General Anesthesia — MCQs

General Anesthesia Indian Medical PG Practice Questions and MCQs

Question 591: Which anesthetic agent does not cause bradycardia?

A. Isoflurane
B. Ketamine (Correct Answer)
C. Thiopentone
D. Halothane

Explanation: ***Ketamine*** - Unlike other anesthetic agents, **ketamine** directly stimulates the sympathetic nervous system and inhibits norepinephrine reuptake, which often leads to **tachycardia** and increased blood pressure, rather than bradycardia. - This sympathetic stimulation makes it a useful agent in trauma or hypovolemic patients where maintaining hemodynamic stability is crucial. *Halothane* - **Halothane** is known to directly depress the myocardium and sensitize the heart to catecholamines, often leading to **bradycardia** and arrhythmogenicity. - It also reduces adrenergic outflow from the central nervous system, further contributing to a slower heart rate. *Isoflurane* - While generally considered more hemodynamically stable than halothane, **isoflurane** can cause **dose-dependent myocardial depression** and a reduction in heart rate at higher concentrations. - It can cause vasodilation, which may initially trigger a reflex tachycardia, but direct myocardial effects can predominate, leading to bradycardia. *Thiopentone* - **Thiopentone**, a barbiturate, causes dose-dependent depression of the central nervous system, including the cardiovascular centers, leading to reduced cardiac output and **bradycardia**. - It also has a direct myocardial depressant effect, contributing to a slower heart rate and hypotension.

Question 592: Which of the following intravenous agents is known to cause pain upon injection?

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

Explanation: ***Propofol*** - **Propofol** is notoriously known to cause significant **pain upon injection**, especially when administered into smaller veins. - This is attributed to its **lipid emulsion formulation** and activation of **TRPA1 receptors** on sensory neurons. *Methohexital* - While **methohexital** can cause localized pain and venous irritation, it is generally less pronounced and less frequent than with propofol. - It is known more for causing **hiccups** and **muscle twitching** upon induction, rather than severe injection pain. *Ketamine* - **Ketamine** typically causes minimal to no pain upon intravenous injection. - Its side effects are often related to its **dissociative anesthetic** properties, such as psychomimetic effects and increased sympathetic activity. *Etomidate* - **Etomidate** is generally considered to be low in causing injection site pain. - Its primary concern is the potential for **adrenocortical suppression** and a high incidence of **myoclonus**.

Question 593: Which organ is most resistant to general anesthesia?

A. Spinal Cord
B. Medulla oblongata
C. Heart (Correct Answer)
D. Liver

Explanation: ***Heart*** - The heart is highly resistant to the direct suppressive effects of **general anesthetics** because its primary function is to maintain circulation, and it has intrinsic automaticity. - While anesthetic agents can influence heart rate and contractility, the heart itself continues to function even at deep anesthetic planes, unlike the brain or spinal cord which are targets of anesthesia. *Spinal Cord* - The spinal cord is particularly sensitive to general anesthetics, as they are crucial in producing the immobility component of anesthesia by **depressing spinal reflexes**. - High concentrations of anesthetics can directly suppress spinal cord activity, leading to muscle relaxation and loss of motor response. *Medulla oblongata* - The medulla oblongata contains vital centers for **respiration** and **cardiovascular control** that are highly sensitive to anesthetic agents. - Anesthetic overdose can lead to profound depression of these centers, resulting in respiratory arrest and severe cardiovascular collapse due to direct effects on neurons located there. *Liver* - The liver is primarily involved in the **metabolism of many anesthetic drugs**, rather than being a direct target for their central depressant effects. - While anesthetic agents can impact hepatic blood flow and function, the liver itself does not exhibit the same level of resistance to the *direct pharmacological effects* of anesthesia as the heart.

Question 594: Historically, which anesthetic agent was considered most effective for uterine relaxation during surgical procedures?

