Complications in Anesthesia — MCQs

An 18-year-old male was undergoing anesthesia for appendectomy. On administration of a muscle relaxant, a gradual fall in the blood pressure together with increased airway resistance was noticed. The airway resistance improved with the administration of diphenhydramine. Which is the most likely muscle relaxant that was administered?

Q58Easy

What is the typical duration of a post-spinal headache?

Q59Easy

Which agent can cause malignant hyperthermia?

Q60Easy

Which of the following anesthetic agents is known to be hepatotoxic?

Complications in Anesthesia Indian Medical PG Practice Questions and MCQs

Question 51: A patient under inhalational anesthesia suddenly develops fever, increased heart rate and BP, acidosis, and arrhythmia during surgery. What is your first step of intervention?

A. Dantrolene (Correct Answer)
B. Sodium bicarbonate
C. Procainamide
D. Antipyretics

Explanation: ### Explanation The clinical presentation of sudden hyperthermia, tachycardia, hypertension, metabolic acidosis, and arrhythmias during inhalational anesthesia is pathognomonic for **Malignant Hyperthermia (MH)**. **Why Dantrolene is the Correct Answer:** MH is a life-threatening hypermetabolic state triggered by volatile anesthetics (e.g., Halothane, Isoflurane) or Succinylcholine. It is caused by a genetic defect in the **Ryanodine Receptor (RYR1)**, leading to an uncontrolled release of calcium from the sarcoplasmic reticulum. **Dantrolene** is the specific antidote and the definitive first-line treatment. It works by binding to the RYR1 receptor and inhibiting calcium release, thereby reversing the muscle rigidity and hypermetabolic cascade. **Why Other Options are Incorrect:** * **B. Sodium Bicarbonate:** While used to treat the resulting metabolic acidosis, it is a supportive measure and does not address the underlying cause. * **C. Procainamide:** Used to treat arrhythmias in MH, but it is secondary to stabilizing the calcium release. Note: Calcium channel blockers are contraindicated in MH as they can worsen hyperkalemia. * **D. Antipyretics:** Fever in MH is due to internal muscular metabolism, not a change in the hypothalamic set-point. Aspirin or Paracetamol are ineffective. **NEET-PG High-Yield Pearls:** * **Earliest Sign:** Increase in **End-Tidal CO₂ (ETCO₂)** despite increased ventilation. * **Late Sign:** Hyperthermia (can rise at 1°C every 5 minutes). * **Gold Standard Diagnosis:** Caffeine Halothane Contracture Test (CHCT) on muscle biopsy. * **Management Mnemonic:** "Stop, Hyperventilate, Dantrolene" (Stop triggers, 100% O₂, and give Dantrolene 2.5 mg/kg IV).

Question 52: During surgery, a patient develops muscle rigidity, increased heart rate, and hypercarbia. Emergence of malignant hyperthermia is suspected. Which anesthetic agent is most commonly implicated in precipitating this condition?

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

Explanation: ### Explanation **Malignant Hyperthermia (MH)** is a life-threatening pharmacogenetic hypermetabolic disorder of skeletal muscle. It is triggered by exposure to specific anesthetic agents in genetically susceptible individuals (mutations in the **RYR1 receptor**). **1. Why Succinylcholine is Correct:** Succinylcholine, a depolarizing neuromuscular blocker, is the most common and potent trigger for MH. It causes a massive release of calcium from the sarcoplasmic reticulum into the myoplasm. This leads to sustained muscle contraction (rigidity), accelerated metabolism, and excessive heat production. Along with **volatile inhalational anesthetics** (e.g., Halothane, Isoflurane, Sevoflurane), succinylcholine is the primary agent implicated in precipitating this crisis. **2. Why the Other Options are Incorrect:** * **B. Dantrolene sodium:** This is the **treatment of choice** for MH, not a trigger. It acts by inhibiting calcium release from the sarcoplasmic reticulum. * **C. Gallamine & D. Pancuronium:** These are non-depolarizing neuromuscular blockers. Non-depolarizing agents are considered **safe** in patients susceptible to MH and do not trigger the condition. **3. High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Increase in End-Tidal CO₂ (**Hypercarbia**) despite increased ventilation. * **Specific Sign:** Masseter muscle rigidity (Trismus). * **Late Sign:** Hyperthermia (can be as high as 1°C every 5 minutes). * **Gold Standard Diagnosis:** Caffeine Halothane Contracture Test (CHCT). * **Management:** Stop triggers, hyperventilate with 100% O₂, and administer **Dantrolene (2.5 mg/kg IV)**. * **Safe Agents:** Propofol, Etomidate, Thiopental, Ketamine, and all local anesthetics.

