Oxygen concentration is the same as
% FiO2
1 L oxygen =
1000 mL oxygen (duh)
What percent of medical air is oxygen?
21%
how much oxygen (in mL) is in 1 L of medical air
1000 mL air x 0.21 = 210 mL
oxygen concentration (% Fi02) =
total oxygen in mL / total gas mixture flow
sample question:
fresh gas flows are set at 1 L oxygen and 1 L air. What oxygen concentration is being delivered via the breathing circuit?
1L oxygen = 1000 mL oxygen
1L air = 210 ml oxygen
1210/2000 = 0.60
=60% FiO2
sample question:
fresh gas flows are set on 7L nitrous oxide and 3L oxygen for pediatric inhalation induction. What oxygen concentration is being delivered via the breathing circuit?
7L N2O = O mL oxygen
3L O2 = 3000 mL oxygen
3000 mL/10,000 mL
=30% FiO2
sample question:
The surgeon requests 30% FiO2 during a tonsilectomy to minimize risk for an airway fire. What is a reasonable air/oxygen flow mixture to achieve FiO2 of 30%?
3.5 L air
0.5 L oxygen
3500x0.21 = 735 mL oxygen
0.5 L = 500 mL oxygen
1235 mL oxygen / 4000 mL total flow
=30.9% FiO2
Clinical use for calculating oxygen delivery time for specific oxygen delivery rate via oxygen tank
-oxygen pipeline failure requiring use of an E-cylinder
-patient transport with oxygen E-cylinder
-how long can you supply oxygen from an oxygen cylinder
Full oxygen tank in Liters
660 L
Full oxygen tank in psig
1900 psig
equation for obtaining remaining tank contents
capacity of tank (L)/service pressure (psi) = content remaining (L)/Gauge pressure (psi)
sample question:
your pressure gauge reads 950 psi. How much in liters is left in your E-cylinder tank of oxyge?
660/1900 = x/950
x=330 L
You have half an E-cylinder of oxygen left. Oxygen is being administered to your patient at 3L/min. How long will your tank last?
330L/(3L/min)
=110 min
oxygen E-cylinder is 1/3 full. What should the pressure regulator read?
660/1900 = 220/x
x=633 psi