Complications in Anesthesia — MCQs

Complications in Anesthesia Indian Medical PG Practice Questions and MCQs

Question 261: Malignant hyperthermia is most common with:

A. Succinylcholine (Correct Answer)
B. Gallamine
C. Dantrolene
D. Ketamine

Explanation: ***Succinylcholine*** - **Malignant hyperthermia** is a life-threatening pharmacogenetic disorder triggered by certain anesthetic agents, predominantly **succinylcholine** and volatile inhalational anesthetics. - Succinylcholine, a **depolarizing neuromuscular blocker**, can induce a massive release of calcium from the sarcoplasmic reticulum in susceptible individuals, leading to sustained muscle contraction and hypermetabolism. *Gallamine* - **Gallamine** is a non-depolarizing neuromuscular blocker and is not known to be a trigger for malignant hyperthermia. - Non-depolarizing neuromuscular blockers work by competitively blocking acetylcholine receptors at the neuromuscular junction without causing depolarization, and thus do not typically induce the uncontrolled calcium release seen in malignant hyperthermia. *Dantrolene* - **Dantrolene** is the specific antidote used to treat malignant hyperthermia; it is not a trigger. - It works by directly interfering with calcium release from the sarcoplasmic reticulum in skeletal muscle, thereby reversing the pathological process of malignant hyperthermia. *Ketamine* - **Ketamine** is a dissociative anesthetic that acts as an NMDA receptor antagonist and is generally considered safe for use in patients susceptible to malignant hyperthermia. - While it can cause an increase in heart rate and blood pressure, it does not trigger the underlying pathophysiology of uncontrolled calcium release characteristic of malignant hyperthermia.

Question 262: Most common post-operative complication of spinal anesthesia?

A. Post-dural puncture headache
B. Hypotension due to spinal anesthesia (Correct Answer)
C. Urinary retention post-anesthesia
D. Infection leading to meningitis

Explanation: ***Hypotension due to spinal anesthesia*** - **Hypotension** is the **most common** immediate complication of spinal anesthesia due to **sympathetic blockade**, leading to **vasodilation** and decreased venous return. - This effect is often dose-dependent and can be managed with fluids and vasopressors if clinically significant. *Post-dural puncture headache* - While a notable complication, a **post-dural puncture headache (PDPH)** is less common than hypotension, occurring in a smaller percentage of spinal anesthesia cases. - PDPH results from persistent leakage of **cerebrospinal fluid** through the dural puncture site, leading to intracranial hypotension. *Urinary retention post-anesthesia* - **Urinary retention** is a relatively common complication after spinal anesthesia, but it is typically not as immediate or frequent as hypotension. - It occurs due to the **blockade of sacral parasympathetic nerves** that control bladder function, requiring temporary catheterization in some cases. *Infection leading to meningitis* - **Meningitis** is a **rare but severe** complication of spinal anesthesia, usually resulting from inadequate aseptic technique during the procedure. - Its incidence is very low compared to hemodynamic changes or even PDPH.

Question 263: In a clinical scenario, a patient presents with respiratory distress after undergoing anesthesia. Which of the following is most likely associated with Mendelson's syndrome?

A. Air leak
B. Tracheal rupture during intubation
C. Oesophageal rupture
D. Aspiration of gastric content (Correct Answer)

Explanation: ***Aspiration of gastric content*** - **Mendelson's syndrome** is a specific type of aspiration pneumonitis caused by the inhalation of **acidic gastric contents**, typically occurring during anesthesia. - The severity of the syndrome is directly related to the **pH** and **volume** of the aspirated material, leading to chemical injury to lung tissue, inflammation, and respiratory distress. *Air leak* - While an air leak can cause respiratory distress, it is more commonly associated with **pneumothorax** or damage to the airways or lungs during procedures, not directly with Mendelson's syndrome. - An air leak describes the escape of air from the respiratory system, which is a symptom or sign, not the primary cause of aspiration pneumonitis. *Tracheal rupture during intubation* - **Tracheal rupture** is a rare but serious complication of intubation, leading to subcutaneous emphysema, pneumothorax, and respiratory compromise. - It's a mechanical injury and does not involve the aspiration of gastric contents, thus not related to Mendelson's syndrome. *Oesophageal rupture* - **Oesophageal rupture** is a medical emergency, often caused by severe vomiting or iatrogenic injury during endoscopy, leading to mediastinitis and sepsis. - While it can manifest with respiratory symptoms due to mediastinal involvement, it is distinct from Mendelson's syndrome, which specifically involves lung damage from aspirated stomach acid.