Question 53: A patient is posted for surgery 6 weeks post-burn. What is a likely cause of increased intraoperative requirements?

A. Succinylcholine (Correct Answer)
B. Anesthetic negligence
C. Post-burn state
D. None of the above

Explanation: ### Explanation **Correct Answer: A. Succinylcholine** The correct answer is **Succinylcholine**, though the question phrasing "increased requirements" refers to the **increased risk/complication** associated with its use in the post-burn period. **Underlying Medical Concept:** In the post-burn state (typically from 24 hours up to 1–2 years post-injury), there is a massive **upregulation of extrajunctional acetylcholine receptors (nAChR)** across the muscle membrane. When Succinylcholine (a depolarizing neuromuscular blocker) is administered, these receptors open simultaneously, causing an efflux of potassium from the cells. In burn patients, this leads to **exaggerated hyperkalemia**, which can result in fatal cardiac arrhythmias or cardiac arrest. Therefore, Succinylcholine is strictly contraindicated in this period. **Why other options are incorrect:** * **B. Anesthetic negligence:** While complications can arise from errors, the physiological response to Succinylcholine in a burn patient is a known pharmacological phenomenon, not a result of negligence. * **C. Post-burn state:** While the "post-burn state" is the *reason* for the physiological change, it is not the "requirement" or the drug causing the specific intraoperative crisis mentioned in the context of anesthesia pharmacology. **High-Yield Clinical Pearls for NEET-PG:** * **The "Safe Window":** Succinylcholine is generally considered safe within the first **24 hours** post-burn. The risk of hyperkalemia peaks between **1 to 6 months** but can persist for over a year. * **Resistance to Non-depolarizers:** Conversely, burn patients show **resistance** to non-depolarizing muscle relaxants (e.g., Vecuronium, Rocuronium) due to the same receptor upregulation, requiring **increased doses** of these specific drugs. * **Potassium Shift:** A normal dose of Succinylcholine usually raises serum $K^+$ by **0.5 mEq/L**; in burn patients, this rise can exceed **5–10 mEq/L**.

Question 54: Which of the following is NOT a complication of surgery performed in the sitting position?

A. Venous air embolism
B. Hemorrhage (Correct Answer)
C. Pneumocephalus
D. Tongue edema

Explanation: The **sitting position** is commonly used in neurosurgery (posterior fossa surgeries) and shoulder surgeries. The primary physiological change in this position is that the surgical site is significantly **above the level of the heart**, creating a negative pressure gradient. ### Why Hemorrhage is the Correct Answer In the sitting position, venous pressure at the surgical site is low (often sub-atmospheric). This leads to **decreased surgical site bleeding** (improved visualization) rather than hemorrhage. Conversely, the main hemodynamic risk is **hypotension** due to venous pooling in the lower extremities, which reduces preload and cardiac output. ### Explanation of Other Options * **Venous Air Embolism (VAE):** This is the most feared complication. Because the surgical site is above the heart, a pressure gradient exists between the atmosphere and the open non-collapsible dural sinuses. Air is sucked into the venous system, potentially leading to cardiovascular collapse. * **Pneumocephalus:** As cerebrospinal fluid (CSF) drains out due to gravity, air can enter the cranial cavity to replace the lost volume (the "inverted pop bottle" effect), leading to tension pneumocephalus. * **Tongue Edema:** Prolonged neck flexion can cause macroglossia (tongue swelling) by obstructing venous and lymphatic drainage from the tongue and oropharynx. ### High-Yield Clinical Pearls for NEET-PG * **Most sensitive monitor for VAE:** Precordial Doppler (placed at the 2nd–4th intercostal space, right sternal border). * **Gold standard for VAE detection:** Transesophageal Echocardiography (TEE). * **First sign of VAE:** Decrease in End-Tidal $CO_2$ ($EtCO_2$) and a "mill-wheel" murmur. * **Management of VAE:** Flood the field with saline, place the patient in **Durant’s position** (Left lateral decubitus with Trendelenburg), and aspirate air via a CVP line.

