Inhalants Flashcards

Question

MW - desflurane

Answer 1

Same as enflur, 185g

Answer 2

Halo, sevo, methoxy

Answer 3

N2O, cyclopropane, xenon

Answer 4

= organic compounds o Aliphatic – straight or branch chained hydrocarbons or ethers - 2 organic radicals attached to atom of oxygen with general structure ROR’

Answer 5

Addition of halogens - gas at room temp, R side of periodic table - Fl, Br, Cl Less reactive, more potent, nonflammable Cl, Br convert many compounds of low potency into more potent drugs

Answer 6

atomic # 9, weight 19

Answer 7

atomic #35, weight 80

Answer 8

atomic # 17, weight 35

Answer 9

Atomic # = # of protons Atomic weight = # protons + # neutrons

Answer 10

improves stability, but lowers potency, solubility * Reduced solubility = lower potency, rapid equilibration

Answer 11

halogenated aliphatic ethane o Halothane + catecholamines increased cardiac arrhythmias o Incidence of arrhythmias reduced by ester linkage – chemical structure preserved across all inhalants developed since

Answer 12

decomposition, addition of thymol  Problem: thymol less volatile, accumulated in vaporizers, malfunction  Fl now used in place of Br, Cl - +shelf life, stability, can go without thymol  Fluorine ion: toxic to organs (kidneys) – only problematic if metabolized

Answer 13

amt of matter or mass percent per unit vol d=m/V

Answer 14

Partial pressure exerted by a gas is proportional to its fractional contents

Answer 15

Amt of gas dissolved in a liquid proportional to partial pressure of that gas at equilibrium with that liquid (blood gases)

Answer 16

Partial vapor pressure of each component in an ideal mixture of liquids = vapor pressure of each component x mole fraction in the liquid

Answer 17

1. Ideal gas molecules do not attract, repel each other - only interaction is elastic collision upon impact with each other or an elastic collision within walls of container 2. Ideal gas molecules themselves take up no vol - gas takes up vol since molecules expand into a large space, but ideal gas molecules approximated as point particles that have no vol in and of themselves

Answer 18

At constant temp, vol of fixed amount of gas varies inversely with its pressure PV=K --> P1V1=P2V2

Answer 19

At constant pressure, the vol of fixed gas varies directly with its absolute temperature V/T = K --> V1/T1=V2/T2 TEMP IS IN KELVIN!!!

Answer 20

At constant vol, pressure of fixed amt of gas varies in proportion with absolute temperature P/T = K --> P1/T1 = P2/T2

Answer 21

Individual pressure of each gas in a mixture of gas, absolute value * Partial pressure of agent same in different compartments that in equilibrium with each other

Answer 22

relates number of molecules, quantity of a substance containing same number of particles as there are atoms in 0.012kg of carbon 12, Avogardo’s number 6.0226x1023 per gram molecular weight

Answer 23

number of gas molecules in 1gm of molecular weight = 22.4L

Answer 24

relative value, ratio of weight of unit vol of one substance to similar vol of water for liquids, vol of air for gases/vapors under similar conditions

Answer 25

pressure exerted by vapor molecules when liquid, vapor phases in equilibrium  Some in surface layer gain sufficient velocity to overcome attractive forces btw neighboring molecules, escape from surface  enter gas phase  Vaporization/evaporation: change in state from liquid to gas  Dynamic, in closed container at constant temp will reach equilibrium: # of molecules leaving = # of molecules entering * Gas phase saturated

Answer 26

Relates VP to ambient pressure * Example: iso – max concentration at 20*C at sea level= 240/760 * 100 = 32%, 760 is sea level pressure * If in Denver at 20*C, 635mm Hg: 240/635 = 37.8%

Answer 27

maximum concentration of molecules in vapor state that exist for a given liquid at each temperature unique to each agent, depends only on temperature – not ambient pressure

Answer 28

o If temp of liquid increases: more molecules escape, enter gas phase--> greater number of molecules in vapor phase = greater VP, concentration o If temp of liquid decrease: fewer molecules escape/more return to liquid phase = less VP, concentration o Liquid cooling = natural consequence of vaporization process  ‘Fastest molecules escape first, avg kinetic energy of those left behind decrease so temp decreases  As temp decreases, VP and vapor concentration decreases

Answer 29

amount of energy consumed for a liquid to be converted to vapor, calories to convert 1g liquid to vapor without change in temperature

