Pediatric Anesthesia
Neonatal physiology, congenital syndromes, peds pharmacology, airway management, NRP, congenital cardiac. ← Back to Q-Bank
Q1. Pediatric airway anatomy
Compared to adults, the pediatric airway:
A. Has its narrowest point at the vocal cords
B. Has its narrowest functional point at the cricoid ring (subglottic), larynx more cephalad (C3–C4), epiglottis omega-shaped and floppy
C. Has identical anatomy
D. Has a thicker epiglottis
E. Has wider trachea
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Answer: B. Pediatric: narrowest functional point at cricoid ring (subglottic) — though anatomically narrowest is still cords. Larynx more cephalad at C3–C4 (adult C4–C5). Epiglottis omega-shaped. Vocal cords angled (anterior caudad). Large tongue, prominent occiput → shoulder roll for sniffing position. Use Miller (straight) blade preferred in infants to lift epiglottis.
Q2. ETT size formula
For a 6-year-old, the appropriate uncuffed ETT size is approximately:
A. 4.0
B. 5.0
C. 5.5
D. 6.0
E. 6.5
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Answer: C. Uncuffed: age/4 + 4 = 5.5. Cuffed: 0.5 size smaller (or age/4 + 3.5 = 5.0). Modern microcuff tubes acceptable from infancy. Confirm leak <25 cm H₂O.
Q3. Neonatal physiology — oxygen consumption
Neonatal oxygen consumption is approximately:
A. 2–3 mL/kg/min (similar to adult)
B. 6–8 mL/kg/min (double adult)
C. 15 mL/kg/min
D. 0.5 mL/kg/min
E. Cannot be measured
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Answer: B. Neonate VO₂ ~6–8 mL/kg/min (adult 3–4). Combined with smaller FRC (30 mL/kg same) → rapid desaturation. Preoxygenation crucial. Closing capacity > FRC in infants — early atelectasis under GA.
Q4. Fetal hemoglobin
HbF differs from HbA in that:
A. Right-shifted oxyhemoglobin curve
B. Left-shifted oxyhemoglobin curve (P50 ~19 vs. adult 27) facilitating placental O₂ uptake
C. Higher affinity for 2,3-DPG
D. Higher methemoglobin tendency
E. No clinical difference
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Answer: B. HbF: γ-chains instead of β, low affinity for 2,3-DPG → leftward shift (high O₂ affinity) → efficient placental transfer. By 6 months, HbF replaced by HbA → P50 normalizes. Hbg nadir at 8–12 weeks of life (~10–11 g/dL in term infants) — physiologic.
Q5. Neonatal blood volume
Term neonate blood volume is approximately:
A. 50 mL/kg
B. 80 mL/kg
C. 100 mL/kg
D. 120 mL/kg
E. 200 mL/kg
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Answer: B. Premature ~90–105 mL/kg; term ~80–90; infant 3–12 mo ~75; child ~70; adult ~65–70 (M)/60 (F). MABL calculation: BV × (Hct_initial − Hct_target) / Hct_initial. Replace 1:1 with crystalloid 3:1 to 1:1 ratio depending on blood product type.
Q6. Pediatric maintenance fluid
For a 25 kg child, the Holliday-Segar maintenance fluid rate is:
A. 25 mL/hr
B. 65 mL/hr
C. 100 mL/hr
D. 150 mL/hr
E. 250 mL/hr
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Answer: B. 4-2-1 rule: 4 mL/kg/hr for first 10 kg + 2 for next 10 + 1 thereafter. 25 kg = (40 + 20 + 5) = 65 mL/hr. Isotonic fluid preferred over hypotonic (recent studies show hyponatremia risk with hypotonic in hospitalized children).
Q7. Neonatal resuscitation HR
Per NRP, chest compressions in newborn are initiated when:
A. HR <100 despite stimulation
B. HR <60 after 30 sec of adequate PPV with supplemental O₂
C. HR <80
D. Apnea alone
E. Immediately after birth
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Answer: B. HR <60 after effective PPV → compressions at 3:1 (90 compressions:30 breaths/min). Epinephrine 10–30 mcg/kg IV q3–5 min if HR remains <60. Volume bolus 10 mL/kg if shock or blood loss. Initial FiO₂ should be 21% (term) or 21–30% (preterm), titrate to SpO₂ target curve.