Question 55: A severely ill patient was maintained on an infusional anesthetic agent. On the 2nd day, he started deteriorating. What is the probable culprit?

A. Etomidate
B. Propofol (Correct Answer)
C. Opioid
D. Barbiturate

Explanation: ### Explanation The correct answer is **Propofol**. The clinical scenario describes a patient deteriorating after a prolonged infusion of an anesthetic agent, which is a classic presentation of **Propofol Infusion Syndrome (PRIS)**. **1. Why Propofol is Correct:** PRIS is a rare but often fatal complication associated with high-dose (>4 mg/kg/hr) or prolonged (>48 hours) infusions of propofol, typically in critically ill patients. The underlying mechanism involves the inhibition of mitochondrial fatty acid oxidation and the electron transport chain. This leads to a severe metabolic crisis characterized by: * Refractory metabolic acidosis * Rhabdomyolysis (leading to hyperkalemia and acute kidney injury) * Hepatomegaly and hyperlipidemia * Cardiac failure/arrhythmias (often Brugada-like ECG patterns) **2. Why Other Options are Incorrect:** * **Etomidate:** While etomidate can cause **adrenocortical suppression** (by inhibiting 11-beta-hydroxylase), it typically presents as a relative adrenal insufficiency rather than the rapid multisystem deterioration seen in PRIS. * **Opioids:** Prolonged opioid infusions (e.g., Fentanyl) primarily cause respiratory depression, ileus, or delayed emergence, but not the metabolic collapse described. * **Barbiturates:** Thiopental infusions are rarely used for maintenance due to accumulation in fat (long context-sensitive half-life), but they do not cause a specific "infusion syndrome" like propofol. **3. High-Yield Clinical Pearls for NEET-PG:** * **PRIS Trigger:** Dose >4 mg/kg/hr for >48 hours. * **Early Sign:** Unexplained metabolic acidosis or green-colored urine (due to phenols). * **Management:** Immediate discontinuation of propofol and supportive care (hemodialysis/ECMO). * **Propofol Composition:** It is an emulsion containing soybean oil and egg lecithin; it supports bacterial growth and can cause hypertriglyceridemia.

Question 56: In all of the following conditions, hyperkalemia produced by succinylcholine is exaggerated, except?

A. Spinal cord transaction
B. Muscle dystrophy
C. Trauma
D. Stroke (Correct Answer)

Explanation: **Explanation:** The administration of **Succinylcholine (SCh)**, a depolarizing neuromuscular blocker, typically causes a transient rise in serum potassium (approx. 0.5 mEq/L). However, in certain clinical conditions, this rise is exaggerated and can lead to fatal cardiac arrest due to **upregulation of extrajunctional acetylcholine receptors (AChRs)**. **Why Stroke is the Correct Answer:** While stroke (hemiplegia/paraplegia) *can* cause hyperkalemia with SCh, the risk is **time-dependent**. The "vulnerable period" usually begins 4–5 days after the neurological insult and lasts for several months. In the context of this competitive exam question, **Stroke** is considered the "except" because the risk is significantly lower and less predictable compared to the massive, systemic upregulation seen in direct muscle trauma or permanent denervation. **Analysis of Incorrect Options:** * **Spinal Cord Transection:** Causes extensive denervation below the level of the lesion. This leads to a massive proliferation of extrajunctional receptors across the entire muscle membrane, making it a classic contraindication for SCh. * **Muscle Dystrophy (e.g., Duchenne’s):** These patients have fragile sarcolemmas. SCh can cause rhabdomyolysis and acute, massive potassium release, often leading to sudden cardiac arrest. * **Trauma:** Major burns and crush injuries trigger systemic inflammatory responses and muscle regeneration, leading to widespread receptor upregulation. The risk peaks between 1 week to 6 months post-injury. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Extrajunctional receptors (containing the **gamma subunit**) stay open longer than mature receptors, allowing massive potassium efflux. * **Safe Alternatives:** In patients at risk for hyperkalemia, **Rocuronium** is the preferred agent for rapid sequence induction. * **The "Rule of 24":** SCh is generally considered safe within the first 24 hours of a burn or spinal cord injury, as receptor upregulation takes time to occur.

