Complications in Anesthesia Practice Questions

Q: Which of the following is the commonest nerve injury due to maintaining the same position for a prolonged period during general anesthesia?

Ulnar neuropathies. **Explanation:** **Ulnar neuropathy** is the most common peripheral nerve injury associated with general anesthesia. The nerve is particularly vulnerable at the elbow as it passes through the **cubital tunnel** (postcondylar groove of the humerus). During anesthesia, the loss of muscle tone and protective pain reflexes, combined with prolonged pressure against the operating table or improper padding, leads to ischemia or compression of the nerve. It is more common in males and patients with a high or low BMI. **Analysis of Options:** * **Ulnar Nerve (Option C):** Correct. Large-scale studies (like the ASA Closed Claims Project) consistently identify ulnar neuropathy as the most frequent nerve injury, often manifesting as "claw hand" or sensory loss in the medial 1.5 fingers. * **Brachial Plexus (Option B):** This is the second most common injury. It typically occurs due to excessive abduction of the arm (>90 degrees), external rotation of the head, or the use of shoulder braces in the Trendelenburg position. * **Common Peroneal Nerve (Option A):** This is the most common nerve injury of the **lower extremity**. It occurs when the lateral aspect of the knee (fibular head) is compressed against stirrups in the lithotomy position, leading to foot drop. **Clinical Pearls for NEET-PG:** * **Most common nerve injured (Overall):** Ulnar Nerve. * **Most common lower limb nerve injured:** Common Peroneal Nerve. * **Most common cause of Brachial Plexus injury:** Excessive arm abduction (>90°). * **Prevention:** Use of foam padding at the elbow, maintaining the forearm in a neutral or supinated position, and avoiding prolonged lithotomy time. * **Radial Nerve Injury:** Usually caused by a tight NIBP cuff or pressure against the humerus (leads to wrist drop).

Q: Which drug is used in the treatment of malignant hyperthermia?

Dantrolene. **Explanation:** **Malignant Hyperthermia (MH)** is a rare but life-threatening pharmacogenetic hypermetabolic crisis triggered by volatile anesthetics (e.g., Halothane, Isoflurane) and the depolarizing muscle relaxant Succinylcholine. **Why Dantrolene is the Correct Answer:** The underlying pathology of MH involves a mutation in the **Ryanodine Receptor (RYR1)**, leading to an uncontrolled release of calcium from the sarcoplasmic reticulum into the skeletal muscle cytoplasm. This causes sustained muscle contraction, excessive heat production, and metabolic acidosis. **Dantrolene** is a direct-acting skeletal muscle relaxant that acts as an antagonist to the RYR1 receptor. It inhibits the release of calcium, thereby reversing the hypermetabolic state. It is the only specific antidote for MH. **Analysis of Incorrect Options:** * **B. Diazepam:** A benzodiazepine used for sedation and anxiolysis; it has no effect on the intracellular calcium release mechanism in skeletal muscles. * **C. Paracetamol:** An antipyretic that acts centrally. It is ineffective in MH because the fever in MH is caused by peripheral muscular metabolic activity, not a change in the hypothalamic set-point. * **D. Phenobarbitone:** A barbiturate used primarily as an anticonvulsant; it plays no role in treating MH. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Increase in **End-Tidal CO₂ (ETCO₂)**. * **Late Sign:** Hyperthermia (can rise 1°C every 5 minutes). * **Dose of Dantrolene:** 2.5 mg/kg IV bolus, repeated every 5–10 minutes until symptoms subside (max dose 10 mg/kg). * **Safe Agents:** Propofol, Ketamine, Etomidate, and Nitrous Oxide. * **Diagnosis:** Gold standard is the **Caffeine-Halothane Contracture Test (CHCT)**.

Q: Neuroleptic Malignant Syndrome (NMS) is caused by which of the following medications?

All of the above. **Explanation:** Neuroleptic Malignant Syndrome (NMS) is a life-threatening idiosyncratic reaction to **dopamine antagonists**. The underlying pathophysiology involves a profound blockade of central **D2 receptors** in the nigrostriatal pathway and hypothalamus, leading to the classic tetrad of: 1. Hyperthermia (Fever) 2. Muscle rigidity ("Lead-pipe" rigidity) 3. Autonomic instability 4. Altered mental status **Analysis of Options:** * **Haloperidol (Option C):** This is a high-potency typical antipsychotic (butyrophenone) and is the most common causative agent associated with NMS. * **Phenothiazines (Option B):** Drugs like chlorpromazine and fluphenazine are typical antipsychotics that frequently cause NMS due to their potent dopamine-blocking properties. * **Metoclopramide (Option A):** Although primarily used as a prokinetic/antiemetic, metoclopramide is a central dopamine antagonist. It is a well-documented, though often overlooked, cause of NMS. Since all three medications act as dopamine antagonists, **Option D (All of the above)** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Biochemical Marker:** Elevated **Creatine Phosphokinase (CPK)** is a hallmark finding due to muscle rigidity and rhabdomyolysis. * **Treatment of Choice:** 1. Immediate cessation of the offending agent. 2. **Dantrolene** (muscle relaxant) or **Bromocriptine** (dopamine agonist). * **NMS vs. Malignant Hyperthermia (MH):** While both present with fever and rigidity, MH is triggered by volatile anesthetics/succinylcholine and involves the ryanodine receptor, whereas NMS is triggered by neuroleptics and involves dopamine blockade. * **Differential:** NMS can also occur upon the sudden **withdrawal of Levodopa** in Parkinson’s patients.

