CNS 4 Flashcards
- ___ (wood alcohol), a constituent of windshield cleaners and “canned heat,” is sometimes ingested intentionally.
- Intoxication causes visual dysfunction, gastrointestinal distress, shortness of breath, loss of consciousness, and coma.
- is metabolized to formaldehyde and formic acid, which causes severe acidosis, retinal damage, and blindness.
Methanol
The formation of formaldehyde is reduced by prompt intravenous administration of ____, an inhibitor of alcohol dehydrogenase, or ____, which competitively inhibits alcohol dehydrogenase oxidation of methanol.
- fomepizole
- ethanol
A 45-year-old moderately obese man has been drinking heavily for 72 h. This level of drinking is much higher than his regular habit of drinking 1 alcoholic drink per day. His only significant medical problem is mild hypertension, which is adequately controlled by metoprolol. With this history, this man is at significant risk for
Arrhythmia
A 42-year-old man with a history of alcoholism is brought to the emergency department in a confused and delirious state. He has truncal ataxia and ophthalmoplegia. The most appropriate immediate course of action is to administer diazepam plus
Thiamine
A freshman student (weight 70 kg) attends a college party where he rapidly consumes a quantity of an alcoholic beverage that results in a blood level of 500 mg/dL. Assuming that this young man has not had an opportunity to develop tolerance to ethanol, his present condition is best characterized as
(A) Able to walk, but not in a straight line
(B) Alert and competent to drive a car
(C) Comatose and near death
(D) Sedated with increased reaction times
(E) Slightly inebriated
Comatose and near death
A state of unconsciousness, analgesia, and amnesia, with skeletal muscle relaxation and loss of reflexes
General anesthesia
Drugs used as general anesthetics are ___ with actions that can be induced and terminated more rapidly than those of conventional sedative-hypnotics.
CNS depressants
STAGES OF ANESTHESIA
• The patient has decreased awareness of pain
• Sometimes with amnesia
• Consciousness may be impaired but is not lost.
Stage 1: Analgesia
STAGES OF ANESTHESIA • The patient appears to be delirious and excited. • Amnesia occurs • Reflexes are enhanced • Respiration is typically irregular • Retching and incontinence may occur
Stage 2: Disinhibition
STAGES OF ANESTHESIA • The patient is unconscious • Has no pain reflexes • Respiration is very regular • Blood pressure is maintained
Stage 3: Surgical Anesthesia
STAGES OF ANESTHESIA
• The patient develops severe respiratory and cardiovascular depression that requires mechanical and pharmacologic support.
Stage 4: Medullary Depression
Anesthesia protocols commonly include ____ drugs to induce the anesthetic state, ___ anesthetics (with or without intravenous agents) to maintain an anesthetic state, and ____ agents to effect muscle relaxation.
- intravenous
- inhaled
- neuromuscular blocking
As CNS depressants, these drugs usually ____ the threshold for firing of CNS neurons. The potency of inhaled anesthetics is roughly proportional to
their lipid solubility.
increase
Drugs that facilitate γ-aminobutyric acid (GABA)-mediated inhibition at GABAA receptors.
- Inhaled anesthetics,
- barbiturates,
- benzodiazepines,
- etomidate,
- propofol
antagonizes the action of the excitatory neurotransmitter glutamic acid on the N-methyl-Daspartate (NMDA) receptor.
Ketamine
The agents currently used in inhalation anesthesia are ____ (a gas) and several easily vaporized liquid halogenated hydrocarbons, including halothane, desflurane, enflurane, isoflurane, sevoflurane, and methoxyflurane.
nitrous oxide
Anesthesia is terminated by ____ of the drug from the brain to the blood and elimination of the drug through the lungs.
redistribution
Metabolism of these drugs has only a minor influence on the speed of recovery from their anesthetic effect but does play a role in potential toxicity of these anesthetics.
halothane and methoxyflurane
Defined as the alveolar concentration required to eliminate the response to a standardized painful stimulus in 50% of patients. And the potency of inhaled anesthetics is best measured by the
minimum alveolar anesthetic concentration (MAC),
Are myocardial depressants that decrease cardiac output
Enflurane and halothane
causes peripheral vasodilation.
isoflurane, desflurane, and sevoflurane
is less likely to lower blood pressure than are other inhaled anesthetics and has the smallest effect on respiration
Nitrous oxide
may sensitize the myocardium to the arrhythmogenic effects of catecholamines.
Halothane, and isoflurane