Pediatric Anesthesia — MCQs

Pediatric Anesthesia Indian Medical PG Practice Questions and MCQs

Question 21: In a child with intestinal obstruction and deranged liver function tests, which anesthetic agent is the preferred choice?

A. Enflurane
B. Isoflurane
C. Halothane
D. Sevoflurane (Correct Answer)

Explanation: ### Explanation The correct answer is **Sevoflurane (Option D)**. **Why Sevoflurane is the preferred choice:** In pediatric anesthesia, especially in cases of **intestinal obstruction**, a rapid and smooth induction is critical to secure the airway quickly and minimize the risk of aspiration. Sevoflurane is the agent of choice because: 1. **Non-pungency:** It has a pleasant odor and is non-irritating to the airway, making it ideal for smooth mask induction in children. 2. **Pharmacokinetics:** It has a low blood-gas partition coefficient (0.65), allowing for rapid induction and emergence. 3. **Hepatotoxicity:** Unlike older halogenated agents, Sevoflurane undergoes minimal metabolism to trifluoroacetic acid, making it **safe in patients with deranged liver function tests (LFTs)**. It does not cause "halothane-like" hepatitis. **Why other options are incorrect:** * **Halothane:** Historically used in pediatrics, it is now avoided in patients with liver dysfunction due to the risk of **Halothane Hepatitis** (mediated by trifluoroacetylated liver proteins) and its tendency to sensitize the myocardium to catecholamines. * **Enflurane:** It is metabolized to inorganic fluoride, which can be nephrotoxic, and it is known to lower the seizure threshold (pro-convulsant). It is rarely used in modern practice. * **Isoflurane:** While safe for the liver, it is highly **pungent**. In a child, it can cause coughing, breath-holding, and laryngospasm during induction, which is dangerous in a patient with a "full stomach" (intestinal obstruction). **NEET-PG High-Yield Pearls:** * **Agent of choice for Pediatric Induction:** Sevoflurane. * **Agent of choice for Maintenance in Liver Disease:** Isoflurane (due to minimal metabolism and preservation of hepatic blood flow), but Sevoflurane is preferred for *induction* in children. * **Compound A:** A nephrotoxic byproduct formed when Sevoflurane reacts with dry soda lime (though clinically rare in humans). * **Intestinal Obstruction:** Always consider these cases as "Full Stomach" status; rapid sequence induction (RSI) is typically indicated.

Question 22: A 5-year-old boy with Duchenne Muscular Dystrophy and polymyositis, who has been fasting for 8 hours, is scheduled for tendon lengthening surgery. Which anesthetic technique should be used?

A. Intravenous thiopental induction with maintenance by nitrous oxide and halothane
B. Intravenous propofol induction with maintenance by nitrous oxide and oxygen
C. Intravenous succinylcholine induction with maintenance by nitrous oxide and halothane
D. Inhalational anesthesia with nitrous oxide, oxygen, and halothane (Correct Answer)

Explanation: **Explanation:** The primary anesthetic concern in patients with **Duchenne Muscular Dystrophy (DMD)** is the high risk of **hyperkalemic cardiac arrest** and **rhabdomyolysis** when exposed to certain triggers. **1. Why Option D is Correct:** Inhalational induction (using agents like Halothane or Sevoflurane) with Nitrous Oxide and Oxygen is considered the safest approach among the given choices. While volatile agents carry a theoretical risk of anesthesia-induced rhabdomyolysis (AIR) in DMD, they do **not** trigger classic Malignant Hyperthermia in these patients. In clinical practice, avoiding intravenous access in a struggling child (to prevent stress-induced catecholamine surge) often makes inhalational induction the preferred route. **2. Why Other Options are Incorrect:** * **Option C (Succinylcholine):** This is **absolutely contraindicated**. In DMD, the sarcolemma is fragile. Succinylcholine causes massive efflux of potassium from up-regulated nicotinic receptors, leading to sudden, refractory hyperkalemic cardiac arrest. * **Option A & B (Thiopental/Propofol):** While these IV agents are not strictly contraindicated, the question specifies the patient has been **fasting for 8 hours**. In DMD, prolonged fasting can lead to **hypoglycemia and metabolic acidosis** due to poor muscle glycogen stores. Furthermore, IV induction requires prior venous access, which can be distressing. Option D remains the traditional "textbook" answer for pediatric induction when avoiding depolarizing relaxants. **Clinical Pearls for NEET-PG:** * **DMD & Succinylcholine:** Never use Succinylcholine in any patient with a known myopathy due to the risk of fatal hyperkalemia. * **Rhabdomyolysis vs. MH:** DMD patients are at risk for **Anesthesia-Induced Rhabdomyolysis (AIR)**, which mimics Malignant Hyperthermia (tachycardia, acidosis) but is driven by calcium-mediated membrane failure rather than the RYR1 mutation. * **Cardiac Monitoring:** Always perform a pre-operative ECG/Echo, as these patients often have subclinical **dilated cardiomyopathy**.

