Complications in Anesthesia — MCQs

Complications in Anesthesia Indian Medical PG Practice Questions and MCQs

Question 151: Which of the following drugs can cause bradycardia during anaesthesia?

A. Pancuronium
B. Vecuronium
C. Atracurium
D. Propofol (Correct Answer)

Explanation: **Explanation:** **Propofol (Correct Answer):** Propofol is a potent intravenous anesthetic agent that frequently causes **bradycardia** and hypotension. The underlying mechanism involves a significant reduction in sympathetic tone and an inhibition of the baroreceptor reflex. Unlike other induction agents, propofol resets the baroreflex, meaning the heart rate does not increase reflexively in response to the drop in blood pressure. In some cases, it can lead to profound vagotonic effects, occasionally resulting in asystole. **Analysis of Incorrect Options:** * **Pancuronium:** This is a long-acting non-depolarizing neuromuscular blocker (NMBA) known for causing **tachycardia**. It has vagolytic properties and stimulates the release of norepinephrine from cardiac sympathetic nerve endings. * **Vecuronium:** This is considered a **cardiovascularly stable** NMBA. It lacks significant vagolytic or histamine-releasing effects, typically resulting in no change in heart rate. * **Atracurium:** While it can cause hypotension due to **histamine release**, the physiological response to this hypotension is usually a compensatory **reflex tachycardia**, not bradycardia. **High-Yield Clinical Pearls for NEET-PG:** * **Propofol Infusion Syndrome (PRIS):** A rare but fatal complication of long-term high-dose infusion characterized by metabolic acidosis, rhabdomyolysis, hyperkalemia, and cardiac failure. * **Drug of Choice:** Propofol is the drug of choice for Day Care Surgery due to its rapid recovery and anti-emetic properties. * **Ketamine vs. Propofol:** While Propofol causes bradycardia and hypotension, Ketamine is the "opposite," causing tachycardia and hypertension (sympathomimetic).

Question 152: Which of the following drugs is used to treat postoperative shivering?

A. Ondansetron
B. Diclofenac Sodium
C. Pethidine (Correct Answer)
D. Paracetamol

Explanation: ### Explanation **Postoperative Shivering (POS)** is a common complication occurring in up to 40% of patients recovering from general or regional anesthesia [3]. It occurs due to intraoperative hypothermia (redistribution of heat) and the lowering of the shivering threshold by anesthetic agents. **Why Pethidine (Meperidine) is the Correct Answer:** Pethidine is considered the **gold standard** and the drug of choice for treating postoperative shivering [1]. Unlike other opioids, pethidine acts on **$κ$ (kappa) receptors** in addition to $μ$ (mu) receptors. Its efficacy in POS is specifically attributed to its ability to **lower the shivering threshold** more effectively than any other opioid, rapidly suppressing the physical manifestations of shivering [1]. **Analysis of Incorrect Options:** * **Ondansetron (Option A):** While some studies suggest 5-HT3 antagonists may have a prophylactic role in preventing shivering by modulating heat loss, they are primarily used as anti-emetics and are not the first-line treatment for active shivering [2]. * **Diclofenac Sodium (Option B) & Paracetamol (Option D):** These are Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) and non-opioid analgesics. While they are excellent for postoperative pain management, they do not significantly influence the central thermoregulatory set-point or the shivering threshold [4]. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Pethidine reduces the shivering threshold via $κ$-receptor agonism. * **Dose:** A low dose (10–25 mg IV) is usually sufficient to stop shivering [1],[2],[3]. * **Other Drugs Used:** Tramadol, Clonidine, and Dexmedetomidine are alternative options [2]. * **Complications of Shivering:** It can increase oxygen consumption by up to **300–400%**, leading to hypoxemia, hypercapnia, and increased risk of myocardial ischemia in susceptible patients [2],[3]. * **Non-pharmacological treatment:** Forced-air warming blankets (Bair Hugger) are the most effective preventive measure [2].