Question 57: An 18-year-old male was undergoing anesthesia for appendectomy. On administration of a muscle relaxant, a gradual fall in the blood pressure together with increased airway resistance was noticed. The airway resistance improved with the administration of diphenhydramine. Which is the most likely muscle relaxant that was administered?

A. Atracurium
B. Pancuronium
C. Vecuronium
D. d-tubocurarine (Correct Answer)

Explanation: ### Explanation The clinical presentation described—**hypotension** (fall in blood pressure) and **bronchospasm** (increased airway resistance) that responds to an antihistamine (**diphenhydramine**)—is a classic manifestation of **histamine release**. **1. Why d-tubocurarine is correct:** **d-tubocurarine**, a benzylisoquinolinium neuromuscular blocker, is notorious for causing significant non-immunologic histamine release from mast cells. Histamine causes peripheral vasodilation (leading to hypotension) and bronchial smooth muscle constriction (leading to increased airway resistance/bronchospasm). Since the symptoms improved with diphenhydramine (an H1-receptor antagonist), the underlying mechanism is confirmed as histaminergic. **2. Why the other options are incorrect:** * **Atracurium:** While atracurium can cause histamine release, it is significantly less potent in this regard than d-tubocurarine. In modern practice, it is a more likely culprit than d-tubocurarine, but in the context of a classic exam question where both are present, d-tubocurarine is the "textbook" answer for profound histamine-induced hypotension. * **Pancuronium:** This is a long-acting aminosteroid muscle relaxant. It does not cause histamine release; instead, it has **vagolytic effects**, typically causing tachycardia and a slight *increase* in blood pressure. * **Vecuronium:** This is an intermediate-acting aminosteroid. It is known for its **cardiovascular stability** and lacks significant histamine-releasing properties. **3. High-Yield Clinical Pearls for NEET-PG:** * **Histamine Releasers:** d-tubocurarine > Atracurium > Mivacurium. * **Cardiovascular Stability:** Vecuronium and Rocuronium are preferred in patients where hemodynamic stability is critical. * **Vagolytic Effect:** Pancuronium (causes tachycardia). * **Hoffman Elimination:** The unique metabolism of Atracurium and Cisatracurium, making them safe in renal and hepatic failure. * **Drug of Choice for Asthmatics:** Vecuronium or Cisatracurium (due to lack of histamine release).

Question 58: What is the typical duration of a post-spinal headache?

A. 10 minutes
B. 1 hour
C. 10 days (Correct Answer)
D. 1 week

Explanation: **Explanation:** **Post-Dural Puncture Headache (PDPH)** is a common complication following spinal anesthesia or accidental dural puncture during epidural placement. It is caused by the persistent leakage of cerebrospinal fluid (CSF) through the dural hole, leading to low CSF pressure and compensatory cerebral vasodilation. **Why 10 days is the correct answer:** While the onset of PDPH typically occurs within 48–72 hours, the natural history of the condition is **self-limiting**. In the majority of patients (over 70–80%), the dural hole heals spontaneously, and the headache resolves without specific intervention within **7 to 10 days**. Therefore, "10 days" represents the standard clinical duration for the resolution of symptoms. **Analysis of Incorrect Options:** * **A & B (10 minutes / 1 hour):** These durations are far too short. PDPH is a physiological process involving fluid dynamics and tissue healing; it cannot resolve in minutes or an hour. * **D (1 week):** While many cases resolve by day 7, standard textbooks and clinical guidelines frequently cite the 10-day mark as the typical upper limit for spontaneous resolution. In the context of NEET-PG, 10 days is the more classically taught "textbook" duration. **High-Yield Clinical Pearls for NEET-PG:** * **Pathognomonic Feature:** The headache is **positional** (worsens when upright, improves when supine). * **Gold Standard Treatment:** For persistent or severe PDPH, the **Epidural Blood Patch (EBP)** is the most effective treatment (success rate >90%). * **Prevention:** Use of small-gauge (25G-27G) and **non-cutting (pencil-point)** needles like **Whitacre or Sprotte** significantly reduces the incidence compared to cutting needles (Quincke). * **Conservative Management:** Includes bed rest, aggressive hydration, and oral/IV caffeine (causes cerebral vasoconstriction).

Question 59: Which agent can cause malignant hyperthermia?