Answer 30

calories required to increase 1g of liquid 1oC

Answer 31

measure of ability to conduct heat o Copper, aluminum, brass >>> steel

Answer 32

temperature of liquid at which VP = Patm (760 mmHg) o Boiling point decreases at increased altitude, no change in vapor pressure but have change in barometric pressure

Answer 33

temperature above which substance cannot be liquefied no matter how much pressure applied

Answer 34

(aka molecular mass): mass of a molecule of a substance based on 12 as the atomic weight of carbon, summing anatomic weights of atoms in molecular formula o Ex: H2O = H – atomic weight of 1, oxygen = 16 so MW of oxygen = 16

Answer 35

temperature, pressure at which solid, liquid, vapor phase all coexist in equilibrium

Answer 36

primary factor for rate of uptake, distribution within body --> primary determinant of speed of ax induction, recovery Also influences how they dissolve in rubber goods on machine

Answer 37

total number of molecules of given gas dissolving in solvent depends on chemical nature of gas, partial pressure of gas, nature of solvent, temperature Vol of gas (V) = partial pressure of gas (P) x Solubility coefficient (S) * S = solubility coefficient for gas in solvent at given T(temperature) * Applies to gases that do not combine with solvents to form compounds

Answer 38

relationship to anesthetic potency  Low solubility = more rapid equilibration – determines speed of induction Uptake = solubility x CO x [(PA-Pv)/Pbar]

Answer 39

each gas dissolves in solvent in proportion to partial pressure of individual gases o Total pressure exerted by all molecules

Answer 40

Passive gradient from gas phase to oil: gas molecules move into oil compartment  gradient develops for gas molecules in oil to move into water At given temperature, when no more gas dissolves into oil (solvent) = fully saturated (equilibrium) At equilibrium, pressures of gas in all three compartments will be the same BUT # of molecules or volume of gas partitioned between two liquids will vary with nature of liquid and gas

Answer 41

at equilibrium at given temperature, PRESSURE of gas in all compartments the same but actual # of molecules in compartments different Less gas dissolves in a solvent as temp increases, more gas taken up as solvent temp decreases * Ex: Gases become more soluble in blood when patient hypothermic

Answer 42

extent to which gas will dissolve in a solvent  Inhalants: usually expressed as partition coefficient (PC), concentration ratio of anesthetic in solvent and gas phases or btw two tissue solvents * Describes capacity of given solvent to dissolve anesthetic gas * Eg how anesthetic will partition itself btw gas and liquid solvent phases after equilibrium established

Answer 43

occurs bc partial pressure difference in gas, liquid solvent phases --> no partial pressure difference (equilibrium), no net movement

Answer 44

Nice dogs serve icy enchiladas (every) holiday meal BUT since blooD, des is actually first then nitrous - order of increasing BG coefficients

Answer 45

predicts speed of anesthetic induction, recovery, change of ax depth o Lower BG, faster onset SOLUBILITY: inversely proportional to BG Sevo is LESS soluble in blood than iso

Answer 46

predicts potency o Lower OG, higher potency Nice dogs serve icy enchiladas (every) holiday meal

Answer 47

* Solubility of tissue determines in part quantity of anesthetic removed from blood by tissue to which exposed o Higher tissue solubility, longer it will take to saturate tissues with anesthetic o All things equal: anesthetics that are very soluble in tissues require LONGER period for induction, recovery

Answer 48

* If amt of rubber goods used in apparatus used to deliver ax to patient is substantial/anesthetic agent very soluble in rubber, amt of uptake of agent by rubber may be significant  less important with current equipment

Answer 49

with Panes in brain tissue

Answer 50

o Move down a series of pp gradients from higher to lower tension until equilibrium  Vapor pressure in vaporizer  patient breathing circuit --> lungs --> arterial blood --> tissues * At induction, Panes at vaporizer is high, progressively decreases as go down chain

Answer 51

is pivotal: usually GE at alveolar level efficient such that PAanes = Paanes  Brain = highly vascular, rapidly equilibrates with Pa anes * By controlling PAanes, reliable indirect control of Pbrain anes  Essentially: PAanes = Paanes = Pbrainanes  Panes = fractional anesthetic concentration x total ambient pressure with fractional anesthetic concentration Canes/100 * In blood or tissues, actual quantity of anesthetic depends on: Panes, anesthetic solubility as determined by PC within solvent (blood or oil) * At equilibrium, partial pressure of gas in alveoli and among tissue compartments will be equal BUT concentrations will vary among tissues