Q8. Postoperative apnea risk
Postop apnea monitoring is recommended for premature infants up to a postconceptual age of:
A. 40 weeks
B. 60 weeks (and up to 46 weeks for term infants — some institutional policies vary)
C. 6 months chronological age
D. 1 year
E. Not needed beyond 36 weeks
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Answer: B. Premature infants <60 weeks PCA → 12–24 hr postop apnea monitoring. Caffeine 10 mg/kg IV is preventive option. Spinal anesthesia without sedation reduces but does not eliminate apnea risk. Anemia (HCT <30%) is an independent risk factor.
Q9. Pyloric stenosis
A 5-week-old male infant presents with projectile non-bilious vomiting, dehydration, and palpable epigastric mass. The classic electrolyte derangement is:
A. Hypochloremic, hypokalemic metabolic alkalosis with paradoxical aciduria
B. Anion gap metabolic acidosis
C. Hyperkalemia and hyperchloremia
D. Hyponatremia and metabolic acidosis
E. Mixed acid-base disorder with hypocalcemia
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Answer: A. Pyloric stenosis = medical emergency (not surgical emergency) — resuscitate before pyloromyotomy. Loss of HCl in vomitus → metabolic alkalosis; volume depletion → secondary hyperaldosteronism → K wasting; eventually paradoxical aciduria (kidney saves Na at expense of K and H). Correct fluid/electrolytes first.
Q10. Tracheoesophageal fistula
The most common type of TEF is:
A. Type A — pure esophageal atresia
B. Type C — esophageal atresia with distal TEF (~85%)
C. Type E — H-type isolated TEF
D. Type D — esophageal atresia with proximal and distal TEFs
E. Type B — esophageal atresia with proximal TEF
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Answer: B. Type C (~85%) — most common. Workup: VACTERL screening (vertebral, anal, cardiac (echo!), TE, renal, limb). Anesthetic priority: avoid gastric distention via fistula. Place ETT below fistula, often with surgeon performing rigid bronch. Right-sided thoracotomy unless right aortic arch (then left).
Q11. Congenital diaphragmatic hernia ventilation
Anesthetic management of congenital diaphragmatic hernia includes:
A. Aggressive ventilation with high PIP
B. Gentle ventilation with low TV, permissive hypercapnia (PaCO₂ up to 65), SpO₂ 90–95% preductally, avoid pulmonary HTN triggers
C. 100% FiO₂ throughout
D. Aggressive volume resuscitation
E. Mask ventilation as first line
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Answer: B. CDH: pulmonary hypoplasia + pulmonary HTN. Gentle ventilation avoids volutrauma → mediator release → worsening PHTN. Maintain normothermia, avoid acidosis. Inhaled NO for refractory PHTN. Avoid mask ventilation (gastric distention).
Q12. Tetralogy of Fallot — "tet spell"
A toddler with uncorrected TOF develops cyanosis, hyperventilation, lethargy during induction. Initial management:
A. 100% FiO₂, knee-chest position, IV fluids, phenylephrine (↑SVR pushes blood through pulmonary outflow), morphine to calm, β-blocker for outflow tract spasm if persistent
B. β-agonist
C. Hyperventilation
D. Vasodilator
E. Diuretics
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Answer: A. "Tet spell" = RV outflow tract spasm → ↑right-to-left shunt → cyanosis. Increase SVR (phenylephrine, knee-chest squat position), reduce PVR (100% O₂, avoid acidosis/hypercarbia/sympathetic stimulation). Volume to fill RV. Morphine reduces sympathetic. β-blocker (esmolol/propranolol) relaxes infundibular spasm.
Q13. Patent ductus arteriosus closure pharmacology
To maintain ductal patency in a duct-dependent congenital heart lesion, give:
A. Indomethacin
B. Alprostadil (PGE1) infusion
C. Ibuprofen
D. Furosemide
E. Acetaminophen
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Answer: B. PGE1 (alprostadil) opens/maintains the duct in duct-dependent lesions: hypoplastic left heart, pulmonary/aortic atresia, coarctation, TGA. Side effects: apnea (have airway ready), hypotension, fever, flushing. To close PDA in premature infants: indomethacin, ibuprofen, or acetaminophen.
