Complications in Anesthesia — MCQs

Complications in Anesthesia Indian Medical PG Practice Questions and MCQs

Question 241: In a patient undergoing a cesarean section under spinal anesthesia, what is the most likely cause of severe headache postoperatively?

A. Hypotension
B. Post-dural puncture headache (Correct Answer)
C. Hypertension
D. Dehydration

Explanation: ***Post-dural puncture headache*** - This is the most common cause of severe headache following **spinal or epidural anesthesia**, due to **CSF leakage** through the dural puncture site. - The headache is typically **postural**, worsening when upright and improving with lying down. *Hypotension* - While hypotension can be a side effect of spinal anesthesia, it generally manifests as **dizziness, nausea, or syncope**, rather than a severe, isolated headache. - Though it can contribute to *cerebral hypoperfusion*, it does not directly cause the characteristic **postural headache** seen with PDPH. *Hypertension* - **Hypertensive headaches** are usually generalized, pulsating, and may be accompanied by visual changes, but they are not specifically linked to the spinal anesthesia itself in this context. - Postoperative hypertension is not a typical complication of spinal anesthesia and does not cause a *postural headache*. *Dehydration* - **Dehydration** can cause a generalized headache, but it is usually mild to moderate and non-postural. - It would not typically result in the severe, characteristic **postural headache** experienced after a dural puncture.

Question 242: In a patient undergoing laparoscopic cholecystectomy, sudden bradycardia and hypotension occur. What is the most likely cause?

A. Gas embolism
B. Hypovolemia
C. Vagal stimulation (Correct Answer)
D. Myocardial infarction

Explanation: ***Vagal stimulation*** - **Peritoneal distension** due to pneumoperitoneum can lead to vagal stimulation, causing **bradycardia** and **hypotension** during laparoscopic cholecystectomy. - Manipulation of the **gallbladder** or surrounding structures can also directly stimulate the vagus nerve. *Gas embolism* - A gas embolism is a less common but serious complication, typically presenting with **sudden desaturation**, **hypotension**, and a **"mill-wheel" murmur**. - While it can cause hypotension, bradycardia is not its hallmark; rather, it often leads to **tachycardia** as the heart attempts to compensate. *Hypovolemia* - Hypovolemia would primarily cause **tachycardia** and hypotension as the body tries to maintain cardiac output. - Bradycardia would be an unusual initial presentation associated with hypovolemia unless it's a profound, pre-terminal event. *Myocardial infarction* - Although possible during any surgical procedure, a myocardial infarction typically presents with **ECG changes** (e.g., ST-segment elevation), **chest pain** (though sometimes masked by anesthesia), and potentially **tachycardia** or other arrhythmias, not typically isolated bradycardia. - While some inferior wall MIs can cause bradycardia due to vagal tone, the combination with sudden hypotension in the context of laparoscopic surgery makes vagal stimulation a more direct and common cause.

Question 243: What is the most likely cause of a sudden increase in end-tidal CO2 in a patient undergoing general anesthesia?

A. Hypothermia
B. Malignant hyperthermia (Correct Answer)
C. Hypoventilation
D. Low cardiac output

Explanation: ***Malignant hyperthermia*** - This condition is characterized by a rapid and severe increase in **metabolic rate**, leading to excessive CO2 production. - A sudden and unexplained rise in **end-tidal CO2** is often the earliest and most sensitive sign during anesthesia. *Hypothermia* - **Hypothermia** generally decreases metabolic rate, leading to a *decrease* in CO2 production and end-tidal CO2, not an increase. - Reduced body temperature slows enzymatic reactions and cellular activity. *Hypoventilation* - While **hypoventilation** leads to an *increase* in end-tidal CO2, it typically occurs due to inadequate ventilation settings or respiratory depression, which would be addressed by increasing ventilation. - A sudden and dramatic increase in end-tidal CO2 in the setting of adequate ventilation often points to increased CO2 production rather than just impaired elimination. *Low cardiac output* - **Low cardiac output** can lead to decreased CO2 delivery to the lungs, resulting in a *decrease* in end-tidal CO2 due to reduced pulmonary blood flow. - This results in a larger difference between arterial and end-tidal CO2, not an increase in end-tidal CO2.

Question 244: A patient undergoing surgery exhibits a sudden drop in oxygen saturation, a decrease in blood pressure, and increased peak airway pressures. Analyze the scenario and determine the likely diagnosis and the immediate action required.