Q: Which of the following anesthetic agents is known to be nephrotoxic?

Methoxyflurane. **Explanation:** **Methoxyflurane** is the correct answer because it is the most potent inhalational anesthetic but is notorious for its dose-dependent **nephrotoxicity**. The underlying mechanism involves the extensive hepatic metabolism of methoxyflurane (up to 50-70%), which releases high levels of **inorganic fluoride ions (F⁻)**. These ions interfere with the concentrating mechanism of the renal tubules, leading to "high-output renal failure" (polyuric renal failure). Due to this severe side effect, its use as a general anesthetic has been largely abandoned. **Analysis of Incorrect Options:** * **Halothane:** Primarily known for **hepatotoxicity** ("Halothane Hepatitis") and sensitization of the myocardium to catecholamines, leading to arrhythmias. It does not cause significant renal damage. * **Ether:** Known for its irritating effect on the airways and high flammability. While it causes sympathetic stimulation, it is not directly nephrotoxic. * **Cyclopropane:** An explosive gas that causes significant cardiac sensitization to adrenaline. Like ether, it lacks specific nephrotoxic properties. **High-Yield Clinical Pearls for NEET-PG:** * **Fluoride Threshold:** Serum fluoride levels >50 µmol/L are typically associated with renal toxicity. * **Sevoflurane:** Another modern agent that releases fluoride ions; however, it is generally safe. Its main concern is the formation of **Compound A** (a nephrotoxic vinyl ether) when reacting with soda lime, though this is rarely clinically significant in humans. * **Metabolism Rule:** Methoxyflurane (70%) > Halothane (20%) > Sevoflurane (2-5%) > Enflurane (2%) > Isoflurane (0.2%) > Desflurane (0.02%). * **Current Use:** Methoxyflurane is now only used in low doses (via the "Penthrox" inhaler) for emergency analgesia, where fluoride levels remain below the toxic threshold.

Q: Complications of spinal anesthesia include all EXCEPT?

Tachycardia. **Explanation:** Spinal anesthesia involves the injection of local anesthetics into the subarachnoid space, resulting in a sympathetic blockade. The correct answer is **Tachycardia** because spinal anesthesia typically causes the opposite effect—**Bradycardia**. **1. Why Tachycardia is the correct answer (The Exception):** Spinal anesthesia leads to a **sympathetic block**. When the block reaches high levels (T1–T4), it inhibits the **cardioaccelerator fibers**. This results in parasympathetic dominance (vagal tone), leading to **bradycardia**, not tachycardia. Tachycardia would only occur as a compensatory mechanism for hypotension if the block is low, but it is not a direct complication of the procedure itself. **2. Analysis of Incorrect Options:** * **Hypotension (A):** This is the most common complication. It occurs due to the blockade of preganglionic sympathetic fibers (T1–L2), leading to arterial and venous vasodilation (decreased systemic vascular resistance and venous return). * **Bradycardia (C):** As explained, blocking the T1–T4 segments or a sudden decrease in venous return (triggering the Bezold-Jarisch reflex) leads to a drop in heart rate. * **Headache (D):** Specifically **Post-Dural Puncture Headache (PDPH)**. It is caused by the leakage of CSF through the dural puncture site, leading to low intracranial pressure. **Clinical Pearls for NEET-PG:** * **PDPH Character:** Typically frontal or occipital, postural in nature (worsens on sitting/standing, relieved by lying flat). * **Treatment of choice for PDPH:** Epidural Blood Patch. * **High Spinal:** Can lead to respiratory paralysis if it reaches C3–C5 (Phrenic nerve). * **Urinary Retention:** The most common reason for delayed discharge after spinal anesthesia.

Q: A 30-year-old female who underwent surgery under spinal anesthesia developed a post-spinal headache. How long does it typically take for the headache to subside?

