Makindo Medical Notes"One small step for man, one large step for Makindo" |
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Hypoxia kills. Oxygen points can usually deliver up to 15 L/min of oxygen. Oxygen delivery depends on many variables including mask type, patient respiratory rate and minute volume. Just increasing flow does not always mean high FiO₂. The concentration of oxygen the patient breathes in is determined by the type of mask as well as the flow from the wall and the breathing pattern. By using a fixed performance system (Venturi)you can gauge the percentage much more accurately
Mode | About | Use | Image |
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Room Air | Atmospheric air contains 21% oxygen. Even a modest increase can improve tissue oxygenation | Those without additional oxygen requirement and SaO₂ > 94% or those with hypercapnia and COPD | |
Nasal Cannula
[Delivers FiO₂ 24-44%] | A nasal cannula (NC) comprises a thin tube with two small nozzles that protrude into the patient's nostrils. It can only comfortably provide oxygen at low flow rates. Low flow delivery system. Flow rate: 1 - 6 L/min. FiO₂ starts at 24% for 1L/min and increases 4% for each L/min up to 44% for 6 L/min. Usually Well tolerated - some find this preferable to a face mask. No dead space. Must be low flow as rate: > 6 L/min cause nasal mucosal drying and nose bleeds. Use: minimal or no respiratory distress or oxygenation problem | Mild hypoxia and stable. O₂ sats stable and above 90% and otherwise normal observations | |
Simple (Hudson)
Face Mask [Delivers FiO₂ 24-44%] | Low flow delivery system. Small space. Use at 5-8 l/min. Must flow at over 5L/min to flush away expired CO₂. Flow rate determines FiO₂: 5 - 6 is 40%, 6 - 7 is 50%, 7 - 8 is 60%. Mask doesn't need tight seal. Use as one would with nasal prongs but requires higher concentrations | Same as nasal cannulae. May be preferred for comfort | |
Venturi Mask | High flow delivery system with flow rate b/w 4 - 12 L/min. FiO₂ can be set specifically with different flow rate and air ports. Fi0₂ can be 24, 28, 31, 35, and 40%. External ports must remain open to entrain room air. Use in COPD patients that require specific oxygen concentrations to administer high Fi02 but not too high such that the hypoxic drive to breath is blunted; titrate to keep sats about 88-92% | Used to give precise FiO₂ so may be useful with COPD and CO₂ retention and need to give 24 or 28% oxygen. Colour codes BLUE = 2-4L/min = 24% O₂ WHITE = 4-6L/min = 28% O₂ YELLOW = 8-10L/min = 35% O₂ RED = 10-12L/min = 40% O₂ GREEN = 12-15L/min = 60% O₂ | |
Non-Rebreather
with Reservoir Bag | High flow delivery system giving high FiO₂. This mask utilizes 3 one-way valves and an oxygen bag reservoir. Supplies the highest possible oxygen concentration of any of the masks. Flow rate 6 - 15 L/min supplies 50-70% Fi02. Requires tight-fitting mask Flow can set to meet the patient's maximum inspiratory needs. The bag should not completely deflate on inspiration. Should be used when over 50% oxygen required. Use it in any spontaneously breathing patient who requires the highest FiO₂. Indications - carbon monoxide poisoning, trauma, severe asthma, pulmonary oedema, acute PE etc | Sick patients severe Asthma, LVF, Shock, Anaphylaxis, Acute PE, Acute pneumonia | |
CPAP/NIV | Positive pressure throughout respiratory cycle Prevents collapse of airways recruiting more alveoli for gas exchange and reduces the work of breathing. Can be accompanied by high FIO₂. Starting pressure is 5 cm H₂O. See topic | Type 1/2 Respiratory failure. NIV used for COPD. CPAP for Pulmonary oedema |