General Anesthesia — MCQs

General Anesthesia Indian Medical PG Practice Questions and MCQs

Question 511: Which of the following inhalational agents sensitizes myocardium to catecholamines?

A. Ether
B. Isoflurane
C. Sevoflurane
D. Halothane (Correct Answer)

Explanation: ***Halothane*** - **Halothane** significantly sensitizes the myocardium to the dysrhythmogenic effects of **exogenous and endogenous catecholamines**, leading to an increased risk of ventricular arrhythmias. - This effect is due to its interaction with myocardial ion channels and adrenergic receptors, making the heart more susceptible to the arrhythmogenic actions of **norepinephrine** and **epinephrine**. *Ether* - **Diethylether** does not significantly sensitize the myocardium to catecholamines; in fact, it tends to have a more stable cardiovascular profile in this regard. - While it can cause some sympathetic stimulation, its arrhythmogenic potential with catecholamines is much lower compared to halothane. *Isoflurane* - **Isoflurane** has a minimal effect on myocardial sensitization to catecholamines, making it a safer option for patients with pre-existing cardiac conditions or those requiring exogenous catecholamine administration. - It maintains cardiac rhythm stability much better than halothane in the presence of adrenergic stimulation. *Sevoflurane* - **Sevoflurane**, similar to isoflurane, causes very little myocardial sensitization to catecholamines and is considered to be a **cardiac-friendly** inhalational agent. - It maintains **hemodynamic stability** and has a low incidence of arrhythmias even with concurrent use of epinephrine.

Question 512: Stage of analgesia in anaesthesia is ?

A. Stage-2
B. Stage-4
C. Stage-3
D. Stage-1 (Correct Answer)

Explanation: ***Stage-1*** - This stage is known as the **stage of analgesia** or disorientation, lasting from the initial administration of anesthetic agents to the loss of consciousness. - During this stage, the patient may experience **analgesia** (pain relief) and amnesia, though they are still conscious. *Stage-2* - This is the **stage of delirium**, characterized by excitement, involuntary movements, and irregular breathing. - Patients are at risk of **laryngospasm** and vomiting during this stage, making it crucial to transition through it quickly. *Stage-4* - This is the **stage of medullary depression** or respiratory arrest, indicating an overdose of anesthetic. - It is characterized by severe cardiovascular and respiratory depression, leading to **circulatory collapse** and death if not immediately rectified. *Stage-3* - This is the **stage of surgical anesthesia**, subdivided into four planes based on depth of anesthesia, ranging from light to deep surgical anesthesia. - Key signs include regular respiration, loss of reflexes, and muscle relaxation, making it suitable for **surgical procedures**.

Question 513: Which of the following inducing agent has analgesic property?

A. Enflurane
B. Halothane
C. Sevoflurane
D. Nitrous oxide (Correct Answer)

Explanation: ***Nitrous oxide*** - **Nitrous oxide** has significant **analgesic properties** due to its action on opioid receptors and NMDA receptor antagonism. - It is frequently used as an adjuvant to other inhalational anesthetics to reduce their required dose and provide pain relief. *Enflurane* - While an inhalational anesthetic, **enflurane** primarily provides **anesthesia** and **muscle relaxation** with minimal analgesic properties at clinically relevant concentrations. - It was associated with central nervous system stimulation (seizures) and is rarely used today. *Halothane* - **Halothane** is a potent volatile anesthetic that provides **muscle relaxation** and **anesthesia** but has very poor analgesic properties. - Its use has largely been replaced due to concerns about **hepatotoxicity**. *Sevoflurane* - **Sevoflurane** is a commonly used volatile anesthetic known for its rapid onset and offset, making it suitable for induction and maintenance of anesthesia. - However, its primary effect is **anesthesia** and it has very **limited analgesic properties** on its own.

Question 514: Which of the following anesthetic agent can cause adrenocortical suppression?

