[Estimation of arterial oxygen saturation in relation to altitude].
OBJECTIVE
Arterial Oxygen Saturation (AOS) predicts altitude sickness.


OBJECTIVE
To estimate the AOS values with relation to altitude. Furthermore, make a graph to use during activity which assesses the AOS for each altitude and the normal range.


METHODS
Values of AOS were assessed during eight high mountain activities in the Alps, Himalaya, Caucasus and Andes; 53 mountaineers participated, 17 of them in more than one activity; 761 measurements of AOS were registered.


RESULTS
A Logistic Regression Model was made to estimate the AOS values dependent on altitude, adjusted to possible related factors. A strong lineal relationship exists between altitude and AOS (R2=.83, P<.001); .7 points more in women. The AOS in a particular altitude is not related to age, weight, height, smoking, heart rate, or even with previous experiences in mountains. The calculation of the AOS responds to the follow equation: Blood Oxygen Saturation=103.3-(altitude × .0047)+(Z), being Z=.7 in men and 1.4 in women. A scatter plot was made to relate the estimated altitude with the AOS, with their normal limits values: percentiles 2.5 and 97.5.


CONCLUSIONS
The simple calculation of the AOS estimated for a particular altitude with the proposed graphic can help in the early decision-making onsite.
Unidad Docente de Medicina de Familia, Huesca, España; Servicio Aragonés de Salud, Huesca, España. Electronic address: tlorente@salud.aragon.es.
Teófilo
T
Lorente-Aznar
Servicio Aragonés de Salud, Huesca, España.
Guillermo
G
Perez-Aguilar
Servicio Aragonés de Salud, Huesca, España.
Alma
A
García-Espot
Unidad Docente de Medicina de Familia, Huesca, España.
Sergio
S
Benabarre-Ciria
Servicio Vasco de Salud, San Sebastián, España.
Juan Luis
JL
Mendia-Gorostidi
Agencia Valenciana de Salud, Castellón, España.
Daniel
D
Dols-Alonso
Servicio Aragonés de Salud, Huesca, España.
Julia
J
Blasco-Romero
D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000097:blood / Q000175:diagnosis; D001158:Arteries; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D012016:Reference Values
D015415:Biomarkers; D010100:Oxygen
Altitude sickness; Arterial oxygen saturation; Mal de altura; Montañismo; Mountaineering; Pulse oximetry; Pulsioximetría; Saturación arterial de oxígeno