Exam 2: Inhalational Agents Flashcards
Characteristics of ether:
Easy to make and administer
Potent
Not organotoxic
Highly flammable
Characteristics of chloroform:
Pleasant odor and nonflammable Hepatotoxin Severe CV depressant High incidence of death Difficult to administer
First halogenated hydrocarbon anesthetic:
Fluroxene; withdrawn due to organ toxicity
Characteristics of methoxyflurane:
Nonexplosive, nonflammable halogenated methyl ethyl ether
Most potent of volatile agents: MAC 0.16
B/G coeff 12
Metabolites nephrotoxic
Areas affected to produce hypnosis/sedation and immobility with GA:
Hypnosis/sedation: cortex, hippocampus
Immobility: spinal cord
Meyer-Overton theory:
Absorption of anesthetic molecules expands hydrophobic region of lipid bilayer, distorts membrane, alters membrane function
Fluidization theory:
Binding of anesthetic molecules to lipid bilayer modifies membrane structures, alters conductance or induces conformational change in channels
Lipid theory:
Demonstrates a correlation between anesthetic potency and lipid solubility
Protein/lipid interface theory:
Anesthetics displace lipids necessary for protein function
Protein receptor theory:
Anesthetics occupy protein receptor sites and block ionic conductance during membrane excitation
Guedel’s four stages of anesthesia:
- Amnesia/analgesia
- Delirium/excitement
- Surgical anesthesia (4 planes)
- Overdose
Pupils/resp pattern/pulse/BP in stage I:
Pupils normal and reactive
Respirations regular, small?
Pulse irregular
BP normal
Pupils/resp pattern/pulse/BP in stage II:
Pupils dilated, overreactive to light
Respirations irregular
Pulse irregular and fast
BP high
Pupils/resp pattern/pulse/BP in stage III:
Pupils normal, unresponsive
Respirations fast, small
Pulse steady and slow
BP normal
Pupils/resp pattern/pulse/BP in stage IV:
Pupils dilated and unresponsive
Respirations minimal and irregular
Pulse weak and thready
BP low
Only inorganic anesthetic gas:
Nitrous oxide
N2O most commonly used in combination with:
Induction agent, NMB, opioids, and/or VA
C2HClBrF3 is:
Halothane
C2HOClF5 is:
Isoflurane
C3H2OF6 is:
Desflurane
C4H2OF7 is:
Sevoflurane (with SEVen F’s)
Lower weight halogens add:
Less potency than higher weight ones
Chloride substitution effects on VA:
More stability, but myocardial depression
Fluoride substitution effects on VA:
Reduction in flammability, but also potential for renal damage
Factors that do not affect MAC:
Species Sex Gender Duration of anesthesia Acid-base disturbances PaO2
Factors that decrease MAC:
↑ age Hypothermia Hyponatremia Hypotension Hypoxemia Anemia Pregnancy Drugs (benzos, opioids, ketamine, α2 agonists, LAs) ETOH (acutely)
Factors that increase MAC:
Hyperthermia
CNS stimulants
Less than 1 y/o
% of MAC that will make 95% of patients immobile to stimulus:
1.3 * MAC
MAC awake is:
The concentration that permits voluntary response
MAC awake of des/sevo/iso:
1/3 MAC
MAC awake of halothane:
1/2 MAC
MAC awake of N2O:
60% of MAC
Mechanism by which halothane potentiates arrythmias:
↓ SA node depolarization; prone to junctional rhythms
↓ AV node, purkinje conduction
Epi max doses when using halothane:
10ml 1:100k or 20ml 1:200k within 10 min
30ml 1:100k or 60ml 1:200k within an hour
Presentation of VA-associated hepatitis:
Fever, anorexia, nausea, chills, myalgias, rash, fever, arthralgia, and eosinophilia –> jaundice 3-6 days later
Risk factors for VA-associated hepatitis:
Prior exposure #1 Age > 40 Obesity Female gender Mexican ethnicity Genetic susceptibility Multiple brief procedures in short amt of time Enzyme induction
Enzyme that metabolizes VAs:
CYP 450 2E1
Pathogenesis of VA-associated hepatitis:
2E1 oxidizes VAs to yield reactive intermediates that bind covalently to hepatocellular macromolecules, triggering immunologic response –> massive hepatic necrosis