Question 264: What is the drug used for the treatment of malignant hyperthermia?

A. Dantrolene (Correct Answer)
B. Valproate
C. Succinylcholine
D. Diazepam

Explanation: ***Dantrolene*** - **Dantrolene** is the specific and most effective treatment for malignant hyperthermia as it acts directly on the **ryanodine receptor** to inhibit calcium release from the sarcoplasmic reticulum. - This action helps to reverse the uncontrolled muscle contraction and hypermetabolism characteristic of **malignant hyperthermia**. *Succinylcholine* - **Succinylcholine** is a depolarizing neuromuscular blocker and is actually a **trigger** for malignant hyperthermia in susceptible individuals. - It causes sustained muscle contraction and calcium release, exacerbating the condition rather than treating it. *Valproate* - **Valproate** is an anticonvulsant and mood stabilizer primarily used for epilepsy and bipolar disorder. - It has no role in the treatment of the acute hypermetabolic crisis seen in malignant hyperthermia. *Diazepam* - **Diazepam** is a benzodiazepine used to treat anxiety, seizures, and muscle spasms, acting as a CNS depressant. - While it can help with muscle spasms, it does not address the underlying pathophysiology of excessive calcium release in malignant hyperthermia.

Question 265: Which of the following conditions does not cause a rise in end-tidal CO2 during thyroid surgery?

A. Anaphylaxis (Correct Answer)
B. Thyroid storm
C. Neuroleptic malignant syndrome
D. Malignant hyperthermia

Explanation: **Anaphylaxis** - During anaphylaxis, there is often **bronchospasm** and **hypoventilation**, leading to a *decrease* or no change in end-tidal CO2 due to reduced gas exchange. - While it can cause cardiovascular collapse, the primary respiratory effect that impacts ETCO2 measurement is typically decreased CO2 excretion rather than increased production. *Malignant hyperthermia* - This condition is characterized by a rapid, uncontrolled increase in **metabolism** and **muscle rigidity**, resulting in massive **CO2 production**. - The increased CO2 production overwhelms the ventilatory capacity, leading to a marked and rapid rise in **end-tidal CO2** despite increased minute ventilation. *Thyroid storm* - Thyroid storm causes a hypermetabolic state with increased **cellular oxygen consumption** and **CO2 production**. - The body's significantly elevated metabolic rate leads to higher CO2 levels that can be reflected in an elevated **end-tidal CO2**. *Neuroleptic malignant syndrome* - This syndrome involves severe **muscle rigidity** and a hypermetabolic state similar to malignant hyperthermia, although with a different etiology. - The uncontrolled muscle activity and enhanced cellular metabolism result in increased **CO2 production** and, consequently, a rise in **end-tidal CO2**.

Question 266: Which of the following statements about malignant hyperthermia is incorrect?

A. End tidal CO₂ is decreased during the episode. (Correct Answer)
B. Dantrolene is the drug of choice for treatment.
C. Most common cause is a mutation in the ryanodine receptor.
D. Tachycardia occurs during the episode.