Question 153: Which of the following complications is likely to result after several units of blood have been transfused?

A. Metabolic alkalosis (Correct Answer)
B. Metabolic acidosis
C. Respiratory alkalosis
D. Respiratory acidosis

Explanation: **Explanation:** The correct answer is **Metabolic Alkalosis**. This occurs primarily due to the metabolism of **sodium citrate**, which is used as an anticoagulant in stored blood bags. 1. **Mechanism of Correct Answer:** Each unit of stored blood contains approximately 3 grams of citrate. Once transfused, the liver metabolizes citrate into **bicarbonate (HCO₃⁻)**. In massive blood transfusions (typically defined as >10 units in 24 hours), the rapid accumulation of bicarbonate exceeds the kidney's excretory capacity, leading to an increase in blood pH and metabolic alkalosis. 2. **Why Incorrect Options are Wrong:** * **Metabolic Acidosis:** While stored blood is slightly acidic due to the accumulation of lactic acid and pyruvic acid during storage, this effect is transient. Once transfused, the metabolic conversion of citrate to bicarbonate overrides the initial acidity. * **Respiratory Alkalosis/Acidosis:** These are primarily driven by changes in CO₂ levels (ventilation). Blood transfusion does not directly alter the respiratory drive or CO₂ elimination in a way that consistently produces these states. **NEET-PG High-Yield Pearls:** * **Citrate Toxicity:** Massive transfusion can lead to **Hypocalcemia** because citrate binds to ionized calcium. This can cause arrhythmias and prolonged QT intervals. * **Electrolyte Shifts:** Stored blood undergoes "storage lesion," leading to **Hyperkalemia** (as K+ leaks out of RBCs). However, post-transfusion, hypokalemia may occur as cells take up potassium. * **Hypothermia:** Transfusing cold blood rapidly can lead to cardiac arrhythmias; hence, the use of blood warmers is essential. * **2,3-DPG:** Stored blood has decreased 2,3-DPG, causing a **left shift** of the oxygen-dissociation curve (increased affinity, decreased O₂ delivery to tissues).

Question 154: After induction of anesthesia, what does the anesthetist monitor for when the surgeon manipulates the medial rectus muscle?

A. Oculocardiac reflex (Correct Answer)
B. Hypertension
C. Oxygen delivery
D. Response to painful stimulus

Explanation: **Explanation:** The correct answer is **A. Oculocardiac reflex**. **1. Why Oculocardiac Reflex (OCR) is correct:** The Oculocardiac reflex, also known as the **Aschner-Dagnini reflex**, is a physiological response triggered by pressure on the globe or traction on the extraocular muscles. The **medial rectus** is the most sensitive muscle for eliciting this reflex. * **Pathway:** The afferent limb is the **Ophthalmic division of the Trigeminal nerve (CN V1)**, and the efferent limb is the **Vagus nerve (CN X)**. * **Clinical Manifestation:** Stimulation leads to sudden bradycardia, arrhythmias, or even asystole. It is a classic intraoperative concern during strabismus surgery. **2. Why other options are incorrect:** * **B. Hypertension:** The OCR typically causes hypotension and bradycardia due to vagal stimulation, not hypertension. * **C. Oxygen delivery:** While oxygenation is always monitored (via pulse oximetry), it is not specifically affected by muscle manipulation. * **D. Response to painful stimulus:** While traction is painful, the specific physiological reflex triggered by this anatomical manipulation is the OCR. In a general anesthesia setting, the autonomic reflex (bradycardia) is the primary concern rather than a conscious pain response. **3. High-Yield NEET-PG Pearls:** * **Mnemonic for Pathway:** "Five and Dime" (Afferent: CN **5**; Efferent: CN **10**). * **Management:** The first step is to ask the surgeon to **stop the stimulus**. If it persists, administer **Atropine** (Anticholinergic). * **Fatigability:** The reflex is known to fatigue (decrease in intensity) with repeated stimulation. * **Risk Factors:** More common in pediatric patients and during light planes of anesthesia.