A. Halothane
B. Ketamine
C. Etomidate (Correct Answer)
D. Propofol

Explanation: ***Etomidate*** - Etomidate is a common **IV anesthetic** that causes dose-dependent, reversible **adrenocortical suppression** by inhibiting the enzyme **11β-hydroxylase**. - This enzyme is crucial for the synthesis of **cortisol** and other adrenal steroids, leading to a temporary decrease in their production, which can be clinically relevant in critically ill patients. *Halothane* - Halothane is an **inhaled anesthetic** known for its potential to cause **hepatotoxicity** (halothane hepatitis) but is not directly associated with adrenocortical suppression. - Its primary cardiovascular effect is **myocardial depression**, leading to reduced cardiac output and hypotension. *Ketamine* - Ketamine is a **dissociative anesthetic** that generally has minimal effects on the adrenal cortex and can even cause a **sympathomimetic effect**, leading to increased heart rate and blood pressure. - It is known for its **bronchodilatory** properties and is often used in patients with asthma or in situations where hemodynamic stability is crucial. *Propofol* - Propofol is a widely used **IV anesthetic** that often causes **hemodynamic depression** (hypotension) and respiratory depression but does not directly induce adrenocortical suppression. - It is rapidly metabolized and is associated with a clear-headed recovery, making it suitable for outpatient procedures.

Question 515: Which of the following inhalational agent is contraindicated in a patient with history of epilepsy -

A. Enflurane (Correct Answer)
B. Isoflurane
C. Sevoflurane
D. Halothane

Explanation: ***Enflurane*** - **Enflurane** is known to cause **epileptiform EEG changes** and seizures, especially at high concentrations or in the presence of hypocarbia. - This proconvulsant effect makes it contraindicated in patients with a history of **epilepsy** due to the risk of inducing or exacerbating seizure activity. *Isoflurane* - **Isoflurane** is generally considered safe in patients with epilepsy as it has **minimal proconvulsant activity** and can even have anticonvulsant properties. - It does not typically produce epileptiform EEG patterns or clinical seizures. *Sevoflurane* - **Sevoflurane** is also considered safe in epileptic patients and is widely used for induction and maintenance of anesthesia. - While there have been reports of seizure-like activity during **Sevoflurane** induction, these are rare and usually resolve quickly without long-term complications. *Halothane* - **Halothane** is largely historical and not commonly used today due to its association with **hepatotoxicity** and cardiac dysrhythmias. - It does not typically induce seizures and historically was not contraindicated in patients with epilepsy based on seizure risk.

Question 516: Heart is not sensitized by –

A. Chloroform
B. Halothane
C. Diethyl–ether (Correct Answer)
D. None of the above

Explanation: ***Diethyl–ether*** - Diethyl ether does not significantly **sensitize the myocardium to catecholamines**, making it less prone to inducing arrhythmias compared to other volatile anesthetics. - Its mechanism of myocardial depression is more subtle and generally involves a **direct negative inotropic effect** rather than arrhythmogenesis. *Chloroform* - Chloroform is known to **sensitize the heart to adrenaline (epinephrine)**, increasing the risk of potentially fatal **cardiac arrhythmias**, including ventricular fibrillation. - Its use has been largely abandoned due to this significant cardiac toxicity and other adverse effects like **hepatotoxicity**. *Halothane* - Halothane potentilaly **sensitizes the myocardium to catecholamines**, leading to an increased incidence of **arrhythmias**, especially when exogenous epinephrine is administered. - This effect contributes to its less favorable cardiac safety profile compared to newer inhaled anesthetics like isoflurane or desflurane.

Question 517: All are features of emergence delirium with ketamine anesthesia except:-

A. No hallucination
B. Auditory, proprioceptive and confusional illusions
C. Cortical blindness (Correct Answer)
D. Visual illusions

Explanation: **Cortical blindness** - **Cortical blindness** is a rare neurological condition resulting from damage to the **visual cortex** in the brain, leading to an inability to process visual information. It is not typically associated with ketamine emergence delirium. - While ketamine can cause visual disturbances, true cortical blindness is not a characteristic feature of **emergence delirium**. *Auditory, proprioceptive and confusional illusions* - Ketamine emergence delirium is well-known for causing various **illusions**, including auditory, proprioceptive, and confusional experiences, due to its dissociative effects on the central nervous system. - Patients may experience distorted perceptions of sound, body position, and their surroundings during recovery from anesthesia. *No hallucination* - This statement is incorrect because **hallucinations** are a common feature of ketamine emergence delirium, particularly vivid and sometimes disturbing visual or auditory hallucinations. - Ketamine's mechanism, involving NMDA receptor antagonism, can lead to these profound perceptual alterations. *Visual illusions* - **Visual illusions** are a very common symptom of ketamine emergence delirium, where patients may perceive objects or their environment in a distorted or unreal way. - These illusions contribute to the disorientation and agitation experienced during recovery from ketamine anesthesia.

