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NU 600

Exam 2 - Inhalational Agents

The pharmacodynamics of inhaled anesthetics refers primarily to the interaction with these agents and target sites in the ______________. brain
What is FD? Fraction of delivered anesthetic
How is FD controlled? Vaporizer dial
What is FGF? Fresh gas flow
What does FGF encompass? All the gases that flow from the machine into the breathing circuit
What is FI? Fraction of inspired gas
What is FA? Fraction of alveolar gas
What structure do inhaled gases first enter during respiration? Alveoli
What does "partial pressure" refer to? Partial pressure exerted by the gaseous form of an agent
The concentration of an anesthetic agent is referred to as the _____________. Partial pressure
How is the partial pressure of a gas measured? Millimeters of mercury (mmHg)
What does the Ventilation Effect state? Anesthesia is achieved more rapidly with greater alveolar ventilation
What does the Concentration Effect state? The higher the concentration of anesthetic delivered, the faster the patient achieves anesthesia.
The Concentration Effect is also referred to as ________________. Overpressuring
Define the Blood/Gas solubility coefficient. The ratio of the amount of anesthetic that is soluble in blood and binds to blood components versus the amount of drug that will leave the blood and quickly diffuse into tissues.
What does the Blood/Gas solubility coefficient represent? What does a high and what does a lower number indicate? Represents the speed of onset for an anesthetic. High B-G coefficient=slow onset, Low B-G coefficient=fast onset
What does the Oil-Gas solubility coefficient define? How efficiently an anesthetic can penetrate lipid membranes and affect the site of action.
The Oil-Gas solubility is a measure of a drug's __________. Potency
What does a high Oil/Gas solubility coefficient represent? A low Oil/Gas solubility coefficient? High O-G coefficient=more potent, Low O-G coefficient=less potent
Define Second Gas Effect. A phenomenon that occurs when the anesthetic onset of a slower absorbing gas becomes more rapid due to the simultaneous use of high concentrations of a faster absorbing gas.
Define Diffusion Hypoxia. The transient dilution of oxygen and carbon dioxide in the lungs that occurs when nitrous oxide is discontinued and rapidly leaves the body via the lungs, thereby diluting the existing concentrations of oxygen and carbon dioxide
How is Diffusion Hypoxia prevented? Administration of 100% O2 for 3-5 min. when N2O is discontinued
What is the Cardiac Output Effect? The effect that an increase or decrease in cardiac output can have on the onset of an inhaled anesthetic.
How does an increased CO affect the onset of anesthetic? A decreased CO? An increased CO prolongs onset. A decreased CO shortens onset
What types of medications are susceptible to the Cardiac Output Effect? Anesthetics with a high degree of blood solubility
How do Ventilation-Perfusion abnormalities affect the onset of anesthesia? Delays the onset of anesthesia
The [insoluble/soluble] medications are more affected by Ventilation-Perfusion abnormalities than the [insoluble/soluble]. Insoluble, soluble
Why do children achieve anesthesia more rapidly than adults? Higher ventilatory rate and greater vessel-rich group blood flow
How does obesity affect onset and emergence from anesthesia? Does not affect onset but may delay emergence due to deposition in fatty tissue
What does Pbr represent? Partial pressure of a gas in the brain
What are three variables that affect the uptake of a inhaled anesthetics? Cardiac output, alveolar-to-venous partial pressure difference (concentration gradient), blood:gas solubility
What is the equation for uptake of a inhaled anesthetic? CO x concentration of agent x Blood-Gas solubility
The Blood-Gas coefficient refers to the solubility of a gas in [oil/water]. water
What is the Rate of Rise? The rate at which the alveoli fill with gas and achieve partial pressure
What does the FA/FI ratio represent? Rate of rise
What are three ways to increase the uptake of an inhaled anesthetic? Increase cardiac output, increase agent solubility and blood, increase alveolar to venous partial pressure gradient
