CH 4 Inhaled Anesthetics Comparative Pharmacology Flashcards
Which two inhaled anesthetics have a low blood and tissue solubility that permits more precise control over the induction of anesthesia and more rapid recovery when the drug is discontinued?
Desflurane and Sevoflurane
Reaction to N2O does not occur until ____% to ____% is inhaled
10% to 20% nitrous oxide is inhaled
Mental impairment is not detectable in volunteers breathing __________ of nitrous oxide or __________halothane
1,600 ppm (0.16%) nitrous oxide or 16 ppm (0.0016%) halothane
Drug-induced increases in CBF may ____________ intracranial pressure (ICP) in patients with space-occupying lesions
increase
Cerebral metabolic oxygen requirements are _______________ in parallel with drug-induced ______________in cerebral activity
decreases
decreases
What concentration of MAC increase the frequency and voltage on the EEG? (Excitement stage)
Volatile anesthetics in concentrations of <0.4 MAC
Cerebral metabolic oxygen requirements begin to decrease abruptly at about _______ MAC
0.4
What happens when volatile anesthetic approaches 1 MAC?
The frequency on the EEG decreases and maximum voltage occurs.
During administration of isoflurane, burst suppression appears on the EEG at about ________MAC, and at ________ MAC, electrical silence predominates
During administration of isoflurane, burst suppression appears on the EEG at about 1.5 MAC, and at 2 MAC, electrical silence predominates
____________ and _____________ cause dose-related changes in the EEG similar to those that occur with isoflurane
Desflurane and sevoflurane
1.5 MAC of isoflurane will cause
burst suppression
2 MAC of Isoflurane will cause
electric silence(isoelectric line)
What is the patients state on EEG when the MAC is 0?
WAKEFUL
What is the patients state on EEG when the MAC is 0.4
SEDATED
What is the patients state on EEG when the MAC is 0.8?
Unresponsive
What is the patients state on EEG when the MAC is 1.3?
Surgically anesthetized
What is the patients state on EEG when the MAC is 2?
Deeply anesthetized
How can volatile anesthetics affect evoked potentials?
Dose-related decreases in the amplitude and increases in the latency of the cortical component of median nerve somatosensory evoked potentials, visual evoked potentials, and auditory evoked potentials.
The decrease in amplitude is more marked than increase in latency
Mental Function and Awareness
Gaseous anesthetics may not be equally effective in preventing awareness.
0.4 MAC isoflurane prevents recall and responses to commands, whereas nitrous oxide requires greater than 0.5 to 0.6 MAC to produce similar effects.
Surgical stimulation may increase the anesthetic requirement to prevent awareness.
Volatile anesthetics administered during normocapnia in concentrations of >0.6 MAC produce
cerebral vasodilation, decreased cerebral vascular resistance, and resulting dose-dependent increases in CBF
Increase in CBF occurs despite concomitant decreases in cerebral metabolic requirements.
Which inhaled anesthetics increases the CBF?
Isoflurane = Desflurane> Sevoflurane
Which inhaled anesthetics do not affect CBF autoregulation?
ISO,DES & SEVO
What can counteract increases in ICP by volatile anesthetics?
Hyperventilation to decrease PaCO2 to about 30mmHg
Which inhaled anesthetic offers a degree of cerebral proctetion? from transient incomplete cerebral ischemia during carotid endarterectomy?
Isoflurane
Circulatory effects of inhaled anesthetics may be different in the presence of
(1) controlled ventilation of the lungs compared with spontaneous breathing,
(2) preexisting cardiac disease, or
(3) drugs that act directly or indirectly on the heart.
The mechanisms of circulatory effects are diverse but often reflect the effects of inhaled anesthetics on
(1) myocardial contractility,
(2) peripheral vascular smooth muscle tone
(3) autonomic nervous system activity
Which inhaled anesthetics cause a decrease in MAP?
