Procedure

High Flow Nasal Cannula

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High Flow Nasal Cannula, High Humidity High Flow Nasal Oxygen, HHFNC

  • Definitions
  1. High Flow Nasal Cannula (HHFNC)
    1. Specially formulated device to deliver Body Temperature, humidified oxygen via a modified Nasal Cannula
  • Indications
  1. Pneumonia
    1. Respiratory distress in a patient who does not require BiPaP
  2. Ventilator Weaning
    1. Patients transitioned off Ventilator to High Flow Nasal Cannula have lower rates of reintubation
    2. Start at highest tolerable flow rates 50-60 L/min for the first day post-Extubation
  3. COPD exacerbation
    1. Consider when BiPaP is not initially tolerated
    2. May bridge to BIPAP or intubation
  4. Endotracheal Intubation Preoxygenation
    1. Adjunct to allow longer safe intubation time (Apneic Oxygenation)
    2. Standard Nasal Cannula is often used in this case (at 15 L/min)
  5. Croup or Bronchiolitis
    1. Increased Work of Breathing (e.g. retractions, grunting, apnea, nasal flaring)
    2. Very effective with common use in the emergency department and in pediatric Intensive Care
    3. Humidification of secretions likely contributes to benefit
  6. Dyspnea in Paliative Care
    1. Symptomatic relief on High Flow Nasal Cannula compared with Supplemental Oxygen
    2. Ruangsomboon (2020) Ann Emerg Med 75(5): 615-26 [PubMed]
  • Contraindications
  1. Pneumothorax
  2. Nasal obstruction (e.g. large Nasal Polyps, Choanal Atresia)
  3. Nasopharyngeal Trauma
  • Mechanism
  1. High flow humidified oxygen delivered via nasal prongs (longer than with standard Nasal Cannula)
    1. Flow rates adjusted between 10-60 Liters/minute
    2. FIO2 titratable up to 100%
    3. Humidity and Temperature adjustable
    4. Nasal prongs do not occlude the nare (50% of the nare is open)
  2. Oxygenates airway dead space
    1. In infants, airway dead space my be 12 ml, with Tidal Volume only 15 ml
    2. High flow nasal oxygen allows for oxygenation of this deadspace and passive oxygenation
  3. Provides CPAP-like positive pressure
    1. PEEP is generated by flow rates above the patient's typical Tidal Volume
    2. PEEP pressure estimated at 3 to 4 cm H2O (up to 7 cm H2O in some studies)
      1. Equivalent to pursed-lip breathing
    3. Decreases work of breathing by 15% while not modifying Tidal Volume
    4. May also decrease Nasal Airway obstruction (in infants and children)
    5. Patient should keep their mouth closed for benefit
      1. Patient can reduce the PEEP by opening their mouth
      2. Does not obstruct the mouth (patient can speak and eat)
  1. Start with FIO2 of 100% and titrate down
  2. Patients should attempt to keep their mouth closed for maximal effect
  3. In adults, start at high rates for stabilization
    1. Titrate down as Tachypnea, Dyspnea and work of breathing improve
    2. In children, use pediatric protocol below (which titrates up)
  4. Maximum Flow rates (based on age and weight)
    1. Age <1 year: 2 L/kg/min or up to 8 L/min
    2. Age 1-12 years: 1 L/kg/min or up to 12 to 20 L/min (L/min >12 may indicate higher level of care)
    3. Adults: 0.5 L/kg/min or 25-35 L/min (may use up to 40 L/min)
      1. During stabilization of acute distress, may start at 50-60 L/min
  5. Pediatric Device Hubs
    1. Extra-Small (Blue Hub)
      1. Weight: 0.5 to 2.5 kg
      2. Flow Rate: 0.5 to 8 L/min
    2. Small (Red Hub)
      1. Weight: 0.9 to 4 kg
      2. Flow Rate: 0.5 to 9 L/min
    3. Medium (Yellow Hub)
      1. Weight: 1 to 10 kg
      2. Flow Rate: 0.5 to 10 L/min
    4. Large (Purple Hub)
      1. Weight: 3 to 20 kg
      2. Flow Rate: 0.5 to 23 L/min
    5. Extra-Large (Green Hub)
      1. Weight: 5 to 30 kg
      2. Flow Rate: 0.5 to 25 L/min
  6. Adult Devices (and children with weight >30 kg)
    1. Cannulas available in small, medium, large
    2. Allows for flow rates from 10-60 L/min
  • Dosing
  • Pediatric Respiratory Distress Protocol
  1. Start
    1. Liter Flow: 4 L/min (2 L/min if weight <10 kg)
    2. FIO2: Titrate to keep Oxygen Saturation above target
      1. Target Oxygen Saturation >90% while awake and >88% while asleep
      2. Adjust target Oxygen Saturation for those with underlying cardiopulmonary disease
  2. Titration Up
    1. Indicated if persistent Tachycardia, Tachypnea, Hypoxia or work of breathing
    2. Increase liter flow rate in 1 L/min increments prn (up to maximum flow rate listed above)
    3. Titrate FIO2 in 5% increments to keep Oxygen Saturation above target
  3. Indications for higher level of care (e.g. PICU, Advanced Airway)
    1. Liter flow rates >2 L/min or >8-12 L/min
    2. FIO2 >50% required for >60 min
    3. Failure to stabilize Tachycardia, Tachypnea, Hypoxia or work of breathing after 30-60 min of titration
  4. Stabilized respiratory status
    1. Wean FIO2 (goal <40%) to maintain Oxygen Saturation (>90% while awake, >88% while asleep)
  5. Weaning
    1. Indications
      1. Stabilized Heart Rate, Respiratory Rate, Oxygen Saturation and work of breathing
      2. FIO2 <40%
    2. Protocol
      1. Start by weaning FIO2 in 5% increments until <35%
      2. Next, wean flow rate by 1-2 L/min every 1 to 4 hours as tolerated
      3. Continue to wean FIO2 to keep Oxygen Saturations above target
    3. Discontinuation
      1. Stop HHFNC when flow rate <2 L/min and FIO2 21% (room air)
      2. Continue to monitor for Tachycardia, Tachypnea, Hypoxia and work of breathing for 4 hours
        1. Oxygen Saturations may be with intermittent spot checks during this time
  6. References
    1. (2021) Masonic University of Minnesota Protocol
  • Complications
  1. Gastric Distention
    1. Consider Nasogastric Tube for gastric decompression
  2. Nasal pressure injury or skin breakdown
    1. Re-evaluate skin every 4 hours
    2. Apply skin barriers as needed
  3. Pneumothorax
    1. Prompt re-evaluation with exam, Chest XRay, Bedside Ultrasound if abrupt respiratory deterioration
  4. Hypercarbic Respiratory Failure
    1. Monitor mental status, Capnography and consider VBG or ABG
    2. Mechanical Ventilation is indicated for inadequate respiratory drive
  5. Secretions
    1. Oral and nasopharyngeal suctioning as needed
  • References
  1. Mallemat and Swadron in Herbert (2013) EM:Rap 13(12): 10-11
  2. Sacchetti in Herbert (2014) EM:Rap 14(2): 9
  3. Sacchetti in Herbert (2018) EM:Rap 18(12): 13
  4. El-Khatib (2012) Respir Care 57(10): 1696-8 [PubMed]
  5. Ojha (2013) Acta Paediatr 102(3): 249-53 [PubMed]