Answer 52

1. Increased alveolar delivery via increased ax concentration, increased alveolar ventilation 2. Decreased removal from alveoli

Answer 53

- increased vaporization of agent - increased vaporizer dial setting - increased FGF - Decreased gas vol of patient BC

Answer 54

1. increased minute ventilation 2. decreased dead space ventilation

Answer 55

- decreased blood solubility of ax - decreased CO - decreased alveolar-venous ax gradient

Answer 56

Balance btw anesthetic input (alveolar delivery), loss (uptake by blood/tissue)

Answer 57

 Upper limit dictated by SVP, dependent on temperature  Characteristics of patient BS also important: volume, amt of rubber/plastic, position of vaporizer (VIC vs VOC), FGI  Characteristics of patient breathing system (volume, material (i.e. rubber, plastic etc), position of vaporizer (inside or outside of circuit), fresh gas inflow

Answer 58

* BC contains gas vol that must be replaced with gas containing desired anesthetic concentration  buffer that delays rise of anesthetic concentration o Small animals with NRB: high FGF should not differ from vaporizer setting o Larger animals on circle – volume may be large compared to FGF – marked delays/must wash out, rebreathing expired gas with less anesthetic than FGF, expired gas contains less anesthetic than FG, inspired gas concentration will be less than FG leaving the vaporizer  Horses, cattle, closed circuit FGF (FGI low vs circuit vol)

Answer 59

 High solubility of some anesthetics (methoxyflurane) in rubber, plastic delays development of appropriate inspired anesthetic concentration * Loss of anesthetic to these equipment ‘sinks’ s apparent vol of circuit, clinically important * No longer relevant with current inhalants used

Answer 60

VIC: increased FGF into circuit decreases Fi (no flow compensation, decreased SA

Answer 61

increased FGF will increase Fi (technically increases RATE of delivery) so reaches equilibrium with FA faster

Answer 62

decreased rate at which alveolar concentration changess over time vs Fi – slower induction, slower changes

Answer 63

administration of potent inhalant eg N2O can speed uptake of concurrently administered inhalant agent Increases rate of rise of alveolar concentration

Answer 64

Eger: anesthetic uptake product of 3 factors – solubility (S; BG PC), cardiac output (CO), difference in anesthetic partial pressure btw alveolus, venous blood returning to lungs (PA-Pv/Pbar) where Pbar = barometric pressure (mm Hg)

Answer 65

 Solubility of inhalation anesthetic in blood, tissues characterized by partition coefficient (PC) * How inhalation agent distributes btw two phases or two solvents eg quantity of agent in blood and alveoli, or btw blood and muscle once equilibrium established

Answer 66

more rapid equilibration, smaller amount of anesthetic must be dissolved in blood before equilibrium reached with gas phase

Answer 67

blood acts like large sink into which anesthetic is poured, reluctant to give up to other tissues including brain * Pharmacologically inactive reservoir interposed btw lungs, brain

Answer 68

 Greater CO more blood passing through lungs carrying anesthetic away from alveoli  delays rise of PA anes * With greater CO, such as with excitement, delay onset * Inhalant cleared away faster  Decreased CO, PA anes will rise more quickly  Remember, gas movement is all about pressure gradients

Answer 69

Magnitude of difference in anesthetic partial pressure btw alveoli, mixed venous blood returning to lungs related to amt of uptake of ax by tissues Largest gradient during induction Once equilibrium reached, tissues no longer absorb anesthetic/no longer tissue uptake from lungs  mixed venous blood returning to lungs contains as much anesthetic as when left lungs - Pv=PA

Answer 70

* Brain, heart, hepatoportal system, kidneys receive ~75% total blood flow per minute --> rapidly equilibrate with Pa anes compared to other body tissues * Skin, muscle = 50% body in humans, at rest receive 15-20% CO – saturation of tissues takes hours to accomplish * Fat = poorly perfused, saturation is slow, anesthetics more soluble in fat than other tissues

Answer 71

% clearance = 100 x VA (agent blood/gas PC x CO + VA) o Affected by alveolar ventilation, CO, agent sol***  Wash out of less solub agents high at first DT lung FRC then rapidly declines to lower output level, continues to decrease but at slower rate  Wash out of more solub agents also high at first but magnitude of decrease less, decreases more gradually with time

