General Anesthesia — MCQs

General Anesthesia Indian Medical PG Practice Questions and MCQs

Question 521: With regard to ketamine, all of the following are true except:

A. It may induce cardiac dysrhythmias in patients receiving tricyclic antidepressants
B. Emergence phenomena are more likely if anticholinergic premedication is used
C. Has no effect on intracranial pressure (Correct Answer)
D. It is a direct myocardial depressant
E. It has bronchodilator properties

Explanation: ***Has no effect on intracranial pressure*** - Ketamine typically **increases intracranial pressure (ICP)** due to cerebral vasodilation, making it potentially problematic in patients with pre-existing elevated ICP. - Therefore, the statement that it has no effect on ICP is incorrect, and the question asks for the statement that is *not* true. *It may induce cardiac dysrhythmias in patients receiving tricyclic antidepressants* - Ketamine can increase **sympathetic nervous system activity** by activating the catecholamine system. - When combined with **tricyclic antidepressants (TCAs)**, which block norepinephrine reuptake, this can lead to an exaggerated cardiovascular response and **cardiac dysrhythmias**. *Emergence phenomena are more likely if anticholinergic premedication is used* - **Anticholinergic premedication** (e.g., scopolamine, atropine, glycopyrrolate) generally helps to reduce emergence phenomena by decreasing secretions and potentially mitigating vivid dreams or psychological reactions. - The statement suggests the opposite, which is incorrect; anticholinergic agents are often used precisely to *reduce* these effects. *It is a direct myocardial depressant* - Ketamine has an **intrinsic direct myocardial depressant effect** on isolated heart muscle preparations. - However, this direct effect is usually masked *in vivo* by its powerful **sympathomimetic effects**, which lead to an overall increase in heart rate, blood pressure, and cardiac output. *It has bronchodilator properties* - Ketamine is a **potent bronchodilator**, making it a useful anesthetic agent in patients with **asthma** or **bronchospasm**. - This effect is mediated partly through its sympathetic stimulating properties and direct relaxation of bronchial smooth muscle.

Question 522: An induction agent of choice for poor-risk patients with cardiorespiratory disease as well as in situations where preservation of a normal blood pressure is crucial:-

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

Explanation: ***Etomidate*** - Etomidate is preferred in patients with **cardiac disease** or **hemodynamic instability** due to its minimal effects on cardiovascular function. - It maintains **cardiovascular stability**, including myocardial contractility and blood pressure, making it ideal for procedures where maintaining a normal blood pressure is crucial. *Ketamine* - Ketamine often causes a **sympathetic stimulating effect**, leading to increases in heart rate and blood pressure, which may be detrimental in such patients. - It is associated with **tachycardia** and **hypertension**, undesirable in a poor-risk patient with cardiorespiratory disease. *Propofol* - Propofol is a potent **vasodilator** and myocardial depressant, which can lead to significant **hypotension**, especially in volume-depleted or critically ill patients. - Its use can result in a dose-dependent decrease in **arterial blood pressure** and **cardiac output**. *Thiopentone* - Thiopentone can cause **myocardial depression** and significant **hypotension**, especially in patients with compromised cardiovascular function. - It leads to a notable decrease in **vascular tone** and venous return, thus lowering blood pressure.

Question 523: Which does not cause malignant hyperthermia

A. Enflurane
B. Isoflurane
C. N2O (Correct Answer)
D. Desflurane

Explanation: **N2O** - **Nitrous oxide (N2O)**, or laughing gas, is an inhaled anesthetic that does not trigger **malignant hyperthermia (MH)**. It is considered a safe anesthetic agent for MH-susceptible patients. - MH is a genetic disorder of skeletal muscle characterized by uncontrolled **calcium release** from the **sarcoplasmic reticulum**, leading to a hypermetabolic state. *Enflurane* - **Enflurane** is a **volatile inhaled anesthetic** that can trigger malignant hyperthermia. Volatile anesthetics are a primary class of agents known to induce MH in susceptible individuals. - It works by affecting the **ryanodine receptor (RyR1)** in muscle cells, leading to excessive calcium release. *Isoflurane* - **Isoflurane** is also a **volatile inhaled anesthetic** and is a known trigger for malignant hyperthermia. - Like other volatile agents, it causes a rapid increase in **intracellular calcium**, muscle rigidity, and a systemic hypermetabolic response. *Desflurane* - **Desflurane** is another **volatile inhaled anesthetic** that is a potent trigger of malignant hyperthermia. - Its rapid onset and offset properties do not prevent it from causing the rapid **calcium release** characteristic of MH.

Question 524: Intraocular pressure rises in ?

