Complications in Anesthesia Practice Questions

Q: Which of the following drugs is NOT implicated in triggering malignant hyperthermia?

Propofol. **Explanation:** **Malignant Hyperthermia (MH)** is a rare but life-threatening pharmacogenetic hypermetabolic disorder of skeletal muscle. It is primarily caused by an abnormal release of calcium from the sarcoplasmic reticulum via mutated **Ryanodine receptors (RYR1)**. **Why Propofol is the correct answer:** Propofol is a phenol derivative used for induction and maintenance of anesthesia. It is considered a **"safe" drug** in patients susceptible to MH. It does not trigger the massive intracellular calcium release associated with the condition. In fact, Total Intravenous Anesthesia (TIVA) using Propofol is the technique of choice for MH-susceptible individuals. **Analysis of incorrect options:** * **Succinylcholine (Option B):** This depolarizing neuromuscular blocker is a potent **triggering agent**. It causes prolonged muscle depolarization, which, in susceptible individuals, leads to the catastrophic metabolic cascade of MH. * **Halothane (Option D):** All **volatile inhalational anesthetics** (Halothane, Sevoflurane, Desflurane, Isoflurane) are classic triggers for MH. Halothane is historically the most frequently implicated volatile agent. * **Lignocaine (Option A):** While older literature once suggested caution with amide locals, modern evidence confirms that **all local anesthetics (including Lignocaine)** are safe and do not trigger MH. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Increase in **EtCO₂** (End-tidal Carbon Dioxide) despite increased ventilation. * **Specific Sign:** Masseter muscle rigidity (Trismus) following Succinylcholine administration. * **Late Sign:** Hyperthermia (can be as high as 1°C every 5 minutes). * **Drug of Choice:** **Dantrolene Sodium** (Mechanism: Binds to RYR1 receptors to inhibit calcium release). * **Safe Drugs:** Propofol, Etomidate, Thiopentone, Ketamine, Nitrous Oxide, and all Non-depolarizing muscle relaxants (e.g., Vecuronium).

Q: Which anesthetic agent causes the maximum emesis?

Diethyl ether. **Explanation:** **Diethyl ether** is historically known for causing the highest incidence of Postoperative Nausea and Vomiting (PONV). The mechanism is multifactorial: it directly stimulates the Chemoreceptor Trigger Zone (CTZ) in the medulla, increases sympathetic outflow (leading to catecholamine release), and has a slow recovery profile due to its high blood-gas solubility, prolonging the emetic effect. While no longer used in modern clinical practice, it remains a classic "textbook" answer for maximum emesis. **Analysis of Incorrect Options:** * **Nitrous oxide (N₂O):** While N₂O is associated with PONV (due to middle ear pressure changes and CTZ stimulation), its emetic potential is significantly lower than that of ether. * **Chloroform:** Though toxic to the liver and heart, its emetic potential is less pronounced compared to the profound gastric irritation and sympathetic stimulation caused by ether. * **Thiopental:** As an intravenous barbiturate, it is generally considered "emetic neutral." In fact, some induction agents like Propofol actually possess anti-emetic properties. **High-Yield Clinical Pearls for NEET-PG:** * **Most Emetic Inhalational Agent:** Diethyl Ether (Historical) > Cyclopropane > Nitrous Oxide. * **Least Emetic/Anti-emetic Agent:** Propofol (Drug of choice for TIVA in patients with high PONV risk). * **Risk Factors for PONV (Apfel Score):** Female gender, non-smoker status, history of PONV/motion sickness, and use of postoperative opioids. * **Gold Standard Treatment:** 5-HT3 antagonists (e.g., Ondansetron) are the first-line prophylaxis for PONV.

Q: Which statement is false regarding intra-arterial injection of thiopental?

Stop the injection and remove the cannula.. **Explanation:** The management of accidental intra-arterial injection of Thiopental is a high-yield topic in anesthesia. Thiopental is highly alkaline (pH 10.5). When injected into an artery, it reacts with the relatively acidic blood, leading to the formation of **thiopental crystals**. These crystals cause mechanical obstruction, intense vasospasm, and endarteritis, which can lead to gangrene. **Why Option D is the correct (False) statement:** When an accidental intra-arterial injection is suspected, the most critical step is to **leave the cannula in situ**. The cannula serves as a direct portal for administering emergency drugs (like vasodilators or local anesthetics) to the affected area. Removing it loses this vital access. Therefore, the statement "remove the cannula" is clinically incorrect. **Analysis of other options:** * **Option A:** A **Stellate Ganglion Block** is a recognized treatment. It provides a chemical sympathectomy, which relieves vasospasm and promotes collateral circulation to the limb. * **Option B:** **Papaverine** (40–80 mg) is a potent direct-acting vasodilator used to counteract the intense arterial spasm caused by the drug. * **Option C:** This is the **pathophysiological basis** of the injury. The precipitation of thiopental crystals in the small arterioles leads to thrombosis and distal ischemia. **Clinical Pearls for NEET-PG:** * **Immediate Management:** Stop the injection, leave the needle/cannula in place, and inject **1% Lidocaine (5-10 ml)** or **Heparin** to dilute the drug and prevent thrombosis. * **Clinical Sign:** The patient typically complains of a sudden, severe "shooting" or "burning" pain radiating down the limb. * **Other Treatments:** Brachial plexus block (for vasodilation) and systemic anticoagulation.

