Regional anesthesia Flashcards
Where is the distal terminus of the subarachnoid space?
S2
What accounts for most of the variability in the spread and regression of neuraxial anesthesia?
CSF volume
What is the primary barrier to drug diffusion from the epidural space to the intrathecal space?
arachnoid mater
What is the mechanism of respiratory arrest in a high/total spinal?
hypoperfusion to central ventilatory centers
Which Rexed lamina layers in the gray matter of the spinal cord are involved in transmission of nociception?
I, II, and V “keep the pain alive”
What agent gives you the longest duration single-shot spinal?
tetracaine (+/- epinephrine or phenylephrine)
What are the mechanisms of spinal anticholinesterases?
increased cholinergic neurotransmission
NO release
Which patient factor has the greatest influence on peak block height of a spinal anesthetic?
patient height
How much does epinephrine extend the duration of epidural lidocaine?
50%
Besides cocaine, which local anesthetic has vasoconstrictive properties?
ropivicaine
How far above the sensory level does the sympathectomy extend in spinal anesthesia? Epidural anesthesia?
2-6 levels above for spinal
same level for epidural
Does neuraxial anesthesia cause primarily arterial vasodilation or venodilation?
venodilation
What factors lead to bradycardia after neuraxial anesthesia?
RA stretch receptors detecting loss of preload from venodilation (Bezold–Jarisch reflex)
Loss of T1-T4 cardiac accelerator fibers
What are the mechanisms of action of intralipid?
lipid sink for local anesthetics
stabilization of mitochondria
What can cause diplopia with a post-dural puncture headache?
traction on the 6th cranial nerve
What is the most common causative organism of an epidural abscess after epidural anesthesia?
staph aureus
What is the relative dosing of epidural vs. spinal medications?
10-fold higher dosing for epidural vs. spinal
Where is the distal terminus of the spinal cord?
varies from L1 in adults to L3 in infants
What are the 3 factors associated with transient neurologic syndrome after neuraxial anesthesia?
lidocaine (concentration-independent)
lithotomy
ambulatory surgery
How do you treat TNS?
NSAIDs and time
What are ASRA guidelines for timing neuraxial anesthesia and low-molecular weight heparin?
Placement > 12 h after prophylactic dose, > 24 h after therapeutic dose.
Resumption > 4 h after catheter removal AND > 12 h (prophylactic) or > 24 h (therapeutic) after placement
How long should Plavix be held prior to neuraxial anesthesia?
7 days
Why is Mg contraindicated in patients with myasthenia gravis?
It causes muscle weakness by blocking ACh release
Which nerve has a characteristic bifurcation used to identify it on ultrasound?
Sciatic nerve popliteal approach (bifurcates into common peroneal and tibial)