Question 155: What is the best treatment for post-dural puncture headache?

A. Caffeine
B. NSAIDs
C. Extradural blood patch (Correct Answer)
D. IV fluids

Explanation: **Explanation:** **Post-Dural Puncture Headache (PDPH)** occurs due to the leakage of cerebrospinal fluid (CSF) through a dural rent, leading to low CSF pressure and compensatory cerebral vasodilation. This results in a characteristic positional headache (worse on standing, relieved by lying flat). **Why Option C is Correct:** The **Epidural (Extradural) Blood Patch** is considered the **gold standard and most effective treatment** for PDPH. It involves injecting 15–20 ml of autologous venous blood into the epidural space near the site of the dural puncture. It works via two mechanisms: 1. **Immediate effect:** The volume of blood increases epidural pressure, compressing the thecal sac and raising CSF pressure. 2. **Long-term effect:** The blood clots over the dural hole, acting as a "plug" to prevent further CSF leakage. **Analysis of Incorrect Options:** * **A & B (Caffeine & NSAIDs):** These are considered **conservative/symptomatic management**. Caffeine causes cerebral vasoconstriction to counteract the vasodilation, and NSAIDs help with pain. However, they do not fix the underlying dural hole. * **D (IV Fluids):** While hydration is traditionally advised to encourage CSF production, clinical evidence suggests it does not significantly resolve the headache or the leak. **High-Yield Clinical Pearls for NEET-PG:** * **Risk Factors:** Young age, female gender, pregnancy, and use of large-bore/cutting needles (e.g., Quincke). * **Prevention:** Use of small-gauge (25G-27G) **pencil-point needles** (e.g., Sprotte or Whitacre) significantly reduces the incidence of PDPH. * **Timing:** PDPH typically presents within 48 hours. If conservative management fails after 24–48 hours, a blood patch is indicated.

Question 156: A patient with a Ryanodine receptor 1 (RYR1) mutation should avoid which of the following anesthetic agents?

A. Succinylcholine (Correct Answer)
B. Nitrous oxide
C. Lidocaine
D. Propofol

Explanation: **Explanation:** The question describes a patient predisposed to **Malignant Hyperthermia (MH)**, a life-threatening hypermetabolic state of skeletal muscle. The underlying pathophysiology involves a mutation in the **RYR1 gene**, which encodes the Ryanodine receptor. This receptor is a calcium release channel in the sarcoplasmic reticulum; when mutated, it causes an uncontrolled release of calcium in response to specific "triggering agents." **Why Succinylcholine is the correct answer:** Succinylcholine (a depolarizing neuromuscular blocker) and all **volatile inhalational anesthetics** (e.g., Halothane, Isoflurane, Sevoflurane) are the primary triggers for MH. In susceptible individuals, these agents cause sustained muscle contraction, leading to hyperthermia, rhabdomyolysis, and metabolic acidosis. **Why the other options are incorrect:** * **B. Nitrous oxide:** This is a non-triggering gas and is considered safe for MH-susceptible patients. * **C. Lidocaine:** Amide and ester local anesthetics do not trigger MH and are safe for regional or local anesthesia. * **D. Propofol:** This is the intravenous induction agent of choice for MH-susceptible patients as it does not affect the RYR1 receptor. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Increase in **EtCO2** (End-tidal Carbon Dioxide) despite increased ventilation. * **Late Sign:** Hyperthermia (can be as high as 1°C every 5 minutes). * **Drug of Choice:** **Dantrolene** (a muscle relaxant that acts directly on the RYR1 receptor to prevent calcium release). * **Safe Agents:** Propofol, Etomidate, Thiopentone, Ketamine, Opioids, and all Non-depolarizing muscle relaxants (e.g., Vecuronium, Atracurium). * **Associated Conditions:** Central Core Disease and King-Denborough Syndrome are also linked to RYR1 mutations and MH risk.

