Pathophysiologic Implications - NMB

Question 1

What does it mean when you have RESISTANCE to a nondepolarizing NMB?

Answer 1

you will have to give more of the medication to get the response wanted

Question 2

what does it mean when you are sensitive to a NMB?

Answer 2

your duration will last longer if you give the normal dose, so give less

Question 3

What does phenytoin (dilantin) due to a nondepolarizing NMB?

Answer 3

• causes shorter duration (resistance)
• Because of
  
  • decreased activity of AChE
  • induced cytochrome p450 in the liver (metabolism)
  • increased number of ACh sites
• can change duration even if you give it intraoperatively!!

Question 4

There are 3 meds mentioned that phenytion causes a decreased duration of. What are the meds and the percentages associated?

Answer 4

Rocuronium 20%
Vecuronium 37%
Pancuronium 40%

Question 5

These meds are given to myesthenia gravis patients (immunosuppressed pt, asthma) to improve neuromuscular function; chronic use has been reported to cause ____ to _____ NMB like vecuronium

Answer 5

resistance, steroidal

Question 6

these two meds inhibit phosphodiesterase which increases cAMP needed to synthesize and release ACh which leads to more ACh

Answer 6

• aminophylline and theophylline

- a greater dose is needed to compete with the increase in ACh

Question 7

This med in large doses, 1-4 mg/kg, inhibits phosphodiesterase which increases cAMP which makes ACh more available

Answer 7

furosemide

-increase the dose due to increased resitance

Question 8

resistance begins 10 days after injury, peaks at 40, and declines after 60 days (463 days is longest)

Answer 8

burn injuries

• would not give depolarizing bc K
• due to a decreased sensitivity of the postjunctional receptors to either ACh or nondepolarizing NMB, basically nondepolarizers will be chewed up

Question 9

Type of patients with increased extrajunctional receptors?

Answer 9

MS, hemiplegic limb, CVA, prolonged immobilization, massive trauma

Question 10

Why is the paralyzed limb of a CVA patient more resistant to NMB?

Answer 10

more extrajunctional cholinergic receptors due to denervation

Question 11

Main reason not to give MS patients NMB?

Answer 11

they are unpredictable! Do not know if pt are in remission periods.
definitely not going to give SCh bc of hyperkalemia

Question 12

this causes increased resistance due to decreasing the resting potential of the membrane which increases the positivity of the cell

Answer 12

chronic hyperkalemia

Question 13

does chronic hyperkalemia increase or decrease sensitivity to SCh?

Answer 13

increases sensitivity because the resting membrane potential is more positive, which is closer to depolarization and closer to an action potential

Question 14

pharmacologic 
   -corticosteroids
   -amino/theophylline
   -furosemide 
burn injuries
increased extrajunctional receptors
chronic hyperkalemia

Answer 14

factors associated with resistance

Question 15

these decrease the skeletal muscle tone and decrease the sensitivity of muscle membranes to depolarizations lower than the ED95; have the greatest impact on long acting NMB (pancuronium)

Answer 15

volatile anesthetics

increase sensitivity

Question 16

these interfere with the release of ACh from the prejunctional receptors, block ion channels, and directly depress skeletal muscle tone

Answer 16

local anesthetics

increase sensitivity

Question 17

these cause a magnesium type effect to decrease release of ACh to make reversal unreliable (can give Ca)

Answer 17

antibiotics

increase sensitivity

Question 18

aminoglycosides - gentamicin, neomycin, streptomycin, kanamycin, amikacin, tobramycin

Answer 18

antibiotics that increase the sensitivity of nmb

Question 19

antibiotics that have NO effect on nmb

Answer 19

penicillins, cephalosporins, erythromycin

Question 20

when given to a patient who is recovering from a nondepolarizing nmb, the block is potentiated by the blockage of the prejunctional release of ACh

Answer 20

lidocaine

increased sensitivity

Question 21

potentiates nondepolarizing nmb and SCh

Answer 21

quinidine

Question 22

this med has a variable effect on nondepolarizing and prolonged onset and duration of depolarizing nmb

Answer 22

lithium

increased sensitivity

Question 23

what production is decreased when giving <1mg/kg of lasix per day resulting in increased sensitivity to nmb

Answer 23

lasix

Question 24

this med increases the sensitivity of nmb (specifically atracurium and vecuronium, and is used for renal replacement pt, rheumatoid, and psoriasis pt

Answer 24

cyclosporine

Question 25

this med reduces the dose required due to membrane desensitization causing enhanced, but not prolonged, blockade by nondepolarizing nmb

Answer 25

succinylcholine

Question 26

if you have a combination of nondepolarizing nmb - you will see a ___ effect

Answer 26

synergistic | -usually combo of drugs from different classes

Question 27

the usual site of action is on the slow channels, not fast channels like the postjunctional receptors so unpredictable effects have been reported

Answer 27

calcium channel blockers

Question 28

acute admin of this med may potentiate nondepolarizing nmb | -the combo of the two types of meds could cause critical illness myopathy

