Complications in Anesthesia — MCQs

Complications in Anesthesia Indian Medical PG Practice Questions and MCQs

Question 11: Which byproduct of vecuronium is associated with peripheral neuropathy on prolonged infusion?

A. 3-hydroxy vecuronium (Correct Answer)
B. 17-hydroxy vecuronium
C. 3, 17 (OH2) metabolite
D. All

Explanation: **Explanation:** Vecuronium is an intermediate-acting aminosteroid neuromuscular blocking agent (NMBA). It undergoes hepatic metabolism via deacetylation to form three metabolites: **3-hydroxy, 17-hydroxy, and 3,17-dihydroxy vecuronium.** **Why Option A is Correct:** The **3-hydroxy vecuronium** metabolite is the primary active byproduct, possessing approximately **50-80% of the potency** of the parent drug. In patients with renal failure or those receiving prolonged infusions (e.g., in the ICU), this metabolite accumulates significantly. Its accumulation is strongly associated with prolonged neuromuscular blockade and **peripheral neuropathy** (specifically, critical illness polyneuropathy/myopathy), as it continues to occupy nicotinic receptors at the neuromuscular junction for extended periods. **Why Other Options are Incorrect:** * **Option B & C:** While 17-hydroxy and 3,17-dihydroxy vecuronium are indeed metabolites of vecuronium, they possess only about **1/50th (2%) of the potency** of the parent compound. They are clinically insignificant and do not accumulate in concentrations high enough to cause prolonged paralysis or neuropathy. * **Option D:** Incorrect because the pathological effects are specifically attributed to the 3-hydroxy form due to its high potency and renal clearance dependency. **High-Yield NEET-PG Pearls:** * **Metabolism:** Vecuronium is primarily excreted by the **bile (40-70%)** and secondarily by the kidneys (20-30%). * **ICU Warning:** Prolonged use of NMBAs (especially vecuronium and pancuronium) in the ICU is a major risk factor for **Post-junctional Myopathy**, especially when co-administered with corticosteroids. * **Drug of Choice in Renal Failure:** **Atracurium or Cisatracurium** are preferred over vecuronium because they undergo Hoffmann elimination and do not rely on organ-based metabolism/excretion.

Question 12: A surgical resident has accidentally administered an intra-arterial injection of thiopental sodium to a patient. The arm has blanched below the level of the injection. Which of the following is NOT recommended for the management?

A. Immediately remove the needle and apply a warm towel (Correct Answer)
B. Perform a brachial plexus block on the affected side
C. Administer IV heparin
D. Administer analgesics

Explanation: **Explanation:** Accidental intra-arterial injection of Thiopental sodium (an alkaline solution with pH 10.5) is a medical emergency. It causes immediate **intense pain, vasospasm, and crystal formation**, leading to thrombosis and distal limb ischemia (blanching). **Why Option A is the Correct Answer (The "NOT" recommended action):** The most critical rule in managing intra-arterial injection is **NOT to remove the needle immediately**. The needle should be left in situ to serve as a portal for administering emergency vasodilators (like 1% Procaine, Lidocaine, or Papaverine) directly into the affected artery to counteract vasospasm and dilute the drug. **Analysis of Incorrect Options (Recommended Managements):** * **Option B (Brachial Plexus Block):** This is recommended as it produces sympathetic blockade, leading to vasodilation and improved collateral circulation, while also providing pain relief. * **Option C (IV Heparin):** Systemic anticoagulation is essential to prevent the progression of thrombosis caused by the endarteritis and crystal deposition. * **Option D (Analgesics):** Severe pain triggers further sympathetic-mediated vasoconstriction; therefore, aggressive pain management is a standard part of the protocol. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Injury:** Thiopental crystals precipitate in the blood (due to pH change), causing mechanical obstruction and a chemical endarteritis. * **First Step:** Leave the needle in place. * **Drug of Choice for Vasodilation:** **Papaverine** or **1% Procaine** (Procaine is also an acid, which helps neutralize the alkaline Thiopental). * **Other Treatments:** Stellat ganglion block, Phenoxybenzamine, and elevating the limb (to improve venous drainage).