Question 157: Pneumothorax is a known complication of which of the following procedures?

A. Axillary block
B. Brachial plexus block (Correct Answer)
C. Epidural block
D. High Spinal block

Explanation: **Explanation:** **1. Why Brachial Plexus Block is Correct:** Pneumothorax is a classic and feared complication of the **Brachial Plexus Block**, specifically when using the **supraclavicular approach**. In this technique, the needle is inserted near the midpoint of the clavicle to target the trunks of the plexus. Due to the close anatomical proximity of the **cupula (apex) of the lung** to the first rib, an inadvertent deep or medial needle angulation can easily puncture the pleura, leading to a pneumothorax. While ultrasound guidance has reduced this risk, it remains a high-yield association in clinical exams. **2. Analysis of Incorrect Options:** * **Axillary Block:** This approach targets the terminal branches of the plexus in the axilla. It is performed far away from the thoracic cavity, making pneumothorax virtually impossible. * **Epidural/High Spinal Block:** These involve the neuraxial space. While they can cause complications like hypotension, "total spinal" (respiratory arrest due to phrenic nerve paralysis), or dural puncture headaches, they do not involve the pleural space and thus do not cause pneumothorax. **3. Clinical Pearls for NEET-PG:** * **Supraclavicular Block** is often called the "Spinal of the Upper Limb" due to its dense, rapid onset. * **Highest risk of pneumothorax:** Supraclavicular approach (0.5%–6% in landmark techniques). * **Lowest risk of pneumothorax (Upper limb):** Axillary or Interscalene approach (though interscalene carries a risk of phrenic nerve palsy). * **Classic Presentation:** Sudden onset pleuritic chest pain and dyspnea, though symptoms may be delayed by 6–12 hours post-procedure.

Question 158: Which of the following anesthetic agents is considered safe even if inadvertently injected intra-arterially?

A. Thiopentone
B. Propofol (Correct Answer)
C. Midazolam
D. Methohexitone

Explanation: **Explanation:** The correct answer is **Propofol**. **1. Why Propofol is the Correct Answer:** Intra-arterial injection of anesthetic drugs is a dreaded complication that can lead to severe vasospasm, endarteritis, and tissue necrosis. **Propofol** is considered relatively safe in this context because it does not cause significant vascular damage or crystal formation. While it may cause transient pain at the injection site, it lacks the potent vasoconstrictive and pro-thrombotic properties seen with barbiturates. **2. Why the Other Options are Incorrect:** * **Thiopentone (Option A):** This is the most classic example of a dangerous intra-arterial injection. Thiopentone is highly alkaline (pH 10.5). When injected into an artery, it reacts with blood to form **insoluble crystals** that cause mechanical obstruction, intense vasospasm, and chemical endarteritis, often leading to gangrene. * **Methohexitone (Option D):** Like Thiopentone, Methohexitone is an alkaline barbiturate. It carries a high risk of vascular injury and tissue necrosis if administered intra-arterially. * **Midazolam (Option C):** While less toxic than barbiturates, intra-arterial Midazolam can still cause significant vascular irritation and has been associated with clinical complications, making it less "safe" than Propofol. **3. Clinical Pearls for NEET-PG:** * **Management of Intra-arterial Thiopentone:** Leave the needle in situ, dilute with saline, and inject **Papaverine** (vasodilator), **Lidocaine** (to prevent spasm), or **Heparin** (to prevent thrombosis). A **Stellate Ganglion Block** or Brachial Plexus block may be performed to induce sympathetic-mediated vasodilation. * **High-Yield Fact:** The primary mechanism of injury in Thiopentone injection is the formation of crystals in the small arterioles, not just the pH itself.

Question 159: A patient developed respiratory distress and hypoxemia after central venous catheterization through the internal jugular vein. What is the most likely reason for this complication?

