2/27 - GA Flashcards
IV sedation definiti
administration of a drug which results in the depression of the CNS
the goal is to produce a state of sedation in which the patient
maintains protective reflexes, and the respiratory and caridovscular systems are minmially affected
rapid onset of IV?
yes - the arm to brain circulation is approx 20-25 seconds
advantages of IV sedation
- rapid onset
- titration
- the drug dosage may be tailored
- suitable level of sedation
- shorter recovery periods - continous IV infusion
- patent vein is maintained throughout procedure - side effects of nausea and vomiting
- rare when administrated as suggested (titrated) - salivation
- control of salivary secretions is possible through the administration of antcholinergics - gag reflex
- is diminished - diminish motor disturbances- diminish seizure activity
titration
titration
- the drug dosage may be tailored
- suitable level of sedation
- shorter recovery periods
advantage of IV sedation
titration
titration
- the drug dosage may be tailored
- suitable level of sedation
- shorter recovery periods
advantage of IV sedation
disadvanta ges of IV
venipuncture is necessary
complications may arise at the site of venipuncture
monitoring **– must be more intensive than that rewuired in most other conscious sedation techniques
revoery not complete – Escort is needed
most IV agents CAN NOT BE reversed – have to be metabolized first
indications for IV sedation
- anxiety and fear
- mentally or physically disabled
- age - infants and children
- amnesia
- med compromised patients
- angina
- HBP
- previous myocardial infarcatin
- previous cerebrovascular accident
- epilepsy - control of secretions
- analgesia
- diminished gagging
contraindications so IV sedation
lack of proper training
pregnancy - relative contra
- hepatic disease due to liver metabolism
- thyroid dysfunction
hyper - thyroid strom could develop
low thyroid - may not metabolize as well
- adrenal insufficiency - crisis
- adrenal insufficiency
patients receiing MAOI’s or TCA’s
- go into seratonin syndrome
extremley obese
inadequte veins
allergy to medications
preganncy in IV sedaion
relative contraindication – bcause most CNS depressants cross the placenta – into the fetus and may produce birth defects in the developing fetus
briefly exaplin anesthesia as a continuum
can eassily move from a deep sedation to GA
ultra-light GA
outpatient general anesthesia using IV barbiturates
advantages of general anesthes eia
cooperation not essential
patient is unconscious
patient does not respond to pain
amnesia is present (they dont remember)
GA may be the only technique that will prove successful for certain patients
rapid onset
tritration is possible
success rate is 100%
disadvantages of GA
patinet unconscious
protective reflexes are depressed
vital signs are depressed
advanced training
anesthesia team is required
special equipment
recovery area must be available
intra-operative and postanestetic complications are more common
patient receiving GA must receive nothing by mouth for 6 hours beore the procedure
patients receiving GA must be evaluated more extensively preoperatively than patients receiving minimal or moderate sedation
contraindications to GA
lack of trining
lack of adequatley trained personnel
lack of adequate equipment or facilitities
ASA IV and certain ASA III medically compromised patients
Hx of poliomyelitit in which chest muscles have been involved
Hx of Myasthenia gravis
obese
patients with significantly decreased cardiac and / or pulmonary reserve
patients with a history of malignant hyperthermia
ASA types contraindicated in GA
ASA IV and some ASA III
indications for GA
extreme anxiety o fear
mentally or physiclly disabled
age - infants and children
short or long traumatic procedures
benefits of outpatient GA v s inpatient
economics - cost is cheeper outpatient
psychological benefits
reduced exposure to nonsocomial infections
parental preference
inpatient is in hospital
types of GA
in - office outpateitn GA
- IV anesthesia - less than 30 minutes
conventional operating theater type of GA more than 30 mins - less than 4 hours
inpatient type
outpatient GA IV using?