Halothane, isoflurane, desflurane, and sevoflurane
In contrast with volatile anesthetics, nitrous oxide produces either _________or _________ in systemic blood pressure
In contrast with volatile anesthetics, nitrous oxide produces either no change or modest increases in systemic blood pressure
Substitution of nitrous oxide for a portion of the volatile anesthetic ___________the magnitude of blood pressure decrease produced by the same MAC of the volatile anesthetic alone
DECREASES
The decrease in blood pressure produced by halothane is, in part or in whole, a consequence of
decreases in myocardial contractility and cardiac output
The decrease in blood pressure produced by isoflurane, desflurane, and sevoflurane is due
the decrease in systemic blood pressure results principally from a decrease in systemic vascular resistance
Which inhaled anesthetics increase HR?
Isoflurane, desflurane, and sevoflurane, but not halothane, increase heart rate when administered
TRUE OF FALSE: A small dose of opioid (morphine in the preoperative medication or fentanyl intravenously immediately before induction of anesthesia) can prevent the heart rate increase associated with isoflurane and presumably the other volatile anesthetics
TRUE
Unchanged heart rate despite a decrease in blood pressure during the administration of halothane may reflect
Depression of the carotid sinus (baroreceptor reflex response) by halothane as well as drug-induced decreases in the rate of sinus node depolarization.
When using Halothane, the Junctional rhythm and associated decreases in systemic blood pressure most likely reflect
suppression of sinus node activity by halothane
Halothane _________ the speed of conduction of cardiac impulses through the atrioventricular node and His-Purkinje system
decreases
In neonates, administration of isoflurane is associated with
attenuation of the carotid sinus reflex response, as reflected by drug-induced decreases in blood pressure that are not accompanied by increases in heart rate
Heart rate responses during administration of isoflurane also seem to be blunted in elderly patients
Which inhaled anesthetic produces dose-dependent decreases in cardiac output when administered?
Halothane
Sevoflurane did decrease cardiac output at __ and __ MAC, but at 2 MAC, cardiac output had recovered to nearly awake values.
1 and 1.5
Which inhaled anesthetics increase right atrial pressure (central venous pressure) when administered ?
Halothane, isoflurane, and desflurane, but not sevoflurane,
Increased right atrial pressure during administration of nitrous oxide most likely reflects
increased pulmonary vascular resistance due to the sympathomimetic effects of this drug.
which inhaled anesthetics decreases the systemic vascular resistance?
Isoflurane, desflurane, and sevoflurane, but not halothane,
Decreases in systemic vascular resistance during administration of isoflurane principally reflect
substantial (up to fourfold) increases in skeletal muscle blood flow
implications of alterations in blood flow when administering inhaled anesthetics may include
(1) excess (wasted) perfusion relative to oxygen needs, (2) loss of body heat due to increased cutaneous blood flow, and (3) enhanced delivery of drugs, such as muscle relaxants, to the neuromuscular junction.
Which is the inhaled anesthetic that only causes dose-dependent CO decrease?
Halothane
Which inhaled anesthetic has better maintenance of HR and minimal depressant effects on CO?
Isoflurane
True or False: All volatile anesthetics, including Isofluranedepress myocardial contractility to some degree
true
Which inhaled anesthetic increases right atrial pressure (CVP)?
Halothane, Desflurane and Isoflurane but not sevoflurane
Which inhaled anesthetic decreases SVR?
ISO
DES
SEVO
But not halothane
Halothane decreases BP principally by decreasing______
CO
A decrease of SVR during the administration of Isoflurane reflect
Increases in skeletal muscle blood flow x4
True or False: Volatile anesthetics appear to exert little or no predictable effect on pulmonary vascular smooth muscle
true
Nitrous oxide may produce
_______________in pulmonary vascular resistance that is exaggerated in patients with preexisting pulmonary hypertension
increases
the neonate with or without preexisting pulmonary hypertension may also be uniquely vulnerable to the pulmonary vascular vasoconstricting effects of nitrous oxide
In patients with congenital heart disease, increases in pulmonary vascular resistance may increase the magnitude of _______________intracardiac shunting of blood and further jeopardize arterial oxygenation.
of right-to-left
The ability of volatile anesthetics to decrease the dose of epinephrine necessary to evoke ventricular cardiac dysrhythmias is greatest with
____________
Minimal to non existent with___________
the alkane derivative halothane and minimal to nonexistent with the ether derivatives isoflurane, desflurane, and sevoflurane
Which inhaled anesthetics prolong QTc interval?