Q: Biphasic respiratory depression is usually seen after which type of anesthesia?

Neuroleptanesthesia. **Explanation:** **Neuroleptanesthesia** is a technique traditionally involving the combination of a potent opioid (typically **Fentanyl**), a neuroleptic (typically **Droperidol**), and Nitrous Oxide. The phenomenon of **biphasic respiratory depression** (also known as "re-narcotization") is a classic complication associated with this technique. The underlying mechanism involves the redistribution and enterohepatic circulation of Fentanyl. Initially, the patient recovers from respiratory depression as the drug redistributes from the brain to muscle and fat. However, a secondary peak in plasma concentration occurs later due to: 1. **Release of sequestered fentanyl** from muscle and fat stores back into the systemic circulation. 2. **Enterohepatic circulation:** Fentanyl is secreted into the gastric juice, sequestered in the acidic environment of the stomach, and later reabsorbed in the alkaline small intestine. This causes a delayed "second peak" of respiratory depression, often when the patient is in the recovery room. **Analysis of Incorrect Options:** * **Regional Anesthesia:** While it can cause respiratory depression (e.g., high spinal block), it does not exhibit a biphasic pattern once the block wears off. * **Halothane & Isoflurane:** These volatile anesthetics cause dose-dependent respiratory depression. Once the agent is washed out of the system, the depression resolves linearly without a secondary recurrence. **High-Yield Clinical Pearls for NEET-PG:** * **Neuroleptanalgesia:** Fentanyl + Droperidol. * **Neuroleptanesthesia:** Fentanyl + Droperidol + $N_2O$. * **Droperidol Warning:** It is associated with **QT interval prolongation** and potential Torsades de Pointes. * **Management:** Biphasic depression requires vigilant postoperative monitoring and may necessitate a repeat dose of **Naloxone** (opioid antagonist).

Q: What is the most common complication of subclavian venous puncture?

Pneumothorax. **Explanation:** **Pneumothorax** is the most common and significant complication associated with subclavian vein catheterization. This occurs because the apex of the lung (cupula) lies immediately posterior and inferior to the subclavian vein. During the infraclavicular approach, if the needle is directed too deeply or at an incorrect angle, it can easily pierce the parietal pleura, leading to an air leak into the pleural space. The incidence of pneumothorax in subclavian puncture ranges from 1% to 3%. **Analysis of Incorrect Options:** * **Infection (A):** While catheter-related bloodstream infections (CRBSI) are a common *late* complication of central lines, subclavian lines actually have a **lower** rate of infection compared to femoral or internal jugular lines. * **Carotid Artery Puncture (C):** This is a common complication of **Internal Jugular Vein (IJV)** cannulation, not subclavian. In subclavian puncture, the accidental arterial puncture involves the **subclavian artery**, which is problematic because it is non-compressible behind the clavicle. * **Atrial Perforation (D):** This is a rare but lethal complication caused by advancing the guidewire or catheter too far into the heart, leading to cardiac tamponade. It is not a common occurrence. **High-Yield Clinical Pearls for NEET-PG:** * **Preferred Site for Long-term Use:** Subclavian vein is preferred for long-term access due to lower infection rates and patient comfort. * **IJV vs. Subclavian:** IJV puncture has a higher risk of arterial puncture (Carotid), while Subclavian puncture has a higher risk of pneumothorax. * **First Step Post-Procedure:** A **Chest X-ray** is mandatory after subclavian cannulation to confirm the catheter tip position and rule out an occult pneumothorax. * **Contraindication:** Subclavian puncture should be avoided in patients with severe coagulopathy because the artery cannot be compressed manually to control bleeding.

Q: Which drug produces a hematological side effect?

Nitrous oxide. **Explanation:** **Nitrous Oxide (N₂O)** is the correct answer because it uniquely interferes with Vitamin B12 metabolism. It irreversibly oxidizes the cobalt atom of **Vitamin B12 (cobalamin)** from the monovalent to the bivalent state. This inactivates the enzyme **methionine synthase**, which is essential for DNA synthesis. Prolonged exposure or repeated use of N₂O leads to: * **Megaloblastic Anemia:** Due to impaired DNA synthesis in the bone marrow. * **Agranulocytosis:** Reduction in white blood cell counts. * **Subacute Combined Degeneration of the Spinal Cord:** Due to impaired myelin formation. **Analysis of Incorrect Options:** * **B. Halothane:** Primarily known for its **hepatotoxicity** ("Halothane Hepatitis") and its potential to trigger Malignant Hyperthermia. It does not have significant hematological side effects. * **C. Ketamine:** Known for **dissociative anesthesia**, emergence delirium, and sympathetic stimulation (tachycardia/hypertension). It has no known effect on the hematological system. * **D. Sevoflurane:** Notable for the production of **Compound A** (nephrotoxic in rats) when reacting with soda lime and for its rapid induction/recovery. It does not cause hematological suppression. **High-Yield NEET-PG Pearls:** * **Enzyme inhibited:** Methionine Synthase. * **Test for N₂O toxicity:** Deoxyuridine suppression test (earliest indicator). * **Contraindication:** N₂O should be avoided in patients with pre-existing Vitamin B12 deficiency (e.g., Pernicious anemia, strict vegans). * **Diffusion Hypoxia:** N₂O can displace oxygen in the alveoli during recovery; always supplement with 100% O₂.

