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1. The oxygen concentration increases by 1% (under normal pressure, the oxygen concentration is 21%), it is equivalent to a 350 meter drop in altitude.
2. The composition of air at high altitude is the same as that at low altitude. Except for water vapor, oxygen accounts for about 21% and nitrogen accounts for about 79%. But the high altitude air is thin, so the absolute concentration of oxygen is also thin.
3. The oxygen concentration below 25% is similar to the oxygen content in the air and has no therapeutic value.
4. Oxygen inhalation concentration: oxygen accounts for 20.93% in the air, carbon dioxide 0.03%, and the remaining 79.04% is nitrogen, hydrogen and trace inert gases. Grasping the oxygen concentration plays an important role in correcting hypoxia.
5. The conversion algorithm of oxygen concentration and oxygen flow can be calculated by the following formula: oxygen concentration of blood gas analysis
The current oxygen inhalation method is open oxygen inhalation due to the nasal oxygen tube inhalation. That is, when a person takes a breath, the amount of oxygen cannot be supplied, and some air (21% oxygen concentration) will be inhaled next to it, and it actually reaches the lungs. The oxygen concentration in the part is the oxygen concentration after mixing air, which is the inhaled oxygen concentration.
Inhaled oxygen concentration=21+4*flow rate*oxygen purity
6. The relationship between oxygen flow rate and oxygen concentration can be found in the table (calculated based on the above formula):
|
Oxygen flow rate L/min |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
|
Oxygen purity FIO2 |
25 |
29 |
33 |
37 |
41 |
45 |
49 |
53 |
57 |
61 |
|
Oxygen purity FIO2 |
24.6 |
28.2 |
31.8 |
35.4 |
39 |
46.2 |
46.2 |
49.8 |
53.4 |
57 |
7.Relationship between altitude and oxygen purity
|
Altitude |
0-2000 |
2500 |
2850 |
3000 |
3100 |
3500 |
3600 |
4000 |
5000 |
|
O2 purity of Air |
21 |
15.3 |
14.5 |
14.2 |
14 |
13.6 |
13 |
12.6 |
11.3 |
|
O2 purity of Oxygen concentrator |
93 |
|
|
62.89 |
|
|
|
55.8 |
|
8.Oxygen concentration and oxygen partial pressure:
In the sea level area, the air pressure per square centimeter is 101.3kPa (760 mmHg). In dry air, oxygen accounts for 20.40%, so the oxygen partial pressure is 21.15kPa (159 mmHg). The proportion of oxygen in the air is basically not affected by the plateau. When the atmospheric pressure decreases due to the increase in altitude, the partial pressure of oxygen decreases proportionally.
|
Altitude |
0 |
1000 |
2000 |
4000 |
|
Atmospheric pressure |
101.3 |
89.87 |
79.5 |
61.64 |
|
90% |
90 |
79.85 |
70.63 |
54.76 |
|
93% |
93 |
82.51 |
72.99 |
56.59 |