Halothane, enflurane, and isoflurane prolong the QTc interval on the electrocardiogram in healthy patients
similar changes may not occur in patients with idiopathic long QTc interval syndrome suggesting that generalizations from healthy patients to patients with long QTc interval syndrome may not be valid.
CO2 accumulation causes __________ of vascular muscle, which can produce ____ in HR and _______ in SVR
RELAXATION
INCREASES
DECREASES
Volatile anesthetics induce coronary vasodilation by preferentially acting on vessels with diameters from ___ TO ____ microns
20 to 50
Which inhaled anesthetic produce coronary steal syndrome?
Isoflurane
as well as other coronary vasodilators (adenosine, dipyridamole, nitroprusside) that preferentially dilate the small coronary resistance coronary vessels would be capable of redistributing blood from ischemic to nonischemic areas
________ is a good inhaled anesthetic choice to treat increases in BP & HR in response to surgical stimulus
Desflurane
Abrupt increases of which volatile anesthetics increase SNS activity & renin-angiotensin activity? increase BP and HR
Abrupt increases in Isoflurane and Desflurane
More desflurane than Isoflurane
Decreased contractility by inhaled anesthetic may be detrimental for patients with hx of
CHF
Abrupt increases in desflurane may be detrimental in patients with hx of
CAD
Peripheral vasodilation by inhaled anesthetics might be detrimental in
Patients with aortic stenosis
Peripheral vasodilation by inhaled anesthetics might be beneficial in
patients with aortic regurgitation
Which medications that alters SNS activity may influence in the magnitude of inhaled anesthetics changes?
Calcium channel blockers
beta blockers
Ace inhibitors
The proposed mechanisms of cardiovascular depressant effects by volatile anesthetics include
1) direct myocardial depression,
(2) inhibition of CNS sympathetic activity,
(3) peripheral autonomic ganglion blockade,
(4) attenuated carotid sinus reflex activity,
(5) decreased formation of cyclic adenosine monophosphate, (
6) decreased release of catecholamines,
(7) decreased influx of calcium ions through slow channels.
negative inotropic, vasodilating, and depressant effects on the sinoatrial node produced by volatile anesthetics are similar to the effects produced by _________________
calcium entry blockers.
______________may be unique among the volatile anesthetics in possessing mild β-adrenergic agonist properties.
Isoflurane
The increase in blood pressure that is associated with rapid increases in desflurane concentration is accompanied by a significant increase in
plasma epinephrine suggesting enhanced release from the adrenal gland.
Nitrous oxide administered alone or added to unchanging concentrations of volatile anesthetics produces signs of mild sympathomimetic stimulation characterized by
(1) increases in the plasma concentrations of catecholamines, (2) mydriasis, (3) increases in body temperature, (4) diaphoresis, (5) increases in right atrial pressure, and (6) evidence of vasoconstriction in the systemic and pulmonary circulations
What is ischemic preconditioning?
cardiac protection (anesthetic preconditioning)
” In theory inhaled gases protect from ischemia insults”
Brief episodes of myocardial ischemia occurring before a subsequent longer period of myocardial ischemia provide protection against myocardial dysfunction and necrosis
Which inhaled anesthetics increases in the frequency of breathing?
All Inhaled anesthetics, except for isoflurane,
Isoflurane increases the frequency of breathing similarly to other inhaled anesthetics up to a dose of _____MAC
1 MAC
At a concentration of >1 MAC, however, isoflurane does not produce a further increase in the frequency of breathing.