A. Pulmonary embolism; administer anticoagulants
B. Anaphylaxis; administer epinephrine immediately
C. Tension pneumothorax; perform needle decompression immediately (Correct Answer)
D. Aspiration pneumonia; initiate broad-spectrum antibiotics

Explanation: ***Tension pneumothorax; perform needle decompression immediately*** - A **sudden drop in oxygen saturation**, **decrease in blood pressure**, and **increased peak airway pressures** are classic signs of a tension pneumothorax during surgery. - **Needle decompression** is the immediate life-saving intervention to relieve trapped air and restore hemodynamic stability. *Pulmonary embolism; administer anticoagulants* - While pulmonary embolism can cause desaturation and hypotension, it typically does not lead to **increased peak airway pressures** unless there is associated bronchospasm or pulmonary edema. - **Anticoagulants** are the treatment for PE, but immediate relief of acute symptoms in this urgent scenario requires addressing the mechanical obstruction. *Anaphylaxis; administer epinephrine immediately* - Anaphylaxis presents with a rapid drop in blood pressure and desaturation, often accompanied by **bronchospasm** (which could increase airway pressures). - However, it typically includes other signs like **rash, angioedema, or wheezing**, which are not mentioned here. *Aspiration pneumonia; initiate broad-spectrum antibiotics* - Aspiration pneumonia is a **slower-onset** process, manifesting hours to days post-aspiration with fever, cough, and infiltrates on chest X-ray. - It would not cause a **sudden, acute deterioration** with increased peak airway pressures and severe hypotension during surgery.

Question 245: Which of the following is the most reliable sign of malignant hyperthermia?

A. Tachycardia
B. Hyperthermia
C. Muscle rigidity
D. Hypercarbia (Correct Answer)

Explanation: ***Hypercarbia*** - **Hypercarbia** (elevated end-tidal CO2) is often the earliest and most consistent sign of malignant hyperthermia, reflecting increased cellular metabolism and CO2 production. - This symptom precedes other clinical signs because the body's compensatory mechanisms for CO2 excretion are overwhelmed quickly. *Tachycardia* - **Tachycardia** is a common sign of stress and can be caused by many factors during surgery, making it a non-specific indicator of malignant hyperthermia. - While it is typically present in malignant hyperthermia, it usually appears after hypercarbia has already developed. *Muscle rigidity* - **Muscle rigidity**, particularly masseter spasm, is a characteristic but not universally present or earliest sign of malignant hyperthermia. - It results from uncontrolled calcium release in muscle cells, but its onset can be delayed, and it may not be apparent in all muscle groups. *Hyperthermia* - **Hyperthermia** is a defining feature of malignant hyperthermia, but it is often a late sign, as the body's temperature regulation mechanisms are overwhelmed. - Measuring core body temperature can be slow, and a significant rise in temperature might occur after other signs like hypercarbia have been present for some time.

Question 246: What is the first-line treatment for malignant hyperthermia?

A. Dantrolene (Correct Answer)
B. Supportive cooling measures
C. Hydration with intravenous fluids
D. Use of vasopressors

Explanation: ***Dantrolene*** - **Dantrolene** is a direct-acting **skeletal muscle relaxant** that works by inhibiting calcium release from the sarcoplasmic reticulum. - This directly addresses the underlying pathophysiology of malignant hyperthermia, which involves excessive intracellular calcium and muscle contraction. *Supportive cooling measures* - While important for managing the **hyperthermia** component, cooling measures alone do not address the fundamental mechanism of excessive calcium release. - They are a crucial adjunct to dantrolene, but not the primary or definitive treatment. *Hydration with intravenous fluids* - **Intravenous fluids** help maintain **hemodynamic stability** and prevent **renal damage** due to rhabdomyolysis, a common complication of malignant hyperthermia. - However, they do not target the excessive calcium release responsible for the muscle rigidity and metabolic crisis. *Use of vasopressors* - **Vasopressors** may be used to manage hypothetical **hypotension** cases occurring in patients, but not as a primary treatment. - These drugs do not tackle the underlying **pathophysiology** of malignant hyperthermia, and their use is purely symptomatic and supportive.

Question 247: Which of the following is a known trigger for malignant hyperthermia?

A. Halothane (Correct Answer)
B. Propofol
C. Thiopental
D. Ketamine

Explanation: ***Halothane*** - **Halothane** is a potent volatile anesthetic and a classic trigger for malignant hyperthermia. - It induces a rapid, uncontrolled rise in intracellular calcium in skeletal muscle cells, leading to a hypermetabolic state. *Propofol* - **Propofol** is an intravenous anesthetic and is considered a safe anesthetic agent for patients susceptible to malignant hyperthermia. - It does not interact with the **ryanodine receptor (RyR1)**, which is central to the pathophysiology of malignant hyperthermia. *Thiopental* - **Thiopental** is a short-acting barbiturate and an intravenous anesthetic also considered safe for patients with a risk of malignant hyperthermia. - Its mechanism of action does not involve the biochemical pathways implicated in this genetic disorder. *Ketamine* - **Ketamine** is a dissociative anesthetic and is another agent that does not trigger malignant hyperthermia. - It is often used as an alternative anesthetic in patients with known or suspected malignant hyperthermia susceptibility.