What effect does increased uptake have on onset and the rate of rise? Delays onset, slows the rate of rise
What are three methods that can offset increased uptake? Increasing the concentration of delivered anesthetic (aka Over-pressuring), increasing FGF, increasing alveolar ventilation
What is the equation that calculates alveolar ventilation? Besides tidal volume, what can be changed to improve alveolar ventilation? (Tidal volume) - (Anatomic dead space). Can increase respiratory rate to increase alveolar ventilation
N2O is not considered to be a potent agent, but rather it is considered to be a __________________. carrier agent
Concentration Effect generally only occurs with the simultaneous administration of what two gases? N2O and oxygen
Distribution of inhaled anesthetics begins with ________________________. uptake
What is the graphical relationship between uptake and distribution? linear
What is the equation for Distribution? Tissue Group Perfusion x Concentration Gradient x Tissue-Blood Coefficient
What are the 5 "vessel rich organ groups"? Brain, heart, liver, lung, kidneys
Blood-Gas solubility is an indication of both ________________ and ________________. speed of uptake, elimination
What does “Blood” in Blood-Gas solubility reflect? The portion of anesthetic that will be soluble in blood and bind to blood components
What does “Gas” in Blood-Gas solubility reflect? The portion of anesthetic that will leave the blood and diffuse into tissue
Gas particles that are soluble in blood [do/do not] participate in anesthesia. Do not
What gas has the highest Blood-Gas solubility? The lowest? Halothane=highest, nitrous oxide=lowest
What is the Blood-Gas solubility of halothane? 2.40:1
What is the Blood-Gas solubility of isoflurane 1.40:1
What is the Blood-Gas solubility of sevoflurane 0.70:1
What is the Blood-Gas solubility of desflurane? 0.45:1
What is the Blood-Gas solubility of nitrous oxide? 0.42:1
Which coefficient measures anesthetic potency? Oil-Gas Solubility coefficient
What does a high Oil-Gas coefficient mean in relation to potency? A highly potent anesthetic agent
What is the Oil-Gas solubility of halothane? 224
What is the Oil-Gas solubility of isoflurane? 98
What is the Oil-Gas solubility of sevoflurane? 80
What is the Oil-Gas solubility of desflurane? 30
What is the Oil-Gas solubility of nitrous oxide? 1.4
A fast onset of anesthesia occurs with an anesthetic that has a [high/low] Blood-Gas coefficient. low
A potent anesthetic is one that has a [high/low] Oil-Gas coefficient. high
What does the Meyer-Overton Theory predict? Agents with high lipid solubility have greater potency
Besides correlating solubility to potency, what else does the Meyer-Overton Theory state? That anesthetic agents cross the neuronal membrane
General anesthesia occurs with what increase in percent of neuronal membrane volume? 0.4%
What is the primary receptor in the CNS that is believed to modulate anesthetic effects? GABA receptors
GABA receptors works in concert with _____________ receptors. glycine
What are 3 factors of agent potency and which factor has the least influence on potency? Size, hydrogen bond activity, shape (least influential)
How does molecular length affect potency? Anesthetic effect is attenuated if the carbon atom chain length exceeds 5 carbon atoms
All commonly used inhaled anesthetics are either ______________ or ____________. Aliphatic hydrocarbons, ethers
What does the Two-Stage mechanism refer to? That an agent must first transfer to the anesthetic site of action and then it must undergo receptor interaction before crossing into the target tissue
What is the primary clinical measurement of anesthetic potency? Minimum alveolar concentration (MAC)
Which physio-chemical coefficient describes potency? Oil-gas
The Oil-Gas coefficient is [directly/inversely] related to MAC values. inversely
What is necessary for anesthetic effect to occur? lipid solubility
How does age affect the MAC of inhaled anesthetics? What is the exception to this rule? MAC decreases with age. The exception is that infant MAC exceeds that of neonates.