Q14. Pediatric drug dosing — pharmacology
Neonatal codeine metabolism is affected by:
A. CYP2D6 (low at birth; ultrarapid metabolizers can cause respiratory arrest in breastfed infants)
B. UGT2B7 — only relevant for morphine
C. CYP3A4 — only adults
D. Plasma esterases
E. Not metabolized
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Answer: A. Codeine → morphine via CYP2D6. FDA black-box warning: codeine contraindicated in <12 yr and after tonsillectomy/adenoidectomy due to ultrarapid metabolizer respiratory depression and breastfeeding mother → infant deaths. Avoid in pediatrics.
Q15. Pediatric MAC
Compared to adults, pediatric MAC for sevoflurane is:
A. Highest in neonates, peaks at 1–6 months, then declines through childhood
B. Highest in adults
C. Identical at all ages
D. Lowest in toddlers
E. Independent of age
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Answer: A. MAC sevoflurane in infants 1–6 mo ~3.2%, declines through childhood, adult ~2%. Premature lower than term neonates. Increased CO + decreased FRC → faster equilibration and emergence in peds. Sevoflurane preferred for inhalation induction (non-pungent, bronchodilator).
Q16. Postintubation croup
A 3-year-old develops stridor after extubation following an 8 hr case. The most appropriate management is:
A. Reintubation immediately
B. Humidified oxygen, racemic epinephrine nebulizer, IV dexamethasone 0.5 mg/kg
C. Steroid bolus only
D. Continue observation only
E. Ipratropium nebulizer
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Answer: B. Postintubation croup: humidified O₂, racemic epinephrine (vasoconstriction of subglottic edema), dexamethasone. Monitor closely — rebound 2 hr after racemic epi. Risk factors: prolonged intubation, large ETT, traumatic intubation, age 1–4 yr.
Q17. Necrotizing enterocolitis
A premature infant with feeding intolerance, abdominal distention, bloody stools, and pneumatosis intestinalis on imaging is diagnosed with NEC. Most appropriate initial management:
A. Stop feedings, IV fluids, broad-spectrum antibiotics, NG decompression, surgical consult
B. Continue feedings to maintain growth
C. Immediate ex-lap regardless
D. Oral antibiotics
E. Probiotics
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Answer: A. NEC: NPO, NG decompression, broad-spectrum abx (ampicillin/gentamicin/clindamycin or metronidazole). Surgery for: perforation (pneumoperitoneum), bowel necrosis, abdominal mass with obstruction, clinical deterioration despite max medical therapy. Risk factors: prematurity, formula feeding, intestinal dysbiosis.
Q18. Foreign body aspiration
A toddler with sudden cough, wheeze, decreased breath sounds on the right side is suspected of foreign body aspiration. The anesthetic plan is:
A. Awake intubation
B. Inhalation induction with sevoflurane maintaining spontaneous ventilation; rigid bronchoscopy by ENT
C. RSI with propofol/rocuronium
D. Mask-only sedation
E. Volatile + neuromuscular blockade for muscle relaxation
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Answer: B. Maintain spontaneous ventilation until foreign body removed — positive pressure can drive object distally. Inhalation induction, deep anesthesia, rigid bronchoscope. Postop laryngospasm/bronchospasm common.
Q19. Cardiac defect — coarctation BP measurement
A child with coarctation of the aorta has:
A. Upper extremity hypertension with low/delayed lower extremity pulses; BP gradient between arms and legs
B. Hypotension only
C. Equal pressures in all extremities
D. Hypertension only in lower extremities
E. Variable pressures with arrhythmia
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Answer: A. Coarctation: stenosis distal to left subclavian. Upper extremity HTN, weak/delayed femoral pulses. Repair in childhood usually elective. Anesthesia: monitor BP in arms, watch for cross-clamp HTN and rebound hypotension; preserve spinal cord perfusion (artery of Adamkiewicz).
