RE Chapter 8 Flashcards
Anesthetic effect is lost if carbon atom chain exceeds ______ carbon atoms
4 or 5 (5 angstroms)
All commonly used inhalation agents are (select two) A. Ethers B. Amides C. Esters D. Aliphatic hydrocarbons
A & D
Halogenation of ethers and hydrocarbons influences what 4 things?
- potency
- arrythmogenic properties
- flammability
- chemical stability
What is the rate of inhaled anesthetic degradation?
sevo=iso > des > N2O
How are all inhaled anesthetics biodegraded?
Hepatic metabolism through oxidation (phase 1 reaction)
What is the Meyer-Overton rule?
Lipid solubility is directly proportional to potency.
What is the definition of “general anesthesia”?
A drug’s capacity to induce and sustain unconsciousness, amnesia, analgesia, and immobility.
What is the definition of MAC?
The minimum concentration at equilibrium in which 50% of subjects will not respond to a painful stimulus.
Isoflurane MAC in 60-70% N2O
0.56
Desflurane MAC in 60-70% N2O
2.38
Sevoflurane MAC in 60-70% N2O
0.66
What are factors that reduce MAC?
Increased age, hypothermia, depressant meds, alpha2 agonists, acute alcohol intox, hypoxemia, anemia, hypotension, pregnancy,
What are factors that increase MAC
young age, hyperthermia, hyperthyroidism, chronic ETOH consumption, acute amphetamine admin, red-headed females.
What is the effect of volatile anesthetics on CMRO2?
Decreases in a dose-dependent manner.
What is uncoupling in relation to CMRO2 and CBF?
When decreases in CMRO2 are accompanied by increases in CBF
What is the effect of N2O on CBF & CMRO2
Increases both CBF & CMRO2
Uncoupling still occurs because increase in CMRO2 exceeds increase in CBF
Which evoked potentials are the most and least sensitive to volatile anesthetics?
Most: visual evoked potentials
Least: brainstem-evoked potentials
A ______(increase / decrease) in latency and a _________ (increase / decrease) amplitude reflect ischemia or secondary to volatile anesthetic.
increase in latency
decrease in amplitude
Which two volatile anesthetics are linked to emergence delirium in children?
Sevoflurane & Desflurane
Which volatile anesthetic decreases MAP the least?
Isoflurane
Of desflurane, isoflurane, & sevoflurane which decreases SVR the least?
sevoflurane
What does N2O do to SVR?
Activates the SNS leading to an increase in SVR, this may lead to increases in CVP and ABP
When N2O is used with volatile anesthetics it may support but may cause cardiac depression when used with opioids because it produces what effect?
Negative inotropic
What are inhaled anesthetics three mechanisms for altering HR?
- antagonism of SA node automaticity
- modulation of baroreceptor reflex activity
- SNS activation via activation of tracheopulmonary systemic receptors.
What is coronary steal?
reduction of perfusion from ischemic myocardium and improvement of blood flow to non ischemic tissue
What is ischemic preconditioning?
A cascade of cellular events that protect the myocardium from ischemic and reperfusion insult.
Volatile anesthetics do this.
What are two mechanisms of preconditioning?
- improves contractile function
2. reduces calcium overload by preventing down-regulation of major sarcoplasmic reticulum Ca+ protiens.
How does N2O affect pulmonary vascular resistance?
increases it
-Only small increases with normal PVR, more notable in patients with pulmonary HTN
How do volatile anesthetics affect PVR?
Most decrease it
Desflurane at 1.6 MAC increases
