Complications in Anesthesia Practice Questions

Q: A 64-year-old hypertensive, obese female was undergoing surgery for a fracture femur under general anesthesia. Intra-operatively, her end-tidal carbon dioxide decreased to 20 mm Hg from 40 mm Hg, followed by hypotension and an oxygen saturation of 85%. What is the most probable cause?

Fat embolism. ### Explanation The clinical presentation of sudden **hypotension**, **hypoxemia** ($SpO_2$ 85%), and a **precipitous drop in End-Tidal $CO_2$ ($EtCO_2$)** in a patient undergoing surgery for a long bone fracture (femur) is a classic triad for **Fat Embolism Syndrome (FES)**. **Why Fat Embolism is Correct:** In orthopedic surgeries involving long bones, fat globules from the bone marrow enter the systemic circulation. These emboli obstruct the pulmonary vasculature, leading to an increase in **alveolar dead space** (areas ventilated but not perfused). This results in a sudden drop in $EtCO_2$ because $CO_2$ cannot be exchanged. The mechanical obstruction and inflammatory response cause acute pulmonary hypertension, right heart strain, and systemic hypotension. **Why Other Options are Incorrect:** * **Hypovolemia:** While it causes hypotension, it usually presents with a gradual decline in $EtCO_2$ and does not typically cause a sudden, severe drop in oxygen saturation to 85% unless associated with shock. * **Bronchospasm:** This would cause an *increase* in $EtCO_2$ (due to obstructive physiology) and a characteristic "shark-fin" appearance on the capnograph, rather than a decrease. * **Myocardial Infarction:** While it causes hypotension, the sudden drop in $EtCO_2$ and severe hypoxemia are more characteristic of a primary pulmonary embolic event in the context of a femur fracture. **Clinical Pearls for NEET-PG:** * **Gurd’s Criteria:** Used for FES diagnosis; look for the triad of respiratory distress, petechial rashes (axilla/conjunctiva), and cerebral involvement. * **EtCO2 Drop:** A sudden decrease in $EtCO_2$ is the earliest sign of any embolism (Air, Fat, or Thromboembolism) under anesthesia. * **Management:** Primarily supportive (oxygenation and hemodynamics). Early fixation of fractures reduces the incidence of FES.

Q: A 28-year-old man is scheduled for shoulder surgery. He has a documented history of malignant hyperthermia during a previous general anesthesia. Which of the following neuromuscular blockers is contraindicated in this patient?

Succinylcholine. **Explanation:** **Malignant Hyperthermia (MH)** is a life-threatening pharmacogenetic hypermetabolic disorder of skeletal muscle. The core pathology involves a mutation in the **RYR1 receptor** (Ryanodine receptor), leading to an uncontrolled release of calcium from the sarcoplasmic reticulum in response to specific "triggering agents." **Why Succinylcholine is the Correct Answer:** Succinylcholine is a **depolarizing neuromuscular blocker** and is one of the two primary triggers for MH (the other being volatile inhalational anesthetics like Halothane, Isoflurane, and Sevoflurane). In susceptible individuals, Succinylcholine causes sustained muscle contraction, leading to hyperlactatemia, hyperkalemia, hyperthermia, and rhabdomyolysis. Therefore, it is strictly contraindicated in this patient. **Why Other Options are Incorrect:** * **Options B, C, and D (Pancuronium, Rocuronium, Vecuronium):** These are **non-depolarizing neuromuscular blockers**. They do not trigger the RYR1 receptor and do not cause the release of calcium that leads to MH. They are considered safe alternatives for muscle relaxation in MH-susceptible patients. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Increase in **End-Tidal CO₂ (ETCO₂)** despite increased minute ventilation. * **Specific Sign:** Masseter muscle rigidity (Trismus). * **Late Sign:** Hyperthermia (can rise at 1°C every 5 minutes). * **Drug of Choice:** **Dantrolene** (Mechanism: Binds to RYR1 receptors and inhibits calcium release). * **Safe Anesthesia Plan:** Total Intravenous Anesthesia (TIVA) using Propofol, Opioids, and Non-depolarizing muscle relaxants. Always flush the anesthesia machine to remove residual volatile gases before use.

