MONITORING: CNS sidenotes Flashcards
Ideal cerebral function monitor measuring the
electrical pattern of electrical activity from the depolarization of cortical neurons.
Motor evoked potentials monitor
electrical activity produced by skeletal muscles when directly stimulated.
SSEP monitor the _____Column
Dorsal column (sensory)
SSEP are stimulated ________and recorded _____
peripherally ; centrally
MEP assess the integrity of the
descending motor pathway in the ventral spinal cord
MEP monitor the _____Column
Ventral column (motor)
With MEP what is stimulated
Peripheral muscles are stimulated.
The MEP is usually detected at what two muscles?
THENAR EMINENCE and ABDUCTOR HALLUCIS MUSCLE
EP Least affected by VA
BAEPs
EP most Affected by VA
VEP
Correct order from MOST TO LEAST SENSITIVE TO VA
VEP>SSEP>BAEP
Nerves that be stimulated to elicit SSEPs are
Posterial tibial
Medial
Peroneal
Ulnar
SSEPs evaluated the integrity of the brain or spinal cord during certain types of surgery by monitoring
Gracilis and cuneatis tracts of the posterior spinal cord.
Burst suppression is a
reversible decrease in cortical neuronal metabolic function (CMRO2)
Characteristic signal often recognized with deepening of anesthesia levels
Burst suppression
Burst suppression is caused by
Barbiturates and propofol
Complete EEG suppression occurs at what temperature
15-18C
BURST SUPPRESSION occurs at what MAC of VA?
~1.5 Iso, DES, sevo
Burst of those agents can turn into epileptic seizures
Sevo and enflurane
Barbiturates on EEG
Reduces EEG electrical activity as much as 50%, dose dependent
In normothermic patient, CBF volume of 20-50 ml/100g/min been associated with
Slowing on the EEG
Normal CBF is
50ml/100g/min
CBF associated with significant neurologic impairment
<18 ml/100g/min
CBF where EEG waveforms are completely abolished
<12 ml/100g/min
CBF is irreversible at
< 6 ml/100g/min
List 4 EEG waveforms from LOW to HIGH frequencies
DTAB
Dela < Theta < Alpha < Beta
Delta frequency
1-4 Hz
Theta Frequency
4-8 Hz
Alpha Frequency
9-14 Hz
Beta Frequency
15-40 Hz
Most feared complications of spinal surgery
Paraplegia
2 methods to detect intraoperative spinal cord function compromise?
Wake-up test
SSEPs
SSEP and wake up monitor the ______column pathways
Dorsal
If acute alterations in SSEP amplitude or latency occur what does it signify?
spinal cord compromise, ischemia, compression or hematoma
If acute alterations in SSEP amplitude or latency occur and there is possible spinal cord compromise what should be done?
Surgery be discontinued, and BP return to normal or 20% above normal.
What is EMG
It is a technique for evaluating and recording the electrical activity produced by skeletal muscles.
What is the GOLD STANDARD for monitoring patients undergoing CAROTID ENDARTERECTOMY under GA?
12-lead EEG
Beside the GOLD STANDARD Of 12-lead EEG for patients undergoing CEA what other pressures can be used?
TCD
Stump pressures.
Shivering cause O2 consumption to increase by
200%
An opioid agonist commonly used to stop shivering is
Meperidine
Best sensors when comparing accuracy, safety and cost
ESOPHAGEAL (should be placed in the lower half or third of the esophagus behind the heart )
What prevents phase I hypothermia and How?
Prewarming a surgical patient in the preoperative area for at least 30 minutes effectively prevents phase I hypothermia by eliminating the CENTRAL-PERIPHERAL temperature gradient.