Question 13: Which of the following are appropriate treatments for malignant hyperthermia?

A. Dantrolene
B. Cooling
C. Deepening plane of inhalation anesthesia
D. Discontinue inhalation anesthesia (Correct Answer)

Explanation: **Explanation:** Malignant Hyperthermia (MH) is a life-threatening pharmacogenetic hypermetabolic crisis triggered by volatile inhalation anesthetics (e.g., Halothane, Isoflurane, Sevoflurane) and the depolarizing muscle relaxant Succinylcholine. **Why "Discontinue inhalation anesthesia" is the correct answer:** The most critical **initial** step in managing MH is the immediate removal of the triggering agent. Continuing the inhalation anesthetic provides a constant stimulus to the ryanodine receptors (RYR1), leading to uncontrolled calcium release from the sarcoplasmic reticulum. By discontinuing the agent and hyperventilating with 100% oxygen, the clinician stops the source of the crisis. **Analysis of Incorrect Options:** * **A. Dantrolene:** While Dantrolene is the **definitive** drug of choice and essential for treatment, the question asks for "appropriate treatments." In many clinical scenarios and standardized exams, the absolute first priority is stopping the trigger. (Note: If this were a "Multiple Select" question, A, B, and D would all be correct). * **B. Cooling:** This is a supportive measure. While necessary to manage hyperpyrexia, it does not treat the underlying pathophysiology. * **C. Deepening plane of inhalation anesthesia:** This is **contraindicated**. Increasing the concentration of the triggering agent will worsen the metabolic crisis and accelerate muscle necrosis. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Increase in End-Tidal CO₂ (ETCO₂) despite increased ventilation. * **Pathophysiology:** Mutation in the **RYR1 receptor** (Ryanodine receptor) on Chromosome 19. * **Definitive Treatment:** Dantrolene (Dosage: 2.5 mg/kg IV bolus, repeated up to 10 mg/kg). * **Safe Agents:** Propofol, Ketamine, Etomidate, and all local/regional anesthetics. * **Gold Standard Diagnosis:** Caffeine-Halothane Contracture Test (CHCT) on muscle biopsy.

Question 14: What is the most common complication associated with the use of a central venous catheter?

A. Local bleeding
B. Thrombosis
C. Catheter-related infection (Correct Answer)
D. Pneumothorax

Explanation: **Explanation:** Central Venous Catheterization (CVC) is a routine procedure in anesthesia and critical care, but it carries significant morbidity. **Why Catheter-related Infection is correct:** Infections, specifically **Catheter-Related Bloodstream Infections (CRBSI)**, are the most common complications associated with CVCs. They occur due to skin flora migration along the external surface of the catheter or hub contamination. While mechanical complications occur during insertion, infections represent a persistent risk throughout the duration the catheter remains in situ. Studies indicate that infection rates are significantly higher than the incidence of mechanical injuries like pneumothorax. **Analysis of Incorrect Options:** * **Local bleeding:** While common during the procedure (especially in patients with coagulopathy), it is usually minor and easily controlled with local pressure. It is not the most frequent overall complication. * **Thrombosis:** Venous thrombosis is a known late complication due to vessel wall trauma and altered blood flow, but its clinical incidence is lower than that of infectious complications. * **Pneumothorax:** This is the most common **mechanical** complication, specifically during subclavian vein cannulation. However, with the advent of ultrasound-guided insertion, the incidence has dropped to <1%, making it less frequent than infections. **High-Yield Clinical Pearls for NEET-PG:** * **Most common mechanical complication:** Pneumothorax (highest risk with Subclavian approach). * **Site with highest infection risk:** Femoral vein (due to proximity to the groin/perineum). * **Site with lowest infection risk:** Subclavian vein. * **Prevention:** The "Central Line Bundle" (hand hygiene, maximal barrier precautions, chlorhexidine skin antisepsis, optimal site selection, and daily review of line necessity) is the gold standard for reducing CRBSI.

