Part 2-4 Flashcards
What are CNS effects of VA
- No retrograde amnesia, but
- No prolonged effects
- Luxury perfusion (blood flow in excess of metabolic needs)
- Occupational exposure causes decrease reaction times after 10-20% N2O is breathed; 0.0016%(0.002MAC) Halothane-no mental impairment
What are VA cardiopulmonary effects
Prominent cardiopulmonary depression
At what MAC is amnesia probable?
0.04
***VA effect on evoked potentials
Decrease amplitude & increase latency
***How to dose VA while doing evoke potentials
- don’t go greater than 1MAC total.
- With 60% N2O,may use 0.5-1 MAC Isoflurane
What agent most likely will be avoided during evoke potential monitoring
N20
How do VA effect seizure activity
- No seizure activity generally seen
- agents are tested for sz. prior to release
- Not seen with Des, Iso, Sevo (2 cases reported w/ sevo.)
- May see clonus or even opisthotonus with N2O
***Effect of cerebral blood flow with a VA > 0.6 MAC
- Cerebral dilation***
- Decreased CVR (Cerebral vascular resistance)
- Increased CBF, despite of decreases in CMRO2(cerebral metabolic response of O2)
Which agent causes the least cerebral vasodilation
isoflurane
***How would you combat increased CBF?
- Hyperventilation (increased CO2> vasodilation)
- May limit by prior (or with Isoflurane simutaneous)
***What is Isoflurane’s effect on CBF
-It preserves auto-regulation therefore, no change to cerebral blood flow
***VA aapproach to cerebral aneurysm clipping
-Controlled hypotension favorable balance btw. lush O2 supply(increased blood flow) & reduced demand (decreased CMRO2)
***Effects of VA on ICP
they all produce increase ICP in parrallel w/ increased CBF
***What patients are most vulnerable to increased ICP from VA. What should be done to help prevent it?
- Pt. with space-occupying lesions(Munroe-Kellie hypothesis)
- Use agent but hyperventilate
What are Servoflurane’s effect on awareness
-produces emergence delirium
in what patient populations has a decline in cognitive function been noted?
- Post CABG
- Children with multiple surgeries (repeat anesthetics)
- Elderly
- Patients with frequent repeat anesthetics (ex. burn pts.)
What influences differences in circulatory/ cardiovascular effects of VA?
- Control vs. spontaneous breathing
- Preexisting cardiac dz.
- Drugs acting directly/ indirectly on the heart.
VA have what type of circulatory effects?
(they are drug-specific, dose-dependent, prominent cardiovascular effects):
- Myocardial contractility
- Peripheral vascular smooth muscle tone
- ANS activity
VA effect on MAP
Increased agent > decrease MAP (Sx. stimulation opposes this effect)
What changes, if any, are noted in hypertension preop after induction?
exaggerated hypotension after inductiob
N2O effect on MAP
- No change or slight increase (doesn’t decrease or support B/P)
- (Substituting N20 for a portion of MAC, & decreases in MAP will be less than if using VA alone)
***Effect of Isoflurane & Desflurane on HR @ 1 MAC
Increase HR
****Effect of Sevoflurane on HR @ 1 MAC
No increase in HR
Des, Sevo, and Iso effects on cardiac output.
- They don’t decreased CO in a dose dependent fashion
- Decrease stroke volume 15-30%, but preserve CO better r/t increase HR & decrease SVR
