What are the indications and uses of different oxygen delivery devices, including their associated FiO2 (Fraction of Inspired Oxygen) levels and oxygen flow rates?

Oxygen Delivery Devices: Indications, FiO2, and Flow Rates

The selection of oxygen delivery devices should be based on the patient's required FiO2, respiratory status, and risk of hypercapnic respiratory failure, with nasal cannulae being preferred for most patients requiring medium-concentration oxygen therapy due to better comfort and compliance. 1

Types of Oxygen Delivery Devices and Their Specifications

Low-Flow Devices

Nasal Cannula

• FiO2 delivery: 24-40% (approximately 24% at 1 L/min, 28% at 2 L/min, 32% at 3 L/min, 36% at 4 L/min, 40% at 5-6 L/min) 1, 2
• Flow rate range: 0.5-6 L/min
• Indications:
  • First-line for most patients requiring medium-concentration oxygen therapy 1
  • Stable patients with mild-moderate hypoxemia
  • Patients who need to eat/drink while receiving oxygen
• Advantages:
  • Better patient comfort and compliance
  • Less likely to be removed during meals
  • Cost-effective 1
• Limitations:
  • Flow rates >6 L/min can cause nasal dryness and discomfort
  • Unpredictable FiO2 at higher respiratory rates 2, 3

Simple Face Mask

• FiO2 delivery: 35-50% (depending on flow rate)
• Flow rate range: 5-10 L/min (minimum 5 L/min to prevent CO2 rebreathing) 1
• Indications: Patients requiring medium-concentration oxygen
• Limitations:
  • Less comfortable than nasal cannula
  • Must be removed for eating/drinking
  • Significant FiO2 reduction at high respiratory rates 2, 3

High-Flow Devices

Reservoir Mask (Non-rebreather)

• FiO2 delivery: 60-85% (not 100% as often quoted) 3
• Flow rate: 15 L/min
• Indications:
  • Critically ill patients requiring high-concentration oxygen
  • First-line for delivering high-concentration oxygen until reliable pulse oximetry monitoring is established 1
• Advantages: Maintains consistent FiO2 even at high respiratory rates 3

High-Flow Nasal Cannula (HFNC)

• FiO2 delivery: 21-100% (precisely controlled)
• Flow rate: 20-60 L/min
• Indications:
  • Hypoxic patients requiring medium to high-concentration oxygen therapy
  • Patients not at risk of hypercapnia 1
• Advantages:
  • Better comfort and tolerance than face masks
  • Associated with better oxygenation and lower respiratory rates
  • Maintains consistent FiO2 at high respiratory rates 4

Fixed Performance Devices

Venturi Mask

• FiO2 delivery: 24%, 28%, 31%, 35%, 40%, and 60% (precisely controlled)
• Flow rate: Varies based on specific entrainment port
• Indications:
  • Patients requiring precise control of FiO2
  • Patients at risk of hypercapnic respiratory failure (e.g., COPD) 1
• Advantages:
  • Delivers consistent FiO2 regardless of breathing pattern
  • Reduces risk of hypercapnia in susceptible patients
  • Less dilution by room air when patient's inspiratory flow exceeds mask flow 1
• Special considerations:
  • For COPD patients with respiratory rate >30 breaths/min, increase flow rate above minimum specified 1
  • Can be substituted with nasal cannulae at 1-2 L/min for 24-28% FiO2 targets 1

Clinical Decision Algorithm for Device Selection

1. Assess oxygen requirement and risk of hypercapnia:

   • If patient has COPD or other risk of hypercapnic respiratory failure:

     • Target SpO2 88-92%
     • Use Venturi mask (24-28%) or nasal cannula at 1-2 L/min 1

   • If patient has no risk of hypercapnia:

     • Target SpO2 94-98% (or 92-96% in most guidelines) 1

2. Select device based on required FiO2:

   • Low oxygen requirement (FiO2 <0.4):

     • Use nasal cannula at 1-6 L/min (first choice)
     • Alternative: Simple face mask at 5-10 L/min

   • Medium oxygen requirement (FiO2 0.4-0.6):

     • Use Venturi mask at appropriate setting
     • Alternative: HFNC if available

   • High oxygen requirement (FiO2 >0.6):

     • Use reservoir mask at 15 L/min
     • Alternative: HFNC if available

3. Monitor and adjust:

   • Check oxygen saturation within 1-2 hours of initiating therapy 1
   • Adjust flow rate or change device if target saturation not achieved

Special Considerations

Humidification

• Consider heated humidification when:
  • Patient reports mucosal dryness
  • Respiratory secretions are thick and tenacious 1
  • Using high-flow oxygen therapy
  • Oxygen therapy is required for extended periods

Oxygen Supplementation with NIV

• Oxygen should be entrained as close to the patient as possible 1
• FiO2 decreases as ventilatory pressure increases due to higher leak 1
• For a given supplemental oxygen flow rate:
  • FiO2 ≈ 31% at 1 L/min
  • FiO2 ≈ 37% at 2 L/min
  • FiO2 ≈ 40% at 3 L/min
  • FiO2 ≈ 44% at 4 L/min 1
• Flow rates >4 L/min may cause mask leak and delayed triggering 1

Pediatric Considerations

• For neonates, start with lower oxygen concentrations (21-30%) and titrate based on pulse oximetry 5
• Target oxygen saturation 90-95% for most neonates 5
• Blow-by methods are significantly less effective at distances >5 cm from the face 6

Common Pitfalls and How to Avoid Them

1. Inadequate flow rates with simple masks:

   • Always maintain minimum 5 L/min to prevent CO2 rebreathing 1

2. Overestimating FiO2 delivery:

   • Actual FiO2 from non-rebreather masks is typically 60-85%, not 100% 3
   • Variable performance devices deliver significantly reduced oxygen at high respiratory rates 2, 3

3. Inappropriate device selection for patients at risk of hypercapnia:

   • Use Venturi masks or low-flow nasal cannula (1-2 L/min) for patients with COPD or other risk of hypercapnic respiratory failure 1

4. Insufficient monitoring:

   • Continuously monitor oxygen saturation
   • Regularly check blood gases in acute settings to assess pCO2 and pH 1

5. Excessive oxygen in patients with chronic hypercapnia:

   • Target SpO2 88-92% in patients with COPD or chronic type 2 respiratory failure 1

By selecting the appropriate oxygen delivery device based on the patient's clinical needs and understanding the capabilities and limitations of each device, clinicians can optimize oxygen therapy while minimizing risks.