Question 15: With respect to cardiac arrests occurring during anesthesia, which of the following statements are correct?

A. The most common preceding arrhythmia is bradycardia and most occur during emergence from anesthesia.
B. The most common preceding arrhythmia is bradycardia.
C. The most common preceding arrhythmia is bradycardia and most are considered unpreventable and untreatable.
D. The most common preceding arrhythmia is bradycardia and the most common cause is failure of ventilation. (Correct Answer)

Explanation: **Explanation:** **Correct Answer: D. The most common preceding arrhythmia is bradycardia and the most common cause is failure of ventilation.** In the perioperative setting, cardiac arrest is most frequently triggered by **respiratory complications**, specifically **failure of ventilation** (hypoventilation or apnea). This leads to progressive hypoxia and hypercarbia. Unlike adult out-of-hospital cardiac arrests (which are often tachyarrhythmic/VF/VT), anesthesia-related arrests are typically preceded by **profound bradycardia** (vagal stimulation or hypoxic myocardial depression) leading to asystole or Pulseless Electrical Activity (PEA). **Analysis of Options:** * **Option A is incorrect:** While bradycardia is the common precursor, most anesthesia-related arrests occur during **induction or maintenance**, not emergence. Induction is a high-risk period due to airway manipulation and the sympatholytic effects of induction agents. * **Option B is incorrect:** While the first half of the statement is true, it is an incomplete explanation compared to Option D, which identifies the primary etiology (ventilation failure). * **Option C is incorrect:** Most anesthesia-related cardiac arrests are considered **preventable**. Studies (like the ASA Closed Claims Project) show that better monitoring (pulse oximetry/capnography) and vigilant airway management could prevent the majority of these events. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of perioperative cardiac arrest:** Airway/Ventilation failure (Hypoxia). * **Most common rhythm:** Bradycardia progressing to Asystole. * **Pediatric Population:** Bradycardia is the most common sign of impending disaster; the most common cause in children is also respiratory (laryngospasm/mucus plugging). * **Medication-related cause:** Overdose of volatile anesthetics or induction agents (causing cardiovascular collapse) is the second most common cause after respiratory issues.

Question 16: Post-spinal headache can be prevented by:

A. Use of a thinner spinal needle (Correct Answer)
B. Administering NSAIDs
C. Providing preanesthetic medication
D. Ensuring adequate oral fluid intake

Explanation: **Explanation:** Post-Dural Puncture Headache (PDPH) is a common complication of spinal anesthesia caused by the persistent leakage of cerebrospinal fluid (CSF) through the dural rent. This leads to low CSF pressure and compensatory cerebral vasodilation, resulting in a characteristic postural headache. **Why Option A is Correct:** The most significant factor in preventing PDPH is the **size and design of the spinal needle**. A thinner needle (higher gauge, e.g., 25G–27G) creates a smaller hole in the dura, significantly reducing the rate of CSF leakage. Additionally, using non-cutting (pencil-point) needles like **Whitacre or Sprotte** further reduces incidence compared to cutting-tip needles (Quincke) because they spread dural fibers rather than cutting them. **Why Other Options are Incorrect:** * **B & D:** While NSAIDs and aggressive hydration (oral or IV) are common **treatments** used to manage symptoms once a headache has occurred, clinical studies have shown they do **not prevent** the occurrence of PDPH. * **C:** Preanesthetic medications (like sedatives or anticholinergics) have no effect on dural integrity or CSF dynamics and thus play no role in preventing PDPH. **High-Yield Facts for NEET-PG:** * **Risk Factors:** Young age, female gender, pregnancy, and the use of large-bore/cutting-tip needles. * **Clinical Feature:** Pathognomonic **postural nature** (worsens on standing/sitting, relieved by lying flat). * **Gold Standard Treatment:** **Epidural Blood Patch** (injecting 15–20 ml of autologous blood into the epidural space to "plug" the leak). * **Conservative Management:** Bed rest, hydration, caffeine (causes cerebral vasoconstriction), and analgesics.