A. Pneumothorax (Correct Answer)
B. Hypovolemia
C. Septicemia
D. Cardiac tamponade

Explanation: ### Explanation **Correct Option: A. Pneumothorax** Pneumothorax is a well-known mechanical complication of central venous catheterization (CVC), particularly when using the internal jugular (IJV) or subclavian vein approach. The apex of the lung (cupula) extends above the level of the first rib; accidental puncture of the pleura during needle insertion allows air to enter the pleural space. This leads to lung collapse, resulting in sudden onset **respiratory distress, tachypnea, and hypoxemia**. While ultrasound guidance has reduced this risk, it remains a high-yield clinical scenario for exams. **Analysis of Incorrect Options:** * **B. Hypovolemia:** This presents with hypotension and tachycardia due to fluid loss, not primary respiratory distress or acute hypoxemia immediately following a procedure. * **C. Septicemia:** This is a late (delayed) complication of CVC (Central Line-Associated Bloodstream Infection - CLABSI). It presents with fever and chills days after insertion, not acute respiratory distress. * **D. Cardiac Tamponade:** While a serious complication of CVC (due to vessel or cardiac wall perforation), it typically presents with **Beck’s Triad** (hypotension, muffled heart sounds, and JVD). While it can cause distress, the primary pathology is obstructive shock rather than isolated hypoxemia. **High-Yield Clinical Pearls for NEET-PG:** * **Highest Risk:** The **subclavian approach** carries a higher risk of pneumothorax compared to the IJV approach. * **Immediate Action:** If pneumothorax is suspected post-CVC, the first diagnostic step is a **Chest X-ray** (expiratory film is preferred). * **Other Acute Complications:** Always rule out **Arterial Puncture** (most common complication of IJV cannulation) and **Air Embolism** (presents with a "mill-wheel" murmur). * **Gold Standard:** Ultrasound-guided insertion is the current standard of care to minimize these mechanical risks.

Question 160: Bradycardia is common after injection of which of the following drugs?

A. Midazolam
B. Succinylcholine (Correct Answer)
C. Dopamine
D. Isoprenaline

Explanation: **Explanation:** **Succinylcholine (Suxamethonium)** is a depolarizing neuromuscular blocker that is structurally composed of two joined molecules of acetylcholine. Its tendency to cause **bradycardia** is primarily due to its action on **muscarinic (M2) receptors** in the sinoatrial (SA) node. This effect is particularly pronounced in children (who have higher vagal tone) and in adults when a second dose is administered within a short interval (usually 5 minutes). **Analysis of Options:** * **Succinylcholine (Correct):** By mimicking acetylcholine at cardiac muscarinic receptors, it can cause profound bradycardia, nodal rhythms, or even asystole. It is also associated with hyperkalemia, which can further exacerbate cardiac arrhythmias. * **Midazolam:** A benzodiazepine that typically causes minimal hemodynamic changes. While it may cause a slight decrease in systemic vascular resistance, it does not characteristically cause bradycardia. * **Dopamine:** A sympathomimetic amine. At moderate to high doses, it stimulates $\beta_1$ receptors, leading to **tachycardia** and increased contractility. * **Isoprenaline:** A potent non-selective $\beta$-adrenergic agonist. It is used clinically to *treat* bradycardia because it significantly increases heart rate (**tachycardia**) and cardiac output. **Clinical Pearls for NEET-PG:** 1. **Pre-treatment:** Atropine is often administered to children before succinylcholine to prevent vagal-induced bradycardia. 2. **Other Side Effects:** Succinylcholine is high-yield for its association with **Malignant Hyperthermia**, hyperkalemia (avoid in burns/crush injuries), and increased intraocular/intragastric pressure. 3. **Phase II Block:** Prolonged exposure to succinylcholine can lead to a Phase II block, which resembles a non-depolarizing block.

Practice by Chapter

Adverse Drug Reactions

Practice Questions

Anaphylaxis and Allergic Reactions

Practice Questions

Malignant Hyperthermia

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Local Anesthetic Toxicity

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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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