A. Succinylcholine (Correct Answer)
B. Halothane
C. Ether
D. Verapamil

Explanation: **Explanation:** **Malignant Hyperthermia (MH)** is a life-threatening pharmacogenetic hypermetabolic syndrome of the skeletal muscle. It is triggered in genetically susceptible individuals (often involving a mutation in the **RYR1 gene**) when exposed to specific anesthetic agents. **Why Succinylcholine is the correct answer:** Succinylcholine, a depolarizing neuromuscular blocker, is a classic and potent trigger for MH. It causes a massive release of calcium from the sarcoplasmic reticulum into the myoplasm. This leads to sustained muscle contraction, excessive ATP consumption, lactic acidosis, and a rapid rise in body temperature. While Halothane and Ether are also triggers, Succinylcholine is frequently highlighted in exams due to its rapid onset of action and its role in causing masseter muscle rigidity. **Analysis of other options:** * **Halothane & Ether:** Both are volatile inhalational anesthetics. Historically, **all volatile halogenated inhalational agents** (Halothane, Isoflurane, Sevoflurane, Desflurane) and Ether are known triggers for MH. However, in the context of this specific question format, Succinylcholine is often prioritized as the primary pharmacological trigger. * **Verapamil:** This is a calcium channel blocker. It is **contraindicated** in the management of MH because, when combined with Dantrolene, it can lead to severe hyperkalemia and cardiovascular collapse. It does *not* cause MH. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Increase in End-Tidal CO2 (ETCO2) despite increased ventilation. * **Specific Sign:** Masseter muscle rigidity (Trismus) following Succinylcholine administration. * **Drug of Choice:** **Dantrolene** (Mechanism: Binds to RYR1 receptors to inhibit calcium release). * **Safe Agents:** Propofol, Etomidate, Ketamine, Thiopentone, and all Local Anesthetics. * **Gold Standard Test:** Caffeine Halothane Contracture Test (CHCT).

Question 60: Which of the following anesthetic agents is known to be hepatotoxic?

A. Ketamine
B. Ether
C. Nitrous Oxide
D. Halothane (Correct Answer)

Explanation: **Explanation:** **Halothane** is the correct answer because it is uniquely associated with drug-induced liver injury, famously known as **Halothane Hepatitis**. This occurs via two mechanisms: 1. **Type I (Minor):** A transient, self-limiting rise in transaminases due to direct toxic metabolites. 2. **Type II (Major):** A rare but severe immune-mediated fulminant hepatic failure. It occurs when halothane is metabolized by Cytochrome P450 to **trifluoroacetyl chloride**, which binds to liver proteins. This creates a neo-antigen, triggering an antibody response that destroys hepatocytes. Risk factors include multiple exposures, female gender, and obesity. **Analysis of Incorrect Options:** * **Ketamine:** Primarily metabolized in the liver but is not hepatotoxic. It is known for its sympathomimetic effects (increased HR/BP) and dissociative anesthesia. * **Ether:** Historically significant but largely obsolete; it is irritating to the airways and highly flammable, but not specifically linked to hepatotoxicity. * **Nitrous Oxide:** Known for inhibiting **Vitamin B12-dependent enzymes** (methionine synthase), leading to megaloblastic anemia or subacute combined degeneration of the cord with chronic use, but it does not cause liver damage. **High-Yield Clinical Pearls for NEET-PG:** * **Metabolism:** Halothane is the most extensively metabolized volatile anesthetic (~20%), which contributes to its toxicity. In contrast, **Desflurane** is the least metabolized (0.02%). * **"Halothane Shakes":** Post-operative shivering is common with halothane. * **Arrhythmias:** Halothane sensitizes the myocardium to catecholamines, increasing the risk of arrhythmias if adrenaline is used concurrently. * **Modern Alternative:** **Isoflurane and Sevoflurane** are preferred in modern practice as they undergo minimal metabolism and lack significant hepatotoxicity.

Practice by Chapter

Adverse Drug Reactions

Practice Questions

Anaphylaxis and Allergic Reactions

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Malignant Hyperthermia

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Local Anesthetic Toxicity

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Perioperative Cardiac Complications

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Pulmonary Complications

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Awareness Under General Anesthesia

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Neurological Complications

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Postoperative Visual Loss

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Perioperative Renal Dysfunction

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Transfusion-Related Complications

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Risk Management and Prevention

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