Inhalational agents - effects on MSK, neuro, hepatic, renal, and metabolism Flashcards
inhaled volatile agents cause a dose dependent _______ ______ _______
relaxation of skeletal muscle
but ______ has no effect on skeletal muscle relaxation
N2O
the higher the MAC multiple, the greater the _____ ____ ______
fade on tetanus
inhaled anesthetics can be used instead of ________ or to enhance the effect of ______
NMB
NMB
this enhanced effect of NMB may be from _____ or _____-______ effects or from effects on the spinal ______ _____
pre or post-synaptic
motor neurons
agents inhibit ______ receptors incompletely at MAC
nicotinic
practical application of inhaled anesthetics (4)
- decreases doses of nondep NMB 25% (50%)
- decreases frequency of redosing
- myasthenia gravis patient - give NO NMB
- patient with hepatic or renal impairment
Roc has a ______ duration depending on the volatile agent interaction:
Des ___ mins
Sevo ___ mins
Iso ___ mins
Prop ___ mins
longer
Des 90 mins
Sevo 59 mins
Iso 35 mins
Prop 35 mins
Roc duration explains the prolonged ______ from ______ when volatile concentration is maintained
recovery from NMB
One study examined the effect of decreasing the concentration of volatile on the twitch height when a vecuronium infusion was maintained. As the % concentration decreased, the twitch height ______, although the vecuronium infusion was ________.
increased
unchanged
Eger demonstrated the “substitution” of ___ ________ for NMB with an abdominal surgery in which muscular relaxation was desired by the surgeon
9% Desflurane
Effects on neuromuscular system: _______ results with ______ agents
different
different
Effects on neuromuscular system: may be explained by ______ of _____
methodology of study
Effects on neuromuscular system: with cisat and roc, _______ caused a prolonged block, and ______ didn’t
sevo
iso
Effects on neuromuscular system: with vecuronium, _____ and _____ both prolonged block
sevo and iso
Effects on neuromuscular system: all volatile agents have an ______ effect with ______
additive effect with succinylcholine
Effects on neuromuscular system: iso causes more rapid shift from ______ to ________ block with succ infusion
phase 1 to phase 2
Effects on neuromuscular system: TIME-dependent enhancement of _________
non-depolarizing NMB (recovery of ToF 1 twitch)
Effects on neuromuscular system: sevo 30 mins delayed recovery from vec ____
89%
Effects on neuromuscular system: sevo 60 mins delayed recovery from vec _____
100%
Effects on neuromuscular system: volatile agents can cause impairment of ______ of ________ NMB
reversal
non-depolarizing
Effects on neuromuscular system: take home message
CAREFULLY administer NMB, use your twitch monitor, and consider using relaxant effect of volatile in lieu of NMB, if possible
Uterine smooth muscle: volatile anesthetics cause dose-dependent ________ of the uterine smooth muscle
relaxation
Uterine smooth muscle: ___ ____ - modest relaxation
0.5 MAC
Uterine smooth muscle: ____ ____ - significant relaxation
greater than 1 MAC
Uterine smooth muscle: positive implication - desirable relaxation for ______ of ______ ______
removal of retained placenta
Uterine smooth muscle: negative implication - contribute to increased _____ ______ with uterine ______
blood loss
uterine atony
Uterine smooth muscle: _____ does not alter uterine contractility in doses used to provide analgesia during vaginal delivery
N2O
Uterine smooth muscle: N2O can be useful to ______ volatile and ______ benzodiazepines/opioids
decrease
avoid
Effect on uterine blood flow: ______ in maternal blood flow
decreases
Effect on uterine blood flow: decreases in uterine blood flow
- maintain ____ _____
- evidence of _____ ______ not present
< 1.5 MAC
fetal distress
Effect on uterine blood flow: ______ with no neonatal distress
amnesia