A. Infusion of IV propofol
B. LMA
C. Bag and mask ventilation
D. Intubation & laryngoscopy (Correct Answer)

Explanation: ***Intubation & laryngoscopy*** - The **stress response** to laryngoscopy and intubation causes an increase in **arterial blood pressure** and venous pressure, which can transiently elevate intraocular pressure. - This effect is mediated by sympathetic stimulation, leading to **increased choroidal blood volume** and consequently higher intraocular pressure. *Infusion of IV propofol* - **Propofol** is known to **decrease intraocular pressure** by reducing blood pressure and relaxing extraocular muscles, making it a favorable induction agent for patients at risk of elevated IOP. - Its mechanism involves a reduction in **aqueous humor production** and an increase in **uveoscleral outflow**. *LMA* - The use of a **Laryngeal Mask Airway (LMA)** generally produces **less hemodynamic stress** and a smaller increase in intraocular pressure compared to tracheal intubation. - While some mild elevation can occur, it is significantly **less pronounced** than with direct laryngoscopy. *Bag and mask ventilation* - **Bag-mask ventilation** without intubation typically causes **minimal change** or even a slight decrease in intraocular pressure, provided there is controlled ventilation and no excessive positive pressure. - If excessive pressure is used or if the patient strains, a transient, mild elevation could occur, but it is not a direct and consistent cause of IOP rise as seen with intubation.

Question 525: Effect of Propofol on coagulation is?

A. Inhibits platelet function
B. Inhibits coagulation cascade
C. Activates coagulation cascade
D. No effect (Correct Answer)

Explanation: ***No effect*** - Propofol is generally considered to have **no direct significant effect** on the coagulation cascade or platelet function in healthy individuals or during typical surgical procedures. - While some studies have explored potential minor antiplatelet effects in specific contexts or with very high doses, these are not clinically significant under normal usage and are not considered a primary action of the drug. *Inhibits platelet function* - While some in vitro studies have suggested a potential for propofol to **inhibit platelet aggregation**, these effects are not consistently observed in vivo at clinically relevant concentrations and are not considered a major pharmacological action. - Other medications, such as **aspirin** or **clopidogrel**, are specifically known for their antiplatelet effects, which are much more potent and clinically significant than any purported action of propofol. *Inhibits coagulation cascade* - Propofol does not directly interfere with the **coagulation cascade factors** (e.g., factors II, VII, IX, X) or their synthesis. - Drugs like **heparin** or **warfarin** are known inhibitors of the coagulation cascade, acting through different mechanisms. *Activates coagulation cascade* - There is no evidence to suggest that propofol causes the **activation of the coagulation cascade**. - In fact, conditions that would activate coagulation are usually independent of propofol administration, such as **trauma** or underlying **prothrombotic states**.

Question 526: Anaesthetic agent causing analgesia?

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

Explanation: ***Ketamine*** - Ketamine provides excellent **analgesia** by acting as an **NMDA receptor antagonist**, making it unique among commonly used intravenous anesthetics [1]. - It induces a state of **dissociative anesthesia**, where the patient is conscious but detached from painful stimuli, maintaining cardiovascular stability [1]. *Thiopentone* - Thiopentone is a **barbiturate** that causes rapid **induction of anesthesia** and profound **sedation** but has no analgesic properties. - Its primary action is through potentiation of GABA-A receptor activity, leading to central nervous system depression. *Propofol* - Propofol is a widely used intravenous anesthetic known for its rapid onset and short duration of action, but it lacks significant **analgesic effects** [3]. - It primarily works by enhancing GABA-A receptor function, leading to **sedation** and hypnosis. *Etomidate* - Etomidate is an intravenous anesthetic characterized by its minimal cardiovascular depression, making it suitable for patients with **hemodynamic instability**, but it provides **no analgesia** [1], [2]. - Its anesthetic effect is mediated through GABA-A receptor potentiation, resulting in rapid loss of consciousness.

Question 527: In Jorgenson technique drugs given by IV routes are:

A. Scopalamine (Hyoscine)
B. Pentobarbitol
C. Mepiridine
D. Pethidine
E. Pethidine, Pentobarbital, and Scopolamine (Correct Answer)

Explanation: ***Pethidine, Pentobarbital, and Scopolamine*** - The Jorgensen technique, a method of intravenous (IV) sedation for dental procedures, typically involves a combination of **Pethidine (Meperidine)**, a short-acting **barbiturate** like **Pentobarbital**, and an **anticholinergic** agent like **Scopolamine (Hyoscine)**. - This specific drug cocktail provides a synergistic effect, offering **analgesia**, **sedation**, and **amnesia** while reducing secretions. *Scopalamine (Hyoscine)* - While Scopolamine is a component, it is usually administered as part of a **drug combination** with an opioid and a sedative/hypnotic in the Jorgensen technique, not as a sole agent. - Its primary role in this technique is to induce **amnesia** and reduce salivation, contributing to patient comfort. *Pentobarbitol* - Pentobarbital is a key sedative in the Jorgensen technique, providing **hypnotic and anxiolytic effects**. - However, it is typically combined with an opioid like Pethidine and an anticholinergic like Scopolamine to achieve the full desired sedation profile. *Mepiridine* - Meperidine, also known as **Pethidine**, is indeed a component of the Jorgensen cocktail, providing **analgesia and sedation**. - This option is partially correct but does not represent the complete combination of drugs used in the technique. *Pethidine* - Pethidine is an **opioid analgesic** that is a crucial part of the Jorgensen sedative regimen, contributing to pain relief and sedation. - However, the Jorgensen technique utilizes a **multi-drug approach**, making this option incomplete as it excludes the sedative and anticholinergic components.