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

Explanation: **Halothane** * **Halothane** was historically well-known for its potent ability to induce **uterine relaxation**, which was crucial for procedures like manual placenta removal or during challenging fetal extraction. * This property, however, also meant that it could cause significant **postpartum hemorrhage** due to uterine atony. * *Sevoflurane* * Sevoflurane provides **moderate uterine relaxation** but is less potent in this regard compared to halothane at equipotent doses. * It is a more modern inhaled anesthetic with a **faster onset and offset** than halothane. * *Nitrous oxide* * **Nitrous oxide** offers very **minimal to no uterine relaxation** and is often used as an adjunct to other anesthetics. * It is an analgesic and weak anesthetic, primarily used for its pain-relieving effects. * *Desflurane* * **Desflurane** also provides **moderate uterine relaxation**, similar to sevoflurane, but is less potent than halothane. * It has a very **rapid onset and offset**, making it suitable for quick adjustments in anesthetic depth, but it is also a respiratory irritant.

Question 595: Which of the following determines the speed of recovery from intravenous anesthesia?

A. Liver metabolism of drug
B. Protein binding of drug
C. Redistribution of the drug from sites in the CNS (Correct Answer)
D. Plasma clearance of the drug

Explanation: ***Redistribution of the drug from sites in the CNS*** - For many intravenous anesthetic agents, **redistribution** from highly perfused central nervous system (CNS) tissues to less perfused peripheral tissues is the primary mechanism for the termination of drug action and recovery from anesthesia. - This rapid decrease in the drug concentration at the site of action (brain) leads to the patient waking up, even before significant metabolism or excretion has occurred. *Liver metabolism of drug* - While liver metabolism is crucial for the **elimination** of many anesthetic drugs from the body, it is typically a slower process and contributes more to the overall drug clearance than to the immediate termination of the anesthetic effect. - Significant metabolism usually occurs after redistribution has already caused the patient to awaken. *Protein binding of drug* - **Protein binding** affects the free fraction of the drug available to act on receptors and to be metabolized or excreted. - However, it does not directly determine the speed of recovery, which is more dependent on the drug's movement between tissue compartments. *Plasma clearance of the drug* - **Plasma clearance** refers to the volume of plasma cleared of the drug per unit time, encompassing both metabolism and excretion. - While important for overall drug removal, it is generally a slower process compared to redistribution in determining the immediate end of intravenous anesthetic action.

Question 596: Which of the following should be considered as the cause of generalized convulsions 20 minutes postoperatively?

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

Explanation: ***Enflurane*** - **Enflurane** is well-known to cause **generalized convulsions** or seizure-like activity during emergence from anesthesia, particularly when inspired concentrations exceed 3.0% or with hypocapnia. - The risk of seizures is a significant reason why enflurane is rarely used in modern anesthetic practice compared to newer volatile agents. *Halothane* - **Halothane** is associated with cardiac arrhythmias and hepatotoxicity but generally does not cause generalized convulsions as a primary side effect. - While it can lower the seizure threshold, overt seizures are not a common complication of halothane administration. *Isoflurane* - **Isoflurane** is associated with CNS depression and can, in rare cases, cause myoclonus, but it is not typically linked to generalized tonic-clonic convulsions. - It is often used in neurosurgery due to its beneficial effects on cerebral blood flow and minimal seizure-inducing potential. *Sevoflurane* - **Sevoflurane**, while capable of causing excitatory movements or myoclonus during induction and emergence, is not a common cause of clear-cut generalized convulsions in healthy patients. - High concentrations in pediatric patients or those with pre-existing seizure disorders might slightly increase the risk of seizure-like EEG changes, but it is less epileptogenic than enflurane.

Question 597: Ketamine is the preferred anesthetic for the following conditions except:

A. Trauma cases that have bled significantly
B. Burn dressing
C. Short operations on asthmatics
D. Hypertensives (Correct Answer)

Explanation: ***Hypertensives*** - Ketamine can cause a significant **increase in blood pressure and heart rate** due to its sympathomimetic effects. - This makes it a less desirable agent for patients with **uncontrolled hypertension**, as it could exacerbate their condition. *Trauma cases that have bled significantly* - Ketamine is preferred in trauma patients with significant blood loss because it **maintains cardiovascular stability** by increasing heart rate and blood pressure, which helps preserve organ perfusion. - Its **sympathomimetic properties** counteract the hypotensive effects of hypovolemia, making it beneficial in these critical situations. *Burn dressing* - Ketamine is well-suited for painful procedures like burn dressing changes because it provides **potent analgesia and amnesia** while largely preserving airway reflexes. - Its ability to maintain **hemodynamic stability** and respiratory function is advantageous for patients undergoing repeated painful interventions. *Short operations on asthmatics* - Ketamine is a good choice for asthmatic patients because it has **bronchodilatory properties**, which can help prevent or ameliorate bronchospasm. - It also **preserves respiratory drive** and airway reflexes, making it safer for patients with reactive airway disease undergoing short procedures.