Up to 2 weeks. **Explanation:** Post-Dural Puncture Headache (PDPH) is a common complication following spinal anesthesia, caused by the persistent leakage of cerebrospinal fluid (CSF) through the dural puncture site. This leads to low CSF pressure and loss of the "cushioning" effect, causing traction on intracranial vascular structures when the patient is upright. **Why Option C is Correct:** While most cases of PDPH are self-limiting and resolve within **5 to 7 days**, clinical studies and standard textbooks (like Miller’s Anesthesia) state that symptoms can persist for **up to 2 weeks** in a significant number of patients. If the headache lasts longer than 14 days, clinicians should investigate alternative diagnoses or consider an epidural blood patch. **Analysis of Incorrect Options:** * **Option A (10 minutes):** This is far too short. PDPH typically has a delayed onset (24–48 hours post-procedure) and requires time for the dural hole to heal. * **Option B (4 days):** While many patients show improvement by day 4, it is not the upper limit of the typical duration. * **Option D (2 months):** Chronic headaches lasting months are rare and usually indicate a complication (like a subdural hematoma) rather than simple PDPH. **High-Yield Clinical Pearls for NEET-PG:** * **Character:** Classically **frontal or occipital** and strictly **positional** (worsens on standing/sitting, relieved by lying flat). * **Risk Factors:** Young age, female gender, pregnancy, and use of large-bore or cutting-tip needles (e.g., Quincke). * **Prevention:** Use of small-gauge (25G-27G) **non-cutting (pencil-point)** needles like **Sprotte or Whitacre**. * **Management:** Conservative (bed rest, hydration, caffeine). The **Gold Standard** treatment for persistent/severe PDPH is an **Epidural Blood Patch**.

Question 1

A 65-year-old man undergoes a technically difficult abdominal-perineal resection for a rectal cancer during which he receives 3 units of packed red blood cells. Four hours later, in the intensive care unit (ICU), he is bleeding heavily from his perineal wound. Emergency coagulation studies reveal normal prothrombin time, partial thromboplastin time, and bleeding times. The fibrin degradation products are not elevated, but the serum fibrinogen content is depressed and the platelet count is 70,000/mL. Which of the following is the most likely cause of his bleeding?

Accepted Answer

A bleeding blood vessel in the surgical field

Answer

Delayed blood transfusion reaction

Answer

Autoimmune fibrinolysis

Answer

Factor VIII deficiency

Question 2

Which of the following is the commonest nerve injury due to maintaining the same position for a prolonged period during general anesthesia?

Accepted Answer

Ulnar neuropathies

Answer

Common peroneal nerve injury

Answer

Brachial plexus injuries

Answer

None of the above

Question 3

Which drug is used in the treatment of malignant hyperthermia?

Accepted Answer

Dantrolene

Answer

Diazepam

Answer

Paracetamol

Answer

Phenobarbitone

Question 4

All are true about accidental intra-arterial injection of Thiopentone except:

Accepted Answer

To relieve pain, we have to immediately remove the misplaced arterial cannula.

Answer

Immediate intense vasoconstriction and excruciating pain

Answer

Cause is precipitation of thiopental crystals in the arterial vessels

Answer

Sympathectomy of the upper extremity produced by stellate ganglion block may relieve vasoconstriction.

Question 5

Neuroleptic Malignant Syndrome (NMS) is caused by which of the following medications?

Accepted Answer

All of the above

Answer

Metoclopramide

Answer

Phenothiazines

Answer

Haloperidol

Question 6

Post-spinal headache is most commonly due to which of the following mechanisms?

Accepted Answer

Cerebrospinal fluid (CSF) leak

Answer

Meningitis

Answer

Encephalitis

Answer

Increased intracranial pressure (ICT)

Question 7

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

Accepted Answer

Methoxyflurane

Answer

Halothane

Answer

Ether

Answer

Cyclopropane

Question 8

Complications of spinal anesthesia include all EXCEPT?

Accepted Answer

Tachycardia

Answer

Hypotension

Answer

Bradycardia

Answer

Headache

Question 9

A 30-year-old female who underwent surgery under spinal anesthesia developed a post-spinal headache. How long does it typically take for the headache to subside?

Accepted Answer

Up to 2 weeks

Answer

Up to 10 minutes

Answer

Up to 4 days

Answer

Up to 2 months

Question 10

A 6-year-old child who has had repeated episodes of otitis media undergoes surgical placement of pressure-equalization (PE) tubes. In the recovery room, she develops a fever of 40degC (104degF), muscle rigidity, dark colored urine, and metabolic and respiratory acidosis. Which of the following therapies is most likely to be beneficial for this child's condition?

Accepted Answer

Intravenous administration of dantrolene

Answer

Acidification of the urine

Answer

Administration of intravenous antibiotics after obtaining blood cultures

Answer

Administration of tetanus immunoglobulin and a booster dose of DTaP

Complications in Anesthesia — MCQs

Complications in Anesthesia — MCQs

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