Hypobaric conditions at increasing altitude

Altitude, ft	Barometric pressure, mmHg	Atmospheric PO₂, mmHg	Tracheal PO₂, mmHg	Gas density*	Gas volume^¶
0 (sea level)	760	159	149	1	1
2000	707	148	138	-	-
4000	656	137	128	0.9	1.1
5000	632	132	122	0.8	1.2
8000	564	118	108	-	1.4
10,000	523	109	100	0.7	1.5
15,000	428	89	80	0.6	1.9
30,000	226	47	38	0.3	4
40,000	141	29	20	0.2	7.6

Fall in ambient pressure and PO₂ at increasing altitude during air travel in commercial airliners. Pressurization of the cabin limits the reduction in cabin pressure, thereby limiting the reduction in inspired PO₂.

* Ratio of density at altitude to density at sea level.
¶ Ratio of volume occupied by a fixed amount of gas at altitude to the volume occupied at sea level.

Adapted from Gong H. Advising pulmonary patients about commercial air travel. J Respir Dis 1990; 11:484.

Graphic 77616 Version 5.0

خرید پکیج

Hypobaric conditions at increasing altitude