Q: A male patient became suddenly tachypneic, hypoxic, and febrile a few hours after anesthesia during an abdominal surgery. Mendelson's syndrome is suspected. What is the likely cause of this syndrome in this patient?

Gastric aspiration. **Explanation:** **Mendelson’s Syndrome** is a specific type of chemical pneumonitis caused by the **aspiration of acidic gastric contents** into the lungs. It typically occurs during the induction or emergence phase of anesthesia when protective airway reflexes are depressed. **Why Gastric Aspiration is Correct:** The syndrome is defined by the aspiration of gastric juice with a **pH < 2.5** and a volume of at least **25 ml (0.4 ml/kg)**. The acidic nature of the aspirate causes immediate chemical damage to the alveolar-capillary membrane, leading to pulmonary edema, bronchospasm, and severe hypoxia. Clinical features include sudden onset of tachypnea, cyanosis, tachycardia, and wheezing (resembling asthma), often occurring within 2–12 hours post-aspiration. **Why Other Options are Incorrect:** * **Option A:** Hypersensitivity (Anaphylaxis) usually presents immediately upon drug administration with hypotension, urticaria, and angioedema, rather than delayed febrile respiratory distress. * **Option C:** Faulty intubation (e.g., esophageal intubation) would cause immediate hypoxia and lack of chest rise, not a delayed febrile syndrome. * **Option D:** Tracheal stenosis is a chronic complication of long-term intubation, presenting with inspiratory stridor weeks after the procedure, not acute post-operative distress. **High-Yield Clinical Pearls for NEET-PG:** * **Risk Factors:** Pregnancy (due to increased intra-abdominal pressure and relaxed lower esophageal sphincter), obesity, and emergency surgeries (full stomach). * **Prevention:** Pre-operative fasting (NPO guidelines), use of H2 blockers (Ranitidine), proton pump inhibitors (Pantoprazole), and non-particulate antacids (Sodium Citrate). * **Management:** Immediate suctioning of the oropharynx, supplemental oxygen, and supportive ventilation. Prophylactic antibiotics and steroids are generally **not** recommended.

Q: Aschner's reflex is seen in which of the following?

Squint surgery. **Explanation:** **Aschner’s Reflex**, also known as the **Oculocardiac Reflex (OCR)**, is a physiological response triggered by pressure on the globe or traction on the extraocular muscles. 1. **Why Squint Surgery is Correct:** Squint surgery involves significant manipulation and traction of the extraocular muscles (most commonly the **medial rectus**). This traction triggers the reflex arc: * **Afferent limb:** Trigeminal nerve (Ciliary nerves → Ophthalmic division $V_1$ → Gasserian ganglion). * **Efferent limb:** Vagus nerve (X). The resulting vagal stimulation leads to **bradycardia**, arrhythmias, or even asystole. It is a classic intraoperative complication in pediatric ophthalmology. 2. **Why Other Options are Incorrect:** * **Cardiac Surgery:** While bradycardia occurs, it is usually due to direct nodal manipulation or drugs, not the trigeminal-vagal reflex. * **Neurosurgery:** Can involve the Cushing reflex (hypertension + bradycardia due to increased ICP), but not the Aschner reflex unless the trigeminal nerve is directly manipulated. * **Spinal Anesthesia:** Bradycardia here is typically due to blockade of cardioaccelerator fibers (T1–T4) or a decrease in venous return (Bezold-Jarisch reflex), not ocular stimulation. **High-Yield Clinical Pearls for NEET-PG:** * **Most common muscle involved:** Medial Rectus. * **Management:** 1. **Immediate step:** Ask the surgeon to **stop** the stimulus (release traction). 2. Ensure adequate oxygenation/ventilation (hypoxia/hypercarbia exacerbates the reflex). 3. If persistent: Administer **Atropine** (0.02 mg/kg) or Glycopyrrolate. * **Fatigability:** The reflex shows "fatigue," meaning the heart rate response diminishes with repeated stimulation.