Question 23: What is the preferred anesthetic agent for pediatric patients?

A. Ketamine
B. Desflurane
C. Sevoflurane (Correct Answer)
D. Propofol

Explanation: **Explanation:** **Sevoflurane** is the preferred anesthetic agent for pediatric patients, particularly for **inhalation induction**. The primary reason is its **low blood-gas partition coefficient (0.65)**, which ensures rapid induction and recovery, combined with its **non-pungent odor**. Unlike other volatile anesthetics, sevoflurane does not irritate the airway, making it the least likely to cause breath-holding, coughing, or laryngospasm during mask induction. **Analysis of Incorrect Options:** * **Ketamine (A):** While useful for procedural sedation or in hemodynamically unstable children, it is not the "preferred" general anesthetic due to side effects like excessive salivation, emergence delirium, and increased intracranial pressure. * **Desflurane (B):** Despite its rapid onset, it is highly **pungent** and irritating to the airway. It frequently causes coughing and laryngospasm, making it unsuitable for inhalation induction in children. * **Propofol (D):** It is the gold standard for intravenous (IV) induction. However, in pediatrics, establishing IV access is often difficult and distressing in a conscious child; therefore, inhalation induction with Sevoflurane is usually preferred over IV induction. **High-Yield Clinical Pearls for NEET-PG:** * **Induction of Choice:** Sevoflurane (Inhalation); Propofol (IV). * **Maintenance of Choice:** Sevoflurane or Isoflurane. * **Halothane:** Previously the gold standard, but now replaced by Sevoflurane due to risks of "Halothane Hepatitis" and sensitization of the myocardium to catecholamines (arrhythmias). * **Key Advantage:** Sevoflurane provides excellent hemodynamic stability in infants compared to other volatile agents.

Question 24: The dose of non-depolarizing muscle relaxants in a neonate is:

A. Decreased as compared to adults (Correct Answer)
B. Increased as compared to adults
C. Same as adults
D. Cannot be predicted

Explanation: **Explanation:** The correct answer is **A. Decreased as compared to adults.** The dosing of non-depolarizing muscle relaxants (NDMRs) in neonates is governed by the physiological immaturity of the **Neuromuscular Junction (NMJ)**. In neonates, the NMJ is characterized by a larger synaptic cleft and an immature fetal isoform of the acetylcholine receptor (gamma subunit instead of epsilon). This makes the NMJ **exquisitely sensitive** to NDMRs. While neonates have a larger volume of distribution for water-soluble drugs (which might suggest a need for higher doses), the profound sensitivity of the receptors outweighs this factor, resulting in a requirement for a **lower dose** to achieve the same degree of blockade compared to adults. **Analysis of Incorrect Options:** * **B & C:** These are incorrect because they fail to account for the heightened sensitivity of the neonatal NMJ. Using adult or increased doses would lead to prolonged and potentially dangerous neuromuscular blockade. * **D:** This is incorrect as neonatal pharmacology is well-studied; the response is predictable based on the maturity of the NMJ and renal clearance rates. **High-Yield Clinical Pearls for NEET-PG:** * **Succinylcholine Exception:** Unlike NDMRs, the dose of **Succinylcholine** (a depolarizing relaxant) is **increased** in neonates (approx. 2 mg/kg) because of their large extracellular fluid volume. * **Diaphragm vs. Peripheral Muscles:** In neonates, the diaphragm is more sensitive to NDMRs than peripheral muscles (the opposite of adults). * **Monitoring:** Always use a peripheral nerve stimulator; neonates have a lower functional residual capacity (FRC), making them prone to rapid desaturation if neuromuscular recovery is incomplete.

