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Oxygen Bleed with CPAP

1,654 bytes added, 03:20, 11 March 2018

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=INTRODUCTION= Many CPAP users also require supplemental oxygen. The air that we inhale on a day to day basis is made up of 21% of oxygen, 78% of nitrogen and 1% of trace elements such as argon, carbon dioxide, neon, helium and methane. For the purposes of this article, fractions and percentages will be used interchangeably for ease of explanation. Sometimes, 21% of oxygen may not be enough to maintain adequate oxygen saturations. In these situations, supplemental oxygen can be administered via various oxygen delivery devices. It may be important to increase the "fraction of inspired oxygen" (FiO2). Introducing oxygen into a respiratory ventilation circuit allows the concentration of oxygen to be increased, potentially increasing the FiO2 to 100%. In non-invasive CPAP and BiPAP applications the delivered oxygen is much lower due to dilution from the CPAP venting rate that exceeds respiratory requirements. With a canula delivery, the approximate correlation between oxygen flow rate and FiO2, is similar to the table below:

=Oxygen Bleed Adapter=

The Oxygen Bleed Adapter is inserted into the CPAP/BPAP circuit to allow oxygen to be mixed into the respiratory circuit. Oxygen is always provided at higher pressure at a set flow-rate, so the dose can be calculated. Several bleed adapters are available, and they are inexpensive. The images below show oxygen bleed adapters for both standard and heated tubing.

=What is the oxygen concentration in the diluted CPAP circuit?=

~~Pending~~he equation to calculate concentration from flow is:(oxygen flow rate (litres) at 100% O2 + air volume (litres) at 21% O2) / Total air volume = oxygen concentration %therefore, at 1 litres/minute oxygen addition and assuming a total CPAP flow of 60 L/min:(1-L/min x 100) + (60-L/min x 21) = 1360 /60-L/min = 22.% Oxygen.at 1 litre/minute oxygen(3-L/min x 100) + (60-L/min x 21) = 1560 / 60 L/min = 26% oxygen. Any variable can be changed based on available data. If the flow rate is 40 L/min from the CPAP, the oxygen concentrations will be higher. If leaks are present or pressure results in a higher average vent-rate, the oxygen concentrations will be lower.

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