What is the MAC of nitrous oxide? 104
What is the MAC of desflurane? In 60-70% N2O? 6.6, 2.38
What is the MAC of sevoflurane? In 60-70% N2O? 1.8, 0.66
What is the MAC of isoflurane? In 60-70% N20? 1.17, 0.56
What is the MAC of halothane? In 60-70% N20? 0.75, 0.29
What are potent agents able to prevent? Motor response to noxious stimuli
The effects of the inhalation agents occurs most likely in the ___________________. Receptor sites in the spinal cord
What does MAC represent? The effective dose at which 50% of patients do not move in response to surgical (noxious) stimuli
What does the structure activity relationship state? The affinity of a drug for a specific macromolecular component of the cell and its intrinsic activity are intimately related to its chemical structure.
True/False: All drugs within a specific drug classification exhibit a Structure Activity Relationship. False
Give an example of a class of medications that do not exhibit Structure Activity Relationship. Volatile anesthetics
What does the Unitary Theory state? Anesthetics act in an undefined manner and not necessarily at the same site of action
How is the Unitary Theory validated in the use of inhaled anesthetics? The additive effects of inhaled agents support the Unitary Theory
The Unitary Theory is supported by what model of pharmacokinetics? Meyer-Overton
What does the Meyer-Overton model state in regards to concentration? Anesthesia is produced by the volume of anesthetic present and dissolved at a receptor site, not by the specific type of anesthetic
What does the additive effect indicate? The simultaneous use of two agents increases potency over using a single agent
In general, the potency of an inhaled anesthetic is directly related to ____________. solubility
How is potency related to MAC? Inversely related – as potency decreases, MAC increases and vice versa
The Oil-Gas coefficient is [directly/indirectly] related to potency. directly
What is likely to occur when increasing the number of halogens on a volatile anesthetic? Cardiac dysrhythmias
Which has greater arrhythmogenic properties: ether or alkane anesthetics? alkane
What element do ether anesthetics contain that make them less arrhythmogenic than alkane anesthetics? oxygen
Substituting a _____________ for a _____________ in the molecular structure of a volatile anesthetic enhances stability and reduces flammability. halogen, hydrogen
List the anesthetic agents in order from least potent to most potent. Nitrous < Desflurane < Sevoflurane < Isoflurane < Halothane
What led to the development of new inhalation agents? Concerns for hepatotoxicity and arrhythmogenicity
Halogenation involves the addition of one or more elements. What are these elements? Fluorine, chlorine, bromine, iodine
Halogenations influences what 4 properties of anesthetics? Potency, flammability, stability, arrhythmogenicity
How does bromine-for-fluorine substitution affect potency and why? Increases potency due its heavier atomic mass
How much sevoflurane undergoes metabolism? 5-8%
What is the primary means of metabolism of inhaled anesthetics? Oxidation
What other pathway can halothane be metabolized and what does this result in? Can be metabolized by reduction, which yields hepatic injury
Which halogen increases the potency of ethers? fluorine
What effect occurs with excessive substitution with fluorine atoms to a compound? seizure
Which halogen has pro-epileptic qualities? fluorine
Halogenation of alkanes can cause what types of side effects? Arrhythmias
When is halogenation less likely to be pro-arrhythmic? When the halogenation involves ether
Which atom decreases the likelihood of arrhythmias with halogenation of an ether? oxygen
How is flammability and chemical stability affected when halogens replace hydrogens? Flammability is reduced, stability is enhanced
Why does desflurane strongly resist biodegradation? It only contains one halogen
Desflurane is metabolized at _______________ the rate of isoflurane. 1/10th
What is the urinary marker that signifies desflurane metabolism? TFA
Quantities of which halogen determines the level of biodegradation? Fluorine (greater number of fluorine means less degradation)
How does body temperature affect anesthetic requirements? A reduction in temperature decreases anesthetic requirements
Prolonged exposures, and hence metabolism, to desflurane is indicated by what marker? TFA in the urine
What are the steps necessary to take prior to administering anesthesia to a patient with susceptibility for MH? 1)AM flush at 10L/min for 20min with FiO2 of 100% 2)Replace breathing circuits 3)Replace CO2 absorbers 4)Drain, inactivate, or remove vaporizers
What is another name for Blood-Brain solubility coefficient? Blood-Tissue
Rate of Rise is a measure of how fast the _________________ fill up with gas molecules. Alveoli
What equation represents the Rate of Rise? FA/FI
What is the Blood-Gas solubility coefficient for ether? 12
The partial pressure of a gas in the alveoli could be interpreted as _____________. The concentration or total amount of anesthetic gas in the alveoli (gas exerts pressure on the alveoli)
