor is a quantitative
electroencephalographic (EEG) device that is widely used to
assess the hypnotic effects of anesthetics and sedatives
• The BIS monitor reports a single number from 0 to 100 that
represents an integrated measure of cerebral electrical activity

16. BIS
• A state of unconsciousness consistent with BIS values less than
60 usually ensures a lack of intraoperative recall.
• In adults, titration of anesthetics to a targeted BIS value
between 40 and 60 results in the administration of smaller doses
of anesthetics and earlier awakening.
• BIS monitoring allows the provider to adjust drugs to the
specific needs of the individual patient, possibly resulting in a
more rapid emergence from anesthesia and reducing the
incidence of intraoperative awareness

17. BIS
• Anesthetic techniques consisting of a low or moderate dose of
an opioid analgesic and a hypnotic drug (e.g., volatile inhaled
anesthetic, IV anesthetic) are the most accurately represented
with BIS monitoring. Low opioid doses enable the BIS index to
accurately reflect the pharmacodynamics of the hypnotic drugs
on the CNS. BIS monitoring, however, has been shown to be less
reliable in anesthetics involving higher-dose opioids and is
insensitive to several commonly used anesthetic agents such as
ketamine and nitrous oxide.

18. BIS monitoring in the ICU/ critical care
• Bispectral index (BIS) monitoring of ICU patients on continuous
infusion of sedatives and paralytics reduces sedative drug
utilization and cost.
• Required in critically ill patients, post op patients requiring
sedation for mechanical ventilation

19. Other uses
• Because BIS is easy to use and widely available, it has also been
used to evaluate brain activity in various pathologic conditions,
such as seizures, anoxic brain injury, and coma

20. PSI – Patient State Index
• Quantifies depth of anesthesia by analyzing EEG
• Comparable to BIS
• Slightly different recommended scores for general anesthesia
(25 – 50)

21. ICP monitoring in critical care

22. Intra cranial pressure
• Intracranial pressure (ICP) is the pressure exerted by fluids such
as CSF inside the skull and on the brain tissue
• Normal value: 8 – 15 mm Hg in adults

23. Indications for monitoring ICP
• Head injury
• Brain tumors / space occupying lesions
• Brain hemorrhage
• Hydrocephalus
• Neurological conditions (stroke, encephalitis)

24. Method for measuring ICP
• Intraventricular catheter - Gold standard
• Catheter is placed inside the lateral ventricle after drilling a hole
in the skull in the OR.

26. Advantages
• Reliable
• Can be used to measure ICP
• Can be used for draining CSF to reduce ICP

27. Risks
• Infection
• Trauma to the brain
• CSF leakage

28. THANK YOU