Q: Intraoperative wheezing can be managed by:

Ketamine. ### Explanation **Correct Answer: B. Ketamine** **Why Ketamine is the Correct Choice:** Intraoperative wheezing is often a sign of bronchospasm. **Ketamine** is the induction agent of choice in patients with reactive airway disease (like asthma or COPD) because of its potent **bronchodilatory properties**. It achieves this through two mechanisms: 1. **Sympathomimetic effect:** It triggers the release of endogenous catecholamines, which stimulate $\beta_2$ receptors in the bronchial smooth muscle. 2. **Direct action:** It has a direct relaxant effect on the bronchial smooth muscle. **Analysis of Incorrect Options:** * **A. Thiopentone:** This is a barbiturate known to cause **histamine release**. It can precipitate or worsen bronchospasm and is generally avoided in asthmatic patients. * **C. Methohexitone:** Like Thiopentone, it is a barbiturate. While it has a shorter duration of action, it does not possess bronchodilatory properties and can also trigger histamine release. * **D. Propofol:** While Propofol is generally safe for asthmatics and does not cause histamine release, it is not as effective as Ketamine for *managing* active intraoperative wheezing. (Note: Propofol is often the preferred induction agent for stable asthmatics, but Ketamine is the specific "rescue" induction agent for bronchospasm). **Clinical Pearls for NEET-PG:** * **Drug of Choice for Induction in Asthma:** Ketamine (due to bronchodilation) or Propofol (due to suppression of airway reflexes). * **Avoid in Asthma:** Thiopentone, Morphine, Atracurium (all cause histamine release). * **Management of Intraoperative Bronchospasm:** Increase $FiO_2$, deepen anesthesia (with Volatile agents like Sevoflurane), administer $\beta_2$ agonists (Salbutamol), and consider Ketamine or Hydrocortisone. * **Halothane** is also a potent bronchodilator but is rarely used now due to its potential for arrhythmias when used with catecholamines.

Q: Which volatile anesthetic agent causes the most renal toxicity?

Methoxyflurane. **Explanation:** The correct answer is **Methoxyflurane**. The primary mechanism behind its renal toxicity is the extensive hepatic metabolism of the drug, which releases **inorganic fluoride ions ($F^-$)**. 1. **Why Methoxyflurane is correct:** Methoxyflurane undergoes the highest degree of metabolism (approx. 50–75%) among all volatile agents. This results in high serum fluoride levels (often exceeding 50 µmol/L). These fluoride ions cause **vasopressin-resistant high-output renal failure** (polyuric renal failure) by damaging the distal convoluted tubules and collecting ducts, making them unresponsive to ADH. Due to this severe nephrotoxicity, it is no longer used for general anesthesia. 2. **Why other options are incorrect:** * **Ether:** Primarily known for its irritant effect on airways and flammability; it does not produce toxic fluoride metabolites. * **Isoflurane:** It is very stable and undergoes minimal metabolism (0.2%), making it exceptionally safe for the kidneys. * **Sevoflurane:** While it does release fluoride ions and can produce **Compound A** (a nephrotoxin in rats) when reacting with soda lime, clinical studies have shown no significant evidence of renal toxicity in humans when used at recommended flow rates. **High-Yield Clinical Pearls for NEET-PG:** * **Fluoride-induced nephrotoxicity:** Characterized by polyuria, hypernatremia, and increased serum creatinine. * **Metabolism Ranking (Highest to Lowest):** Methoxyflurane (50-75%) > Halothane (20%) > Sevoflurane (2-5%) > Enflurane (2%) > Isoflurane (0.2%) > Desflurane (0.02%). * **Compound A:** Associated with **Sevoflurane**; formed by degradation in carbon dioxide absorbers (especially with low-flow anesthesia). * **Agent of choice in Renal Failure:** Isoflurane or Desflurane.