Nitrous oxide increases the frequency of breathing more than other inhaled anesthetics at concentrations of ___MAC
> 1
Effects on the pattern of breathing by inhaled
Increase in the frequency of breathing.
CNS stimulation
Reduction of tidal volume
Decrease in Minute ventilation.
Ventilatory response to CO2
dose-dependent depression (medullary resp center)
N2O does not increase CO2 (used as an attenuator)
Inhaled anesthetics produce dose-dependent and drug-specific effects on the
(1) pattern of breathing, (2) ventilatory response to carbon dioxide, (3) ventilatory response to arterial hypoxemia, and (4) airway resistance.
Volatile anesthetics stimulate central respiratory chemoreceptor neurons likely through activation of
THIK-1 (potassium channel subfamily K member 13; K2p13.1) receptors, a two-pore potassium channel that is responsible for a background potassium current
Surgical stimulation increases minute ventilation by about
_____ because of increases in tidal volume and frequency of breathing.
40%
Anesthetic-induced depression of ventilation as reflected by increases in the ________ most likely reflects the direct depressant effects of these drugs on the _______________________
PaCO2
medullary ventilatory center.
The predictable ventilatory depressant effects of volatile anesthetics are most often managed by institution of __________________ ventilation of the patient’s lung
mechanical (controlled)
______________ is useful during thoracic surgery as it is a potent bronchodilator, its low blood-gas solubility permits rapid adjustment of the depth of anesthesia, and effects on hypoxic pulmonary vasoconstriction are small
Sevoflurane
Risk factors for developing bronchospasm during anesthesia include
young age (<10 years),
perioperative respiratory infection,
endotracheal intubation,
the presence of COPD.2
Which inhaled anesthetic produces bronchodilation in patients with COPD?
isoflurane and sevoflurane
Which inhaled anesthetic produces bronchocosntriction?
Desflurane
specially in smoker pts and COPD
Which inhaled anesthetic has the greater risk for irritability?
Desflurane
Which inhaled anesthetic has the least risk of irritability?
Sevoflurane
Which inhaled anesthetic is a vasodilator of the hepatic circulation?
isoflurane is a vasodilator of the hepatic circulation providing beneficial effects on hepatic oxygen delivery
Which inhaled anesthetic is a vasoconstrictor of the hepatic circulation?
halothane acts as a vasoconstrictor on the hepatic circulation
True or False: Volatile anesthetics may interfere with clearance of drugs from the plasma.
True
Which drug is greatly affected due to intrinsic clearence of hepatic metabolism?
Propanolol
Intrinsic clearance by hepatic metabolism of drugs such as propranolol is decreased by 54% to 68% by inhaled anesthetics
Which Inhale anesthetic transiently increases the plasma alanine aminotransferase activity?
Desflurane
Transient increases in the plasma alanine aminotransferase activity follow administration of desflurane,
Which Inhale anesthetic transiently increases the plasma concentrations of α-glutathione transferase (sensitive indicator of hepatocellular injury)?
Transient increases in plasma concentrations of α-glutathione transferase (sensitive indicator of hepatocellular injury) follow administration of isoflurane or desflurane for surgical anesthesia.
How does administration of isoflurane and surgical stimulation affect liver function test?
In the presence of surgical stimulation, bromsulphalein retention and increases in liver enzymes follow transiently the administration of even isoflurane, suggesting that changes in hepatic blood flow evoked by painful stimulation can adversely alter hepatic function independent of the volatile anesthetic.
Which inhaled anesthetic causes the most clinical and relevant hepatotoxicity?
Halothane
However, post op liver dysfunction has been associated with most volatile anesthetics
How does the metabolism of halothane affects the liver?
Metabolism of halothane can produce free radicals that can alter hepatic proteins, creating antigens that stimulates the immune system
you should avoid halothane on patients with liver disease such as hepatic cirrhosis because
Preexisting liver disease, such as hepatic cirrhosis, may be associated with marginal hepatocyte oxygenation, which would be further jeopardized by the depressant effects of anesthetics on hepatic blood flow and/or arterial oxygenation.