Answer 72

Percutaneous loss Intertissue diffusion of agents * Limited clinical important Metabolism * Methoxy, maybe halothane Transcutaneous movement of inhalation agent * Small amt

Answer 73

DURATION OF AX o Rebreathing circuits: circuit may reduce rate of recovery bc need to wash out inhalant, can reduce via high FGF of O2 only  Essentially use RBC as NRB

Answer 74

Fink Effect, Third Gas Effect

Answer 75

at end of giving N2O, patient goes to room air – lrg vols N2O return from blood to lung, displace other gases in lung esp oxygen  If on room air (21% oxygen), N2O will dilute alveolar oxygen: decreased PaO2 from levels found in room air  life threatening hypoxia  Mitigate by 100% oxygen for 5-10min after discontinuation if N2O

Answer 76

o Most inhalation anesthetics not chemically inert, varying degrees of metabolism  Primarily liver, lesser in lung, kidney, GIT o Metabolism: may facilitate in recovery of anesthesia, may result in acute/chronic toxicities from intermediate or end metabolites  Magnitude: by chemical structure, hepatic enzyme activity (cytochrome P450 in ER of hepatocyte), blood concentration of anesthetic, disease states, genetic factors.

Answer 77

Least N2O, most methoxy Never deny iguanas sunny eateries (that) have mangos.

Answer 78

- Increased alveolar ventilation - Decreased CO - Decreased BG PC - Decreased Duration of GA

Answer 79

Agent Vaporization Vaporizer Setting Increased FGF Increased MV

Answer 80

Increased vol of breathing circuit Increased dead space volume Lower BG PC Lower CO Lower arterial-venous anesthetic gradient

Answer 81

* 1963 Merkel and Eger made the standard index of anesthetic potency: MAC o Minimum alveolar concentration of an anesthetic at 1 atm that produces immobility in 50% of subjects exposed to a supramaximal noxious stimuli o Corresponds to the effective dose50 (ED50) o ED95 (humans) 20-40% > MAC

Answer 82

* Anesthetic potency = 1 / MAC o MAC is inversely related to oil/gas PC o Very potent anesthetic like methoxy (high oil/gas PC) has a low MAC o Agent with low oil/gas PS = high MAC

Answer 83

Healthy patients without any other influence of drugs

Answer 84

initial noxious stimulus = skin incision

Answer 85

o SA (mice to dogs, pigs): forceps or other surgical instrument to tail base or base of dewclaw  In dogs, ovarian/ovarian ligament traction  sevoflurane MAC vs tail clamp

Answer 86

humans on emergence, MAC in which humans open eyes after verbal stimulus (coined by Stoelting) o Verbal stimulus less intense than surgical incision, response occurs at lower concentration of ax than movement following incision

Answer 87

MAC required to not have increases in catecholamines when skin incision made

Answer 88

o Because nitrous MAC > 100%, cannot be used by itself at one atmosphere pressure in any species and still provide adequate amounts of O2 o Usually administered with another mower potent agent to reduce concentration of that more potent agent necessary for anesthesia

Answer 89

o Significantly less MAC reduction in dogs vs humans: 60% N2O with halothane = 55% decrease in healthy humans vs 20-30% in dogs

Answer 90

1MAC, light plane of ax

Answer 91

voluntary responses, awareness MAC 0.3-0.5

Answer 92

Prevent movement to sx stimulus in 50% of population, ED50

Answer 93

Prevents movement in 95% of individuals, prevents response to tracheal intubation - ED95

Answer 94

MAC-BAR: blunts autonomic response to sx stimulus

Answer 95

Apneic Index = 1.5-3MAC

Answer 96

Drugs that cause MAC: amphetamine, ephedrine, morphine (horses), laudanosine, physostigmine Hyperthermia Hypernatremia

Answer 97

ABP >50mmHg Atropine, glycol, scopolamine Duration of ax Gender Hyper/hypokalemia Metabolic AB change PaO2 >40mmHg PaCO2 15-95mmHg

Answer 98

o Reversible, dose-related state of CNS depression (somatic, motor) o Hemodynamic, endocrine unresponsiveness to noxious stimuli o Exact MOA unknown  Influence electrical activity of brain, cerebral metabolism, cerebral perfusion, ICP, analgesia

Answer 99

1. Meyer-Overton 2. Cantor

Answer 100

strength of inhalants based on lipid vs water affinity: oil:water partition coefficient  Cell lipid membrane = site of action  Limitations: does not explain effect of differences btw stereoisomers, ax cut off effect or non-immobilizers

