Venturi Mask Colour Coding in Oxygen Therapy
Venturi masks use a standardized color coding system to indicate the precise oxygen concentration delivered, with each color corresponding to a specific FiO2 percentage, allowing healthcare providers to deliver controlled oxygen therapy accurately for patients requiring precise oxygen concentrations.
Understanding Venturi Masks
- Venturi masks provide accurate and controlled oxygen concentrations regardless of the patient's breathing pattern, using the Venturi principle where oxygen flow through an adaptor entrains a precise amount of room air 1
- These masks deliver constant oxygen percentages through a color-coded system that corresponds to specific FiO2 (fraction of inspired oxygen) values 1
- The oxygen concentration remains constant because gas flow into the mask is diluted with air entrained via the cage on the Venturi adaptor 1
Venturi Mask Color Coding System
- Blue: 24% oxygen concentration (typical flow rate: 2 L/min, total gas flow: 51 L/min) 1, 2
- White: 28% oxygen concentration (typical flow rate: 4 L/min, total gas flow: 44 L/min) 1, 2
- Yellow: 31% oxygen concentration 2
- Green: 35% oxygen concentration 2
- Pink: 40% oxygen concentration 2
- Orange: 60% oxygen concentration 2
Clinical Application
- Venturi masks are the preferred delivery method for patients at risk of hypercapnic respiratory failure (particularly COPD patients) who require precise control of oxygen concentration 1, 2
- For patients with COPD and acute exacerbations, oxygen administration should start at a low dose (24% by Venturi mask) with arterial blood gas monitoring to avoid CO2 retention 1
- The target oxygen saturation for patients at risk of hypercapnic respiratory failure should be 88-92%, which can be achieved with the appropriate Venturi mask setting 2
Flow Rate Considerations
- Each Venturi mask color has a minimum recommended flow rate to ensure proper functioning 1
- For patients with respiratory rates >30 breaths/min, the flow rate should be increased above the minimum specified on the packaging to maintain accuracy 1, 3
- Increasing the oxygen flow rate into a Venturi mask does not increase the concentration of oxygen delivered, but ensures the system can meet the patient's inspiratory demand 1
Advantages of Venturi Masks
- Provides precise and consistent oxygen concentration regardless of the patient's breathing pattern 1
- Allows for controlled oxygen therapy in patients who are sensitive to high oxygen concentrations 1
- Enables clinicians to make incremental adjustments in oxygen therapy by changing to different colored adaptors 2
Common Pitfalls and Caveats
- The accuracy of oxygen delivery is greatly reduced if the mask is not properly positioned on the patient's face 1
- Fixed Venturi systems have been found to comply better with recommendations than variable systems 4
- For tachypneic patients (respiratory rate >30/min), oxygen flow should be increased by approximately 50% above the recommended rate to maintain accuracy 3
- Some patients may find Venturi masks less comfortable than nasal cannulae, potentially affecting compliance with therapy 1
When to Use Alternative Oxygen Delivery Methods
- For patients requiring medium-concentration oxygen therapy who don't need precise FiO2 control, nasal cannulae (1-4 L/min) may be more comfortable and equally effective 1, 2
- For severe hypoxemia without risk of hypercapnia, consider starting with a reservoir mask at 15 L/min and then adjusting downward as the patient stabilizes 1
- High-flow nasal oxygen may be considered as an alternative to Venturi masks in selected patients, though studies show no significant difference in outcomes for immunocompromised patients with acute respiratory failure 5