Question 17: Which position is best for patients with suspected air embolism?

A. Supine
B. Left Lateral
C. Trendelenburg
D. Left Lateral Decubitus with Trendelenburg (Correct Answer)

Explanation: **Explanation:** The correct position for managing a suspected venous air embolism (VAE) is the **Left Lateral Decubitus with Trendelenburg position**, also known as the **Durant’s Maneuver**. **1. Why it is correct:** When air enters the venous circulation, it travels to the right atrium and then the right ventricle. In the right ventricle, air can form an "air lock" in the pulmonary outflow tract, obstructing blood flow to the lungs and causing cardiovascular collapse. * **Left Lateral Decubitus:** By placing the patient on their left side, the right ventricular outflow tract (RVOT) is positioned inferior to the right ventricular body. This causes the air bubble to float upward, away from the RVOT, and remain trapped in the apex of the right ventricle. * **Trendelenburg (Head-down):** This further helps in trapping the air in the apex and increases venous pressure, preventing further air entry if the source is above the heart level. **2. Why other options are incorrect:** * **Supine:** In this position, air can easily move from the right atrium into the RVOT, increasing the risk of a fatal air lock. * **Left Lateral:** While helpful, it is incomplete without the Trendelenburg tilt, which provides the gravitational advantage needed to keep air away from the pulmonary artery. * **Trendelenburg:** Alone, this does not prevent the air from migrating into the pulmonary circulation as effectively as when combined with the left lateral tilt. **3. Clinical Pearls for NEET-PG:** * **Most sensitive monitor:** Transesophageal Echocardiography (TEE). * **Most sensitive non-invasive monitor:** Precordial Doppler (placed at the 3rd–6th intercostal space, right sternal border). * **Classic Sign:** "Mill-wheel murmur" (a late sign heard via esophageal stethoscope). * **Immediate Management:** 100% Oxygen, Durant's maneuver, and aspiration of air via a Central Venous Catheter (if present).

Question 18: Post-anesthetic muscle soreness is most commonly caused by which of the following medications?

A. Gallamine
B. D-tubocurarine (d-TC)
C. Suxamethonium (Correct Answer)
D. Dantrolene

Explanation: **Explanation:** **Suxamethonium (Succinylcholine)** is the correct answer. It is a depolarizing neuromuscular blocker that works by mimicking acetylcholine at the motor endplate. Upon administration, it causes a characteristic disorganized contraction of muscle fibers known as **fasciculations**. These intense, unsynchronized contractions lead to micro-trauma of the muscle fibers and the release of lactic acid, resulting in **post-operative myalgia (muscle soreness)**. This is most commonly seen in the neck, shoulders, and abdominal muscles, particularly in young adults undergoing ambulatory surgery. **Analysis of Incorrect Options:** * **Gallamine & D-tubocurarine (d-TC):** These are non-depolarizing neuromuscular blockers (NDMRs). They act as competitive antagonists at the nicotinic receptors and do not cause depolarization or fasciculations; therefore, they do not cause muscle soreness. In fact, a small "pre-curarizing" dose of an NDMR is often used to *prevent* suxamethonium-induced soreness. * **Dantrolene:** This is a muscle relaxant that acts directly on the Ryanodine receptor (RyR1) to inhibit calcium release from the sarcoplasmic reticulum. It is the drug of choice for treating Malignant Hyperthermia and actually reduces muscle contraction rather than causing soreness. **Clinical Pearls for NEET-PG:** * **Incidence:** Muscle soreness is more common in females and "early-ambulated" patients (outpatient procedures). * **Prevention:** Pre-treatment with a small dose of non-depolarizing relaxant (e.g., Vecuronium or d-TC) or NSAIDs can reduce the severity of myalgia. * **Biochemical marker:** Post-suxamethonium soreness is often associated with a transient rise in serum **creatine phosphokinase (CPK)** and myoglobinuria.

Question 19: A patient undergoing eye surgery received propofol for intravenous anesthesia and succinylcholine as a muscle relaxant. Recovery from anesthesia was uneventful. However, 8 hours post-surgery, the patient complained of leg pain upon walking. What is the most likely cause of this symptom?