What are the kinetic four kinetic principles that control the input of anesthetics into the alveoli? 1)Inspired concentration 2)alveolar ventilation 3)Characteristics of the anesthesia system 4)Patient FRC
FRC dilutes our efforts to obtain FI/FA equilibrium due to the presence of what element? nitrogen
What dilutes our efforts to fill up the alveoli and increase our rate of rise? FRC
Despite having fast respiratory rates, why are infants and neonates able to achieve fast onset of anesthetic? They have minimal FRC and therefore minimal dilution of anesthetic upon delivery
What are 3 factors that determine the inspired partial pressure gradients necessary to establish anesthesia? 1)Anesthetic input from the machine to the alveoli 2)Anesthetic uptake from the alveoli to arterial blood 3)Anesthetic transfer of the gas from arterial blood to the brain
The amount of anesthetic transferred from the blood to the brain is expressed as _____________. Pbr
What are two machine related factors that affect the uptake of inspired medication? Solubility of the drug in the plastic and rubber of the machine; machine liter flow of the chosen gases
Anesthetic uptake [slows/quickens] throughout the anesthetic procedure. slows
The Concentration Effect consists of what two factors? The concentrating effect and the augmentation of tracheal inflow
What does augmentation of tracheal inflow do? Increases the inflow of inhaled gases to fill the void space produced by the uptake of gases
What does augmented tracheal inflow prevent? Alveolar collapse
What occurs over time during a case utilizing inhaled anesthesia and how will this direct your care? Blood uptake of the agent decreases, the amount delivered should be decreased to prevent “over anesthetizing”
How many time constants does it take for total equilibration of brain to blood of anesthetic gases? 3
What is the time constant of isoflurane? What is the time constant for the remaining anesthetics? 4 minutes. 2 minutes for the remaining gases.
How does the Second-Gas Effect work? Giving high volumes and concentrations of a fast-acting anesthetic (first gas) will accelerate the onset of a slower anesthetic that is delivered concurrently (companion gas)
What is the equation for Alveolar Ventilation? Tidal Volume (gas) – Anatomic Dead Space (gas)
What does Alveolar Ventilation represent? The amount of gas that crosses alveolar membrane and enters the blood
Which equation describes the amount of physiological dead space in a person’s lungs? Bohr
What two things are added to obtain the amount of physiologic dead space? Anatomic dead space + alveolar dead space
The Bohr equation is given as a ratio of ____________ to ____________. Dead space, tidal volume
What is anatomic dead space? The portion of airways which conduct gas to the alveoli and where gas exchange is not possible
Which method of measurement most accurately measures alveolar dead space in a healthy lung? Fowler’s method (aka. Nitrogen washout)
Halothane is a halogenated ________________. alkane
What two side effects of halothane led to the desire for scientists to create new anesthetics? Arrhythmogenicity and hepatotoxicity
Branched chains of inhaled anesthetics exhibit diminished effect with ______________ or more carbon atoms. 5
How does increasing the potent agent during anesthesia affect the airways? causes bronchodilation
How can reversal of anesthetic effect be achieved? Applying measures to restore membrane shape
What does nitrous oxide have the capability of doing in relation to other tissues in the body? Diffuses into air-containing cavities and can expand the cavity if that cavity has the ability to expand
What are examples of the scenarios involving expandable air cavities? Air embolism, pneumothorax, acute intestinal obstruction, intraocular air bubbles, pneumoperitoneum
What are three pieces of medical equipment that could possibly undergo nitrous oxide expansion? PA catheter balloon, LMA, ETT cuff
Sevoflurane degradation to Compound A in CO2 absorbers is decreased by increasing ______________. fresh gas flow
What two types of absorbers decrease the production of Compound A over soda lime? Amsorb, DragerSorb Free
What effect does dehydration of soda lime have on the production of Compound A? Increases Compound A content
Inhaled agents mediate immobility to painful stimuli by acting on what three receptor sites? Tandem-pore-domain Weak Inward-Rectifying K+ channels (TWIK), GABA, and glycine
How are TWIK channels affected by inhaled anesthetics? Enhances background potassium currents
How are GABA receptors affected by inhaled anesthetics? Reduces spontaneous action potential of spinal neurons
What is unique about GABA modulation by inhaled anesthetics? The anesthetic effect of immobility is obtained at the spinal cord and supraspinal levels
What is the definition of “respond” or “response” as it pertains to MAC levels? Response occurs with purposeful movement of the head or extremities during anesthesia
What does MAC Awake refer to? The MAC at which 50% of subjects will respond to the command “open your eyes”.
