Inhalation anesthesia 3 Flashcards
T/F: MAP decreases as concentration of desflurane, sevoflurane, and isoflurane increases, in a dose dependent manner.
True
T/F: Increase in MAP reflects a decrease in systemic vascular resistance (SVR).
False
T/F: Desflurane decreases MAP by decreasing CO/ direct myocardial depression.
False (Halothane)
____ activates the sympathetic nervous system and increases SVR, which can lead to an increase in CVP and arterial pressure.
N2O
Alterations in HR from inhaled anesthetic gases are a result of several variable. What are they?
Antagonism of SA node automaticity
Modulation of baroreceptor reflex activity
Sympathetic nervous system activation via tracheopulmonary and systemic receptors.
T/F: Incremental increases in delivered concentrations of inhaled agents increase heart rates in patients.
True
T/F: Responses in heath rate occurs at unique concentration for each agent.
True
What is the heart rate response of Forane?
Starting at concentrations 0.25 MAC, a linear, dose dependent increase in HR is observed
What is the heart rate response of Desflurane?
Minimal increase in HR at concentrations < 1 MAC
At concentrations ≥ 1 MAC , a linear, dose dependent increase in HR is observed
What is the heart rate response of Sevoflurane?
HR does not increase until concentrations >1.5 MAC
T/F: Cardiac index is minimally influenced by inhalation agents.
True
T/F: TEE demonstrates that desflurane produces minor increase in EF compared with awake measurements.
True
What gas would you avoid if pt. is known to have congenital long QT syndrome.
Sevoflurane (Safe if on B-blocker therapy)
T/F: No data effectively demonstrates a difference in outcomes between inhalation and IV opioid anesthesia.
True
What is coronary steal?
a reduction in perfusion of ischemic myocardium with simultaneous improvement of blood flow to nonischemic tissue.
What might forane do to the heart vessels?
dilate small-diameter coronary arteries might cause a susceptible patient to develop regional myocardial ischemia as a result of coronary vasodilatation…. Questionable validity.
What is ischemic preconditioning?
Protective benefits of volatile anesthetics against myocardial ischemia in setting of compromised regional perfusion.
Not related to alteration of myocardial oxygen supply-demand ratio.
Ischemic preconditioning has two periods. What are they?
First period
1-2 hours after the conditioning episode.
Second period
Benefit reappears 24° later and can last as long as 3 days.
What confers the protective activity to ischemic preconditioning?
Opening of mitochondrial adenosine triphosphate (ATP)-sensitive potassium channels (KATP) is the crucial event that confers the protective activity.
T/F: Patients given a general anesthetic and who are on amiodarone can have significant dysrhythmias intraoperatively or postoperatively
True
What do you do if atropine is not working for bradycardia?
Isoproterenol infusion
AV sequential pacing
How long can Amiodarone and its major metabolites be detectable in plasma.
9 months.
_________ respiratory rate and _______ tidal volume as anesthetic concentration ______.
Increased, decreased, increases
Minute ventilation is relatively preserved, but the decreased TV leads to greater ______ space ventilation relative to alveolar ventilation.
dead
T/F: Gas exchange becomes more efficient as anesthetic depth increases.
False (less)
T/F:PaCO2 increases proportionate to anesthetic depth.
True
Ventilatory stimulation response evoked by arterial hypoxemia is ________ by volatile anesthetics.
blunted
Dose related blunting of the respiratory response to _________ CO2.
increased
Cephalad _________ of the diaphragm and inward displacement of the rib cage occur from enhanced expiratory muscle activity. This results in a ________ in FRC.
displacement, reduction
T/F:Atelectasis occurs in dependent areas of the lung and to a greater extent when spontaneous ventilation is permitted.
True
T/F:Inhalation agents have major effect on the principle of “hypoxic pulmonary vasoconstriction”.
False (Limited)
T/F: In the absence of bronchoconstriction, bronchodilating properties of inhalation agents are limited.
True
What are the non-pungent inhalation gases?
Sevoflurane, halothane, and nitrous oxide
What are the pungent inhalation gases?
Desflurane (>6% for mask induction) and forane
T/F: Volatile agents decrease cerebral metabolic rate of O2 consumption in a dose dependent manner with N20 being the exception ~ increase CMRO2
True
Nitrous oxide has what effect on the CNS?
Causes cerebral vasodilation
Increases CMRO2
Coadministration of opioids, barbiturates, or propofol (not ketamine) counteract these effects.
What occurs to the ICP after a MAC of greater than 1 with colatile anesthetics.
Increases
T/F: Autoregulation is impaired at concentrations < 1 MAC.
True
What is the most sensitive evoked potential of the CNS when using volatile agents?
Visual
What is the most resistant evoked potential of the CNS when using volatile agents?
brainstem
Evoked potentials may be abolished at ___ MAC.
1
N20 and 0.5 MAC inhalation also abolish _______ potential.
evoked
T/F: Low concentrations 0.2-0.3 MAC decrease the reliability of motor evoked potentials.
True
What level must MAC get to for isoelectric pattern to predominate?
1.5-2
Sevoflurane and ethrane may be associated with _________ activity on the EEG, especially at high concentrations.
epleptiform
T/F: Inhalation agents produce a dose dependent skeletal muscle relaxation and enhance the activity of neuromuscular blocking drugs.
True
What least to greatest what is the likely hood that a inhalation agent will trigger MH.
Desflurane<Halothane
T/F: Immune mediated liver injury can occure with all inhalation agents?
True
What is the causative agent thought to cause liver damage with inhalation agents?
trifluoroacetate metabolite
What inhalation agent show to increase or maintain hepatic blood flow?
Iso, des, sevo
What will methoxyflurane produce and what does it cause?
inorganic fluoride, and nephrotoxicity
Sevoflurane should only have how many hours of low fresh gas (<2 L/min)?
2 hours of MAC
What does Nirtrous Oxide do and what does it cause?
inactivates methionine synthase, enzyme that regulate vitamin b12 and folate metabolism
When is N2O contraindicated?
Preexisting vitamin B12 deficiency or underlying critical illness
T/F: Full desiccation of conventional carbon dioxide absorbents containing sodium and potassium hydroxide causes degradation and carbon monoxide production from all volatile anesthetic agents regardless of temperature.
True
T/F: Low fresh gas flow rates (exceeding normal minute ventilation) accelerate the desiccation of CO2 absorbents, and thus accelerated degradation of inhaled agents.
False (High)
What determines the concentration of the anesthetic gas leaving the vaporizer?
Relative flow togas through the reservoir channel versus the bypass channel
How is each inhalation gas container unique?
Temperature compensated
Calibrated for individual anesthetic d/t differing vapor pressures
Tilting or overfilling may lead to overdose if liquid anesthetic gets into bypass channel
Vapor pressure of desflurane at sea level is ___mm Hg at __°C
700, 20
T/F: A variable bypass vaporizer is used for desflorane.
False (Heated Vaporizer Tec 6)
What is another name for desflorane?
Suprane
T/F: At high altitudes, the partial pressure of desflurane will be lower at a give Tec 6 vaporizer setting and output concentration will be lower, leading to underdosing if no adjustments are made to account for higher altitude.
True