Question 528: Emergence Delirium is characteristic of?

A. Midazolam
B. Thiopentone
C. Opioids
D. Ketamine (Correct Answer)

Explanation: ***Ketamine*** - **Emergence delirium**, characterized by vivid dreams, hallucinations, and confusion upon recovery from anesthesia, is a known side effect of **ketamine**, particularly in adults. - This effect is attributed to ketamine's action on **NMDA receptors** and can be attenuated by co-administration of benzodiazepines. *Midazolam* - **Midazolam** is a benzodiazepine often used for sedation and anxiolysis, and it typically causes amnesia and relaxation rather than a delirious state upon emergence. - While it can cause paradoxical agitation in some patients, it does not characteristically lead to emergence delirium similar to ketamine. *Thiopentone* - **Thiopentone** is a short-acting barbiturate used for induction of anesthesia, known for rapid onset and offset, leading to smooth emergence without significant delirium. - Its primary effect is general central nervous system depression, not dissociative anesthesia associated with emergence phenomena. *Opioids* - **Opioids** are potent analgesics that, at higher doses, can cause respiratory depression, nausea, and somnolence; however, they do not characteristically cause emergence delirium. - While they can contribute to postoperative cognitive dysfunction, it is distinct from the dissociative emergence state seen with ketamine.

Question 529: Which of the following agents is not used to provide induced hypotension during surgery ?

A. Mephenteramine (Correct Answer)
B. Sodium nitroprusside
C. Hydralazine
D. Esmolol

Explanation: ***Mephenteramine*** - **Mephentermine** is a **vasopressor** used to **increase blood pressure**, acting primarily through the release of **norepinephrine**. - Its effects are opposite to what is desired for **induced hypotension** during surgery, as the goal is to lower systemic blood pressure to reduce blood loss and improve surgical field visibility. *Sodium nitroprusside* - **Sodium nitroprusside** is a potent **vasodilator** that directly relaxes both **arterial** and **venous smooth muscle**, leading to a rapid and significant decrease in blood pressure. - Its rapid onset and offset of action make it a valuable agent for **controlled induced hypotension** during surgery. *Hydralazine* - **Hydralazine** is a **direct-acting arterial vasodilator** that primarily relaxes arterial smooth muscle, leading to a decrease in **peripheral vascular resistance** and blood pressure. - It can be used to induce or maintain **hypotension** during surgery, although its onset of action is slower compared to nitroprusside. *Esmolol* - **Esmolol** is a **short-acting beta-1 selective adrenergic blocker** that reduces heart rate and myocardial contractility, thereby decreasing cardiac output. - By reducing cardiac output, esmolol can contribute to **induced hypotension**, often used in conjunction with vasodilators or in situations where controlling heart rate is also desired.

Question 530: Maximum Airway Irritation caused by:-

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

Explanation: ***Desflurane*** - **Desflurane** has a pungent odor and is known to cause significant **airway irritation**, leading to coughing, breath-holding, laryngospasm, and secretions, especially during induction. - Its high volatility and low blood-gas solubility contribute to its rapid onset and offset, but also increase its propensity for airway irritation. *Halothane* - **Halothane** has a sweet, non-pungent odor and is generally well-tolerated during induction, causing minimal airway irritation. - Although it causes myocardial depression and is associated with hepatotoxicity, airway irritation is not a primary concern. *Enflurane* - **Enflurane** has a mild, sweet odor and causes less airway irritation than **desflurane**, but more than halothane or sevoflurane. - It can cause central nervous system excitation at high concentrations, but airway irritation is not its most prominent side effect. *Sevoflurane* - **Sevoflurane** has a pleasant, non-pungent odor and is known for its minimal airway irritation, making it an excellent choice for inhalational inductions, particularly in pediatric patients. - It is often preferred over other volatile anesthetics when airway reactivity is a concern. *Isoflurane* - **Isoflurane** has a pungent odor and can cause moderate airway irritation, but generally less than desflurane. - It is associated with a higher incidence of coughing and breath-holding during induction compared to sevoflurane.

Practice by Chapter

History of Anesthesia

Practice Questions

Preoperative Evaluation

Practice Questions

Pharmacology of Inhalational Anesthetics

Practice Questions

Pharmacology of Intravenous Anesthetics

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Neuromuscular Blocking Agents

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Airway Management

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Endotracheal Intubation

Practice Questions

Difficult Airway Algorithms

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Intraoperative Monitoring

Practice Questions

Depth of Anesthesia Monitoring

Practice Questions

Emergence from Anesthesia

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Postoperative Care

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