propofol or barbiturates
N2O2-O2 (along with the case)
benzodiazepine / versad
opiods - like fentynol
LA* - block of the responses
- like what you see in the oral surgery clinic
outpatient GA -conventional type of operating room GA
used in cases 30 mins to 4 hours
patient undergoes same GA prep as the inpatient
limited to ASA I and II – selected III
completed training in anesthesiology
inpatient GA
patient admitted to hospital prior to procedure
undergoes workup to determine risk , undergoes procedure and then remains in hospital post-op
ANesthesiologist is responsible for the administration for the anesthetic* (vs outpatient - you have to be certified)
armamentarium
anesthesia machine IV equip ancillary anesthesia equipment monitoring equip emergency equipment and drugs
ancillary anesthesia equipment
face masks and appropriate connectors
laryngoscopes, blades
monitoring equipment
stethoscopes
- precordial
- pretracheal
- esophageal
pulse oximeter end-tidal CO2 blood pressure cuff ECG temperature
TIVA
total inervenous anesthesia
- a continous IV infusion is commonly used for all general anesthetic procedures
- indwelling catheters are preferred
- tubing and bags of IV solution are requred
- disposable syringes and needles should be available
- adhesive tape
endotracheal tubes and connectors
part of armamentarium
LMA
laryngeal mask airways
- acts like an endotracheal tube
does not get fully patent airway
- used in the field more
Bispecteral electroencephalographic monitoring
BIS monitoring
-
intra arterial blood pressure
degree of accuracy is great but not really needed during outpaient sedation
indicaed in both general anesthetic proccedures involving greater degree of risk
- neuro or cardiac surgery
and when degree of risk presented by the patient (ASA IV or V) is significant
types of benzodiazepines used
diazepam - valium
midazolam - versed
mechanism of benzo’
becoming less excitebale
binds to stereospecific benzo recepetors on the postsynaptic GABA neuron at several sites within the central nervous system, including the limbic system, reticular formation
increase inhibitory effect of GABA by increased neuronal excitablility - INCREASE PERM TO CHLORIDE IONS
- hyperpolarization – less excitable state
contraindications to benzo
allergy to diazepam
acute narrow glaucoma and wide angle glacuoma
contraindications to benzo of valium (diazepam)
allergy to diazepam
acute narrow glaucoma and wide angle glacuoma
psychosis
pregnancy
versed aka
midazolam - benzo
used more versed vs valium
versed – need to know the comparisons of these
versed is more potent
barbiturates?
their indication
not used as much today but served a lot in terms of sedative drugs
can produce any level of sedation ranging from light sedation through hypnosis - GA , coma and death
indication – induction and maintenance of GA anesthesia for short procedure
pentobarbital
barbitruate
classified as short acting barbiturate
IV sedation
seizure control
effects and side effects
- reduces cerebral metabolism
- modest decrease in blood pressure
- temporary respiratory depression
- hangover effect
reversal agent to benzo
flumazenil
flumazenil
reversal agent to benzo
contraindicated in
- allergy to benzo or flumazenil
- if being treated for stuff on benzo’s like status epilepticus, or control of intracranial pressure
opioid antagonist
naloxone
most commonly used inhalation
nitrous
nitrous oxide not used for GA?
what is its use
not strong enough – not potent enough
MAC is not high enough to get to general - it is 104-105%
second gas effec**
primary function of nitrous oxide in GA?
SECOND GAS EFFECTS
in GA it is used to potentiate the actions of the other more potent drugs (IV or inalation) and thus permits a smaller dose or lesser concentration of this drug needed to produce the desired level of GA
neuroleptanesthesia
produced how?
type of GA that is produced by the administration of
neuroleptic drug
- and an opioid are administered together characterized by
- sleepiness, psychological indifference to environment, no voluntary movements, analgesia, satisfactory amnesia
produced by administering?
***(droperidol) = neuroleptic drug (does have black box warning)
- opiod - fentanyl
- nitrous oxide -oxygen
- muscle relaxant
dissociative anesthesia
type of GA
- dissociative anesthesia and analgesia as produced by KETAMINE
patient appears to be awake
maintain many reflexes
unaware of,or dissociate from the environment
eyes open - may see nystagmus
disadvantages of ketamine / contraindications
used in dissociation anesthesia (type of General)
increased heart rate, blood pressure and intraoclular pressure
eye movements and nystagmus can occur
no antagonist is available for it
can produce a confused state, associated with unpleasant dreams and frightening hallucinatins
(more common to occur with adults ) – so use with a benzzo
contraindications to ketamine
intraocular surgery, patietns with history of increased CSF pressure, CVA, psychiatric problems , and HTN
four mechanisms of muscle relaxants
muscular blocking agents
- interfere with the transmission of impulses from motor nerves to muscles at the skeletal neuromuscular junction
- deficiency block
- nondepolarizing block
- depolarizing block
- dual block
no drug ever exerts a single action?