Question 25: All of the following statements about the pediatric airway are true EXCEPT:

A. The narrowest part is the glottic region. (Correct Answer)
B. The larynx is funnel shaped.
C. The epiglottis is long and floppy.
D. There is a relatively large tongue.

Explanation: In pediatric anesthesia, understanding the anatomical differences between the infant and adult airway is crucial for successful intubation and airway management. **Explanation of the Correct Answer (Option A):** Historically, it was taught that the cricoid cartilage (subglottic region) was the narrowest part of the pediatric airway, giving it a "funnel shape." However, recent MRI and bronchoscopy studies have shown that in a **functional, awake child**, the **glottis (vocal cords)** is actually the narrowest part. **Wait, why is A the "Except" answer?** In the context of NEET-PG and traditional anesthesia textbooks (like Miller’s), the classic teaching remains that the **cricoid ring** is the narrowest part of the pediatric airway, whereas in adults, it is the glottis. Therefore, the statement "The narrowest part is the glottic region" is considered **False** for a child in a traditional exam setting. **Analysis of Other Options:** * **B. The larynx is funnel-shaped:** Unlike the cylindrical adult larynx, the pediatric larynx is tapered towards the cricoid, creating a funnel shape. * **C. The epiglottis is long and floppy:** It is often described as "U" or "Omega" shaped, longer, and stiffer than in adults, making it harder to displace with a Macintosh blade (hence the preference for Miller blades). * **D. Relatively large tongue:** The tongue is large relative to the oral cavity, making it a common cause of airway obstruction and making laryngoscopy more difficult. **High-Yield Clinical Pearls for NEET-PG:** * **Position of Larynx:** C3–C4 in infants (more cephalad/anterior) vs. C4–C5 in adults. * **Blade Choice:** A straight blade (Miller) is preferred in infants to directly lift the floppy epiglottis. * **Mainstem Intubation:** The right and left main bronchi arise at equal angles from the trachea until age 2, making bilateral accidental endobronchial intubation equally likely.

Question 26: A 5-year-old boy with Duchenne muscular dystrophy requires a tendon lengthening procedure. Which is the most appropriate anesthetic approach?

A. Induction with intravenous thiopentone and N2O; maintenance with halothane. (Correct Answer)
B. Induction with intravenous suxamethonium and N2O; maintenance with oxygen.
C. Induction with intravenous suxamethonium and N2O; maintenance with halothane.
D. Inhalation induction with halothane and N2O; maintenance with oxygen.

Explanation: ### Explanation **1. Why Option A is Correct:** In patients with **Duchenne Muscular Dystrophy (DMD)**, the primary anesthetic concern is the integrity of the muscle cell membrane (sarcolemma). The most critical contraindication is the use of **Succinylcholine (Suxamethonium)**. DMD patients have fragile membranes; succinylcholine can cause massive efflux of potassium, leading to **hyperkalemic cardiac arrest**. While volatile agents like **Halothane** carry a risk of "Anesthesia-Induced Rhabdomyolysis" (AIR) or triggering Malignant Hyperthermia-like reactions in DMD, they are not strictly contraindicated if used cautiously for maintenance. **Thiopentone** is a safe intravenous induction agent as it does not affect the neuromuscular junction or muscle membrane stability. **2. Why Other Options are Wrong:** * **Options B and C:** These are **absolutely contraindicated** because they include **Succinylcholine**. In DMD, succinylcholine-induced hyperkalemia is often refractory to standard resuscitation and can be fatal. * **Option D:** While inhalation induction is common in pediatrics, the combination of halothane induction without a stable IV access in a DMD patient increases the risk of early-onset rhabdomyolysis or arrhythmias. Option A provides a more controlled IV induction. **3. NEET-PG High-Yield Pearls:** * **The "Black Box" Warning:** Succinylcholine is contraindicated in children with undiagnosed skeletal muscle myopathy due to the risk of hyperkalemic cardiac arrest. * **DMD vs. Malignant Hyperthermia (MH):** DMD patients are at high risk for **Rhabdomyolysis**, which can mimic MH. However, the mechanism is different (membrane fragility vs. calcium channel defect). * **Safe Alternatives:** Total Intravenous Anesthesia (TIVA) with **Propofol** and the use of non-depolarizing muscle relaxants (e.g., Vecuronium, Rocuronium) are considered the safest approaches in modern practice. * **Pre-op Check:** Always check **Serum Creatine Kinase (CK)** and perform an **ECG/ECHO**, as these patients often have associated cardiomyopathy.

