Exam1Lec6GeneralandLocalAnesthetics Flashcards
What are the inhaled volatile liquid general anesthetics?
Halothane
Isoflurane
Desflurane
Enflurane
Sevoflurane
HIDES and -ane
What are the inhaled gas general anesthetics?
Nitrous Oxide
Do you pass gas? NO
What are the IV general anesthetics?
Thiopental
Midazolam
Propofol
Morphine
“Too Many People Miss” IV
What are the local anesthetics?
Cocaine
Procaine
Tetracaine
Lidocaine
Bupivacaine
local anaesthetic=caine
NO PAIN WITH CAINE
2 I’S=AMIDE
What is general anesthesia?
Drug induced absence of all sensations. Surgical general anesthesia is a state of unconsciousness, analgesia, amnesia and loss of reflexes.
ALL SENSASTIONS:
unconscuousness (asleep)
analgesia (no pain)
amnesia (no memory)
loss of reflexes ( dont move)
How are general anasthesia mainly administered?
Inhalation and IV routes
What does balanced anesthesia mean?
Anesthesia produces by a mixture of drugs that often include both inhaled and IV anesthetics
General anesthetics are among the most dangerous drugs approved for general use. Why?
Their therapeutic indices range from about 2-4
Which inert gas has the most ideal anasthetic?
Xenon
For volatile liquid anesthetics, why is it not explosive?
Hydrogen ions have been replaced with halogens
The kinetics of uptake and distribution of anesthetic gases are characterized by two new features, what are they?
The rate of entry is controlled by respiration, a cyclic process.
They are almost entirely eliminated by lungs ( with exception of methoxyflurane and halothane)
What does the minimum alveolar concentration (MAC) of an anesthetic is defined as what?
The concentration that results in immobility in 50% of patients when exposed to a noxious stimulus (surgical incision)
The larger the MAC the ____ concentration of drug
needed to have an effect.
more (NO with MAC conc >100%)
The smaller the MAC the ____ concentration needed to have an effect
less (methoxyflurane with MAC conc 0.16%)
at this dose, is ko 50% of ppt
the lower the dose, the better
What is the most important factor influencing the transfer of inhaled anesthetic from the lungs to the arterial blood?
Solubility
What is the index of solubulity?
Blood: gas coefficient. It defines the relative affinity of an anesthetic for blood in comparison to air.
the lower the coefficient the better
What is the relationship of solubility with the rate of rise of its tension of the blood and brain?
The lower the solubility of a given anesthetic, the faster the rate of its tension in blood and then in the brain
The solubility in blood (blood: gas partition coefficient) for nitrous oxide and desflurane is low or high?
Low (less than 0.5)
The solubility in blood (blood:gas partition coefficient) for methoxyflurance (or diethyl ether) is low or high?
High (12)
What is the relationship between the anesthetic concentration and rate of induction.
Incr the inspired anesthetic concentration , incr the rate of induction.
If you incr pulmonary ventilation, how does that affect rate of uptake?
Incr pulmonary ventilation, speeds up the uptake
What does Meyer-Overton hypothesis explain?
There is a direct correlation between lipid solubulity and potency
Does potency and rate of uptake mean the same thing?
NO. Potency means how much drug you need to produce an effect and Rate of uptake talks about pressure equilibrium
Which receptor is the prime target for general anesthetics?
GABAa receptors (ion channels)
Which drugs binds with high affinitty for Gaba a receptor?
Barbiturates (thiopental), benzodiazepines, propofol, enflurane
These anesthetics incr the affinity of the GABAa receptor for GABA so we see in incr in GABAa channel activity
What are 3 responses to anesthesia that we see in patients?
If the eyelid blink (reflex is abolished) when the eyelashes are stroked
If the patient swalling refelxes disaspeprs
If the repsiration become irregular in rate and depth
as anesthesia deepens, all the abive responses are reduced
With an incr in depth of general anesthesia, what happens to your breath?
There is a progressive reduction in respiratory tidal volume. ( your breathing becomes shallow)
What tends to vary directly with the depth of anesthesis ( this gives us an index of dosage)?
Arterial blood pressure
For all halogenated inhalational anesthetics, there is a dose-dependsent reduction in what?
Blood pressure
This is the most practical way to measure depth of anesthesia
All halogenated inhalationla anestheits reduce spontaneous ventilation in a concentration-dependent manner by doing what?
Depressing meduallry centers in the brainstem, reducing minute ventilation
decr medulla therefore red minute ventilation
What is one main adverse effect of using anestheisa?
Malignant hyperthermia which is rare but lethal for genetically susceptible patients. It happens with the combined uses of halothane and succinylcholine. You see a lot of muslce rigifdity because you can’t requester the Ca2+ channel so actin and myosin can’t dissociate from each other.
ca fails to sequester
kind of like contracting, but you cant stop, so you incr body temp
If a patient is experiencing malignant hyperthermia, what must be administered immediately?
