DRUGS FOR LOCAL & GENERAL ANESTHESIA Flashcards
what is local anesthesia?
loss of sensation to a limited body region, w no loss of consciousness
what is regional anesthesia?
loss of sensation to a larger body area, w no loss of consciousness
what is general anatheisa?
loss of sensation throughout entire body, accompanied by loss of consciousness
what is monitored anatheisa care?
sedation, client remains responsive, used during diagnostic procedures, or in combination with local anesthetic for minor surgeries
what is the method of a topical route?
creams, sprays, lozenges, drops, suppositories
what is the method of infiltration (field block) route?
direct injection into tissue immediate to the surgeries call site
what is the method of nerve block route?
direct injection into tissue that may be distant from operation site
what is the method of a spinal route?
injection into the cerebrospinal fluid (CSF)
what is the method of an epidural route?
injection into epidural space of spinal cord
- always a higher dose then spinal
to improve a local anesthetics duration of action, it can be co administered with?
epinephrine
what is the mechanism of action for a local anesthetic?
-block voltage gated sodium channels
-blocks action potentials
-inhibit both motor an sensory neuronal signalling
-bind to open sodium channels
-active neurons ate the most susceptible
what is an ester anesthetic?
-rapidly metabolized in the bloodstream
-don’t need to be metabolized by liver
-short half life (1-2 mins)
-pKa ranges from 8.6-8.9
what is an amide anesthetic?
-metabolized in the liver (CYP 450)
-longer half lives (60-240 mins)
-pKa ranges from 7.5-8.0
what is Bupivaccaine (marcaine)?
anesthetic drugs, affects more visceral (C fibres)/somatic pain fibres (A& fibres) rather than motor fibres (Alpha fibres)
when a local anesthetic is administered into the epidural space, how is it different than an intrathecal (spinal) administration?
more anesthetic is required
is the epidural space a vascularized area?
yes. highly vascularized
if a local anesthetic is properly applied, what should happen?
the drug should predominately affect the nerve roots passing through the epidural space (somatosensory)
when administering a local anesthetic directly into the CSF, is it a clear end point? And when do you know you’ve reached the spinal cord?
Yes
- when pulling back syringe there is CSF fluid
when is a local anesthetic generally administered?
during scheduled surgical procedure (c section)
what is the difference between a local anesthetic and an epidural?
local anesthesia has a higher rate of efficacy, but requires less anesthetic than an epidural
CANNOT inject epidural in the wrong place
what is the function of opioids?
-bind to presynaptic receptors in the dorsal horn of the spinal cord (substantia gelatinous), inhibits release of pain signalling neurotransmitters
-bind to postsynaptic receptors in the brain; decreasing neuronal excitability
-NO ACTIVITY on motor neurons; mobility, proprioception and sense of touch are maintained
-very effective in controlling visceral pain
why can opioids be administered with local anesthetics?
lowers the dose of local anesthetic required
what are adverse effects local anesthetics?
- pruritus (itching) is common and can be treated with antihistamines
-nausea an vomiting may occur if drug reaches the area postrema in the brain stem
-respiratory depression (very rare) in cases of epidural regional anesthesia
what are adverse effects of epidural and intrathecal anesthesia?
-inadequate anesthesia
-backache (20%)
-infection (1%)
-arachnoiditis
-spinal headache (1-5%) - CSF leak, causing traction on the brain from the meninges - treated with a blood patch, 15-20 ml autologous blood transfusion to the puncture site
