studies-words

Room oxygen enrichment improves sleep and subsequent day-time performance at high altitude

Andrew M. Luks, Harm van Melick, Rodolfo R. Batarse, Frank L. Powell, Igor Grant and John B. West Respiration Physiology Volume 113, Issue 3, 1 September 1998, Pages 247-258 Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0623, USA Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0680, USA White Mountain Research Station, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0689, USA
Accepted 17 August 1998.

Abstract
We carried out a randomized, double-blind trial at 3800 m altitude to test whether a small degree of room oxygen enrichment at night improves sleep quality, and performance and well-being the following day. Eighteen sea-level residents drove from sea level to 3800 m in one day, and then slept one night in ambient air, and another night in 24% oxygen, the order being randomized.

With oxygen enrichment the subjects had fewer apneas (P<0.01) and spent less time in periodic breathing with apneas (P<0.01) than when they slept in ambient air. Subjective assessments of sleep quality were also significantly improved. There was a lower acute mountain sickness score during the morning after oxygen-enriched sleep (P<0.01) and a greater increase in arterial oxygen saturation from evening to morning (P<0.05). The larger increases in arterial oxygen saturation from evening to morning suggest that the control of breathing may have been altered.

Six Percent Oxygen Enrichment of Room Air at Simulated 5000 m Altitude Improves Neuropsychological Function

To cite this paper: Andre B. Gerard, Michele K. McElroy, Michael J. Taylor, Igor Grant, Frank L. Powell, Sebastiaan Holverda, Nicole Sentse, John B. West. High Altitude Medicine & Biology. March 1, 2000, 1(1): 51-61. doi:10.1089/152702900320685.

Andre B. Gerard
Departments of Medicine and White Mountain Research Station, University of California San Diego, La Jolla CA.
Michele K. McElroy
Departments of Medicine and White Mountain Research Station, University of California San Diego, La Jolla CA.
Michael J. Taylor
Department of Psychiatry, University of California San Diego, La Jolla CA.
Igor Grant
Department of Psychiatry, University of California San Diego, La Jolla CA.Frank L. Powell Departments of Medicine and White Mountain Research Station, University of California San Diego, La Jolla CA.
Sebastiaan Holverda
Department of Medicine, University of California San Diego, La Jolla CA.
Nicole Sentse
Department of Medicine, University of California San Diego, La Jolla CA.
John B. West
Department of Medicine, University of California San Diego, La Jolla CA.

Cognitive and motor function are known to deteriorate with the hypoxia accompanying high altitude, posing a substantial challenge to the efficient operation of high altitude industrial and scientific projects. To evaluate the effectiveness of enriching room air oxygen by 6 enrichment at 5000 m. Each subject was tested in both conditions in a randomized, double-blinded fashion. The 2-h test battery of 16 tasks assessed various aspects of motor and cognitive performance. Compared with simulated breathing air at 5000 m, oxygen enrichment resulted in higher arterial oxygen saturations (93.0 vs. 81.6 additional oxygen.

Nocturnal O2 Enrichment of Room Air at High Altitude Increases Daytime O2 Saturation Without Changing Control of Ventilation

To cite this paper: Michele K. McElroy, Andre Gerard, Frank L. Powell, G. Kim Prisk, Nicole Sentse, Sebastiaan Holverda, John B. West. High Altitude Medicine & Biology. September 1, 2000, 1(3): 197-206. doi:10.1089/15270290050144190.

Michele K. McElroy
Department of Medicine and White Mountain Research Station, University of California San Diego, La Jolla CA
Andre Gerard
Department of Medicine and White Mountain Research Station, University of California San Diego, La Jolla CA
Frank L. Powell
Department of Medicine and White Mountain Research Station, University of California San Diego, La Jolla CA
G. Kim Prisk
Department of Medicine, University of California San Diego, La Jolla CA
Nicole Sentse
Department of Medicine and White Mountain Research Station, University of California San Diego, La Jolla CA
Sebastiaan Holverda
Department of Medicine and White Mountain Research Station, University of California San Diego, La Jolla CA
John B. West
Department of Medicine, University of California San Diego, La Jolla CA

In a randomized, double-blind study, 24 sea-level residents drove to 3800-m altitude in 1 day, and then slept the first night in either ambient air or 24% oxygen, and the second night in the treatment that they did not receive on the first night. Oxygen enrichment, compared with ambient air, resulted in significantly fewer apneas, and significantly less time spent in periodic breathing during the night. The increase in SaO2 between evening and morning was significantly higher after sleeping in the oxygen-enriched atmosphere, compared with ambient air.

Safe Upper Limits for Oxygen Enrichment of Room Air at High Altitude

To cite this paper:
John B. West. High Altitude Medicine & Biology. March 1, 2001, 2(1): 47-51. doi:10.1089/152702901750067918.

John B. West
Department of Medicine, University of California San Diego, La Jolla CA 92093-0623.

Oxygen enrichment of room air at high altitude has been shown to improve mental performance, sleep quality, and work capacity. Until now, the usual strategy has been to use an oxygen concentration that reduces the equivalent altitude to about 3000 m, where the equivalent altitude is that which gives the same inspired PO2 during air breathing. However, standards adopted by the National Fire Protection Association allow considerably higher oxygen concentrations without introducing a fire hazard. For example, by raising the oxygen concentration to 31.5% at an altitude of 5000 m, the equivalent altitude can be safely reduced to less than 2000 m. At the extreme altitude of 8000 m, the equivalent altitude can be reduced to less than 4000 m without increasing the fire hazard.

Fire hazard in oxygen-enriched atmospheres at low barometric pressures.
Aviat Space Environ Med. 1997 Feb;68(2):159-62 West JB.

Department of Medicine, University of California, San Diego, La Jolla 92093-0623, USA.

Pilot studies are presently being carried out to determine the efficacy of raising the oxygen concentration in the room air of commercial and scientific facilities at altitudes of 4000-5500 m. This is a remarkably effective way of relieving hypoxia. For example, oxygen enrichment by only 5 percent (i.e., raising the oxygen concentration from 21 to 26 percent) reduces the equivalent altitude by 1500 m. However, concern has been expressed about the possibility of fire hazard. In this article, existing data from various sources have been analyzed to determine the burning rate of materials such as paper and cotton clothing at various altitudes when the PO2 in the air is increased to 110 mmHg to give an equivalent altitude of 3000 m. The analysis shows that in spite of the increase in oxygen concentration, the burning rate is much less than at sea level primarily because the PO2 is so much lower even with oxygen enrichment.

http://www.ncbi.nlm.nih.gov/pubmed/9125094