Intra Operative Neuro Monitoring Flashcards
What is an electroencephalogram used for intraoperatively?
Monitoring and diagnosis of:
- CNS function and ischemia
- Burst suppression
- Depth of anesthesia
T/F: A progressive reduction in CBF will produce a reliable pattern change in the EEG
True
What are the 3 steps of EEG changes during ischemia?
- Loss of high frequency activity
- Loss of power
- Eventual progression to EEG silence
Describe cerebral oximetry
Noninvasive cerebral oxygenation measurement using near-infrared spectroscopy (NIRS) technology
When should cerebral oximetry be used intraoperatively?
Any procedure where there may be vascular compromise to the brain from restriction of blood flow or patient positioning
What signifies a significant change in cerebral oximetry
- A decrease of 20% from baseline is significant
What is a BIS monitor used for?
To measure the depth of anesthesia intraoperatively
What is occurring at the following BIS Index Ranges? 0, 20, 40, 60, 80, 100
0 - flat line EEG
20 - Burst suppression
40 - Deep Hypnotic State
60 - General Anesthesia (low probability of explicit recall, unresponsive to verbal stimulus)
80 - Responds to loud commands or mid prodding/shaking
100 - Responds to normal voice
What is evoked potential monitoring?
EP modalities detect signals that are the result of specific stimuli applied to the patient
What is SSEP?
Somatosensory Evoked Potential
What is BAEP?
Brainstem Auditory Evoked Potential
What is VEP?
Visual Evoked Potential
What is MEP?
Motor Evoked Potential
What is the benefit of Evoked Potential Monitoring?
To identify the deterioration of neuronal function, this providing an opportunity to correct offending factors before they are irreversible
What are potential offending factors that can that can be identified with EP monitoring? (4)
- Position of Patient
- Hypotension
- Hypothermia
- Surgical intervention
What is monitored with SSEP?
A signal that is detectable on EEG Monitoring the primary somatosensory cortex, and is generated by a CUTANEOUS ELECTRICAL STIMULATION OF A PERIPHERAL SENSORY NERVE, OR A CRANIAL NERVE WITH A SENSORY PATHWAY
What 2 things are used to describe SSEP?
- Polarity - direction of wave deflection
2. Latency - time required for a signal to be detected after a stimulus has been applied
What 2 things is SSEP monitoring quantified by?
- Amplitude of the resulting signal
2. Latency of the resulting signal
T/F: Mechanical disruptive changes are more common than ischemic changes for SSEPs?
False - Ischemic change is more common than mechanical disruptive change
How is ischemia displayed in SSEP waves?
Causes the amplitude of the signal to decrease the latency of the signal to increase
What are clinically significant changes in SSEPs?
- 50% decrease in signal amplitude
- 10% increase in signal latency
What does MEP evaluate?
Descending motor pathways
What monitoring system complements SSEP monitoring?
What information do the 2 modalities provide?
- Complemented by SSEP, particularly in spine surgeon
- The 2 modalities provide information about the integrity of anatomically different areas of the spinal cord
Motor evoked potential stimulus is applied in a ____A___ fashion over the __B__.
A. Transcranial fashion
B. Motor cortex
