Exam 3 part V Flashcards
which concentration of epi would have a higher plasma concentration @ 1mL (thus increased risk of toxicity) - 1% or 2%
2% ; 2% = 20 mg/ml which is a higher DOSE than 1%. plasma concentration of LA is directly proportional to the dose
plasma concentration of lido is directly proportional to the ________________
dose
all LA anesthetics cause vasodilation –> increased absorption, decreased DOA, and increased risk of toxicity EXCEPT _____________, __________, _____________
cocaine (inhibits reuptake of NE) lidocaine ropivicaine
what is the rapid phase of the two compartment model (for LA)
highly perfused tissues (VRG) reach equilibrium quickly
what is the slow phase of the two compartment model (for LA)
equilibrium of lesser perfused tissues happens slower
which tissue group recieves the highest concentration of LA from redistribution
muscle group
order of distribution of LA throughout the body
- VRG 2. muscle group 3. fat group 4. vessel poor group
saturated, inhibited, or atypical p-AchE can _______________ the 1/2 life of __________ LA
prolong; ester
all amide LA are metabolized by the hepatic biotransformation via CYP450 except __________________, which is metabolized via _____________________
articaine; plasma cholinesterase
T/F: poorly functioning P-AchE effects DOA of ester LA
false; the absorption away from the site of action remains unchanged
Amides should be avoided in patients with ____________________
renal failure
if pt has hepatic dysfunction you should _______________ single dose and ____________ infusions of amide LA
make no adjustment; decrease by 10-50%
during pregnancy, women will have increased ______________ & __________ of the LA with spinals and epidurals
spread; depth
why do pregnant women have increased spread and depth of LA with spinals and epidurals
- decreased thoracolumbar CSF 2. increased susceptibility to LA d/t increased progesterone 3. gravid uterus = dilated epidural veins = narrowed SA and epidural space
modification to dose of LA in spinals and epidurals for pregnant women
you decrease dose
T/F: epi markers will prolong the DOA to the same extent with all LA
FALSE
purpose of epi additives to LA
- used to detect intravacular injection with PNB and epidurals 2. prolongs the intensity of the block 3. increases safety, quality, rate of onset, and reduced blood loss
epi markers in LA will have much more pronounced effects with ____________acting LA
short
how do epi markers prolong the intensity of the LA
local vasoconstriction which: 1. decreases rate of vascular absorption 2. decreases risk of toxicity 3. increases the LA available at the site
what is the typical concentration of epi with LA
1:200,000 (5 mcg/mL)
when testing an epidural catheter you are going to place _________ cc of LA + epi, and if you are in the right place, ______________ will happen
3; nothing (no raise in HR, BP, or anesthesia)
effect of vasoconstrictive additive on the LA is influenced by:
- drug (LA and vasoconstrictor) 2. dose of each 3. concentration of each 4. site of injection
what vasopressor drugs can be used as additives to LA
- epi (superior) 2. phenylephrine 3. norepinephrine
which vasoconstricting additive is the best for the nerve stimulator technique with peripheral blocks
epi
alpha2 adrenergic agonist additives to LA are most effective on ______________ & ____________ fibers
C (sensory); A-delta (motor)
MOA of adding alpha 2 agonist to LA
- effect spinal and supraspinal receptors 2. interrput the nerves ability to achieve resting membrane potential from the inactive state
alpha-2 agonists are added to LA for what type of blocks
- caudal (peds) 2. neuraxial 3. PNB
s/e of adding clonidine to LA block
- hypotension 2. bradycardia 3. sedation
______________ mcg of clonidine added to LA will increase analgesic effect by about _______________ minutes
100; 100
“updosing an epidural” means that you are adding _________________ to the LA
sodium bicarbonate
sodium bicarb is widely used as an additive to LA in ________________ anesthesia
epidural
effects of adding sodium bicarb to LA in epidural
- increases the pH of the solution –> increased non-ionized form of LA 2. with injection more LA crosses the membrane –> increased speed of onset 3. also decreases pain and stinging
if adding sodium bicarb to LA you should beware of NaHCO3 ability to __________________
precipitate
effect of adding hyaluronidase to LA
increases the spread of LA via facilitating diffusion into the nerve
MOA of hyaluronidase
enzyme that hydrolysis hyaluronic acid (which inhibits the spread of substances through tissues)
hyaluronidase as an additive to LA is commonly seen with _______________ procedures
opthalamic
potential adverse effects of hyaluronidase into LA
- allergic response 2. shorten DOA 3. increased risk of toxicity
what types of blocks can ketamine be added to
- spinals (intrathecal) 2. epidural 3. PNB
what is the effect of adding ketamine to LA for an intrathecal (spinal) injection
- shortens onset of LA analgesia 2. shortens DOA of analgesia
what is the effect of adding ketamine to LA for epidural
effect is unclear
what is the effect of adding ketamine to LA for PNB
prolongs post-op analgesia
what concentration of ketamine would you expect to add to LA for regional anesthesia?
