Tet Spell

Aka: Tet Spell, Hypercyanotic Episode

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II. Pathophysiology: Tet Spell (Hypercyanotic Episode)

  1. Inciting event (e.g. crying or feeding)
    1. Increased pulmonary outflow obstruction
    2. Decreased Systemic Vascular Resistance
  2. Results in Right-to-left Shunting
    1. Hypercarbia
    2. Hypoxemia
  3. Results in Increased pulmonary vascular resistance
    1. Worsens right-to-left shunting in cycles of worsening hypercarbia and Hypoxemia
  4. Management (see below) goals
    1. Increase Systemic Vascular Resistance (e.g. knees to chest, Supplemental Oxygen)
    2. Decrease hyperpnea (deep, rapid breathing)

III. Causes: Cyanotic Episodes ("Tet Spells")

  1. Hypoxia responsive to Supplemental Oxygen
    1. Impaired alveolar gas exchange (e.g. Pneumonia, Pulmonary Edema)
  2. Hypoxia UNresponsive to Supplemental Oxygen
    1. Decreased pulmonary Blood Flow via ductus arteriosus (ductus stent Occlusion, closure of unstented ductus)

IV. Symptoms

  1. Hypercyanotic, intermittent episode
  2. Occurs in early morning with awakening
  3. Hyperpnea
  4. Irritibility
  5. Central Cyanosis
  6. Grunting

V. Signs

  1. See Tetralogy of Fallot
  2. Ill appearing child
  3. Refractory Hypoxia
  4. Right ventricular outflow related murmur decreases with a lowering of right sided-flow
  5. VSD-related murmur persists

VI. Differential Diagnosis

  1. See Tetralogy of Fallot

VII. Management

  1. See Tetralogy of Fallot
  2. Knee-to-chest position
    1. Increases Systemic Vascular Resistance
    2. Similar to older children who squat during episodes
    3. Place infant in mothers arms with their knee flexed against their chest
    4. Decreases venous return and excessive Preload
  3. Avoid upsetting child
    1. Decrease stress (to reduce Heart Rate and allow for pulmonary vascular filling)
    2. Delay IV starts during initial stabilization
    3. Keep child with parent or guardian
    4. Calming measures
    5. Treat pain and avoid painful procedures
      1. Use EMLA cream prior to IV insertion
      2. Intranasal anxiolysis and Analgesics
        1. Intranasal Fentanyl
        2. Intranasal Midazolam
        3. Intranasal Ketamine
  4. Manage Hypoxia (to reduce pulmonary vascular resistance)
    1. Decreases pulmonary vascular resistance (PVR)
    2. Supplemental Oxygen
    3. Critically ill children may require Endotracheal Intubation (high risk)
      1. Ensure adequate preoxygenation and hydration prior to intubation
      2. Have Phenylephrine or neorepinephine available bedside to immediately treat Peri-Intubation Hypotension
  5. Opioid Analgesics
    1. Quiets child, reduces Tachypnea and reduces systemic venous return
    2. Morphine Sulfate 0.1 to 0.2 mg/kg SQ or IM (or 0.05 to 0.1 mg/kg IV)
    3. Fentanyl 1.5 to 2 mcg/kg intranasal via mucosal atomization device (MAD Device)
    4. Ketamine 1 to 2 mg/kg IV
  6. Treat Hypovolemia and Hypotension with volume expansion
    1. Rehydration with IV fluid boluses
      1. Consider Normal Saline bolus (10-20 ml/kg)
      2. Increases Preload and improves right end-diastolic volume
    2. Vasopressors that do not increase Heart Rate
      1. Phenylephrine
      2. Norepinephrine
  7. Advanced medications
    1. Consult pediatric cardiology
    2. Phenylephrine
      1. Increases Systemic Vascular Resistance
      2. Dose: 0.2 mg/kg IV
    3. Beta Blocker
      1. Reduces right ventricular outflow obstruction
      2. Acute: Propranolol 0.05 to 0.01 mg/kg IV
      3. Chronic: Propranolol 1 to 4 mg/kg/day PO

VIII. References

  1. Broder (2023) Crit Dec Emerg Med 37(9): 22-3
  2. Civitarese and Crane (2016) Crit Dec Emerg Med 30(1): 14-23
  3. Cyran (1998) PREP review lecture, October, Phoenix
  4. Merenstein (1994) Pediatrics, Lange
  5. Tsze and Spangler in Herbert (2015) EM:Rap 15(4): 2-3
  6. Saenz (1999) Am Fam Physician 59(7):1857-66 [PubMed]

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