Question 248: In the event of an airway fire during surgery, what is the most appropriate immediate action to take?

A. Pour saline into the airway
B. Ventilate with 100% oxygen
C. Use a fire extinguisher
D. Remove the endotracheal tube immediately (Correct Answer)

Explanation: **_Remove the endotracheal tube immediately_** - Prompt removal of the **endotracheal tube (ETT)** is the most crucial first step in an airway fire to eliminate the primary fuel source and prevent further damage to the airway. - This action immediately stops the flow of oxygen and anesthetic gases, which are significant contributors to the **combustion triad**. *Pour saline into the airway* - While adding saline may help extinguish the fire, it is not the immediate first step and can cause complications like **fluid aspiration** and further airway obstruction. - The priority is to remove the fuel source (ETT) and stop the oxygen flow before considering other extinguishing methods. *Ventilate with 100% oxygen* - Ventilating with **100% oxygen** would exacerbate the fire by providing more fuel for combustion, making the situation significantly worse. - Oxygen is a potent oxidizer and essential for sustaining a fire, thus it should be immediately turned off, not increased. *Use a fire extinguisher* - Using a standard fire extinguisher directly in the airway is **contraindicated** due to the potential for severe tissue damage from the chemicals and powders it contains. - Fire extinguishers are designed for external fires, not internal airway emergencies.

Question 249: During general anesthesia, if a patient develops tachycardia, hyperthermia, and muscle rigidity, what is the initial treatment?

A. Administer dantrolene (Correct Answer)
B. Administer a muscle relaxant
C. Administer supportive intravenous fluids
D. Implement cooling measures

Explanation: ***Administer dantrolene*** - The combination of **tachycardia**, **hyperthermia**, and **muscle rigidity** during general anesthesia is highly indicative of **malignant hyperthermia (MH)**, a life-threatening pharmacogenetic disorder. - **Dantrolene** is the specific and most effective antidote for MH, acting by inhibiting calcium release from the sarcoplasmic reticulum in muscle cells, thereby reducing muscle rigidity and heat production. *Administer supportive intravenous fluids* - While **intravenous fluids** are crucial for maintaining hydration and supporting cardiovascular function during MH, they are **supportive measures** and not the primary, specific treatment. - Fluids alone will not address the underlying pathophysiology of excessive calcium release and hypermetabolism in muscle cells. *Implement cooling measures* - **Cooling measures** (e.g., ice packs, cold IV fluids, gastric lavage) are essential to combat the severe **hyperthermia** seen in MH, which can lead to organ damage. - However, cooling is a **symptomatic treatment** and must be initiated *in conjunction with* dantrolene, as it does not address the root cause of the metabolic crisis. *Administer a muscle relaxant* - Administering a **general muscle relaxant** without dantrolene is generally ineffective in MH because traditional muscle relaxants like rocuronium or vecuronium act at the neuromuscular junction, whereas the rigidity in MH is due to **intracellular calcium dysregulation** within the muscle fiber itself. - In fact, depolarizing muscle relaxants like succinylcholine can trigger MH in susceptible individuals, and non-depolarizing agents would not effectively reverse the sustained muscle contraction of an MH crisis.

Question 250: Which medication is contraindicated in a patient with a history of malignant hyperthermia?

A. Propofol
B. Rocuronium
C. Sevoflurane (Correct Answer)
D. Etomidate

Explanation: ***Sevoflurane*** - **Sevoflurane** is an **inhaled volatile anesthetic** known to be a potent trigger for **malignant hyperthermia (MH)** due to its ability to induce uncontrolled calcium release from the sarcoplasmic reticulum in susceptible individuals. - Patients with a history of MH, or those genetically predisposed to it, should strictly avoid sevoflurane and other volatile anesthetics (e.g., halothane, isoflurane, desflurane) to prevent a life-threatening hypermetabolic crisis. *Propofol* - **Propofol** is an **intravenous anesthetic** and is considered a **safe anesthetic agent** in patients with a history of malignant hyperthermia. - It does not trigger the unregulated calcium release in muscle cells that characterizes malignant hyperthermia. *Rocuronium* - **Rocuronium** is a **nondepolarizing neuromuscular blocking agent** and is **safe for use** in patients susceptible to malignant hyperthermia. - It works by competing with acetylcholine at the neuromuscular junction without directly affecting calcium regulation within muscle cells. *Etomidate* - **Etomidate** is an **intravenous hypnotic agent** commonly used for induction of anesthesia, and it is **not a known trigger for malignant hyperthermia**. - Its mechanism of action involves enhancing GABAergic transmission, which does not interfere with the calcium channels implicated in MH.

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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