Q: Shortly after the administration of an inhalational anesthetic and succinylcholine for intubation prior to an elective inguinal hernia repair in a 10-year-old boy, he becomes markedly febrile, displays a tachycardia of 160, and his urine changes color to a dark red. Which of the following is the most appropriate initial management?

Hyperventilate with 100% O2 and initiate cooling measures.. ### **Explanation** **Diagnosis: Malignant Hyperthermia (MH)** The clinical presentation of rapid-onset fever, tachycardia, and dark red urine (myoglobinuria) following the administration of **succinylcholine** and **inhalational anesthetics** is a classic triad for Malignant Hyperthermia. This is a pharmacogenetic hypermetabolic state caused by a mutation in the **Ryanodine receptor (RYR1)**, leading to massive calcium release from the sarcoplasmic reticulum. **1. Why Option D is Correct:** The immediate priority in MH is to stop the triggering agents and manage the hypermetabolic crisis. * **Hyperventilation with 100% O2:** This addresses the severe respiratory and metabolic acidosis and washes out the volatile anesthetic. * **Cooling Measures:** Essential to combat life-threatening hyperthermia. * **Definitive Treatment:** Though not listed as the sole step here, the administration of **Dantrolene** (a muscle relaxant that binds to RYR1) is the gold standard. **2. Why Other Options are Wrong:** * **Option A:** MH is a surgical emergency with high mortality if not treated immediately. The procedure must be aborted, and Dantrolene must be given *now*, not just as prophylaxis for future surgeries. * **Options B & C:** Inhalational agents and succinylcholine are the **primary triggers** of MH. Administering more would worsen the muscle rigidity, hyperkalemia, and hyperthermia, likely leading to cardiac arrest. **3. NEET-PG High-Yield Pearls:** * **Earliest Sign:** Increase in **End-Tidal CO2 (ETCO2)** (due to hypermetabolism). * **Most Common Trigger:** Halothane and Succinylcholine. * **Safe Agents:** Propofol, Ketamine, Etomidate, and Nitrous Oxide. * **Gold Standard Diagnostic Test:** Caffeine Halothane Contracture Test (CHCT) on a muscle biopsy. * **Dantrolene Dosage:** 2.5 mg/kg IV bolus, repeated every 5–10 minutes until symptoms subside.

Q: Following accidental intra-arterial injection of thiopentone, which of the following should not be done?

Remove the needle. ### Explanation The accidental intra-arterial injection of Thiopentone (an alkaline solution with pH 10.5) is a medical emergency. When injected into an artery, thiopentone reacts with blood to form **crystals**, leading to intense vasospasm, chemical endarteritis, and subsequent thrombosis, which can result in gangrene. **Why "Remove the needle" is the correct answer:** The most critical initial step is to **leave the needle in situ**. Removing the needle loses the only direct access to the affected arterial tree. The needle should be used immediately to administer vasodilators and anticoagulants to counteract the vasospasm and prevent clot formation. **Analysis of Incorrect Options:** * **Intra-arterial Heparin:** This is a standard treatment to prevent thrombosis and further propagation of clots distal to the site of crystal formation. * **Intra-arterial Papaverine:** This is a potent vasodilator used to relieve the intense arterial spasm caused by the alkaline drug. Other alternatives include Lidocaine or Priscoline. * **Stellate Ganglion Block:** This procedure (or a brachial plexus block) is performed to produce sympathetic blockade, which results in vasodilation and improved collateral circulation to the affected limb. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Injury:** Precipitation of thiopentone crystals in the small arterioles due to the change from high pH (drug) to lower pH (blood). * **Immediate Management:** 1. **Leave the needle in place.** 2. Dilute the drug by injecting Normal Saline through the needle. 3. Administer vasodilators (Papaverine 40-80mg or 1% Lidocaine). 4. Heparinization to prevent thrombosis. 5. Sympathetic block (Stellate ganglion block). * **Clinical Sign:** The patient typically complains of a sudden, "scalding" or shooting pain down the limb during injection.

