general and local anesthetics Flashcards
inhaled anesthetics
desflurane enfluane halothane isoflurane sevofulane nitrous oxide (gaseous)
IV anesthetics
propofol fospropfol barbituates benzodiazepines etomidate ketamine dexmedetomidine
barbituates
thiopental
methohexital
benzodiazepeins
midazolam
lorazepam
diazepam
local anesthetics
end in ‘caine’
esters
only have one i
amides
have 2 ‘i’s
desired effects of general anesthesia
-unconciousness
-amnesia
-analgesia
-inhibition of autonomic reflexes
-skeletal mm relaxation
to achieve all 5 must mix meds
balanced anesthesia
IV and inhaled combo
monitored anesthesia care
profound analgesia w/retention of pt ability to maintain a patent airway and respond to commands
volatile anestetics
must be administered with vaporizer
driving force for uptake of inhales anesthetics
alveolar concentration which is controlled with inspired concentration (partial pressure) and/or alveolar ventilation
the quicker the FA/FI approaches 1 the faster drug onset of action
blood:gas partition coefficient
defines relative affinity for blood compared to inspired gas
inverse relationship btwn blood:gas partition coefficient and rate of anesthesia onset
cardiac output
greater the CO slower onset of action
alveolar-venous partial pressure differences
anesthetic partial pressure differences btwn alveolar and mixed venous blood is dependent on tissue up-take
elimination of inhaled anesthetics
primarily by lungs
same as uptake principles, but in reverse
controlled with 2 parameters:
-concentration in inspired air
- alveolar ventilation
concentration cannot be below 0, but can induce hyperventillation
MAC
1 MAC is percent of anesthetic needed to sedate 50% of people
additive
stage I of CNS depression
Analgesia
initially experiences analgesia w/p amnesia, later both produces
stage II of CNS depression
excitement
delirious, may vocalize, but completely amnesiac
respiration, HR, and BP increase
stage III CNS depression
surgical anesthesia
begin w/slowing respiratory rate, HR
extends to complete cessation of spontaneous respiration (apnea)
changes in occular mvmts, eye reflexes, and pupil size
stage IV CNS depression
medullary depression
vasomotor centrer in medulla dn respiratory center
w/o respiratory and circulatory support death would ensue rapidly
reliable test to indicate stage III
loss of responsiveness to pain
trap squeeze
CV effects of inhaled anesthetics
depress normal cardiac contractility decrease MAP (dosage dependent) decrease in arterial BP -> activation of autonomic nervous system -> increased HR
respiratory effects of inhaled anesthetics
respiratory depressants -> rapid shallow breathing
ventilation usually required
w/prolonged exposure mucus pooling and plugging -> atelectasis -> post op complications
toxicity of inhaled anesthetics
nausea and vomiting
halothane- hepatitis on multiple exposures
renal toxicity
malignant hyperthermia
propofol MOA
potentiation of Cl curent via GABAaR
propofol allergic rxns
has soybean oil
glycerol
lecithin
egg yolk phosphatide
advantages of propofol
fast onset
fast clearance
recovery more complete (less hangover effect)
context-sensitive half time small
context-sensitive half time
time to elimination after discontinuation of drug
dependent on duration of use
propofol CNS effects
general suppression
no analgesic properties
decreases cerebral blood flow -> decreased ICP and IOP
burst suppression in EEG which is neuroprotective in neurosurgical procedures
propofol CV effects
most pronounced decrease in systemic BP d/t profound vasodilation in aa and vv
hypotensive effects potentiated by impaired baroreflex response
propofol respiratory effects
potent respiratory depressant -> apnea
greater reduction in upper airway good for instrumentation of airway
propofol uses
anesthesia induction continuous infusion maintence of anesthesia sedation in ICU conscious sedation short duration general
fospropofol MOA
similar to propofol
fospropofol PK
onset and recovery are prolonged compared to propofol
fospropofol uses
sedation during monitored anesthesia care
fospropofol ADRs
less pain on administration then propofol
paresthesia in perianal region
barbituates MOA
act on GABAaR to increase action
also inhibits excitatory transmission
barbituates PK
methohexital faster and more complete recovery than thiopental
CNS effects of barbituates
dose-dependent CNS depression
no analgesia
anti-convulsant, with the exception of methohexital which can induce seizures
benzodiazepines MOA
GABAaR to increase its activity
can be countered with antagonists Flumazenil
benzodiazepines PK
midazolam shortest context-sensitive half time and the only one that can be used for continuous infusion
benzodiazepines CNS effects
potent anticonvulsants for status epilepticus, alcohol withdrawal, local-anesthetic induced seizures
benzodiazepines respiratory effects
severe respiratory depression when administered w/opioids
benzodiazepines uses
produces anxiolysis and anterograde amnesia
extremely useful as premedication
IV sedation and suppression of seizures
etomidate MOA
GABA like effects via GABAaR Cl current
etomidate PK
minimal effects on hemodynamics and short context-sensitive half-time
larger doses or repeated buluses safe
etomidate CNS
potent cerebral vasoconstrictor decreased blood flow and ICP
etomidate CV
minimal hemodynamic effects
etomidate endocrine
adrenocortical suppression -> dose dependent inhibition of 11beta-hyroxylase -> decreased cortisol
etomidate uses
alternative to propofol or barbiturates for rapid IV induction of anesthesia especially in those with compromised cardiac fnx
does NOT provide analgesia and post-op nausea and vomiting more common
ketamine MOA
complex
inhibition of NMDA R
ketamine CNS
cerebral vasodilator and increases ICP
emergence rxns
dissociative anesthesia (eyes open w/slow nystagmic gaze)
emergence rxns
vivid colorful dreams
tactile and auditory sensitivity
associated with fear/confusion
can also cause euphoric state
ketamine CV
can increase BP, HR, CO, via sympathetic stimulation
ketamine uses
profound analgesia
sympathetic stimulation
bronchodilation
minimal respiratory depression
ketamine other
lacrimation and salvation can occur and premedication with anticholinergic may be indicated
dexmedetomidine MOA
highly selective alpha adrenergic agonist may be antagonized by alpha 2 antagonists
dexmedetomidine PK
metabolites excreted in urine and bile
significant increase in context-sensitive half time with duration of use
dexmedetomidine CNS
hypnosus from stimulation of alpha2 Rs in locus caeruleus and analgesia at level of spinal cord
sedative effect resembles physioplogic sleep state
dexmedetomidine CV
moderate decrease in HR and systemic vascular resistance -> increased BP
bradycardia may require Tx
dexmedetomidine uses
short term sedation of intubated and ventilated pts in ICU, operating room anesthesia adjunct, awakening and transition to post-op
local anesthetics
most consist of lipophilic grp connected by ester or amide to ionizable grp
esters- shorter duration of action
local anesthetics metabolism and excretion
excreted in urine
toxicity more likely in those with hepatic disease
local anesthetics MOA
block voltage gated NaCh
fiber diameter
smaller the diameter the faster complete block will occur
myelin
myelinated nn block quicker
firing frequency
higher firing frequency blocks faster
order of block
temp> pain>light touch >motor
benxocaine
pronounced lipophilicyt and poor water solubilty
derm, hemorrhoids, anesthetic lubricant
bupivacaine
agent with long duration of action
sensory > motor
peripheral anesthesia, analgesia post-op, anesthetic infiltration
cocaine
blockade of nn impulses and local vasoconstriction
topical anesthetic of upper respiratory tract for intense vasoconstriction
lidocaine
prototypical amide local anesthetic
faster, more intense, longer lasting, more extensive anesthesia
IV, opthalmic gel, topical, patch
