General Anesthetics: Properties and Uses

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Questions and Answers

Which statement best describes the mechanism by which volatile anesthetics exert their effects on neuronal activity?

Volatile anesthetics selectively enhance excitatory neurotransmission by increasing glutamate release at presynaptic terminals, leading to a generalized increase in neuronal firing.
Volatile anesthetics act primarily by modulating the function of ligand-gated ion channels, such as the GABAa receptor, and by interacting with lipid membranes to alter ionic currents. (correct)
Volatile anesthetics primarily target voltage-gated sodium channels, prolonging their inactivation and thereby suppressing action potential propagation in nociceptive pathways.
Volatile anesthetics directly inhibit the release of acetylcholine at the neuromuscular junction, leading to muscle relaxation and indirectly reducing neuronal activity in the brain.

A patient undergoing an open-appendectomy experiences a sudden onset of tachycardia, rigidity, and elevated end-tidal CO2 levels shortly after the administration of succinylcholine and isoflurane. Which intervention is MOST critical?

Administer intravenous lidocaine to suppress ventricular arrhythmias, while continuing the surgical procedure under regional anesthesia.
Immediately administer dantrolene, discontinue the triggering agents, administer 100% oxygen, and manage hyperkalemia, acidosis and provide cooling measures. (correct)
Administer a rapid sequence induction with propofol and rocuronium to deepen the anesthetic plane and prevent further muscle fasciculations.
Administer a bolus of intravenous saline to correct the presumed hypovolemia, while titrating inhaled sevoflurane to maintain adequate depth of anesthesia.

A researcher is investigating the effects of a novel inhalation anesthetic on cerebral blood flow (CBF) and intracranial pressure (ICP) in a population of traumatic brain injury patients. Which finding would raise the greatest concern:

The anesthetic leads to a dose-dependent increase in CBF and ICP due to vasodilation of cerebral vasculature. (correct)
The anesthetic causes a mild decrease in CBF while maintaining stable ICP, suggesting preserved cerebral autoregulation.
The anesthetic significantly reduces CBF and ICP, potentially improving cerebral perfusion pressure in the short term.
The anesthetic has no impact on CBF or ICP, indicating a lack of central nervous system penetration.

An anesthesiologist is preparing to administer a combination of nitrous oxide and sevoflurane to a patient with a known history of severe chronic obstructive pulmonary disease (COPD). Which adjustment to the standard anesthesia protocol is MOST warranted to account for second gas effect?

Administer a higher fraction of inspired oxygen (FiO2) during both induction and emergence to counteract potential hypoxemia. (B) Signup and view all the answers

Which of the following inhaled anesthetics is most likely to cause tonic-clonic muscle spasms as a rare but significant adverse effect, particularly at deeper levels of anesthesia?

Enflurane (D) Signup and view all the answers

A 78-year-old patient with severe hypothyroidism is scheduled for elective hip replacement under general anesthesia. Considering the effects of age and thyroid status on MAC, which action is MOST appropriate?

Reduce the initial dose of the volatile anesthetic by 30-50% and titrate carefully, monitoring depth of anesthesia closely. (B) Signup and view all the answers

A patient undergoing prolonged anesthesia with isoflurane experiences a significant drop in mean arterial pressure (MAP). Which mechanism is MOST directly responsible for this effect?

Vasodilation due to inhibition of sympathetic nerve activity and reduced vascular smooth muscle tone. (D) Signup and view all the answers

Which pre-anesthetic medication is LEAST likely to cause significant respiratory depression when administered in combination with an inhaled anesthetic?

Atropine (C) Signup and view all the answers

A researcher aims to develop a novel inhaled anesthetic agent with properties mirroring the 'ideal' anesthetic. Which combination of characteristics would be MOST desirable?

Rapid induction, low blood/gas partition coefficient, potent analgesic, minimal cardiovascular and respiratory effects. (C) Signup and view all the answers

During emergence from anesthesia following a lengthy neurosurgical procedure, a patient exhibits signs of diffusion hypoxia. What is the MOST appropriate immediate intervention?

Administer 100% oxygen via a non-rebreather mask for several minutes to counteract the reduction in alveolar oxygen tension. (B) Signup and view all the answers

A patient with severe aortic stenosis is scheduled for non-cardiac surgery. Which inhaled anesthetic should be avoided or used with extreme caution due to its potential to cause significant reflex tachycardia, which can be poorly tolerated in aortic stenosis?

Desflurane (B) Signup and view all the answers

Which inhaled anesthetic is most associated with the potential for significant fluoride-induced nephrotoxicity due to its extensive hepatic metabolism?

Methoxyflurane (B) Signup and view all the answers

A patient with elevated intracranial pressure (ICP) requires general anesthesia. Which of the following inhaled anesthetics would be LEAST desirable for maintaining cerebral perfusion pressure (CPP)?

Desflurane, due to its tendency to cause cerebral vasodilation and increase ICP. (B) Signup and view all the answers

A researcher is investigating the Meyer-Overton rule in the context of novel halogenated anesthetics. Which physicochemical property would be MOST predictive of anesthetic potency according to this rule?

The agent's partition coefficient between lipid and gas phases. (B) Signup and view all the answers

A patient undergoing general anesthesia with sevoflurane experiences a transient episode of bronchospasm. Which of the pre-anesthetic medications would be MOST appropriate to administer to alleviate this condition?

Atropine. (C) Signup and view all the answers

In a study comparing different volatile anesthetics, researchers find that anesthetic X has a MAC value of 0.5% while anesthetic Y has a MAC value of 2%. Which of these anesthetics is more potent and what does this imply about the dosage required?

Anesthetic X is more potent, implying that a lower dosage is required to achieve the same level of anesthesia compared to Anesthetic Y. (A) Signup and view all the answers

An anesthesiologist is administering balanced anesthesia using intravenous induction agents followed by maintenance with an inhalation anesthetic. What is the PRIMARY rationale for this approach?

To achieve rapid induction with intravenous agents while maintaining anesthesia with the desirable properties of inhaled anesthetics. (C) Signup and view all the answers

A patient with a history of opioid abuse requires general anesthesia. What is the MOST important consideration regarding pre-anesthetic medication?

Administer a higher-than-normal dose of opioid to manage potential opioid tolerance and prevent withdrawal. (B) Signup and view all the answers

What best describes the effect of increased ventilation rate on the induction rate of soluble vs insoluble anesthetic gases.

Increases the rate of loss of consciousness more for soluble gases than insoluble gases. (B) Signup and view all the answers

A patient with a known allergy to ester-type local anesthetics requires pre-anesthetic sedation. Which of the following would be the safest choice?

Diazepam (A) Signup and view all the answers

Flashcards

Goals of general anesthesia?

Preserving the life of the patient, providing an adequate surgical field, and blocking pain.

Characteristics of an ideal general anesthetic?

Smooth induction, amnesia, inhibits reflexes, muscle relaxation, analgesia, rapid emergence, and no lasting adverse effects.

What is 'balanced anesthesia'?

Combines multiple drugs to maximize benefits and minimize side effects, often with IV induction and inhaled maintenance.

Purpose of preanesthetic meds?

To decrease anxiety, facilitate smooth induction, provide amnesia, relieve pain, and minimize side effects.