92 terms

Anesthesia

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volume of distribution equation
dose/concentration. only constant if excretion proportional to distribution
amount required to elicit effect
potency (small c50)
how effective a drug is once it occupies a receptor
efficacy (agonist vs partial agonist)
MAC definition
minimum concentration to stop movement upon incision in 50% of population.
Lower MAC = higher potency
blood gas partition coefficient is related to
higher coefficient means a higher blood:alveolar concentration which means a higher solubility

think: more in blood
relationship between solubility, potency, MAC, coefficient, etc
Low coefficient = higher sol
lower MAC = higher potency
Longer onset but less amt needed
solubility inc or dec when temp decreases
Lower temps = higher solubility
Higher temps = lower solubility
Deso has the lowest/highest solubility and therefore slow/fast onset
lowest solubility b/c fastest onset
inhaled gas that is insoluble
NO
anxiety causes fast/slow induction
What about shock
anxiety = high CO = more rapid uptake into blood = SLOW onset

shock = low CO = FAST induction
IV anesthetic that blocks NMDA receptors
Ketamine
iv anesthetic that is an alpha 2 agonist
precedex (dexmedetomidine)
name 2 iv anesthetics that decrease dissociation of GABA and receptor
propofol and barbituates (thiopental)
opioids increase or decrease potency of inhaled/volatile anesthetics
increase (reduce MAC) (think that patient retains more of anesthetic b/c of hypoventilation)
carboxyhemoglobin produces a falsely high or low SpO2
high
at Hemoglobin of 15, cyanosis occurs at SaO2___. At Hb of 9, cyanosis occurs at SaO2 ___
80
66
things that cause a low sp02
blue dyes, blue nail polish, low PERFUSION, low CO, anemia, low perfusion, inc sVR
leads sensitive for detecting ischemic events
lead V, II, IV
more distal sites have lower/higher SBP and pulse pressure
higher
plateau pressure vs inpiratory pressure
Rise in inspiratory P only = airway resistance
Rise in both = dec chest wall compliance (pulmonary edema, tension pneumo, etc.
If you do not have any ETCo2 reading, you expect
esophageal intubation
if ETCO2 does not return to 0-5 mmHg, expect...
exhaustive CO2 absorbent
causes of increased etco2 and paco2 gradient
PE, cardiac arrest, low CO, extubation,
increase in ETCO2 may indicate ROSC
true
gold standard and 3 other methods that measure core temp
pulmonary artery
nasopharyngeal (brain)
oropharyngeal
tympanic membrane
esophageal
at higher altitudes, will you have a lower or higher effect of anesthesia with the same concentration of an inhaled anesthetic
lower because Patm is lower
order of highest FA/FI (alveolar concentration to reach inspired) rate (fastest onset)
N2O > des > sevo > iso > halo
NO MOA
NMDA antagonist
nitrous oxide common use
volatile adjuvant especially if BP is low
highly pungent, may cause coronary steal but is used during neuroanesthesia
isoflurane
can cause fires
has least irritation so used when inhaled is means of induction
sevo
as high vapor pressure and boils at sea level so therefore must be in heated pressurized container
deso
some factors that increase MAC
increased metabolism, highest at 6 months old (age decreases), hyperthermia, central catecholamines, chronic ETOH
factors that dec MAC (inc potency)
pregnancy (ironic b/c you'd think inc metabolism)
age, acute alcohol, low BP, acidosis
T/F a patient's size affects their MAC
FALSE. neither does sex, lenght of induction and arterial BP > 50
most common sensation under anesthesia
hearing voices
what is the bispectral index?
monitors consciousness or brain function to detect anesthesia depth
30-65 - gen anesthesia
65-85 = sedation
IV anesthetic that increases GABA coupling and chloride conductance/repolarization
benzos
iv anesthetic causing least cardiac depression
etomidate
Etomidate AEs
myoclonus
PONV
pain on injection
inhibits adrenocortical axis
only IV anesthetic that INCREASES CBF, ICP, cerebral metabolic O2 requirements
ketamine - do not use in neurosurg
IV anesthetic that is antiemetic and anticonvulsant
propofol
IV anesthetic that precipitates in acidic solutions like LR or Roc
Thiopental
most likely to preserve airway reflexas among IV anesthetics
ketamine
also causes bronchodilations and increased secretions
iv anesthetic with opioid sparing effect (less resp depression)
precedex - short term sedation in icu patients or awake FOB intubation
watch out for liver or renal failure
common opioid used for post op analgesia that has rapid onset and is 8x as potent as morphine
dilaudid - hydromorphone
fastest onset and 100 fold more potent than morphine
fentanyl
sufentanil has slightly slower onset than fentanyl but is...
more potent and has more rapid recovery
fastest time of onset of all opioids
afentanil but has most AEs, resp depression and N/V
opioid metabolized by plasma esterases and does not accumulate with prolonged infusion
remifentanil
peak effects of opioids
hydromorphone is high along with morphine but slightly slower onset than others
what to use for intra-op analgesia
fentanyl - more re-dosing
hydromorphone - lasts long
treats post op shivering
meperidine - renally excreted
if surgery is ambulatory or patient is tolerating PO, consider these post op analgesic drugs
vicodin (acetaminophen-hydrocodone) or percocet (acetaminophen - oxycodone)
MAP equation
(2DPB + SBP) / 3
wide PP
high output, AR, atherosclerotic vessels
hyper/hypotension page 28
p 28
MOA of succinylcholine
depolarizing neuromuscular blocker. mimics ACh and causes desensitization. Not readily metabolized by acetylcholinesterases
succinylcholine AEs
hyperkalemia - arrythmias
fasiculations (use Roc to decrease)
increased pressures
nondepolarizing nmba moa
competitive antagonist at ACh receptor of NMJ. Bind but don't cause ion channel opening
neostigmine moa
NMBA reversal
acetylcholinesterase inhibitor >> more ACh > contraction