Q20. Emergence delirium in children
The most evidence-based prophylaxis for emergence delirium after sevoflurane in a 5-year-old is:
A. Dexmedetomidine 0.15 mcg/kg IV before emergence
B. Diphenhydramine
C. Ondansetron
D. Naloxone
E. Atropine
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Answer: A. Sevoflurane > desflurane > others for emergence delirium incidence in peds. Prophylaxis options: dexmedetomidine, clonidine, fentanyl, propofol bolus before emergence, ketamine. Address pain, hypoxia, full bladder. Self-limited typically (10–30 min).
Q21. Crouzon syndrome
Anesthetic considerations in Crouzon syndrome include:
A. Mandibular hypoplasia like Pierre Robin
B. Craniosynostosis with shallow orbits, proptosis, maxillary hypoplasia, beaked nose; upper airway obstruction, difficult mask ventilation, intubation usually OK if cervical mobility preserved
C. Normal airway
D. Macroglossia only
E. Atlantoaxial instability mandates fiberoptic only
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Answer: B. Crouzon: craniosynostosis + midface hypoplasia. Difficult mask, easier intubation. Compare with Pierre Robin (micrognathia, glossoptosis, cleft palate → difficult mask AND intubation, use LMA), Treacher Collins (mandibular hypoplasia → similar challenges), Goldenhar (unilateral facial asymmetry → use LMA).
Q22. Down syndrome (Trisomy 21)
Anesthetic considerations in Down syndrome include:
A. No special considerations
B. Atlantoaxial instability (15%), congenital heart disease (50%), subglottic stenosis, OSA, hypothyroidism, increased sensitivity to atropine
C. Hypertension only
D. Easy intubation always
E. Hyperthyroidism only
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Answer: B. Down syndrome: AAI (avoid neck extension; screen with C-spine films per current guidelines or proceed cautiously). CHD (AVSD/VSD most common). Subglottic stenosis (use smaller ETT). OSA. Hypothyroidism. Macroglossia. Atropine sensitivity (use cautiously).
Q23. Pediatric defibrillation dose
Pediatric defibrillation initial dose:
A. 0.5 J/kg
B. 1 J/kg
C. 2 J/kg (initial), 4 J/kg subsequent
D. 5 J/kg
E. Same as adult (200 J)
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Answer: C. PALS defibrillation: 2 J/kg initial, 4 J/kg subsequent (up to 10 J/kg, max adult dose). Synchronized cardioversion: 0.5–1 J/kg initial, 2 J/kg subsequent. Use AED on age >1 yr if no pediatric pads available.
Q24. Sickle cell perioperative
A child with sickle cell disease undergoing tonsillectomy. Perioperative priorities:
A. Avoid hypoxia, hypothermia, dehydration, acidosis; consider preop simple transfusion to Hgb 10 (TAPS trial showed equivalence to exchange transfusion for low-to-medium risk surgery)
B. Hyperventilation
C. Tourniquet on arm
D. NPO 12 hours
E. Avoid all IV fluids
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Answer: A. Sickle cell: 6 H's of sickling (hypoxia, hyperthermia, hypothermia, hypotension, hypovolemia, H⁺/acidosis). Simple transfusion to Hgb 10 noninferior to exchange transfusion for moderate-risk surgery (TAPS trial). Hbg goal differs from healthy (21–30%): aim 30–40%. Hematology consult for high-risk surgery.
Q25. Pediatric pharmacology — total body water
Compared to adults, neonates have:
A. Lower total body water (~50%)
B. Higher total body water (~75–80%) → larger Vd for hydrophilic drugs (e.g., succinylcholine, antibiotics, digoxin), requiring larger weight-based loading doses
C. Identical body composition
D. Higher fat content
E. Lower protein binding only
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Answer: B. Neonates: ↑TBW, ↑ECF, ↓fat, ↓muscle, ↓albumin → larger Vd of hydrophilic drugs, more free drug for highly protein-bound drugs (phenytoin, barbiturates, bupivacaine). Hepatic enzymes mature over first 1–2 years. Renal function ~30% adult at birth, matures by 1 year.