Question 598: Which anesthetic agent is considered the least cardiotoxic?

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

Explanation: ***Sevoflurane*** - Sevoflurane is known for its **smooth induction** and rapid recovery, making it a common choice, especially in pediatric anesthesia [3]. - It has a relatively **low pungency** and minimal cardiovascular depressant effects compared to other volatile anesthetics, contributing to its favorable cardiotoxicity profile [1], [4]. *Enflurane* - Enflurane can cause **myocardial depression** and may induce **seizures** at higher concentrations, limiting its use [1]. - Its widespread use has decreased due to concerns about its **cardiovascular effects** and potential for **renal toxicity**. *Isoflurane* - While Isoflurane is a commonly used anesthetic, it can cause **coronary steal phenomenon** in patients with coronary artery disease due to its potent vasodilatory effects. - It also causes dose-dependent **myocardial depression** and can increase heart rate, which may be detrimental in some patients [4]. *Halothane* - Halothane is known for significant **myocardial depression**, causing a decrease in cardiac output and systemic vascular resistance [2]. - It also sensitizes the myocardium to **catecholamines**, increasing the risk of arrhythmias, and is associated with **halothane hepatitis**, a rare but severe liver injury [3].

Question 599: Which of the following factors does not affect the Minimum Alveolar Concentration (MAC) of anesthetics?

A. Species variability
B. Sex differences
C. Age of the patient
D. Duration of anesthesia (Correct Answer)

Explanation: ***Duration of anesthesia*** - The **Minimum Alveolar Concentration (MAC)** is primarily determined by factors such as age, body temperature, and the presence of other sedatives, not by how long the anesthetic has been administered. - Once a steady state is reached, the MAC required to prevent movement to a surgical stimulus remains constant, regardless of the duration of exposure. *Species variability* - Different species exhibit varying sensitivities to anesthetics, meaning the **MAC value can differ significantly** between, for example, humans and other mammals. - This variability is due to differences in receptor density, metabolic rates, and central nervous system organization across species. *Sex differences* - While there can be minor physiological differences between sexes, **sex alone does not significantly alter the MAC** required for general anesthesia. - Other factors, such as hormonal influences or body composition, might indirectly affect anesthetic requirements but are not considered primary determinants of baseline MAC. *Age of the patient* - **MAC decreases with increasing age**, especially after infancy, due to age-related physiological changes in the central nervous system. - Conversely, infants and young children generally require a higher MAC compared to adults, with the peak MAC often observed around 6 months of age.

Question 600: Probable indicators of reversal of neuromuscular blockade are all EXCEPT:

A. Sustained hand grip for 5 seconds
B. Lift head for 5 seconds
C. Leg lift for 10 seconds (Correct Answer)
D. Ability to perform sustained tongue depressor test

Explanation: ***Leg lift for 10 seconds*** - A **leg lift for 10 seconds** is a test of lower limb strength, which can be affected by residual neuromuscular blockade, but it is **not a primary or standard indicator** used to assess the reversal of neuromuscular blockade for airway protection and overall recovery. - While it demonstrates muscle strength, it isn't as critical for assessing readiness for extubation as upper airway and respiratory muscle function tests. *Sustained hand grip for 5 seconds* - **Sustained hand grip for 5 seconds** demonstrates adequate neuromuscular transmission in the forearm muscles and is a generally accepted indicator of reversal of neuromuscular blockade. - It suggests sufficient recovery of peripheral muscles to perform voluntary movements effectively. *Lift head for 5 seconds* - The **ability to lift the head off the bed for 5 seconds** is a crucial clinical test indicating significant recovery of the neck and upper airway muscles, which are vital for maintaining airway patency. - This demonstrates adequate strength in the diaphragm, intercostals, and upper airway muscles, suggesting readiness for extubation. *Ability to perform sustained tongue depressor test* - The **sustained tongue depressor test** involves the patient holding an object between their teeth, indicating sufficient strength of the jaw musculature. - This test is a reliable indicator of adequate neuromuscular recovery in the muscles essential for airway protection and swallowing.

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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