What are the different types of oxygen delivery devices and their respective uses?

Types of Oxygen Delivery Devices

Oxygen delivery devices fall into three main categories: low-flow variable performance systems (nasal cannulae, simple face masks), fixed performance systems (Venturi masks), and high-flow/reservoir systems, each with specific clinical indications based on the patient's oxygen requirements and risk of hypercapnia. 1

Low-Flow Variable Performance Devices

Nasal Cannulae

• Nasal cannulae should be the first-choice delivery device for most patients requiring supplemental oxygen due to superior patient comfort and tolerance, particularly for prolonged use 1, 2
• Each liter per minute of oxygen flow adds approximately 3-4% to inspired oxygen concentration, though actual delivery varies significantly between patients (24-35% at 2 L/min) 1
• Flow rates typically range from 0.5-6 L/min, with higher rates causing upper airway discomfort 1
• Performance decreases at high respiratory rates, as increased inspiratory flow dilutes the oxygen concentration with entrained room air 3, 4
• Preferred for medium-concentration oxygen therapy targeting saturations of 94-98% in patients without hypercapnic risk 5, 2

Simple Face Masks

• Deliver oxygen concentrations between 40-60% at flow rates of 5-10 L/min 5
• Never use simple face masks at flow rates below 5 L/min due to significant risk of carbon dioxide rebreathing 5
• Performance significantly deteriorates at high respiratory rates, making them unsuitable for tachypneic patients 4
• Less preferred than nasal cannulae due to reduced patient comfort and interference with eating/drinking 2
• Should not be used in patients at risk of hypercapnic respiratory failure 5

Fixed Performance Devices

Venturi Masks

• Venturi masks are the preferred device when precise oxygen control is essential, particularly in patients with hypercapnic respiratory failure or COPD 1, 5
• Deliver accurate fixed concentrations of 24%, 28%, 31%, 35%, 40%, and 60% oxygen when used with specified flow rates 1, 5
• Maintain consistent oxygen delivery across varying respiratory rates for concentrations up to 40%, though 60% settings show reduced performance at high respiratory rates 4
• Specifically indicated for patients requiring controlled oxygen with target saturations of 88-92% 1
• Consider in confused or cognitively impaired patients where flow rates might be inadvertently altered 1

High-Flow and Reservoir Systems

Non-Rebreather/Reservoir Masks

• Deliver oxygen concentrations between 60-90% at flow rates of 15 L/min, making them suitable for critically ill patients requiring high-concentration oxygen 5
• Recommended for trauma and emergency situations in patients without carbon dioxide retention risk 5
• Performance is significantly affected by mask leaks, with oxygen concentration dropping substantially when the mask is not properly sealed 3
• Should be used until reliable pulse oximetry monitoring is established in critically ill patients 2

High-Flow Humidified Nasal Oxygen

• Should be considered as a potentially superior alternative to reservoir masks in acute respiratory failure without hypercapnia 1
• Not appropriate for routine home oxygen use but valuable in acute hospital settings 1

Specialized Delivery Systems

CPAP with Entrained Oxygen

• CPAP with entrained oxygen (targeting 94-98% saturation) should be considered for cardiogenic pulmonary oedema not responding to standard treatment 1
• Patients with sleep-disordered breathing on home CPAP should continue therapy perioperatively, with oxygen entrained to achieve 88-92% if needed 1

Oxygen-Conserving Devices

• Deliver oxygen during inspiration only, reducing oxygen waste during expiration and extending cylinder duration by up to 50% 1
• Should be considered for active patients requiring ambulatory oxygen following proper assessment 1
• Variable performance between different models; some patients (particularly mouth breathers) may struggle to trigger them 1
• Require ambulatory assessment before prescription to ensure adequate oxygen delivery during exercise 1

Tracheostomy Masks and T-Pieces

• Tracheostomy masks are the primary delivery device for patients with tracheostomy or laryngectomy, with T-piece devices reserved for deteriorating patients 1
• Humidification is essential for tracheostomized patients to maintain airway patency and prevent secretion buildup 1

Trans-Tracheal Oxygen

• Rarely used, requires dedicated trained team support 1
• Reduces anatomical dead space and work of breathing, allowing lower oxygen requirements than nasal cannulae 1
• Serious complications include catheter displacement, mucous obstruction, and infection 1

Humidification Considerations

• Humidification is not required for low-flow oxygen or short-term high-flow oxygen use 1
• Consider humidification for patients requiring high-flow oxygen systems for >24 hours or those with upper airway discomfort 1
• Bubble bottles should never be used due to infection risk without clinical benefit 1
• Large volume humidifiers should be considered for patients with viscous secretions causing expectoration difficulty 1

Clinical Decision Algorithm

For patients WITHOUT hypercapnic risk:

• Medium oxygen needs (SpO2 target 94-98%): Start with nasal cannulae at 2-6 L/min 2
• High oxygen needs: Use reservoir mask at 15 L/min 5, 2

For patients WITH hypercapnic risk (COPD, obesity hypoventilation):

• Use Venturi mask at 24% or 28% (SpO2 target 88-92%) 1, 5
• Alternative: Nasal cannulae at 0.5-2 L/min with careful monitoring 1

For nebulized treatments:

• Asthma: Use oxygen as driving gas at 6-8 L/min 1
• COPD/hypercapnic risk: Use air-driven nebulizer with supplemental oxygen via nasal cannulae at 2-6 L/min 1

Critical Pitfalls to Avoid

• Never use simple face masks below 5 L/min - causes dangerous CO2 rebreathing 5
• Mask effectiveness is greatly reduced if not properly positioned and sealed 5
• Variable performance devices (nasal cannulae, simple masks) deliver inconsistent oxygen at high respiratory rates 3, 4
• Avoid high-flow oxygen in patients at risk of hypercapnic respiratory failure without controlled delivery systems 1, 5
• Oxygen-conserving devices require pre-assessment; do not assume all patients can trigger them effectively 1