Conjunctival oxygen tension at high altitude
Mader, T.H.; Friedl, K.E.; Mohr, L.C.; Bernhard, W.N.
Aviation Space and Environmental Medicine 58(1): 76-79
1987
ISSN/ISBN: 0095-6562 PMID: 3814036 Document Number: 299835
Transconjunctival oxygen tension (PciO2) was studied using a hypobaric chamber and during mountaineering excursions. Measurements obtained during acute chamber exposures (15-20 min) at sea level, 1829 m (6000 ft), 3048 m (10,000 ft), 4267 m (14,000 ft) and return to sea level were (means .+-. SEM): 60.1 .+-. 2.7, 49.1 .+-. 1.8, 38.3 .+-. 2.4, 27.4 .+-. 1.5, and 61.1 .+-. 2.8 mm Hg,respectively (n = 13). The ratio of PciO2 to arterial blood oxygen tension (PaO2) did not change in a consistent manner between sea level and 4267 m; PciO2 was 74 .+-. 6.9% of PaO2. The 16 subjects participating in the mountaineering phase of the study revealed similar means at sea level and 1829 m (57.4 .+-. 2.4 and 46.3 .+-. 1.9 mm Hg respectively), but a smaller decrement was observed at 3048 m (43.0 .+-. 1.6 mm Hg). The difference between mountain and chamber values may be accounted for by a partial acclimatization to altitude brought about by longer exposure on the mountain excursions. A comparison between PciO2 and transcutaneous oxygen tension during the chamber study suggests that a greater precision and sensitivity is obtained with measurement of oxygen tension at the conjunctival site. PciO2 measurement is a non-invasive reflection of PaO2 which is suitable for continuous monitoring during hypoxia studies.