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→What is the oxygen concentration in the diluted CPAP circuit?
The equation to calculate concentration from flow is:<br
(oxygen flow rate (litres) at 100% O2) + (air volume (litres) at 21% O2)) / Total air volume = oxygen concentration Percent in circuit <br>
therefore, :<br>at 1 litres/minute oxygen addition at 100% and assuming a total CPAP flow of 30 L/min:<br>(1-L/min x 100) + (30-L/min x 21) = 730/31-L/min = 23.55% Oxygen.<br><br> at 3 litre/minute oxygen at 100% and assuming a total CPAP flow of 30 L/min:<br>
(3-L/min x 100) + (30-L/min x 21) = 930/33 L/min = 28.18% oxygen.
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