true
william harvey
provided much of the groundwork for the future of IV medication - stating that there was a continuous circulation of blood within a closed system
showed that because of valves in heart and veins - blood flow within circulatory system was unidirectional
jorgensen
first to use IV route for premedication
combo of barbiturate (phentobarbital and opioid (meperidine) and scopolamine
mcantosh blade is ?
miller blade is?
mcantosh is curved
miller is straight
miller straight blade into the oral cavity?
underneath the epiglottis
mcantosh blade into the oral cavity?
curved so want it – go into velecula
NOT under the epiglottis
do NOT rotate on it – b/c if you do then you can hit the maxillary teeth
oropharyngeal and nasopharyngeal airways?
if using oropharyngeal airway – patient has to be out - if semi-conscious they can choke on it
nasopharyngeal airway - semi-conscious
measure from corner of mouth to angle of the mandible
pretracheal stethescope
around the trachea - and can pick up on breath sounds
- gurgling
obstruction early
different wave form
esophageal stethescope
for patient already intubiated and able to hear heart sounds better as well
can add a thermometer and get a core temperature reading
why temp
making sure patients – especially younger populations are not going through malignant hypothermia
Not commonly used monitors
EEG
arterial blood pressure
Central venous pressure (CVP) - invasive and goes into the atrium
collection and measurments of urine output
EEG
gets a number
shows the person is sedation
electroencephalogram
identifying hypnotic effects of anesthersia
BIS (bispectral) index - continuous EEG parameter that ranges from awake - no drug to effect value of 95-100
intra arterial blood pressure
CONTINOUS blood pressure
artery
radial artery
more in the obese patient
degree in accuracy is great but not really needed during outpatient
indicated in GA involving greater risk - neuro or cardiac surgery or when patient is ASA III
NOT needed during outpatient setting -
opiod agonist / antagonisht?
pentazocine
nalbuphine
anticholinergics
atropine
scopolamine
antidotal drugs
flumazenil - reverses benzo’s
indications for valium
oral med for preopertative dental anxiety
sedative component in IV sedation in oral surgery
skeletal muscle relaxant
medical - management of anxiety disorders, alcohol withdrawl symptoms, skelteal muscle relaxant and convulsive disorders
eyelid halfway over pupil?
veral sign
know in good state of relax
indications for versed
Miazolam ( m =more - using it more)
dental - sedation component in IV sedation in OS patients
syrup formulation used in children to help alleviate anxiety before dental procedure
medical - preoperative sedation and provides IV ssedation prior to diagnostic or radiographic proceddures
amnesia produced in midazolam and diazepam
anterograde
better in midazolam / versed – “need to foreget - versed”
biotransformation of midazolam and diazepam
midazolam = 1.7- 2.4 hours
vs diazepam = 31/3 hr
which benzo has pain on injection and why?
diazepam and b/c of its medium - of propylene glycol
* so put into bigger vein so it does not irritate it as much
*none in midazolam because versed / midazolam is WATER BASED
what benzo to use when the patient needs to forget?
VERSED – midazolam
respiratory system effect of diazepam vs midazolam
diazepam causes more depression
analgesic with the benzo?
NO
sedation effect with midazolam and diazepam
higher levels of sedation with diazepam / valium
than midazolam / versed
biggest reason why people started using midazolam over diazepam
because of the differences in the half lives of them
active metabolite half life of midazolam is less than that of diazepam
*but versed is more potent
contraindications for barbs
allergy uncontrolled pain addiction to sedative hypnotics porphyria respiratory diseasae with dyspnea or obstruction
reversal agent to barbiturates?