Explanation: ***End tidal CO₂ is decreased during the episode.*** - Malignant hyperthermia causes **increased metabolism and CO₂ production**, leading to a significant **elevation in end-tidal CO₂**, not a decrease. - The rapid rise in **end-tidal CO₂** is often one of the earliest and most sensitive signs of a malignant hyperthermia crisis. *Dantrolene is the drug of choice for treatment.* - **Dantrolene** is indeed the specific treatment for malignant hyperthermia, as it acts on the **ryanodine receptor** to reduce calcium release from the sarcoplasmic reticulum. - This statement is **correct**, and therefore not the incorrect statement sought by the question. *Most common cause is a mutation in the ryanodine receptor.* - The most common genetic defect underlying malignant hyperthermia is a mutation in the **RYR1 gene**, which codes for the **ryanodine receptor type 1** (RyR1). - This mutation leads to an uncontrolled release of **intracellular calcium** from the sarcoplasmic reticulum in muscle cells. *Tachycardia occurs during the episode.* - **Tachycardia** is a common and early sign of malignant hyperthermia due to the increased metabolic rate and sympathetic nervous system activation. - This rapid heart rate contributes to the overall physiological stress during the crisis.

Question 267: What is a potential consequence of repeated exposure to halothane?

A. Halothane hepatitis (Correct Answer)
B. Pancreatitis due to gallstones
C. Bacterial meningitis
D. Viral encephalitis

Explanation: ***Halothane hepatitis*** - Repeated exposure to halothane, especially within a short period (e.g., 28 days), significantly increases the risk of **halothane hepatitis**, a severe and potentially fatal liver injury. - This idiosyncratic reaction is due to the formation of **halothane metabolites** that bind to hepatocyte proteins, triggering an immune response. *Pancreatitis due to gallstones* - **Pancreatitis** is inflammation of the pancreas and is commonly caused by gallstones obstructing the common bile duct or by alcohol abuse. - There is no direct association between **halothane exposure** and the formation of gallstones or the development of pancreatitis. *Bacterial meningitis* - **Bacterial meningitis** is an infection of the meninges, typically caused by bacteria such as *Streptococcus pneumoniae* or *Neisseria meningitidis*. - It is an infectious disease of the central nervous system and is not a known complication of **halothane exposure**. *Viral encephalitis* - **Viral encephalitis** is an inflammation of the brain tissue caused by a viral infection (e.g., herpes simplex virus, arboviruses). - Like bacterial meningitis, it is an infectious condition of the central nervous system and has no known link to **halothane exposure**.

Question 268: A patient under general anesthesia develops hyperthermia and muscle rigidity. Which anesthetic agent is likely responsible for this reaction?

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

Explanation: ***Sevoflurane*** - **Sevoflurane** is a potent **volatile anesthetic** known to be a common trigger for **malignant hyperthermia (MH)** in susceptible individuals. MH presents with **hyperthermia**, **muscle rigidity**, and a rapid increase in **carbon dioxide production**. - The underlying mechanism involves an uncontrolled release of calcium from the sarcoplasmic reticulum in muscle cells, primarily due to mutations in the **ryanodine receptor (RyR1)**. *Nitrous oxide* - **Nitrous oxide** is an inhalational anesthetic, but it is not known to trigger **malignant hyperthermia**. It acts primarily as an analgesic and weak anesthetic. - It does not cause the massive calcium release from the sarcoplasmic reticulum characteristic of MH. *Thiopentone* - **Thiopentone**, a **barbiturate**, is an intravenous anesthetic that functions by enhancing GABAergic inhibition in the central nervous system. - It is not associated with triggering **malignant hyperthermia** and is considered a safe anesthetic for individuals susceptible to MH. *Halothane* - **Halothane** is a potent **volatile anesthetic** that was historically a major trigger for **malignant hyperthermia**. However, its use has largely been replaced due to its hepatotoxicity and higher incidence of MH compared to newer agents. - While it can cause MH, **sevoflurane** is more commonly encountered in modern anesthetic practice as a trigger, and the question implies a common modern agent.

Practice by Chapter

Adverse Drug Reactions

Practice Questions

Anaphylaxis and Allergic Reactions

Practice Questions

Malignant Hyperthermia

Practice Questions

Local Anesthetic Toxicity

Practice Questions

Perioperative Cardiac Complications

Practice Questions

Pulmonary Complications

Practice Questions

Awareness Under General Anesthesia

Practice Questions

Neurological Complications

Practice Questions

Postoperative Visual Loss

Practice Questions

Perioperative Renal Dysfunction

Practice Questions

Transfusion-Related Complications

Practice Questions

Risk Management and Prevention

Practice Questions

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