Hypothermia ___________ hepatic oxygen demand
decreased
Hypothermia may protect the liver from drug-induced events that decrease hepatic oxygen delivery.
Halothane produces ___ types of hepatotoxicity
2
An estimated 20% of the patients that develop a mild sel-limited post operative hepatoxicity will experience
Nausea
Lethargy
Fever
Minor increases in plasma concentrations of liver transaminase enzymes
Halothane Hepatitis is estimated to occur in ___ in ____ to ____ in _______ adult patients
The other and rarer type of hepatotoxicity (halothane hepatitis) is estimated to occur in 1 in 10,000 to 1 in 30,000 adult patients
Halothane Hepatitis may lead to
massive hepatic necrosis and death
Which patient
(age ) population is more susceptible to experiencing halothane hepatoxicity?
Adults. Children are less susceptible
Halothane Hepatitis/Hepatoxicity is
Rare
Life-threatening form of hepatic dysfunction
Most likely to be an immune-mediated hepatoxicity
What are the clinical manifestations of halothane hepatitis suggesting an immune-related response?
eosinophilia, fever, rash, arthralgia, and prior exposure to halothane
Risk factors commonly associated with halothane hepatitis include
female gender, middle age, obesity, and multiple exposures to halothane
The predominant histologic feature of halothane hepatitis is
Acute hepatitis
The most compelling evidence for a Halothane hepatitis immune-mediated mechanism is the presence of
circulatory immunoglobulin G antibodies in at least 70% of those patients with the diagnosis of halothane hepatitis
Halothane Metabolism
This chemical structures belongs to
desflurane
This chemical structures belongs to
Isoflurane
This chemical structures belongs to
Halothane
The mild, self-limited postoperative hepatic dysfunction that is associated with all the volatile anesthetics most likely reflect anesthetic-induced alterations in hepatic oxygen delivery relative to demand that results in
inadequate hepatocyte oxygenation.
Halothane is metabolized to
a trifluoroacetylated (TFA) adduct (altered protein) that binds to liver proteins.
In susceptible patients, this adduct (altered protein) is seen as nonself (neoantigen), generating an immune response (production of antibodies).
Subsequent exposure to halothane may result in hepatotoxicity.
enflurane, isoflurane, and desflurane are oxidatively metabolized by
liver cytochrome P450 enzymes to form acetylated liver protein adducts by mechanisms similar to that of halothane
Which inhaled anesthetic could possibly produce hepatoxicity by a similar mechanism to that of halothane?
Enflurane, isoflurane, and desflurane could produce hepatotoxicity by a mechanism similar to that of halothane ,but at a lower incidence because the degree of anesthetic metabolism appears to be directly related to the potential for hepatic injury.
The incidence of anesthetic-induced hepatitis would be greatest with
Halothane
the incidence of anesthetic-induced hepatitis would be intermediate with
Enflurane
the incidence of anesthetic-induced hepatitis would be rare to occur with
Isoflurane
Which inhaled anesthetic “should be very safe to administer to a liver/hepatic patient?
Desflurane should be very safe because it would have the lowest level of adduct formation.
True or False:
Environmental exposure of operating room personnel to trace concentrations of volatile anesthetics could stimulate antibody production.
It is presumed that pediatric anesthesiologists experience greater occupational exposure to trace concentrations of volatile anesthetics due to the frequent use of nonrebreathing anesthesia delivery systems and use of uncuffed endotracheal tubes.
Despite these higher antibody levels, pediatric anesthesiologists did not have increased liver transaminase enzymes compared with general anesthesiologists, suggesting these antibodies may be insufficient to cause appreciable damage to normal hepatic cells
true!!!
very scary
Does sevoflurane undergo metabolism to an acetyl halide?
NO
The chemical structure of sevoflurane, unlike that of other fluorinated volatile anesthetics, dictates that it cannot undergo metabolism to an acetyl halide
______________metabolism does not result in the formation of trifluoroacetylated liver proteins and therefore cannot stimulate the formation of antitrifluoroacetylated protein antibodies.