Answer 28

hydrocortisone

Question 29

this med is given as a stress dose to people on chronic steroids

Answer 29

hydrocortisone

Question 30

these meds can decrease sensitivity of the muscle membrane to cause relaxation of its own and potentiate nondepolarzing nmb

Answer 30

trimethaphan and hexamethonium

Question 31

these meds inhibit plasma cholinesterase activity to cause prolongation of depolarizing block

Answer 31

trimethaphan and hexamethonium | ganglionic blockers

Question 32

prolongs duration by slowing clearance via hepatic enzymes, renal pathways, hofmann elimination, and ester hydrolysis

Answer 32

hypothermia

Question 33

``` antihypertensives hydrocortisone ca channel blockers SCh cyclosporine lasix lithium lidocaine quinidine antibiotics volatile and local anesthetics ```

Answer 33

pharmacologic factors associated with increased sensitivity

Question 34

increases membrane potential (hyperpolarization) and increases sensitivity to nondepolarizing nmb (resistant to SCh)

Answer 34

acute hypokalemia

Question 35

decreased release of ACh from prejunctional receptors which causes an enhanced block (think pregnant women and preterm labor)

Answer 35

hypermagnesium

Question 36

___ causes decreased volume of distribution of nmb so more drug reaches the receptors

Answer 36

dehydration, seen with hypernatremia

Question 37

difference in muscle mass from men cause __ block in women with similar mg/kg (really not clinically relevant)

Answer 37

greater

Question 38

chronic autoimmune disorder caused by a decrease in functioning acetylcholine receptors at the NMJ by antibodies

Answer 38

myasthenia gravis

Question 39

treatment of myasthenia gravis includes anticholinesterases and immunosuppressive drugs. More ACh is available which causes

Answer 39

resistance to nondepolarizers and sensitivity to SCh

Question 40

what muscles are first to show fatigue, weakness in undiagnosed myasthenia gravis

Answer 40

ocular, pharyngeal, and laryngeal muscles

Question 41

with these patients it is very important to get a baseline TOF and reduce the dose by 1/2 or 1/3

Answer 41

myasthenia gravis because they may become weak with even 1/10 of the normal intubating dose!! prob shouldn't use nmb

Question 42

seen with oat cell carcinoma of the lung; autoimmune disease where presynaptic calcium channels are destroyed by antibodies

Answer 42

myasthenic syndrome - eaton lambert

Question 43

sensitive to both nondepolarizing and SCh

Answer 43

myasthenic syndrome - eaton lambert

Question 44

normal or possible prolonged effect of nondepolarizing nmb when muscle weakness, atrophy, exists

Answer 44

muscular dystrophy

Question 45

SCh causes prolonged contraction but nondepolarizing blockades have a normal response

Answer 45

myotonia dysrophica

Question 46

a degenerative disease of motor ganglia in the anterior horn of the spinal cord and spinal pyramidal tracts that causes skeletal muscle atrophy and weakness

Answer 46

amyotrophic lateral sclerosis

Question 47

what does als cause

Answer 47

prolonged response to nondepolarizing nmb (sensitivity) and hyperkalemia with SCh

Question 48

have a different volume of distribution which makes the dose less concentrated "water babies"

Answer 48

pediatric population

Question 49

vecuronium onset is quicker in infants and children due to ____ times

Answer 49

faster circulation

Question 50

infants and neonates have prolonged recovery to vecuronium because .. while children have a faster recovery

Answer 50

liver function isnt as good

Question 51

neonates require __ lower dose by weight due to increased sensitivity when given atracurium

Answer 51

25%

Question 52

special considerations for the elderly, dried up little old people

Answer 52

- decreased total body fluid, fat, lean muscle - decreased plasma protein, CO, kidney/liver function - priming technique causes rapid desat - basically more free drugs floating around

Question 53

even though this nmb is age and organ independent, the histamine release was found to be greater because of increased exposure to things

Answer 53

atracurium

Question 54

these two nmb cause no significant difference in duration or sensitivity to the elderly

Answer 54

pipecurium and mivacurium

Question 55

no difference in onset time but prolonged recovery with this nmb in the elderly mainly due to decreased liver/kidney function

Answer 55

rocuronium

Question 56

with this nmb, recovery times are prolonged in obese pop so dose based on ideal body weight

Answer 56

vecuronium

Question 57

there is no significant difference with this nmb in the obese pop

Answer 57

atracurium

Question 58

dose this nmb based on ideal body weight in the obese pop

Answer 58

roc

Question 59

due to plasma cholinesterase, dose with drug based on total body weight in the obese pop

Answer 59

SCh

Question 60

what measurement matters in ideal body weight?

Answer 60

height

Question 61

if this is given prior to admin of recuronium, you will see a decreased onset time (works faster)

Answer 61

ephedrine because it increases HR and CO so gets to site faster

Question 62

if this is given prior to admin of rocuronium, the onset time was increased by 26%

Answer 62

esmolol because of decreased CO, EF so took longer to travel to sites