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Prevalence of oxygen desaturation and use of oxygen at home in adults at sea level and at moderate altitude

¹ National Institute of Respiratory Diseases, Mexico City, Mexico, ² University of the Republic, Faculty of Medicine, Montevideo, Uruguay, ³ Pulmonary Division, Hospital Universitario de Caracas, Universidad Central de Venezuela, Caracas, Venezuela, ⁴ Federal University of Pelotas, Pelotas, Brazil.

CORRESPONDENCE: R. Perez-Padilla, Instituto Nacional de Enfermedades Respiratorias, Tlalpan 4502, DF 14080, Mexico. Fax: 52 5556668640. E-mail: perezpad{at}servidor.unam.mx

Keywords: Altitude, gas exchange, hypoxia, oxygen saturation, Proyecto Latinoamericano de Investigacion en Obstruccion Pulmonar (PLATINO) study

Received: June 27, 2005
Accepted October 21, 2005

The aim of this study was to determine the prevalence of oxygen desaturation in adults aged 40 yrs as altitude above sea level increases.

A population-based, cross-sectional study with a multistage cluster sampling of 1,063 subjects from metropolitan Mexico City (Mexico; 2,240 m above sea level), 1,357 from Caracas (Venezuela; 950 m) and 943 from Montevideo (Uruguay; 35 m). The mean of six measurements of arterial oxygen saturation (S_P,O2) was estimated using a pulse oximeter.

Mean S_P,O2 decreased with altitude. No subject from Montevideo had a mean S_P,O2 88%. Prevalence of subjects with S_P,O2 88%, a common criterion used for oxygen prescription, was 1.0% in Caracas and 6.0% in Mexico City. Additional predicting factors for hypoxaemia in multiple regression models were age, body mass index and a low forced expiratory volume in one second as a percentage of the predicted value. In Mexico City and Caracas, <10% of the hypoxaemic subjects reported use of domiciliary oxygen, whereas at least half of the subjects reporting use of oxygen at home had a resting S_P,O2 >88%.

In conclusion, the prevalence of hypoxaemia was closely related to altitude. Priorities for oxygen prescription must be defined in moderate altitudes because it is unfeasible to provide it to all subjects fulfilling the criteria commonly used.