Answer 101

may alter molecular composition, forces within bilayer plane --> change within lateral pressure profile exerted upon proteins in lipid membrane  Non-immobilizers: may not access interfacial regions of membrane critical to modulation of embedded protein R  Ion channels/membrane lipids: chiral centers that may interact differently with anesthetic stereoisomers  Fills in gaps of Meyer-Overton

Answer 102

Inhaled anesthetics bind proteins, modulate function in absence of lipid environment Potentiate inhibitory target cells: GABAA, glycine, two pore domain K channels Inhibit excitatory cell targets: NMDA, AMPA, nicotinic R, VG Na channels Inability to identify R for anesthetic action --> multiple cell R, ion channel target modulation

Answer 103

cerebral cortex, amygdala, and hippocampus  hypnosis, amnesia * Amnesia= amygdala and hippocampus * EEG: hippocampal-dependent -rhythm frequency slows  to amnestic effects with subanesthetic doses of iso * alpha4, beta3 subunits of GABA partly responsible for iso depression * Mice: antagonism of 5 subunit-containing GABAA R restores hippocampal-dependent memory during sevo * GABAA vs TREK-1 K+ channels

Answer 104

critical site for suppressing noxious-evoked movement (immobility) * Principally responsible for preventing movement during surgery with inhaled anesthetics * NMDA, glycine receptor antagonism * Depression of locomotor neuronal networks located in ventral horn

Answer 105

Supraspinally DH of SC analgesia via glutamatergic R inhibition, inhibit NMDA receptors and K2P/TREK1 receptors o Additional modulation of noradrenergic opioid R pathways o Ca channels: decrease Ca available and responsiveness – BP and negative inotropic effects (not true with xenon

Answer 106

decreased but do NOT prevent wind-up/central sensitization o No benefit of higher concentrations

Answer 107

decreases withdrawal responses to noxious stimuli, but can actually cause hyperalgesia o Peak effect at 0.1MAC o Potent nicotinic cholinergic R inhibition

Answer 108

Autonomic effects

Answer 109

No parameter has sensitivity/specificity to justify use of EEG alone as reliable index of ax depth * Improvements in technology: Bispectral index As depth of ax increases, cerebral cortex becomes desynchronized - decreased in frequency, increase in EEG activity

Answer 110

increased frequency of EEG activity ~0.4MAC wave amplitude increases then progressively declines ~1MAC Burst suppression ~1.5MAC Isoelectric activity (flat late) at ~2.0MAC iso, servo, des; 3.5 halothane

Answer 111

spontaneous or noise-initiated sz in dogs, people o Substantial increases in cerebral blood flow, CMO2

Answer 112

all decrease cerebral metabolic rate (CMR), least with halo

Answer 113

--Either no change or increase - dose-related VD from ax, decreased CMO2 Halothane (greatest) > N2O > enf, iso, des > sevo (least) * N2O: severe vasodilation * increased CBF --> increase blood brain vol, ICP * Most likely DT time-dependent increase in NO synthase inhibition Horses: regional CBF constant over wide range of CPPs despite changes in ICP

Answer 114

uncoupling of CP from CMO2 o 0.5MAC: diminished, obtunded o High MACs: cerebrovascular autoregulation very diminished --> CBF simply function of CPP o Effects on CBF = duration-dependent Sevo: best at maintaining cerebral autoregulation

Answer 115

* Autoregulation lost, CBF increases at lower MAC when patients hypoventilate * Interaction greater with iso + CO2 than sevo + CO2

Answer 116

Increases DT increased CBF * Regardless of species, cerebrovascular autoregulation better preserved at MAC-multiple of halothane ax when hyperventilation maintained, PaCO2 decreased

Answer 117

--Decreased SpV as dose increases: VT>RR --Decreased minute ventilation, increased dead space ventilation (increased VD/VT >0.3-0.5) --Hypercapnia DT depression of alveolar minute ventilation, stimulation of ventilation by central and chemoR blunted --Bronchospasm --Respiratory depression worsened with concurrent drugs

Answer 118

--BD DT decreased cholinergic transmission --iso, +/- enflurane, sevo, des: relaxation of constricted bronchial SmM least equal to or exceeds that caused by halothane via inhibition of M3 --Airway irritation: desflurane at >7%, lesser extent with iso