SEVOFLURANE
Therefore, unlike all the other fluorinated volatile anesthetics, sevoflurane would not be expected to produce immune-mediated hepatotoxicity or to cause cross-sensitivity in patients previously exposed to halothane
Which inhaled anesthetics are metabolized to reactive acetyl halide metabolites?
metabolism does not result in the formation of trifluoroacetylated liver proteins and therefore cannot stimulate the formation of antitrifluoroacetylated protein antibodies.
Which inhaled anesthetic unlike all the other fluorinated volatile anesthetics, would not be expected to produce immune-mediated hepatotoxicity or to cause cross-sensitivity in patients previously exposed to halothane?
Sevoflurane
What are the renal effects of volatile anesthetics
Volatile anesthetics produce similar dose-related decreases in renal blood flow, glomerular filtration rate, and urine output
Changes in renal system by volatile anesthetics are due to
The effects of volatile anesthetics on systemic blood pressure and cardiac output
What can be done preoperatively to attenuate or abolish changes in renal function associated with volatile anesthetics?
Preoperative hydration attenuates or abolishes many of the changes in renal function associated with volatile anesthetics.
S/S of Fluoride-induced nephrotoxicity
polyuria, hypernatremia, hyperosmolarity, increased plasma creatinine, inability to concentrate urine)
Fluoride-induced nephrotoxicity quick facts
first recognized in patients after the administration of methoxyflurane, which undergoes extensive metabolism (70% of the absorbed dose) to inorganic fluoride, which acts as a renal toxin.
Sevoflurane causes the following transient changes in the renal system:
transient impairment of renal concentrating ability
increased urinary excretion of β-N-acetylglucosaminidase in patients exposed to sevoflurane
developing peak plasma inorganic fluoride concentrations >50 μmol/L
What is considered to be the indicator of acute proximal renal tubular injury?
Urinary excretion of β-N-acetylglucosaminidase is considered an indicator of acute proximal renal tubular injury.
_____________ undergoes greater hepatic metabolism, thus accounting for the higher plasma concentrations of fluoride
Sevoflurane
Carbon dioxide absorbents containing potassium and sodium hydroxide react with _____________ and eliminate hydrogen fluoride from its isopropyl moiety to form a breakdown product
sevoflurane
The degradation product produced in greatest amount by sevoflurane is
The degradation product produced in greatest amounts is fluoromethyl-2,2-difluoro-1-(trifluoromethyl)vinyl ether (compound A).
What is another name for this degradation product?
Compound A
carbon dioxide production _________ the absorbent temperature and thus the production of compound A
increases
The rationale for the limitation of gas flow to at least 2 L per minute when administering sevoflurane is
to minimize the concentration of compound A that may accumulate in the anesthesia breathing circuit.
Which inhaled anesthetic shows maintenance of total hepatic blood flow and hepatic arterial blood flow?
Isoflurane
Risk factors for halothane hepatitis
Female
Middle Age
Obese
Prior exposure to Halothane
True or False: Sevoflurane undergoes metabolism to acetyl halide
False
Which inhaled anesthetic has the greatest metabolite recovery?
Halothane with a 15-20%
Factors that increase the production of Compound A
Higher concentrations of Baralyme (not available anymore)
Higher temperatures
Longer exposure of sevoflurane (4-8 hrs)
Low flows <2L/min
Which inhaled anesthetics produce skeletal muscle relaxation twofold that of halothane?
Ether derivative fluorinated volatile anesthetics (isoflurane, sevoflurane, and desflurane)
produce skeletal muscle relaxation that is about twofold greater than that associated with a comparable dose of halothane.
What are the skeletal muscle effects of N2O ?
