Complications in Anesthesia — MCQs

Complications in Anesthesia Indian Medical PG Practice Questions and MCQs

Question 111: 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?

A. Epidural blood patch is the next step in management.
B. This is a major complication requiring immediate intervention.
C. Seepage of cerebrospinal fluid (CSF) resulted in the present condition. (Correct Answer)
D. Early ambulation resulted in the present condition.

Explanation: ### Explanation The clinical presentation describes a classic case of **Post-Dural Puncture Headache (PDPH)**, a common complication following spinal anesthesia or accidental dural puncture during epidural placement in obstetric patients. **Why Option C is Correct:** The pathophysiology of PDPH involves the **seepage of cerebrospinal fluid (CSF)** through a hole in the dura mater. This loss of CSF leads to low intracranial pressure (intracranial hypotension). When the patient is upright, the brain loses its buoyant support and sags, causing traction on pain-sensitive structures like the meninges and cranial nerves, resulting in a characteristic **postural headache** (worse on standing, relieved by lying flat). **Analysis of Incorrect Options:** * **Option A:** While an **Epidural Blood Patch (EBP)** is the "gold standard" treatment, it is usually reserved for severe cases that fail conservative management (bed rest, hydration, caffeine, analgesics) for 24–48 hours. It is not necessarily the "next step" before trying conservative measures. * **Option B:** PDPH is considered a **minor (though distressing) complication**. While it requires management, it is not typically a life-threatening emergency requiring "immediate intervention" in the same vein as local anesthetic toxicity or high spinal block. * **Option D:** Early ambulation does **not** cause PDPH; the dural puncture does. Historically, patients were told to lie flat to prevent PDPH, but evidence shows that bed rest does not prevent the occurrence, though it does alleviate the symptoms. **High-Yield Clinical Pearls for NEET-PG:** * **Risk Factors:** Young age, female gender, pregnancy, and use of large-bore/cutting needles (e.g., Quincke). * **Needle Type:** Incidence is significantly reduced by using **pencil-point needles** (e.g., Sprotte, Whitacre) which separate rather than cut dural fibers. * **Presentation:** Typically occurs within 48–72 hours; bifrontal or occipital; may involve cranial nerve palsies (most commonly **CN VI**, leading to diplopia). * **Definitive Treatment:** Epidural Blood Patch (injecting 15–20 ml of autologous blood into the epidural space to "plug" the hole).

Question 112: Which of the following drugs is NOT implicated in triggering malignant hyperthermia?

A. Lignocaine
B. Succinylcholine
C. Propofol (Correct Answer)
D. Halothane

Explanation: **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).

Question 113: Which anesthetic agent causes the maximum emesis?

A. Nitrous oxide
B. Diethyl ether (Correct Answer)
C. Chloroform
D. Thiopental

Explanation: **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.

Question 114: Which statement is false regarding intra-arterial injection of thiopental?

A. Stellate ganglion block can cause sympathectomy and vasodilation.
B. Papaverine is used for dilatation of an artery that is in spasm.
C. Crystallization of thiopental in arterial blood is the main cause of complications.
D. Stop the injection and remove the cannula. (Correct Answer)

Explanation: **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.

Question 115: What is the underlying mechanism for increased heat production in malignant hyperthermia, given the mutation in the gene coding for ryanodine receptors?

A. Increased muscle metabolism due to excess calcium ions. (Correct Answer)
B. Thermic effect of blood flow.
C. Increased sympathetic nervous system discharge.
D. Mitochondrial thermogenesis.