Answer 119

1. Ventilation - assisted not usually effective in substantially lowering PaCO2, CMV best 2. Duration of ax: higher MAC for prolonged periods = significant temporal increase in PaCO2 3. Respiratory depression blunted by sx, noxious stimulus - effect diminishes at increased deoth

Answer 120

Myocardial depression (interference with Ca), decreased symapthoadrenal activity Decreased CO = dose dependent, DT decrease in SV from decreased myocardial contraction **HALOTHANE** --Also affected ABP Variable effects on HR

Answer 121

Increased automaticity of myocardium, increased likelihood of propagated impulses from ectopic sites (especially ventricle) * Newer ether-derived agents: do not predispose heart to extrasysoles **Spontaneous dysrhythmias- halothane** * Markedly decreases amount of epi necessary to cause VPCs Halothane > Enflurane, methoxy > des, sevo iso  ALL agents exaggerate adrenergic agonist associated dysrhythmias

Answer 122

1. Mode of Ventilation/PaCO2 - CV usually depressed during IPPV 2. Noxious Stimulation - blocked at MACbar/MAC1.5-2.0

Answer 123

Direct mechanical action (increase intrathoracic pressure, resultant decrease in venous return to heart) Indirect (pharmacologic action of PaCO2) o Increase PaCO2 = direct depression of heart, SmM of peripheral blood vessels (dilation) Indirect (via sympathetic activity) stimulation of circulatory function

Answer 124

MAC reduction --> decreased CV effects N2O may directly depress myocardium, counterbalanced by sympathomimetic effect - net improvement of CV function

Answer 125

All useful agents: similar, mild, reversible dose-related decrease in renal BF, GFR --> anesthesia-related decrease in CO  Smaller vol concentrated urine vs awake  increased BUN, creatinine, inorganic phosphate may accompany prolonged ax Renal function reduction highly influenced by hydration, hemodynamics during GA  Mitigated by IVF, prevention of marked reduction in renal BF

Answer 126

Renal failure characterized by polyuria unresponsive to VP n MOA: biotransformation of methoxyflurane, large release of **free fluoride ions** * Peak levels, prolonged exposure DT high adipose accumulation during ax Free fluoride ions cause **direct damage to renal** tubules  Reported in dogs in conjunction with tetracycline, banamine Enflurane: also able to produce fluoride ions, above nephrotoxic threshold in humans but not seen

Answer 127

--Production of FI ions in humans > nephrotoxic threshold --Histological, clinical, biochemical evidence of injury rare

Answer 128

**Area under serum fluoride concentration vs time curve may more important determinant of nephrotoxicity than peak serum fluoride concentrations** o Sevo = poorly soluble, rapidly eliminated by lungs o Duration of availability for biotransformation limited **Hepatic metabolism vs methoxy = hepatic, renal o Lack of intrarenal ax defluorination may markedly reduce nephrotoxic potential** o Horse: increase serum fluorine, magnitude/time course of increase similar to humans, no evidence untoward renal effects

Answer 129

degradation of sevoflurane by CO2 absorbents Nephrotoxic = renal injury, death in rats Proposed MOA: species-specific metabolic degradation to directly nephrotoxic compounds most commercially available absorbents in US no longer contain KOH, NaOH  Baralyme>Sodalime, not Amsorb

Answer 130

--**hepatocellular injury DT decreased HBF, DO2**  **Isoflurane better maintains O2 delivery, agent less likely to cause hepatocellular injury** --Iso >/~ Sevo, Des >>> Halothane  Cofounding factors: N2O, concurrent hypoxia, prior induction of hepatic drug-metabolizing enzymes, mode of ventilation, PEEP * May worsen conditions,  likelihood of hepatocellular damage

Answer 131

1. Inhibition of drug metabolizing capacity 2. Mild, self-limiting hepatocellular damage 3. Halothane hepatitis - fatal immune-meditated toxicity

Answer 132

Pharmacogenetic myopathy via activation of RYR1 – swine, horses, dogs, humans Halothane = most potent triggering agent, can be any volatile anesthetic o Rapid rise in cellular metabolic activity, death if not treated quickly o Monitoring of temp, CO2 production, other signs of metabolic imbalance IE ABG warranted and susceptible, suspected patients  Avoid triggering agents, prophylactic tx with dantrolene

Answer 133

Pietrain, Landrace, Poland China Pigs

Answer 134

muscle rigidity, hyperthermia with 1*C increase Q5min, tachyarrhythmias, tachypnea