Question 27: During intubation of a child, what type of endotracheal tube and laryngoscope blade is typically used?

A. Uncuffed tube with a curved blade
B. Uncuffed tube with a straight blade (Correct Answer)
C. Cuffed tube with a straight blade
D. Cuffed tube with a curved blade

Explanation: **Explanation:** The correct choice is **Option B: Uncuffed tube with a straight blade.** This preference is based on the unique anatomical differences between pediatric and adult airways. **1. Why Uncuffed Tube?** In children (especially those under 8 years), the narrowest part of the airway is the **cricoid cartilage**, which is circular and acts as a natural physiological seal. Using an uncuffed tube prevents excessive pressure on the delicate subglottic mucosa, reducing the risk of post-extubation edema and subglottic stenosis. While modern "micro-cuff" tubes are increasingly used, the classic teaching for exams remains the uncuffed tube. **2. Why Straight Blade (Miller)?** A child’s epiglottis is relatively larger, stiffer, and **omega-shaped (Ω)**. It projects more posteriorly and is floppier than an adult's. A straight blade is used to **directly lift the epiglottis** to visualize the glottis, whereas a curved blade (Macintosh) is placed in the vallecula to lift the epiglottis indirectly—a maneuver that often fails in infants due to the laxity of the hyoepiglottic ligament. **Analysis of Incorrect Options:** * **A & D (Curved Blade):** These are generally avoided in infants/young children because they do not provide adequate control over the floppy epiglottis. * **C (Cuffed Tube):** While used in adults to prevent aspiration and air leaks, in children, the cuff can cause pressure necrosis at the narrow cricoid ring if not monitored meticulously. **High-Yield Clinical Pearls for NEET-PG:** * **Narrowest part of airway:** Cricoid cartilage (Infants); Vocal cords (Adults). * **Larynx Position:** Higher and more anterior in children (C3–C4) compared to adults (C4–C5). * **Formula for Uncuffed ETT Size:** (Age/4) + 4. * **Formula for Cuffed ETT Size:** (Age/4) + 3.5. * **Blade Choice:** Miller (Straight) is preferred for infants; Macintosh (Curved) is preferred for older children/adults.

Question 28: How does a pediatric airway differ from an adult airway?

A. Large tongue (Correct Answer)
B. Sharp epiglottis
C. Narrowest part is the glottis
D. Larynx in a lower position

Explanation: In pediatric anesthesia, understanding the anatomical differences of the airway is critical for successful intubation and ventilation. **1. Why "Large Tongue" is Correct:** Infants have a **disproportionately large tongue** relative to the size of the oral cavity. This makes the tongue the most common cause of airway obstruction in an unconscious child and can obscure the view of the larynx during direct laryngoscopy. **2. Why the other options are incorrect:** * **Sharp epiglottis:** The pediatric epiglottis is not "sharp"; it is typically described as **long, stiff, and U-shaped (or Omega-shaped)**. It is also more floppy and angled posteriorly, often requiring a straight blade (Miller) to lift it directly. * **Narrowest part is the glottis:** In adults, the narrowest part is the glottis (vocal cords). In children (traditionally under age 8), the narrowest part is the **subglottic region at the level of the cricoid cartilage**. This is why uncuffed tubes were historically preferred to prevent subglottic edema. * **Larynx in a lower position:** The pediatric larynx is actually in a **higher (more cephalad) position**. In an infant, the larynx is at the level of **C3–C4**, whereas in an adult, it sits lower at **C4–C5**. This makes the airway appear more "anterior." **High-Yield Clinical Pearls for NEET-PG:** * **Occiput:** Infants have a large occiput, which causes neck flexion when supine. A shoulder roll (not a head ring) is often needed to align the axes for intubation. * **Head Position:** The "sniffing position" is less pronounced in infants; a neutral position is often optimal. * **Oxygenation:** Children have a **higher functional residual capacity (FRC) to body weight ratio but a much higher metabolic rate**, leading to rapid desaturation during apnea.