MAC Awake values are generally ________________ the amount of MAC values. 1/3
MAC Awake concentrations are usually associated with ________________. loss of recall
What are the two variables utilized to obtain the amnestic qualities of a gas? MAC Awake and MAC
How do you obtain the amnestic value of a gas? MAC Awake divided by MAC
MAC-awake/MAC ratio of between _________ and ________ indicate potent anesthetics. 0.3, 0.4
What does the MAC-BAR represent? The MAC necessary to block the adrenergic response to skin incision
cWhat are the adrenergic parameters that are altered with skin incision? HR, MAP, plasma norepinephrine concentration
What are the two most commonly used inhalational agents for induction? Sevoflurane, halothane
Name three anesthetics with potent amnestic qualities. Desflurane, sevoflurane, isoflurane
Name an anesthetic with weak amnestic qualities. Nitrous oxide
How much does the MAC need to be increased to blunt adrenergic response to surgical stress? 10-30% above MAC
What is MAC-Bar? The MAC necessary to block the adrenergic response to skin incision
What requires a greater depth of anesthesia, blocking beta-adrenergic response or blocking skeletal muscle movement? Blocking beta-adrenergic response
List the inhaled anesthetics in order from greatest to lowest Blood-Gas coefficient. Halothane > Isoflurane > Sevoflurane > Nitrous > Desflurane
List the inhaled anesthetics in order from greatest to lowest Oil-Gas coefficient. Halothane > Isoflurane > Sevoflurane > Desflurane > Nitrous
What are the 4 determinants of cerebral blood flow? PaO2, PaCO2, CPP, autoregulation
What is the equation for CPP? MAP-ICP or RAP (whichever is greater)
What homeostatic mechanism allows for a constant rate of CBF between a wide range of perfusion pressures? autoregulation
Autoregulation maintains a constant CBF between what two MAP levels? 60-150mmHg
How does chronic HTN affect the autoregulation curve? Shifts to the right, therefore requiring higher MAP to maintain CBF
With chronic HTN, a case needs to be started within what percentage of baseline BPs? Within 20% to maintain organ perfusion (verbal from T.Kelly)
What is the average CBF? 50ml per 100 gm brain tissue per min
The normal relationship between CMRO2 and CBF is _______________. linear or direct
What is the normal cerebrovascular response to hypocapnia? Hypercapnia? vasoconstrict, vasodilate
When does uncoupling of CBF and CMRO2 occur? When decreases in CMRO2 are accompanied by increases in CBF
What types of anesthetics create the paradoxical response of CBF and CMRO2? volatile anesthetics
How is the magnitude of uncoupling determined? Dose of anesthetic delivered
Volatile anesthetics are potent [vasodilators/vasoconstrictors] in the presence of normocapnea. vasodilators
What cerebrovascular changes occur with the use of inhaled anesthetics? Increase in ICP & CBV, decrease in CMRO2 & CPP
Uncoupling is most evident above 1 MAC for what two medications? Isoflurane and halothane
What action should an anesthetist take if CBF is reduced? Hyperventilate to cause cerebral vasoconstriction
Nitrous oxide [increases/decreases] both CMRO2 and CBF. increases
How can the increase in CBF with NO2 be attenuated? Decreasing ventilation
The goal EtCO2 for neuro cases is approximately _________ mmHg. 25 (Verbal from T.Kelly)
What is the PaCO2 target in patients where a decrease in intracranial volume is warranted? 30-35 mmHg
What are two ways to manage the increase in CBF noted with volatile anesthetics? Hyperventilation and utilization of MAC concentrations of <1.5
How is the level of suppression of EEG activity determined? By the dose of VAA delivered
Electrical quiescence is achieved at [low/high] doses of anesthetic delivery. high
What is burst suppression? The cessation of EEG activity