A. Propofol
B. Succinylcholine (Correct Answer)
C. Post-surgical pain
D. Early mobilization

Explanation: ### Explanation The correct answer is **Succinylcholine**. **Why Succinylcholine is the cause:** The patient is experiencing **postoperative myalgia (POM)**, a well-known side effect of Succinylcholine (Suxamethonium). Succinylcholine is a depolarizing neuromuscular blocker that acts by mimicking acetylcholine at the motor endplate. This causes disorganized muscle contractions known as **fasciculations** before paralysis occurs. These fasciculations lead to microscopic muscle fiber damage and the release of prostaglandins and lactic acid, resulting in muscle pain. * **Timing:** Typically occurs 12–24 hours post-surgery (though can start sooner). * **Location:** Most common in the neck, shoulders, and abdominal muscles, but often felt in the legs upon mobilization. * **Risk Factors:** Young adults, females, and patients undergoing minor/ambulatory surgery (early mobilization exacerbates the pain). **Why other options are incorrect:** * **Propofol:** While propofol can cause pain on injection, it does not cause delayed systemic muscle pain. * **Post-surgical pain:** Pain from eye surgery (ophthalmic) would be localized to the periorbital area, not the legs. * **Early mobilization:** While walking triggers the sensation of myalgia, it is the *inciting agent* (Succinylcholine) that is the underlying cause. **High-Yield Clinical Pearls for NEET-PG:** * **Prevention:** Pre-treatment with a small dose of a **non-depolarizing muscle relaxant (NDMR)** (e.g., Vecuronium or Rocuronium) can reduce the severity of fasciculations and subsequent myalgia. * **Contraindications:** Avoid Succinylcholine in patients with burns, massive trauma, or upper motor neuron lesions due to the risk of **hyperkalemia**. * **Association:** Succinylcholine is a potent trigger for **Malignant Hyperthermia**.

Question 20: What is the primary treatment for malignant hyperthermia?

A. Dantrolene sodium (Correct Answer)
B. Potassium chloride
C. Atropine
D. Corticosteroids

Explanation: **Explanation:** **Malignant Hyperthermia (MH)** is a life-threatening hypermetabolic crisis triggered by volatile anesthetics (e.g., Halothane, Sevoflurane) or depolarizing muscle relaxants (Succinylcholine) in genetically susceptible individuals (mutations in **RYR1 or CACNA1S genes**). **Why Dantrolene is the Correct Answer:** Dantrolene sodium is the specific antidote for MH. It acts as a **postsynaptic muscle relaxant** by binding to the **Ryanodine Receptor (RYR1)**. This inhibits the excessive release of calcium from the sarcoplasmic reticulum into the myoplasm, effectively halting the uncontrolled muscle contractions and hypermetabolic state that characterize the condition. **Analysis of Incorrect Options:** * **B. Potassium Chloride:** Incorrect. MH causes severe **hyperkalemia** due to rhabdomyolysis. Administering potassium would be fatal. Management actually involves lowering potassium levels (e.g., insulin/glucose). * **C. Atropine:** Incorrect. While MH presents with tachycardia, Atropine (an anticholinergic) would worsen the tachycardia and interfere with temperature regulation. * **D. Corticosteroids:** Incorrect. These have no role in the pathophysiology of MH, which is a calcium-channel disorder, not an inflammatory or allergic reaction. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Increase in **End-Tidal CO₂ (ETCO₂)** despite increased ventilation. * **Late Sign:** Hyperpyrexia (can exceed 110°F). * **Dose:** Initial dose of Dantrolene is **2.5 mg/kg IV**, repeated until symptoms subside (up to 10 mg/kg). * **Gold Standard Diagnosis:** Caffeine Halothane Contracture Test (CHCT) on a muscle biopsy. * **Safe Agents:** Propofol, Ketamine, Etomidate, and non-depolarizing neuromuscular blockers (e.g., Vecuronium).

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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