Dantrolene
it acts on RYR receptors
What is nitrous oxide?
Colorless gas with no odor/taste and it is administered with other inhalational anesthetics
neverrrr used alone, always as a mixture.
20% of nitrous oxide has what effect?
analgesia
NO analgesic (NO pain)
very low potency
What class drug is Thiopental?
Barbituate
Thiopental
Analgelsic? Hyponitic? amnesic?
Lower or incr BP and why
Lower or Incr Minute ventilation and why
Very powerful hypnotic, poor analgesic (can incr sensitivity to pain if injected in inadequate amonts
Lower BP
decr Minute ventilation
reduces bp, bc is reduces cardiac output
redcues respiarion bc lowers sensitivity to meduallry respiratory center to CO2.
Propofol is an ____ room temperature
oil
you have to make an emulsion of it, more soluble in lipid than in water
Does propofol induce anestheisa faster, slower, or the same as thiopental.
Induces anesthesia the same as thipental BUT is has a significantly shorter half life.
Propofol
amensic? analgesic? hyponitic?
incr or dec bp and why?
incr or decr ventilation?
is it used for day surgery?
hypnotic
decr bp bc. VASODILATION
decr ventilatiom
used for day surgery
it decr ventilation so much gthat is can cause apnea. you also experience pain at the site of injection
Compared to thiopentol (barbituate), does diazepam take longer or slower for its anesthetic effect?
It is slower because its a benzodiazepam
Midazolam is what class of drug?
Benzodiapines
has more rapid onset than diazepam or lorazepam
Benzodiazepines
analgesic? hypnotic? amnesia?
Incr or decr BP?
Incr or decr Respiration
amensia (HALLMARK), very powerful (also causes sedation, reduction in anxiety)
decr BP moderately
decr respiration moderately
used alot in cardiac surgery
What two types of drugs are analgesic?
Nitrous oxide and opiods
What drug can reverse the action of benzodiazepines?
Flumazenil
Are opiods powerful analgesics?
Yes
Two examples of opiods to know
morphine and fetanyl
What is a sever effect with a large dose of opiods?
respiratory depression (impariring ventilatation/respiration)
this is how they kil! They inr chest wall rigidity, hard to expand
What is the antagonsits for opiods?
Naloxone (narcan)
naltrexone is another antagonist.
What do local anesthetics do?
They reversibly block impulse conduction along nerve axons and other excitable membrhaners that use sodium channels as their primary means of action potential generation
blocks voltage gates sodium channels/ neural impulses on any tissue
want to keep it local bc if it gets into systemic circ it can cause severfe toxicity.
Local anesthetics is used to achieve the loss of sesnation without the loss of
consciousness
blocks pain sensation
Explain the chemistry of local anesthetics?
Lipophillic group (aromatic grp) connected by an intermediate chain (ester or amide) to an ionizable group (tertiary amine)
its a weak base
Which local anesthetics are esters? Also mention if they are vasoconstrictors or vasodilators.
Cocaine (vasoconstrictor)
Procaine (vasodilator)
Tetracaine (vasodilator)
Which local anesthetics are amides? Also mention if they are vasoconstrictors or vasodilators.
Lidocaine (vasodiltor)
Bupivacaine (vasodilator)
amide have two I’s
Are local anesthetics weak bases or weak acids?
Weak bases pka ranges from 8-9
What does the non-ionized and ionized form of weak bases do?
Non-ionized form penetrates the cells
Ionized form occupies sodium channels
What is an example of a vasoconstrictor substance that reduce systemic absorption of the local anesthetics from the depot site by decreasing the blood flow.
Epinephrine
know that is is a vasoconstrictor, when it reducdes bf, there is less chance of it getting into systemic circulation to causing toxicity.
Should epinephrine be co-administered when anesthestizing tissues with end arteries
NO
Which have a shorter half-life ester or amide?
Ester
Ester local anesthetics are rapidly transformed to inactive products through hydrolysis by what enzymes?
Plasma cholinesterase and liver esterase
goes through liver and plasma compartment
Local anesthetics have higher affinity for activated, inactivated states, or resting (closed) state of the sodium channel.
They have a higher affinity for the activated and inactivated states than the resting state.
local anesthetics bind selectvly to the intracellular surface of voltage gates sodium channels and block the entry of sodium into the cell
The. binding of local anesthetics to sodium channel is conformational (state) dependent or independent?
Dependent
CNS toxcity
excitation, convusion, respiratory depression, seizures. It is impt to preveent hypoxemia and acidosis
Cardiovascular toxicity
result partly from:
direct effect upon the cardiac and the smooth muscle indirect effect upon the autonomic nerves.
Local anesthetics block cardiac sodium channels, thus depress the cardiac function. With the exception of cocaine, they also depress the strength of cardiac contraction and cause arteriolar dilation.
cocaine does not cause contraction, incr dialtion