administer with glycopyrollate (anticholinergic) to prevent AEs

edrophonium/atropine (immediate)
neo (intermediate)
pyridostigmine (long)
suggamadex
reverses neuromuscular blockade by nondepolarizing nmbas like rocuronium, etc.
Use in pregnancy, when neo fails or when cannot intubate/cannot ventilate
train of four ratio
fatio of 4th twitch height: 1st twitch height
threshold for TOF
must be > 0.9 for good post op recovery
mallampati I - IV
1 - everything including tonsillar pillars
2 - no more pillars
3 - only base of uvula and soft palate
4 - only hard palate (no soft palate/darker area)
cormack lehane laryngoscopy views
1 - most glottis
2 - only posterior glottis
3 - epiglottis but no glottis (no vocal cords)
4 - soft palate only
a preoxygenated patient can be apneic fo rhow many min before desat?
8-10 min
4-2-1 flud rule
4 mg/kg/hr for forst 10 kg
2 for 2nd 10 kg
1 for every kg above 20
hyperventilation = low CO2 = alkalosis = hypokalemia
...
hypocalcemia tx
calcium gluconate/chloride
not calcium bicarb or will precipitate
treat hypoMg
PONV risk factors
female, young, non smoker
volatile anesthetics, post op narcotics/opioids
longer surg
history of it
hypervolemia (gut edema)
tidal volume for extubation
more than 5 ml/kg
stages of anesthesia
stage 1 - amnesia (awake to LOC)
stage 2 - delirium/excitement, sympathetic response,
stage 3 - surgical, no movement
stage 4 - overdose, heart fail
colors for Oxygen, air, n20
green, yellow, blue
anaphylactoid reaction
first exposure. direct activation of mast cells by non Ig-e mechanisms
most common cause of anaphylaxis
muscle relaxants roc > vec > cis > sux
latex
abx
local anesthetic moa
block VG sodium channels
inhibit influx of Na preventing AP from being reached
non ionized or ionized is the form that crosses neuronal membrane for faster onset
non-ionized / base / lipid soluble

ionized binds to Na channel
speed of onset for local anesthetic is related to
pKa (degree of ionization) - needs to be closer to physiological pKa
epinephrine effects on a block
can prolong block but delay systemic uptake
don't use in fingers or areas where no collateral flow
local anesthetics AEs
entrance into blood
CNS toxicity - tinnitus, tingling, seizures; more likely
CV - hypotension, arrythmias (bupivicaine)
tx of local anesthetic toxicity
avoid propofol in cV
give benzo
ACLS
intralipid therapy
malignant hyperthermia physiology
hypermetabolic state
increased Ca levels in muscles
ryanoidine receptor
sequence of events for MH
trigger such as succinylcholine
trismus/rigidity
INC CO2 PRODUCTION (specefic), hypermetabolism
cell damage
temp rise

tx = 02 and dantrolene
caffeine halothane contracture test
testing for MH gold standard muscle bx
clean procedure abx
cefazolin
bowel surgeries
cefoxitin
craniotomy abx
ceftriaxone
bacterial endocarditis ppx
amp gent for prosthetic, hx, transplant
trendelenburg within 1 min
inc CO - levels at 10 minutes
sitting complication
venous air embolism
spinal vs epidural anesthesia
spinal is smaller amt, rapid