Modes of Oxygen Delivery
Jacob Lee
Definitions
- Entrainment – the process of oxygen being mixed with ambient air that impacts the true fraction of inspired oxygen delivered to the patient
Non-Invasive modes of oxygenation augmentation
These modes of oxygen delivery focus on oxygenation as opposed to ventilation
System |
L/min |
%O2 |
Comments |
|---|---|---|---|
| Blow by (ex: Trach collar) | Depends on O2 delivery device | 21-100% | Used for patients who cannot tolerate more direct devices (agitated, cuffed tracheostomy) |
| Nasal cannula | 1-6 | 24-45% | Add 3-4% to Room Air FiO2 (21%) for each liter of supplemental oxygen administered. Flows in excess of 6 L/min will not appreciably increase the FiO2 |
| Large bore nasal cannula | Up to 15 | Up to 80% | This is NOT high flow nasal cannula (HFNC) although it may be documented in the chart as such. The nasal cannula prongs have a larger radius allowing for additional flow that will reliably increase flow rate up to 15 L/min |
| Venturi mask | 2-15 | Up to 60% | Color-coded adaptors allow for specific entrainment that deliver more accurate FiO2 delivery at given flows. Actual FiO2 is dependent on pt effort |
| Non-rebreather | 10-15 | 60-90% | Reservoir bag is filled with pure oxygen, with one-way valves that prevent patient from breathing ambient air. Often used as a bridge to a higher tier of oxygen delivery |
| HFNC: Optiflow, AirVo, Vapotherm | 50-6- | 30-100% | Used for hypoxic respiratory failure; although does deliver roughly 0.6-1.2 cm/H20 of PEEP per 10L of flow, not typically used for hypercapnic respiratory failure |
Non-invasive positive pressure ventilation
- Deliver set pressures by adjusting flow. Note, while flow and pressure are inter-related, they cannot be inter-converted. Pressure is maintained by regulating flow dynamically based on patient effort and lung mechanics
- Supplemental flow and FiO2 can be delivered into the tubing or blended into the machine (bled in) to give FiO2 reliably up to 60% (outpatient with oxygen bled in) or close to 100% (inpatient using high-flow devices)
System |
Settings |
Indications |
Comments |
|---|---|---|---|
| CPAP | Pressure (CPAP), FiO2 | OSA, Tracheomalacia | FiO2 delivery varies due to leaks, mask type, and patient breathing pattern. Not indicated solely for oxygen delivery but can bleed oxygen in if hypoxia is also present |
| BiPAP | IPAP, EPAP (nomenclature is IPAP/EPAP), FiO2, RR | Hypoxic and/or hypercapnic respiratory failure, cardiogenic pulmonary edema, OSA, obesity hypoventilation syndrome, prevention of post-extubation respiratory failure in high-risk patients | Delta between IPAP and EPAP = driving pressure (higher driving pressure improves ventilation not oxygenation). Increasing EPAP can improve oxygenation by increased mean airway pressure but will not improve ventilation FiO2 delivery varies due to pressure cycling, leaks, and inspiratory flow changes Generally contraindicated if patient unable to remove mask themself, vomiting, or lots of secretions |
*** All of the above oxygen delivery systems are used in spontaneously breathing patients***
Invasive positive-pressure ventilation
- See “Intubation and Extubation” chapter (chapter prior to this one) for indications
- See “Introduction to Ventilator Management” for ventilator modes