Question 1

A 40-year-old paraplegic patient is scheduled for cholecystectomy due to acute cholecystitis. Succinylcholine is administered prior to intubation. Immediately after induction of anesthesia, the patient develops cardiac arrest. What is the most likely cause?

Accepted Answer

Hyperkalemia

Answer

Esophageal intubation

Answer

Perforation of gallbladder

Answer

Hypovolemic shock

Question 2

A 64-year-old hypertensive, obese female was undergoing surgery for a fracture femur under general anesthesia. Intra-operatively, her end-tidal carbon dioxide decreased to 20 mm Hg from 40 mm Hg, followed by hypotension and an oxygen saturation of 85%. What is the most probable cause?

Accepted Answer

Fat embolism

Answer

Hypovolemia

Answer

Bronchospasm

Answer

Myocardial infarction

Question 3

A 28-year-old man is scheduled for shoulder surgery. He has a documented history of malignant hyperthermia during a previous general anesthesia. Which of the following neuromuscular blockers is contraindicated in this patient?

Accepted Answer

Succinylcholine

Answer

Pancuronium

Answer

Rocuronium

Answer

Vecuronium

Question 4

A male patient became suddenly tachypneic, hypoxic, and febrile a few hours after anesthesia during an abdominal surgery. Mendelson's syndrome is suspected. What is the likely cause of this syndrome in this patient?

Accepted Answer

Gastric aspiration

Answer

Hypersensitivity reaction to anesthetic agent

Answer

Faulty intubation

Answer

Asphyxia due to tracheal stenosis

Question 5

Aschner's reflex is seen in which of the following?

Accepted Answer

Squint surgery

Answer

Cardiac surgery

Answer

Neurosurgery

Answer

Spinal anesthesia

Question 6

Intraoperative wheezing can be managed by:

Accepted Answer

Ketamine

Answer

Thiopentane

Answer

Methohexitone

Answer

Propofol

Question 7

Which volatile anesthetic agent causes the most renal toxicity?

Accepted Answer

Methoxyflurane

Answer

Ether

Answer

Isoflurane

Answer

Sevoflurane

Question 8

A patient presents to the emergency department with a stab injury to the left side of the abdomen. She is hemodynamically stable, and a contrast-enhanced CT scan reveals a splenic laceration. Laparoscopy is planned. The patient's pO2 suddenly drops as soon as pneumoperitoneum is created. What is the most likely cause?

Accepted Answer

Gaseous embolism through splenic vessels

Answer

Inferior vena cava compression

Answer

Injury to the left lobe of the diaphragm

Answer

Injury to the colon

Question 9

Shortly after the administration of an inhalational anesthetic and succinylcholine for intubation prior to an elective inguinal hernia repair in a 10-year-old boy, he becomes markedly febrile, displays a tachycardia of 160, and his urine changes color to a dark red. Which of the following is the most appropriate initial management?

Accepted Answer

Hyperventilate with 100% O2 and initiate cooling measures.

Answer

Complete the procedure but pretreat with dantrolene prior to future elective surgery.

Answer

Administer additional inhalational anesthetic agents.

Answer

Administer additional succinylcholine.

Question 10

Following accidental intra-arterial injection of thiopentone, which of the following should not be done?

Accepted Answer

Remove the needle

Answer

Intra-arterial heparin

Answer

Intra-arterial papaverine

Answer

Perform a stellate ganglion block

Complications in Anesthesia — MCQs

Complications in Anesthesia — MCQs

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