Sams Monitoring/Surg Notecards Flashcards
What are the two different classifications of neuro monitoring?
Blood Flow/Metabolic
Name 3 blood flow monitors?
Cerebral oximetry
Transcrania doppler
Jug Bulb Venous O2 saturation
Name 4 nervous system function monitors
EEG SSEP BAEP VEP MEP
What law estimates brain tissue saturation?
Beer–lambert
Beer lambert law devise that detects decreases in CBF in relation to CMRO2?
Cerebral Oximetry Near–Infrared Spectroscopy
Name 5 things that change accuracy of cerebral oximetry
BP PaCO2 Hgb Regional blood flow Scalp O2
Measure NIRS initially when?
Prior to induction
What is your goal in maintaining NIRS during surgery?
75% of baseline
When is NIRS used the most? 2nd most?
Carotid surgery
Cardiac surgery
Normal cerebral venous O2 saturation?
60–80%
Limitation of NIRS?
ONly measures regional oxygenation
What rule says that the depth of tissue being measured by NIRS is directly proportional to the distance between the LED and sensor?
Spatial Resolution
NIRS monitors what lobe?
Frontal
Do electrocautery interfere with NIRS?
Yes
What displays the difference between regional O2 and baseline?
Delta Base
What index quantifies that depth and duration of patient staying under user–define rSO2 limit alarm?
Area Under Curve (AUC)
What is shorthand for NIRS tissue oxygen saturation?
rSO2
What displays the differnce between SpO2 and rSO2?
Delta SpO2
The top number in NIRS is the _ side of the head.
Left
Trancranial doppler ultrasonography measures _____ not ______.
Velocity not Volume
Narrowed segments of blood will show increased ________ even though there is lower volume of blood traversing.
Velocity
TC Doppler is MOST commonly positioned over the _______ to monitor the ______.
Temporal Bone
MCA
Would increased temporal bone thickness mess with your doppler?
Yes
Where does the doppler measure blood flow velocity?
Circle of Willis
What monitor provides information regarding flow direction, peak systolic and end–diastolic velocity, flow acceleration time, intensity of pulsatile flow, and detection of microemboli?
Doppler
Doppler on the base of the neck monitors the ____ artery.
Basilar
How much blood flow does the jugular bulb drain from the ipsilateral side?
70%
What is the dominant IJ in most patients? What does it drain?
Right
Cortical blood
What is the non–dominant IJ in most patients? What does it drain?
Left
Subcortical
Where is the jugular bulb accessed?
1cm below and 1cm anterior to the mastoid process.
The jugular bulb is near what sinus?
Sigmoid
SjvO2 monitors for ischemia in patients with increased _____. Maintenance goal percent?
ICP
55–75%
Is the SjvO2 the same bilaterally?
no
SjvO2 less than 55% indicates what 2 things
Inadequate delivery
Excessive consumption
SjvO2 greater than 75% indicates what 2 things?
Hyperemia
Stroke
EEG only monitors what structures?
Cortical (outer 2–3cm)
3 basic components of EEG?
Frequency
Amplitude
Morphology
EEG measures the difference of _____ between groups of neurons
Electrical Potentials
Will ischemia be detected in the subcortex or spinal cord by EEG?
No
List of EEG waves from fastest to slowest?
Gamma Beta Alpha Theta Delta
What is my mnemonic for remembering the EEG waves from high to low?
Go Buy A Truck Dear
_____ waves signal the potential for increased ischemia and ischemic damage
Delta
What wave initially occurs when the brain expereinces ischemia? What increases after that?
Beta
Amplitude
After beta waves and amplitude increase, what waves appear during ischemia?
Theta and Delta
Which style of anesthetic depresses EEG more at equal doses?
Inhalation
Inhalation agents increase the ______ and decrease the _____ of EEG waveforms at low and moderate doses
Increased frequency
Decreased Amplitude
Just like inhalation agents, induction doses of etomidate, propofol, and ketamine cause _____ waves at low and moderate doses?
Beta
Once stage 3 anesthesia is reached, frequency is _____ and amplitude is _______
Frequency lower
Amplitude Higher
Which anesthetic produces no theta and delta waves, just high oscillation waves?
Ketamine
Delta waves are mostly if the patient is very _____
Deep
What type of wave is usually evident at a full anesthetic depth?
Theta waves
Gamma hz?
30–100
Beta Hz?
10–30
Alpha hz?
8–15
Theta hz?
4–8
Delta hz?
0.5–4
Which EEG waves occur with: Heightened perception Learning Problem solving tasks Cognitive processing
Gamma waves
Awake Alert Conscious Thinking Excited
Beta waves
Physically and mentally relaxed waves
Alpha
Creative, insightful, dreaming, meditating, reduced consciousness?
Theta waves
Deep sleep without dreams, loss of bodily awareness, repair?
Delta waves
True or false: Etomidate and prop can cause burst suppression
TRUE
Burst suppression occurs with Iso at ____ MAC.
1.5
Burst suppression occurs with Sevo or Des at _____ MAC.