The use of volatile anesthetic agents can skew the function of what 5 body systems? Motor, auditory, brainstem, visual, and corticol somatosensory evoked potentials
Volatile anesthetics are not induced in what surgical scenario? When neuromonitoring is involved in the case
Give two reasons why volatile anesthetics are not generally utilized during neuro-monitoring? Alter latency and decrease amplitude
Why is sevoflurane avoided in pediatrics? Has epipleptiform activity in pediatrics
Patients emerge from neurosurgery faster with [TIVA/inhaled anesthesia] over [TIVA/inhaled anesthesia]. TIVA, inhaled anesthesia
What neuro benefit do volatile anesthetics have over TIVA in relation to surgery? VAAs may provide protection from modest ischemic injury
Emergence in children is most often associated with what two volatile anesthetics? Sevoflurane, desflurane
Emergence delirium is most often associated with what patient populations? Infants, children, young adults
Besides infants, children, and young adults, what other patient populations are associated with emergence delirium? Older patients
Co-administration with what two medications can reduce the incidence of emergence delirium? Fentanyl, dexmedetomidine
Propofol and midazolam [do/do not] reduce the effect of emergence delirium. do not
How do volatile anesthetics affect the cardiovascular system? Reduces SVR, CO, CI
Which VAA directly causes myocardial depression? Halothane
Which inhaled anesthetic supports MAP by increasing SVR? nitrous oxide (N2O)
How does N2O support MAP? Increasing SVR by increasing the sympathetic nervous system
Which gas has a direct negative inotropic effect? N2O
Nitrous oxide given in combination with ________________ augments cardiac depression. Opioids
What occurs in MH? Calcium is poured out into the vascular system
VAA [reduce/increase] intracellular free calcium. reduce
The reduction of intracellular free calcium from VAAs occurs in what types of cells? heart and vascular smooth muscle
The use of VAAs [reduce/increase] calcium influx into the ______________. reduce, sarcolemma
The use of VAAs depresses the [release/absorption] of calcium from the ___________. release, sarcoplasmic reticulum
Which volatile anesthetic has the highest risk for tachycardia? desflurane
Which two VAA generally increase heart rate? isoflurane, desflurane
Which VAA has minor effects on heart rate? sevoflurane
Which VAA should not be used in patients with myocardial ischemia due to the increase in cardiac demand? Desflurane due to the increase in HR
Which opioid has been shown to modulate the effects of desflurane on the heart rate? Fentanyl
Fentanyl is most effect at attenuating the cardiac effects of desflurane when given [before/after/during] induction. after
Esmolol and lidocaine may be effective at attenuating the cardiac effects of desflurane when given [before/after/during] induction. during
How is blood routed in coronary steal? Perfusion towards ischemic tissue is decreased while blood flow towards nonischemic tissue is increased
Coronary steal is most dramatic in the presence of [hypotension/normotension/hypertension]. Hypotension
Coronary steal is more likely to occur with which two VAAs? Isoflurane and desflurane
What are two benefits of isoflurane? cardio- and neuro- protective
What is anesthetic preconditioning? A cascade of intracellular events by which VAAs attenuate the effects of myocardial injury and reperfusion injury
What occurs in a reperfusion injury? The return of nutrient rich blood to ischemic tissue causes inflammation and oxidative damage
What is IPC and what can it lead to? Ischemic preconditioning, as used with VAAs, and it may lead to long-term cardioprotective effects