Question 518: A patient with mitral stenosis is having surgery tomorrow. There is some liver compromise. Which of the following inhalational agents is preferred?

A. Enflurane
B. Xenon
C. Sevoflurane (Correct Answer)
D. Halothane

Explanation: ***Sevoflurane*** - **Sevoflurane** is preferred due to its **minimal hepatic metabolism** and rapid elimination, making it a safer option in patients with **liver compromise**. - It maintains **cardiovascular stability**, which is beneficial in mitral stenosis and avoids the arrhythmogenic potential seen with other agents. *Enflurane* - **Enflurane** is extensively metabolized in the liver, leading to the production of inorganic fluoride ions, which can cause **renal toxicity**. - It can also induce a decrease in **hepatic blood flow**, exacerbating existing liver compromise. *Xenon* - While **Xenon** has excellent cardiovascular stability and minimal metabolism, its **high cost** and **limited availability** make it an impractical choice for routine use. - Its anesthetic potency is relatively low, requiring **higher concentrations** for surgical anesthesia. *Halothane* - **Halothane** is associated with a significant risk of **halothane-induced hepatitis** due to its extensive hepatic metabolism and the production of toxic metabolites. - It can also cause **cardiac depression** and **arrhythmias**, which are undesirable in patients with mitral stenosis.

Question 519: Which of the following non-depolarising muscle relaxant is excreted maximally through the kidney?

A. Gallamine (Correct Answer)
B. Rocuronium
C. Vecuronium
D. Pancuronium

Explanation: ***Gallamine*** - **Gallamine** is predominantly cleared by the kidneys, with **80-100% of the unchanged drug** excreted via **renal elimination**. - Its use can be problematic in patients with renal impairment due to the risk of **prolonged paralysis** and **tachycardia**. *Rocuronium* - Rocuronium is primarily eliminated through the **bile** and **liver**, with a small fraction excreted renally. - While some renal excretion occurs, it is not the main pathway, making it a safer option than gallamine in patients with renal dysfunction. *Vecuronium* - Vecuronium undergoes significant **hepatic metabolism** to inactive metabolites, with subsequent biliary and renal excretion. - Its elimination half-life can be extended in patients with **liver disease**, but **renal excretion is minimal** for the parent drug. *Pancuronium* - **Pancuronium** is mainly eliminated by a combination of **hepatic metabolism** and **renal excretion**. - Approximately **40-60%** of the drug is excreted unchanged in the urine, but a substantial portion is metabolized by the liver.

Question 520: All of the following causes decrease in CMRO2, CBF and ICP except:-

A. Etomidate
B. Propofol
C. Thiopentone
D. Ketamine (Correct Answer)

Explanation: ***Ketamine*** - Ketamine is a dissociative anesthetic that typically causes an **increase in cerebral blood flow (CBF)** and **intracranial pressure (ICP)**, while its effect on cerebral metabolic rate of oxygen (CMRO2) can be variable but often does not decrease significantly. - It works by antagonizing **NMDA receptors**, inducing a state of dissociation rather than global cerebral depression. *Etomidate* - Etomidate is an anesthetic agent that effectively **decreases CMRO2, CBF, and ICP**, making it suitable for neurosurgical procedures. - Its mechanism involves enhancing **GABA-A receptor activity**, leading to global central nervous system depression. *Propofol* - Propofol is a commonly used intravenous anesthetic that significantly **reduces CMRO2, CBF, and ICP**. - It primarily acts on **GABA-A receptors** to induce sedation and anesthesia, making it a good choice for patients with elevated ICP. *Thiopentone* - Thiopentone, a barbiturate, is known to produce a dose-dependent decrease in **CMRO2, CBF, and ICP**. - It also enhances **GABA-A receptor-mediated inhibition**, resulting in cerebral vasoconstriction and metabolic suppression.

Practice by Chapter

History of Anesthesia

Practice Questions

Preoperative Evaluation

Practice Questions

Pharmacology of Inhalational Anesthetics

Practice Questions

Pharmacology of Intravenous Anesthetics

Practice Questions

Neuromuscular Blocking Agents

Practice Questions

Airway Management

Practice Questions

Endotracheal Intubation

Practice Questions

Difficult Airway Algorithms

Practice Questions

Intraoperative Monitoring

Practice Questions

Depth of Anesthesia Monitoring

Practice Questions

Emergence from Anesthesia

Practice Questions

Postoperative Care

Practice Questions

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