II. Pathophysiology: Tet Spell (Hypercyanotic Episode)
- Inciting event (e.g. crying or feeding)
- Increased pulmonary outflow obstruction
- Decreased Systemic Vascular Resistance
- Results in Right-to-left Shunting
- Hypercarbia
- Hypoxemia
- Results in Increased pulmonary vascular resistance
- Worsens right-to-left shunting in cycles of worsening hypercarbia and Hypoxemia
- Management (see below) goals
- Increase Systemic Vascular Resistance (e.g. knees to chest, Supplemental Oxygen)
- Decrease hyperpnea (deep, rapid breathing)
III. Causes: Cyanotic Episodes ("Tet Spells")
-
Hypoxia responsive to Supplemental Oxygen
- Impaired alveolar gas exchange (e.g. Pneumonia, Pulmonary Edema)
-
Hypoxia UNresponsive to Supplemental Oxygen
- Decreased pulmonary Blood Flow via ductus arteriosus (ductus stent Occlusion, closure of unstented ductus)
IV. Symptoms
- Hypercyanotic, intermittent episode
- Occurs in early morning with awakening
- Hyperpnea
- Irritibility
- Central Cyanosis
- Grunting
V. Signs
- See Tetralogy of Fallot
- Ill appearing child
- Refractory Hypoxia
- Right ventricular outflow related murmur decreases with a lowering of right sided-flow
- VSD-related murmur persists
VI. Differential Diagnosis
VII. Management
- See Tetralogy of Fallot
-
Knee-to-chest position
- Increases Systemic Vascular Resistance
- Similar to older children who squat during episodes
- Place infant in mothers arms with their knee flexed against their chest
- Decreases venous return and excessive Preload
- Avoid upsetting child
- Decrease stress (to reduce Heart Rate and allow for pulmonary vascular filling)
- Delay IV starts during initial stabilization
- Keep child with parent or guardian
- Calming measures
- Treat pain and avoid painful procedures
- Use EMLA cream prior to IV insertion
- Intranasal anxiolysis and Analgesics
- Intranasal Fentanyl
- Intranasal Midazolam
- Intranasal Ketamine
- Manage Hypoxia (to reduce pulmonary vascular resistance)
- Decreases pulmonary vascular resistance (PVR)
- Supplemental Oxygen
- Critically ill children may require Endotracheal Intubation (high risk)
- Ensure adequate preoxygenation and hydration prior to intubation
- Have Phenylephrine or neorepinephine available bedside to immediately treat Peri-Intubation Hypotension
-
Opioid Analgesics
- Quiets child, reduces Tachypnea and reduces systemic venous return
- Morphine Sulfate 0.1 to 0.2 mg/kg SQ or IM (or 0.05 to 0.1 mg/kg IV)
- Fentanyl 1.5 to 2 mcg/kg intranasal via mucosal atomization device (MAD Device)
- Ketamine 1 to 2 mg/kg IV
- Treat Hypovolemia and Hypotension with volume expansion
- Rehydration with IV fluid boluses
- Consider Normal Saline bolus (10-20 ml/kg)
- Increases Preload and improves right end-diastolic volume
- Vasopressors that do not increase Heart Rate
- Rehydration with IV fluid boluses
- Advanced medications
- Consult pediatric cardiology
- Phenylephrine
- Increases Systemic Vascular Resistance
- Dose: 0.2 mg/kg IV
- Beta Blocker
- Reduces right ventricular outflow obstruction
- Acute: Propranolol 0.05 to 0.01 mg/kg IV
- Chronic: Propranolol 1 to 4 mg/kg/day PO
VIII. References
- Broder (2023) Crit Dec Emerg Med 37(9): 22-3
- Civitarese and Crane (2016) Crit Dec Emerg Med 30(1): 14-23
- Cyran (1998) PREP review lecture, October, Phoenix
- Merenstein (1994) Pediatrics, Lange
- Tsze and Spangler in Herbert (2015) EM:Rap 15(4): 2-3
- Saenz (1999) Am Fam Physician 59(7):1857-66 [PubMed]