Q: Malignant hyperthermia is caused by a defect in which receptor?

Ryanodine receptor. **Explanation:** **Malignant Hyperthermia (MH)** is a life-threatening, pharmacogenetic hypermetabolic disorder of skeletal muscle. The correct answer is the **Ryanodine receptor (RYR1)**. 1. **Why Ryanodine Receptor is Correct:** MH is primarily caused by a mutation in the **RYR1 gene**, which encodes the ryanodine receptor located on the **sarcoplasmic reticulum (SR)** of skeletal muscle. When triggered by volatile anesthetics (e.g., Halothane, Sevoflurane) or succinylcholine, the defective receptor remains open, leading to an uncontrolled release of calcium ($Ca^{2+}$) from the SR into the cytoplasm. This causes sustained muscle contraction, massive ATP consumption, heat production, and rhabdomyolysis. 2. **Why Other Options are Incorrect:** * **Nicotinic Receptors:** These are found at the neuromuscular junction. While Succinylcholine acts here to trigger MH in susceptible individuals, the underlying *defect* is not in the receptor itself but in the downstream calcium release mechanism. * **Muscarinic Receptors:** These are G-protein coupled receptors involved in the parasympathetic nervous system; they do not play a role in the pathogenesis of MH. * **NMDA Receptors:** These are glutamate-gated ion channels in the CNS involved in memory and pain signaling (targeted by Ketamine), unrelated to MH. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Increase in **EtCO₂** (End-tidal Carbon Dioxide) despite increased ventilation. * **Specific Sign:** Masseter muscle rigidity (Trismus). * **Late Sign:** Hyperthermia (can be as high as 1°C every 5 minutes). * **Drug of Choice:** **Dantrolene** (Mechanism: Inhibits RYR1 to prevent calcium release). * **Gold Standard Test:** Caffeine Halothane Contracture Test (CHCT). * **Safe Agents:** Nitrous oxide, Ketamine, Propofol, Etomidate, and all local anesthetics.

Question 1

A 26-year-old female who underwent cesarean section complains of severe occipital headache since day 2 after surgery. The headache is associated with neck pain and stiffness. What is the most accurate statement regarding this clinical presentation?

Accepted Answer

Seepage of cerebrospinal fluid (CSF) resulted in the present condition.

Answer

Epidural blood patch is the next step in management.

Answer

This is a major complication requiring immediate intervention.

Answer

Early ambulation resulted in the present condition.

Question 2

Which of the following drugs is NOT implicated in triggering malignant hyperthermia?

Accepted Answer

Propofol

Answer

Lignocaine

Answer

Succinylcholine

Answer

Halothane

Question 3

Which anesthetic agent causes the maximum emesis?

Accepted Answer

Diethyl ether

Answer

Nitrous oxide

Answer

Chloroform

Answer

Thiopental

Question 4

Which statement is false regarding intra-arterial injection of thiopental?

Accepted Answer

Stop the injection and remove the cannula.

Answer

Stellate ganglion block can cause sympathectomy and vasodilation.

Answer

Papaverine is used for dilatation of an artery that is in spasm.

Answer

Crystallization of thiopental in arterial blood is the main cause of complications.

Question 5

What is the underlying mechanism for increased heat production in malignant hyperthermia, given the mutation in the gene coding for ryanodine receptors?

Accepted Answer

Increased muscle metabolism due to excess calcium ions.

Answer

Thermic effect of blood flow.

Answer

Increased sympathetic nervous system discharge.

Answer

Mitochondrial thermogenesis.

Question 6

Biphasic respiratory depression is usually seen after which type of anesthesia?

Accepted Answer

Neuroleptanesthesia

Answer

Regional anesthesia

Answer

Halothane anesthesia

Answer

Isoflurane anesthesia

Question 7

What is the most common complication of subclavian venous puncture?

Accepted Answer

Pneumothorax

Answer

Infection

Answer

Carotid artery puncture

Answer

Atrial perforation

Question 8

A patient presents with systemic symptoms of pallor and unconsciousness following local anesthesia. What is the patient experiencing?

Accepted Answer

Syncope

Answer

CNS depression

Answer

Tonic reaction to local anesthesia

Answer

Allergic response

Question 9

Which drug produces a hematological side effect?

Accepted Answer

Nitrous oxide

Answer

Halothane

Answer

Ketamine

Answer

Sevoflurane

Question 10

Malignant hyperthermia is caused by a defect in which receptor?

Accepted Answer

Ryanodine receptor

Answer

Nicotinic receptor

Answer

Muscarinic receptor

Answer

NMDA receptor

Complications in Anesthesia — MCQs

Complications in Anesthesia — MCQs

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