Answer 135

metabolic acidosis, hypercapnia, base deficit >8mEq/L, hyperlactatemia, hyperkalemia

Answer 136

active cooling, CMV, TURN OFF VAPORIZER, HCO3 PRN (0.3*kgs*desired change), switch circuits, TIVA or xenon, dantrolene 5mg/kg IV or 10mg/kg PO via stomach tube

Answer 137

low blood solubility, limited CV/resp system depression, minimal toxicity o Not potent – MAC humans 100%, dogs 188%, cats 255%- will not anesthetize healthy individual as solo agent Main benefit: allow reduction of primary more potent inject/inhal  As concentrations of N2O increases, change in proportion, partial pressure of other constituents of inspired breath esp O2  **No more than 75% N2O to avoid hypoxemia (usually 66%)**  **>sea level, lower N2O to ensure adequate PIO2**

Answer 138

Very low blood solubility = rapid onset **Large vol of N2O leaves alveoli, allowing for concentrating effect of second gas to create faster induction** High concentration of N2O administered concurrently in mixture with inhalation agent, alveolar concentration of simultaneously administered anesthetic increases more rapidly than when ‘second’ gas administered without N2O

Answer 139

ruminants/horses, pneumothorax, GDV, FB, air embolism, cavotomy , esophageal FBs

Answer 140

-Direct myocardial depression, counteracted by SNS stimulation - increased BP, arrhythmias -Little effects on resp, kidney, liver

Answer 141

rapid, exhaled breath  Biotransformation to molecule N2 very small, mainly by intestinal flora

Answer 142

o Decreases uterine SmM contractility, BF

Answer 143

1. Prolonged exposure = megaloblastic hematopoiesis DT interference with RBC/WBC production by BM 2. Polyneuropathy 3. Vascular inflammation 4. Induced inactivation of vit B12-dependent enzyme methionine synthase via oxidation of cobalt from B12 - interruptions of folic acid metabolism 5. Abuse potential 6. Interference with some respiratory monitoring

Answer 144

When N2O introduced into inspired breath, re-equilibration of gases in gas spaces N2O quickly enters, N2 slowly leaves --N2O = 30x more soluble in blood (BG PC 0.47): vol of N2O that can be transported to closed gas space many times vol of N2 can be carried away (BG PC 0.015) Result: net transfer of gas to gas space as increased in vol with gut, pneumothorax, blood embolus; increased pressure; pneumocephalogram,

Answer 145

ETT Gut Middle Ear Sinuses

Answer 146

Lrg vol N2O stored in body during ax, **unequal exchange of N2O for N2**, deficiency in blood oxygenation may occur at end of ax if abrupt substitution of air for N2O Rapid outpouring of N2O from blood into lung = transient but marked decrease in PAO2

Answer 147

Lrg vol N2O stored in body during ax, **unequal exchange of N2O for N2**, deficiency in blood oxygenation may occur at end of ax if abrupt substitution of air for N2O Rapid outpouring of N2O from blood into lung = transient but marked decrease in PAO2

Answer 148

Stratospheric ozone layer known to be damaged by rapid, widespread global usage and subsequent atmosphere presence of volatile, synthetic, long lived organochlorine and bromine containing compounds = chlorofluorohydrocarbons, CFCs All contemporary volatile anesthetics = potentially destructive to ozone layer as halogenated compounds In effect only chlorine containing halothane, isoflurane (less so) * Relative contribution of these two volatile agents estimated at most 0.01% of annual global release of CFC's Substances that contain only fluorine do not harm the ozone layer

Answer 149

 Emission highlighted as single most important ozone depleting emission, expected to remain largest throughout 21st century  Long atmospheric lifetime so contributes to warming as well as ozone depletion

Answer 150

has highest heat trapping effects, now removed from markets in some countries  MAC Basis: desflurane >>> iso > sevo

Answer 151

o Iso, halothane = chloroflurocarbon, ozone depleting capacity  Des, sevo = hydrofluorocarbons, no ozone depleting potential N2O: ozone depleting potential

Answer 152

--Inert noble gas, MAC 71% --No compounds, no biotransformation - requires prolonged denitrogenation --BG PC 0.14 --> rapid induction --CV safe, no potential to induce MH --Used for contrast imaging, neuroprotectivity --Not FDA approved - research only

Answer 153

post synaptic NMDA R blockade at K2P - decreases in excitatory neurotransmission

Inhalants Flashcards

(237 cards)