Nitrous oxide does not relax skeletal muscles
in doses of >1 MAC (delivered in a hyperbaric chamber), it may produce skeletal muscle rigidity
The ability of skeletal muscles to sustain contractions in response to continuous stimulation (such as with a nerve-muscle stimulator) is impaired in the presence of
increasing concentrations of ether derivative volatile anesthetics but not in the presence of halothane or nitrous oxide
True or False All volatile anesthetics including desflurane and sevoflurane can trigger malignant hyperthermia in genetically susceptible patients even in the absence of concomitant administration of succinylcholine
True
Which volatile anesthetics is the most potent trigger for malignant hyperthermia?
Halothane
Which inhaled anesthetics does not trigger malignant hyperthermia?
N20
Xenon
What are the obstetric effects caused by inhaled anesthetics?
Volatile anesthetics produce similar and dose-dependent decreases in uterine smooth muscle contractility and blood flow
These changes are modest at 0.5 MAC (analgesic concentrations) and become substantial at concentrations of >1 MAC
Which inhale anesthetic is useful in obstetrical anesthesia to help reduce concentration of volatile anesthetics, benzos and opioids?
nitrous oxide is particularly useful in obstetrical anesthesia to reduce the need to volatile anesthetic that promotes uterine atony while avoiding opioids and benzodiazepines that may cause prolonged depression of the newborn.
_________ reduce the need to volatile anesthetic that promotes uterine atony
N2O
uterine relaxation produced by volatile anesthetics may contribute to
blood loss due to uterine atony
FYI uterine atony refers to a soft and weak uterus after childbirth. It happens when the uterine muscles don’t contract enough to clamp the placental blood vessels shut after childbirth. This can lead to life-threatening blood loss after delivery.
Inhaled anesthetics and immune system effects
normal functions of the immune system are depressed after patient exposure to the combination of anesthesia and surgery
inhaled anesthetics, particularly nitrous oxide, produce dose-dependent inhibition of polymorphonuclear leukocytes and their subsequent migration (chemotaxis) for phagocytosis, which is necessary for the inflammatory response to infection.
Which inhaled anesthetics produce a dose dependent inhibition of leukocytes?
N20
How is compound A formed?
Compound A, which is formed from sevoflurane degradation by carbon dioxide absorbent
which inhaled anesthetic irreversibly oxidizes the cobalt atom of vitamin B12 such that the activity of vitamin B12–dependent enzymes is decreased?
N20
methionine synthetase is neccesary for the formation of
myelin
thymidylate synthetase is important for
DNA synthesis
Which inhaled gas could lead to spontaneous abortion, bone marrow depression, and neurologic disturbances?
N20
Chronically Inhalation of N2O causes
neuropathy characterized by sensorimotor polyneuropathy which is associated with Vit B12 enzyme interference
The oxygen requirements of the __________decrease more than those of other organs
heart
Decreased oxygen requirements would protect tissues from _________ that might result from decreased oxygen delivery due to drug-induced decreases in perfusion pressure.
ischemia
Decreases in total body oxygen requirements reflects a
depressed metabolism
alveolar ventilation is principally responsible for the elimination of
enflurane and isoflurane (presumably also desflurane and sevoflurane)
Which gases are known to participate in the chlorine-mediated catalytic destruction of the ozone layer?
isoflurane, enflurane, and halothane
Which gases produce CF3O2 radicals?
Desflurane and sevoflurane
Which gas is a prominent contributor to both ozone destruction as well as the greenhouse effect?
N2O
The gas with the greatest green house effect is
Desflurane
desflurane run at 1 to 2 L of fresh gas flow produces 58 to 116 days’ worth of average auto emissions.
Desflurane demonstrates roughly 26 and 13 times the global warming potential of sevoflurane and isoflurane, respectively.
The gas with the lowest green house effect is
sevoflurane (2 L fresh gas flow) and isoflurane (1-2 L fresh gas flow) produce the equivalents of 4.3 and 4.8 to 9.6 days of average auto emissions
Proposed mechanisms for limiting the environmental impact of inhalational agents include
closed-circuit anesthetics,
low-flow administration of the less environmentally detrimental inhalational agents
total intravenous anesthetic techniques.
The use of propofol in place of inhalational agents