no
pharmacology of barbs
no effect on pain threshold except in doses that affect level of consciousness
anticonvulsant properties
eliminated by biotransformation in the liver and excretion through the kidneys
indications for opiod agonists
supplementatino of GA
Pain releif
premedication
conraindications for opioid agonists
allergy
COPD and decrease respiratory reserve
patietns receiving MAO inhibitors within the previous 14 days
increased inracranial presure
side effects of opiod agonist
resp deprssion nausea / vomitt hypotension drowsniness histamine release
fentanyl aka? what type? indications
sublimaze - opiod agonist
dental - adjunct in preoperative IV sedation in patients going surgery
medical - sedation - releief of pain, preop med, adjunct to general or regional anesthesia, management of chronic pain
side effects of fentanyl / submlimaze
rapid IV infusion may result in skeletal muscle and chest wall rigidity , impaired ventilation, respiratory distress, apnea, bronchoconstriction, laryngospasm
INJECT SLOWLY over 3-5 minutes, non-depolarizing skeletal muscle relaxant may be required
dosage of flumazenil
benzo antagonist
.2mg IV repeat 1 minute interval
average reversal dose is .2mg
max dose is 1.0 mg
given IV
do NOT give patients being treated for status epilepticus, or control of intracranial pressure (can increase it)
naloxone hydrochloride
opiod antagonist
- contraindications
opiod dependence and allergy
dose is .1 to .2 mg IV over 2-3 minutes
average reversal dose is .4 mg
max dose is 1.2 mg for adult
types of GA
- inhalation anesthetics
- most frequently used means of producing general anesthesia - neuroleptanesthesia
- dissociative anesthesia
halothane
inhalation
MAC of .75% - pretty potent
- rarely used
disadvantages
- myocardial depression, produces cardiac dsyrhthmias, sensitization of myocardium to actions of catecholamines , potent urine relaxant, possible hepatic necrosis
have to be aware if using this with vasoconstrictors
enflurane
MAC of 158%
compatible with epinephrine
good for asthmatics
pleasant odor, rapid inductin, nonirritating, BRONCHODILATOR, good muscle relaxatnt, no dysrrthmias, non an emetic, nonexplosive and non flammable
isoflurane
MAC 1.28%
pleasnat odor, rapid inductino, nonirritating , bronchodilatort, muscle relaxant, stable cardaic rhythm, compatible with epi,
disadvantages
- myocardial depression, depressed BP, postanesthetic shivering, not given to decreased renal renal function
sevoflurane * noted for?
MAC 1.71%
used fo outpatient more
LOW SOLUBILITY , rapid induction and emergence from anesthesia,
less irritating to the airway
*commonly used inhalation anesthetic in ambulatory dental anesthesia cases
desflurane
irritating - unpleasant odor - so NOT RECOMMENDED for induction because of this
MAC 4.6-6.0%
rapid onset and recovery
- recovery seems to be advantage
patent airway can be maintained with ketamine? advantages?
yes
non irritating to bloos vessels and tissues, muscle tone is preserves and laryngeal and pharyngeal reflexes are not depressed
can use in children
used in patietns who are hemodyanmically unstable or hypovolemic - b/c it can increase blood pressure
can be used with asthmatic patients
increase salivation?
ketamine
dysphoric emergence with?
ketamine – so use a benzo with it
greater chance happening if older
antagonist to ketamine
no
indications for propofol
induction of anesthesia
maintenaince of anesthesia
postop antiemetic
mechanism of action
- hindered phenolic compound
- UNRELATED to any other barbs, opioid, benzo o
careful in older adults - but only major disadv is pain on injection
deficiency block
muscle relaxent
- synthesis and/ or transmission of acetycholine is interfered with
- neomycin, kenamycin, clostridiu botulinum
non- depolarizing block
muscle relaxant
- COMPETITVE BLOCK
- drug attaches to cholinergic receptors , preventing acetycholine from attaching to the receptor (curare, pancuronium
depolarizing block
muscle relaxant
- dru acts in a manner similar to acetycholine but for prolong period of time (succinycholine)
dual block
muscle relaxant
DESENSITIZATION BLOCK
- the membrane is depolarized (phase 1) and then is slowly repolarized
drug enters into the fiber and acts as a nondepolarizing agent (phase II)
pre-oxidate
then
relaxe - versed
then fentynol
breathing then propofol (put to sleep)
then muscle relaxant
laryngoscope ready
purposes of record keeping
- trend plot of vital
- as an aid to the clinicians memory
- as a documentation of a patients response to the administration of drugs and the operative procedure
- nonclinically - as a legal document
eating and drinking before surgery
nothing after midnight
if infant - no solid food or milk 6 hours before - clear liquids up to 4 hours before