Effect on uterine blood flow: amnesia with no neonatal distress
- ____ MAC with ____ ____
- consider avoiding _____ in fetal distress
- 0.5 MAC with 50% N2O (total equivalent of 1 MAC)
- consider avoiding N2O in fetal distress
Malignant Hyperthermia: ____ ____ agents can trigger MH (even without ______)
all volatile
succinylcholine
Malignant Hyperthermia: _______ is the most potent trigger
halothane
Malignant Hyperthermia: ______ is a much weaker trigger and is on the MHAUS safe list
N2O
Malignant Hyperthermia: is a pathologic change in _____, ________ state
muscle
hypermetabolic
Malignant Hyperthermia: exposure to triggering agents cause the ______ ______ to release calcium from the ______ _____ to enter the muscle cell
ryanodine receptor
sarcoplasmic reticulum
Malignant Hyperthermia: muscle contraction occurs due to interaction of _____ and _____
actin and myosin
Malignant Hyperthermia: both aerobic and anaerobic muscle metabolism increase producing massive amounts of _____, _____, and ______
heat, CO2, and lactate
Malignant Hyperthermia: muscle membrane permeability allows ______
leakage
Malignant Hyperthermia: time to onset with volatile agent trigger only
- Des ____ minutes
- Iso _____ minutes
- Halo ____ minutes
- Des 260 mins (pt could even be home at this time)
- Iso 140 mins
- Halothane 35 minutes
CNS: CMRO2 requirements decrease at approx. ______ as the patient moves towards unconsciousness
0.4 MAC
CNS: reduction in CMRO2 is _____ ______
dose dependent
CNS: once an ______ _____ is produced, further increases in the agent concentration do not further decrease CMRO2
isoelectric EEG
CNS:
- CMRO2 - ______ ______ 60% + _____ _____ 40%
electrical activity
cellular homeostasis
CNS:
CMRO2 decreases normal response with no volatile anesthesia: brain _____ (____) its blood flow with its ______ ______
matches (couples)
metabolic requirements
CNS:
CMRO2 decreases when ______ _____ decrease, blood vessels _______, and _____ decreases
metabolic demands
constrict (CVR increases)
CBF
CNS:
2 opposing factors with volatile anesthetics
- vasoconstriction from _______ of _____
- vasodilation from _______ _____ _____
- reduction of CMRO2
- anesthetic agent directly
CNS: no uncoupling if ______ of des or iso
less than or equal to 1 MAC
CNS: ________ can occur at higher doses
uncoupling
CNS: N2O causes increased ______ and _____.
CMRO2 and CBF
CNS: However, with N2O there is still _______ due to the greater increase in ______ than ______
uncoupling
CMRO2
CBF
CBF: may ______, remain _______, or _______ - different studies
increase
unchanged
decrease
What affects change in CBF? (5)
- dose of volatile
- other drugs administered (prop, opioids, barbiturates, nitrous)
- rate of change of concentration of volatile
- ventilation (hyper- )
- animal used in study
she alluded that this was a test question
CBF: volatiles cause dose-dependent ______ in CBF
increase
CBF: normocarbia, > 0.6 MAC causes (4 things)
- cerebral vasodilation
- decreased CVR
- increased CBF (potential increased ICP)
- OBTW: decreased CMRO2 (coupling should result in decreased CBF)
cerebral vasodilation: ____ = ____ > ____
iso = des > sevo
increase in CBF occurs _____ _____ of administration of inhaled agent
within minutes
increased CBF is independent of _____ and can be sustained for as long as ___ ____ during an anesthetic
MAP
4 hours
greater decrease in CMRO2 by ______ may explain why CBF is not significantly increased at ____ _____
isoflurane
< 1 MAC
lower metabolism = ____ _____ production, _____ ____dilation
less CO2
less vasodilation
CNS: ______, ______, & _______ maintain the cerebral vascular reactivity to CO2 at less than __ MAC
desflurane, sevoflurane, and isoflurane
< 1 MAC
CNS: Iso, Des, and Sevo at ___ ____ preserve autoregulation of _____
1 MAC
CBF
CNS: Halothane _____ ______
eliminates autoregulation