Question 29: Why is there a higher incidence of endobronchial intubation in pediatric patients?

A. Short trachea (Correct Answer)
B. Longer pediatric endotracheal tube
C. Both
D. None of the above

Explanation: ### Explanation **1. Why "Short Trachea" is Correct:** The primary anatomical reason for the high incidence of accidental endobronchial intubation in pediatric patients is the **short length of the trachea**. At birth, the trachea is approximately **4–5 cm** long, increasing to about **7 cm** by 18 months of age. Because the distance between the vocal cords and the carina is so small, even a slight downward displacement of the endotracheal tube (ETT)—caused by neck flexion or surgical manipulation—can easily result in the tube entering the right mainstem bronchus. **2. Analysis of Incorrect Options:** * **Option B (Longer pediatric ETT):** This is incorrect. Pediatric tubes are manufactured in various lengths, and the clinician selects the length based on the child’s age or height (using formulas like *Age/2 + 12 cm*). The length of the tube itself is not the anatomical cause; rather, it is the **incorrect positioning or migration** of the tube within a limited anatomical space. * **Option C & D:** These are incorrect as the anatomical "short trachea" is the definitive physiological predisposition. **3. Clinical Pearls for NEET-PG:** * **The "Rule of Movement":** In pediatrics, **flexion** of the neck moves the ETT deeper (towards the carina), potentially causing endobronchial intubation. **Extension** of the neck moves the ETT cephalad (towards the mouth), potentially causing accidental extubation. ("The tube follows the nose"). * **Narrowest Part:** Historically, the **cricoid cartilage** was considered the narrowest part of the pediatric airway (funnel-shaped). However, recent MRI studies suggest it may be the **glottis** (cylindrical), though "cricoid" remains a common exam answer. * **Mainstem Anatomy:** Unlike adults, the angles of the right and left mainstem bronchi are more symmetrical in infants (approx. 30-35°), though the right side remains a more frequent site for accidental intubation.

Question 30: In a child, what is the anaesthetic of choice?

A. Enflurane
B. Isoflurane
C. Sevoflurane (Correct Answer)
D. Halothane

Explanation: **Explanation:** The anesthetic of choice for pediatric induction is **Sevoflurane**. The primary goal in pediatric anesthesia is a smooth, rapid inhalation induction, as children often fear needles. **Why Sevoflurane is the Correct Choice:** 1. **Low Blood-Gas Solubility (0.65):** This allows for rapid induction and quick emergence from anesthesia. 2. **Non-Pungency:** Unlike other agents, Sevoflurane is sweet-smelling and non-irritating to the airway. It does not cause coughing, breath-holding, or laryngospasm, making it ideal for mask induction. 3. **Hemodynamic Stability:** It maintains heart rate and blood pressure better than older agents. **Why Other Options are Incorrect:** * **Halothane:** Historically the gold standard due to its pleasant smell, it is no longer the first choice because it sensitizes the myocardium to catecholamines (increasing risk of arrhythmias) and carries a risk of "Halothane Hepatitis." It also has a slower onset than Sevoflurane. * **Isoflurane & Enflurane:** These agents are highly **pungent**. They irritate the upper airway, leading to coughing, salivation, and a high incidence of laryngospasm during induction in an awake child. **High-Yield Clinical Pearls for NEET-PG:** * **Agent of choice for Day Care Surgery:** Sevoflurane (due to rapid recovery). * **Metabolism:** Sevoflurane is metabolized to **Compound A** (in soda lime), which is nephrotoxic in rats, though not proven significant in humans. * **Induction Technique:** "Single-breath induction" is possible with Sevoflurane due to its lack of pungency. * **Emergence Delirium:** A common side effect of Sevoflurane in children during the recovery phase.

Practice by Chapter

Anatomical and Physiological Differences in Children

Practice Questions

Pharmacological Considerations in Pediatrics

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Preoperative Evaluation of Pediatric Patients

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Induction Techniques in Children

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Airway Management in Children

Practice Questions

Fluid Management in Pediatric Anesthesia

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Temperature Regulation in Children

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Regional Anesthesia in Children

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Anesthesia for Common Pediatric Surgeries

Practice Questions

Anesthesia for Congenital Heart Disease

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Emergence Delirium in Children

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Perioperative Pain Management in Children

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