50 or 100 mg/mL
opioids as additive or single agent can only be used for _________________ blocks
neuraxial
what is the other name for morphine that is specifically used in neuraxial anesthsia
duramorph - preservative free morphine
which opioids can be added or used a sole agent for spinal anesthesia
- intrathecal morphine 2. intrathecal fentanyl 3. intrathecal sufentanil
what is the dose of morphine if used as additive or sole agent in spinal or epidural?
0.1-0.2 mg
intrathecal morphine (spinal) can provide analgesia for ____________ hours post C-section
20
s/e of intrathecal morphine (duramorph)
pruritus commonly atarax given with it because itching is SO bad
dose of intrathecal fentanyl
10-25 mcg
effects of intrathecal fentanyl on your block
- improves spread 2. prolongs block 3. dose dependent effects
dose of intrathecal sufentanil
5 mcg
5 mcg of intrathecal sufentanil is similar to a _________ mg intrathecal dose of morphine
0.2
benefit of intrathecal sufentanil over morphine / fentantyl?
shorter DOA with decreased pruritus
epidural morphine is a _________________ shot that is effective for postop analgesia in ________________ & _______________ procedures
single; ortho; OB
___________________ with epidural morphine can last longer than analgesic effect, monitor closely and be sure to report that you used it to recovery staff
respiratory depression
dose of epidural fentanyl
2 - 10 mcg /mL
dose of epidural sufentanil
0.75- 1.0 mcg/mL
T/F: IV effects of sufenta = epidural effects of sufenta
TRUE
dose of hydromorphone in epidural
20 mcg/mL
what opioids can be added or used as sole agent in epidural
- morphine (single shot) 2. fentanyl 3. sufentanil 4. hydromorphone
respiratory depression is a common s/e with opioids in neuraxial anesthesia, but onset varies. place in order from earliest onset to latest onset respiratory depression with epidural opioids
- sufentanil (earliest onset d/t most lipophillic) 2. fentanyl 3. hydromorphone 4. morphine (latest onset)
dose of ketamine for intrathecal block
5-25 mg
dose of clonidine for neuraxial or PNB block
max = 1 mg/kg of ideal body weight
decadron is commonly added to ________________ blocks
peripheral
dose of decadron additive to PNB
2-4 mg
dose of precedex in spinal
10 mcg
dose of precedex in epidural
0.5 mcg/kg
dose of precedex in peripheral nerve block
0.5-1 mcg/kg
ion trapping is an effect of LA that can happen with what situations ?
- respiratory depression, hypoxia, acidosis 2. LA injection into infected tissues 3. storage of LA in acidic solutions 4. LA accumulation into fetal circulation
why is there ion trapping of LA with respiratory depression, hypoxia, and acidosis
- increased ionization of LA within CNS 2. decreases ability of LA to cross BBB out of the brain 3. potential to prolong and enhance CNS toxicity of LA
effect of injecting LA into infected tissues
infected tissues are acidotic and have no lipid solubility –> LA ionizing and being ineffective bc it cannot absorb
why do you have ion trapping of LA in the fetal circulation
fetal pH is lower than maternal pH –> LA enters fetal blood ionizes and is trapped in fetal circulation potential for high fetal levels of LA
if LA was stored in the non-ionized form what would happen
- can photodegradgate 2. forms aldehydes –> aldehyde toxicity
which agent is MOST likely to cause LAST
bupiv
causes of LAST
- inadvertent IV injection or absorption of large amounts of drugs 2. occasionally d/t continuous infusions 2/2 accumulation of drug/metabolites over many days 3. high systemic blood levels
single injection LA will have onset of LAST within ____________ minutes; continuous infusions it will take __________________ before see sx
5 (but as fast as 30-60 s); hours or days
LAST occured most commonly in which type of block?