Which three inhalational agents are considered the standards for inhalational induction? Sevoflurane, halothane, nitrous oxide
Which VAA is considered to be a respiratory irritant? Desflurane
What are three drawbacks to the use of VAA in regards to the effects on the respiratory system? Blunt’s the body’s natural response to CO2, impairment of the hypoxic ventilatory response, reduces tidal volumes
What is one respiratory of benefit of VAAs and in what scenario are they beneficial? Produces bronchodilation and has been used in refractory status asthmaticus
Why is sevoflurane not recommended for low-flow anesthesia? Has been shown to degrade into Compound A (nephrotoxic) and Compound B in CO2 absorbers
What is the recommended FGF and MAC of sevoflurane in order to prevent accumulation of Compound A? 2L/min of FGF and 2 MAC of sevoflurane
What are 3 conditions that lead to increased production of Compound A in CO2 absorbers? Low flow anesthesia, high concentrations of sevoflurane, dehydrated CO2 absorbers
Name 2 newer CO2 absorbers that do not produce Compound A as is found with soda lime. Amsorb, DragerSorb Free
Which inhaled anesthetic attenuates portal vein blood flow to the greatest degree? Halothane
What do all VAAs have in common in relation to hepatic effect? Decreases hepatic blood flow
Hepatic arterial blood flow is maintained with what three anesthetics? Sevo-, iso-, des- flurane
When does a mild hepatic reaction to halothane occur and how does it manifest? Occurs after one exposure to halothane and manifests with elevated levels of GST and/or transient jaundice
What condition must be present in order for halothane hepatitis to occur? Hepatocyte hypoxia
Mild halothane hepatitis can occur after one exposure in as many as____________% of patients. 50
When does fulminant hepatic failure occur with exposure to halothane and why does it occur? occurs after multiple exposures to halothane due to the inflammatory response of the body to TFA proteins
What are TFA proteins? A TFA protein is a byproduct of trifluoroacetyl chloride binding to liver proteins
What two other VAAs share a similar CYP450 pathway to yield TFA proteins? Isoflurane, desflurane
Which VAA does not appear to degrade into TFA proteins? Sevoflurane
What is the incidence of halothane hepatitis? 1:35,000 cases
What is the incidence of isoflurane induced liver failure? 1:3,500,000 anesthetics
How do all volatile agents affect skeletal muscle and NMBDs? Produce dose-dependent relaxation of skeletal muscle and potentiates all NMBDs
What are two mechanisms by which volatile anesthetics potentiate the effect of NMBDs and cause skeletal muscle relaxation? Decreasing neural activity in the CNS and pre- and post- synaptic effects at the neuromuscular junction
Neural activity in the CNS is [increased/reduced] with the use of volatile anesthetics. reduced
Where does the effect of skeletal muscle relaxation primarily occur when achieved through inhaled anesthesia? Predominantly at the post-junctional membrane
In comparison to TIVA, how much should the dose of a non-depolarizing muscle relaxant be reduced when used in combination with a VAA? 25-50%
True/False: There is a wealth of data that correlates which agents will potentiate specific NMBDs. False
TIVA [does/does not] require higher doses of NMBDs for muscle relaxation in comparison to IV+gas for muscle relaxation. Does
True/False: All inhaled agents are capable of triggering MH. True
What is the treatment protocol for MH? Dantrolene 2.5mg/kg repeat q5min up to 10mg/kg
Lidocaine is a [weak/strong] trigger agent for MH. Weak
Nitrous oxide is considered a [weak/strong] trigger agent of MH. Weak
What equation is used to calculate FRC? FRC=25cc/kg
Time Constant is ____________ divided by ______________. dissolved gas, blood flow
Created by: philip.truong