1.2
Is BIS more predictive with inhalation?
Yes
BIS less than _____ reflects low probability of recall
60
What lobe does BIS look at
Frontal
GA BIS?
40–60
Awake BIS
80–100
Mild/mod sedation BIS?
60–80
Deep hypnotic BIS?
20–40
Burst suppression BIS?
Less than 20
Flat line EEG BIS (lack of brain activity) value?
0
True or False: BIS values under 40 for greater than 5 minutes increases mortality
TRUE
What anesthetic produces falsely high BIS at appropriate levels of anesthesia?
Ketamine
Mechanical stress to brain?
Retraction
Loss of functional intergity of brain?
Transection
Ligation, edema, or vessel damage to the brain causes?
Ischemia
Heat to the brain is caused by?
Cautery
T or F: Anemia, hypothermia, hotn, and positioning affect evoked potentials
TRUE
3 evoked potentials monitor _ function
Sensory
_____ decrease in amplitude or ______ increase in latency is indicative of CNS ischemia?
50% amplitude
10% latency
Positive and neg deflection on EPs are what letter? What number is listed by them?
P
N
Time until response (latency)
Which EP detects localized injury to specific area of the neural axis by assessing cortically generated waves?
SSEP
Can SSEP serve as a non–specific indicator of adequacy of cerebral oxygenation?
Yes
The main purpose of SSEP is to evaluate the integrity of the brain or _________
Spinal cord
SSEP specifically monitors the _______ and ______ tracts of the dorsal lemniscal system.
Cuneatus
Gracilis
The cunateus is more ______, while the gracility is more _______.
Cuneatus = Lateral
Gracilis = Medial
SSEP is altered if brain or ______ spinal cord ischemia occurs
Posterior
Which lemnicscal system monitors the cervical and thoracic regions?
Cuneatus
The fasciculus gracilis measures the _____ and _____ regions
Sacral and Lumbar
SSEPs monitor integrity of the ________ cortex.
Somatosensory
What three sensations does the dorsal lemniscal tract carry?
Discrete Touch
Vibration
Proprioception
Where do the first order neurons synapse with second order neurons in the dorsal lemniscal system?
Nucleous Gracilis/Cuneatus
Where do second order neurons of the dorsal lemniscus system synapse with third order neurons?
Thalamus
SSEP stimulating electrodes are placed ______
Peripherally
Most common 2 nerves for SSEP stimulating electrode?
Posterior Tibial
Median
Backup nerve sites for SSEP stimulating electrodes?
Common Peroneal
Ulnar
Primary SSEP detecting electrodes are on the ______. Secondary recordings are on the _____
Scalp
Spine
Where do you record a nerve itself peripherally for verifying stimulation of SSEPs in the lower extremity?
Iliac Crest
Where do you record a nerve itself peripherally for verifying stimulation of SSEPs in the upper extremity?
ERB’s point
What body part is Erb’s point located
Neck
SSEP latency increases 3ms for every 2 degree ______ in temp
Decrease
________ suppreses SSEP amplitude to 15% of normal
Hyperthermia
Which 2 anesthetics increase SSEP amplitude 2–6x?
Ketamine and Etomidate
With SSEP’s avoid ________ of anesthesia which could be confused for ischemia
Boluses/changes
What CN does BAEP monitor
CN 8 Vestibulocochlear
also for brainstem surg
What evoked potential is least sensitive to anesthesia?
BAEP
The only non–damange factor the increases latency of BAEP?
Hypothermia
What happens to BAEP as temp increases?
Amplitude Increases
Electromyography senses mechanical and thermal damage to what CN?
7 (facial)
Standard of care for acoustic tumor surgery
Electromyography
What CN can electromyography measure
3, 4, 7, 10, 11, 12
What should you avoid when doing electromyography facial nerve monitoring?
Muscle relaxants
____________ monitor optic chasm, optic nerve, retina to occipital cortex?
VEP
Patterned flash VEP’s are used on _____ patients.
Awake
_______ flast VEPS via goggles are contacts are used under anesthesia
Unpatterned
When do you have to cover the contralateral eye for VEPs?
Monocular
_____ are rarely used under anesthesia because stable recordings vary among patients
VEP
MEPs assess the ______ spinal cord and __________ tract.
Anterior
Corticospinal
Volatiles and NMB suppress MEPs. Avoid NMB to a level greater than ____ reduction in height of ulnar nerve response.
70%
Best anesthetic for MEPs?
TIVA (prop, ket, narc)
List the most affected evoked potentials to the least.
VEP>MEP>SSEP>BAEP
MEPs are mostly used during _____ procedures
Spinal
Where is the stimulating electrode placed for MEPs?
Centrally (motor cortex, SC)
Use less than ____ MAC for SSEP or MEP
0.5
What is avoided for MEPs w/ PPM, bladder/spinal stimulator, previous crani, metal in body?
Magnetic stimulation
How to remember anestehtic effects on evoked potentials
Very affected
Moderately affected
Somewhat affected
Barely affected
First compensatory mechanism for increased ICP
CSF absorption or shunt to SC