single shot epidurals
LAST prevention
- test doses 2. incremental dosing 3. using pharmacologic biomarkers (epi) 4. restricted use of 0.75% bupiv in OB 5. use the lowest dose possible
sx of LAST
- lightheadedness 2. tinnitus 3. circumoral and tongue numbness 4. metallic taste 5. visual disturbances 6. muscle twitching 7. unconsciousness/convulsions 8. coma 9. respiratory arrest 10. CVS depression
which agents cause CV depression the most (with LAST)
- bupiv ** (MOST) 2. tetracaine 3. etidocaine
systemic blood levels of LA vary with?
- area of blockade 2. technique 3. specific drug used
if performing regional anesthesia you should always be prepared to manage what complication?
LAST
tx of LAST
- airway management - 100% FiO2 2. seizure suppression - BZ 3. BLS/ACLS 4. infuse 20% lipid emulsion 5. call cardiopulmonary bypass team & make arrangements for the possibility it is needed 6. keep epi doses < 1 mg/kg
if you suspect LAST and your patient goes into cardiac arrest, what drugs should be avoided
- vasopressin 2. CCB 3. BB 4. LA 5. propofol (if pt is grossly HD unstable)
if you perform a regional block, you should consider LAST in any pt with:
- altered mental status 2. neurologic sx 3. CV instability
T/F: propofol is a substitute for lipid emulsion therapy in tx’ing LAST
FALSE
effects of 20% lipid emulsion with LAST tx
- lipid sink - captures LA in blood 2. metabolic effect - increases fatty acid uptake 3. membrane effect - interference with LA binding to VG Na channel 4. cytoprotection - activation of the Akt cascade 5. ionotropic effect - promotes Ca entry via VG Ca channels 6. pharmacokinetic effect - accelerated shunting
recommended dosing of 20% lipid emulsion in Tx of LAST
DOSING ON LEAN BODY MASS 1. initiate IV bolus of 1.5 cc/kg 2. continue infusion at 0.25 cc/kg/min x 10 min after return of cardiac fx 3. if CV instability continues, consider repeating bolus and increasing infusion to 0.5 cc/kg/min 4. max = 10 cc/kg over 30 min for initial dosing
you can redose the 20% lipid emulsion bolus _____________x
2-Jan
T/F: 20% lipid emulsion therapy can be used to treat LAST in pregnant patients
TRUE
which LA cause methemoglobinemia
- benzocaine 2. prilocaine
tx of methemoglobinemia
methylene blue 1-2 mg/kg IV over 30 min
benzocaine and prilocaine are c/i under the age of __________ 2/2 ability to cause ___________________
2; methemoglobinemia
what is methemoglobinemia
when Fe2+ (ferrous form of hgb) is oxidized to form Fe3+ (ferric form of hgb)
high concentrations of metHb in the blood causes ________________ & ____________
- tissue hypoxia 2/2 reduced capacity to carry O2 2. left shift of the oxyhgb curve
s/sx of methemoglobinemia
- cyanosis 2. decreased SaO2 despite O2 tx 3. chocolate colored blood 4. tachypnea/tachycardia 5. confusion 6. HA 7. dizziness 8. coma 9. death
cauda equina syndrome
irritation of the sacral spinal cord
which LA was responsible for cauda equina syndrome due to inadvertent intrathecal injection
chloroprocaine
sx of cauda equina syndrome
- acute loss of function to the lumbar plexus 2. saddle anesthesia (S3-S5 dermatome) –> pins and needles in perineum, genitals, anus, and lower extremities 3. bowel and bladder dysfunction 4. could be permanent
cauda equina syndrome 2/2 LA injection disappeared when they started using ____________________
preservative free solutions