Explanation: ### Explanation **Malignant Hyperthermia (MH)** is a pharmacogenetic hypermetabolic disorder of skeletal muscle. The core pathophysiology involves a mutation in the **RYR1 gene**, which codes for the **Ryanodine Receptor**. **1. Why Option A is Correct:** The Ryanodine receptor is a calcium-release channel located on the **Sarcoplasmic Reticulum (SR)**. In MH-susceptible individuals, exposure to triggering agents (volatile anesthetics like Halothane or depolarizing relaxants like Succinylcholine) causes these receptors to remain stuck in an open state. This leads to a massive, uncontrolled release of **calcium ions ($Ca^{2+}$)** into the myoplasm. * The excess calcium causes continuous muscle contraction (rigidity). * To sequester this calcium back into the SR, the **SERCA pump** works overactively, consuming massive amounts of **ATP**. * This accelerated hydrolysis of ATP and hypermetabolism generates the characteristic excessive heat and respiratory/metabolic acidosis. **2. Why Other Options are Incorrect:** * **Option B:** While vasodilation occurs, the heat is generated biochemically within the muscle cell, not by the physical movement of blood. * **Option C:** Sympathetic overactivity (tachycardia, hypertension) is a *result* of the hypermetabolic state and hypercarbia, not the primary source of heat production. * **Option D:** While mitochondria are involved in ATP production, the primary site of the defect and the heat-generating "calcium cycle" is the Sarcoplasmic Reticulum and the contractile apparatus. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Increase in **EtCO₂** (End-tidal Carbon Dioxide). * **Late Sign:** Hyperthermia (can rise at 1-2°C every 5 minutes). * **Drug of Choice:** **Dantrolene** (Mechanism: Binds to RYR1 to inhibit calcium release). * **Safe Agents:** Nitrous oxide, Ketamine, Propofol, Etomidate, and all Non-depolarizing muscle relaxants. * **Gold Standard Test:** Caffeine Halothane Contracture Test (CHCT).

Question 116: Biphasic respiratory depression is usually seen after which type of anesthesia?

A. Neuroleptanesthesia (Correct Answer)
B. Regional anesthesia
C. Halothane anesthesia
D. Isoflurane anesthesia

Explanation: **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).

Question 117: What is the most common complication of subclavian venous puncture?

A. Infection
B. Pneumothorax (Correct Answer)
C. Carotid artery puncture
D. Atrial perforation

Explanation: **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.

Question 118: A patient presents with systemic symptoms of pallor and unconsciousness following local anesthesia. What is the patient experiencing?

A. CNS depression
B. Syncope (Correct Answer)
C. Tonic reaction to local anesthesia
D. Allergic response

Explanation: **Explanation:** The patient is experiencing **Vasovagal Syncope**, which is the most common systemic complication associated with the administration of local anesthesia in a dental or clinical setting. **Why Syncope is Correct:** Syncope is primarily a psychogenic response to anxiety, pain, or the sight of a needle. It involves a sudden transient loss of consciousness due to cerebral hypoxia. The pathophysiology involves a massive parasympathetic discharge leading to bradycardia and peripheral vasodilation, resulting in hypotension. The classic clinical presentation includes **pallor**, diaphoresis (cold sweat), nausea, and rapid loss of consciousness. **Analysis of Incorrect Options:** * **CNS Depression:** While local anesthetics (LA) can cause CNS depression, it usually follows a period of CNS excitation (seizures) in the context of Local Anesthetic Systemic Toxicity (LAST). Isolated pallor and sudden unconsciousness without prior agitation are more characteristic of syncope. * **Tonic Reaction:** This refers to muscle spasms or seizures. While this can occur in severe LAST, it is typically preceded by symptoms like perioral numbness, metallic taste, or tinnitus, rather than simple pallor. * **Allergic Response:** True allergy to amide LAs is extremely rare. Anaphylaxis typically presents with skin changes (urticaria, angioedema), respiratory distress (wheezing), and tachycardia, rather than isolated pallor and fainting. **NEET-PG High-Yield Pearls:** * **Management:** Place the patient in the **Trendelenburg position** (head low, legs elevated) to increase cerebral blood flow. * **Prevention:** Administer LA in a supine or semi-reclined position to minimize the risk of syncope. * **Differential:** If a patient remains unconscious despite positioning, consider hypoglycemia or LAST. * **Epinephrine:** Tachycardia and palpitations following LA are usually due to the epinephrine additive or accidental intravascular injection, not an allergy.

Question 119: Which drug produces a hematological side effect?

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

Explanation: **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.

Question 120: Malignant hyperthermia is caused by a defect in which receptor?

A. Ryanodine receptor (Correct Answer)
B. Nicotinic receptor
C. Muscarinic receptor
D. NMDA receptor

Explanation: **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.

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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