Provoked periodic breathing in simulated moderate and high altitude in healthy young adults

Background: It's common sense that periodic breathing increases linear with greater heights. Cut off points for periodic breathing at specific altitudes are not known and seem to be very individual. Our aim was to study the difference of breathing patterns n healthy adults between simulated 3500 m and 4500 m.

Methods: 12 male and 6 female subjects with a mean age of 24,78 ± 1,86 had a 12 channel PSG randomly assigned at either 3500 m or 4500 m simulated altitude (Normobaric hypoxia, Low Oxygen Systems; Berlin-Buch, Germany).

Results: We've seen a statistically high significant decrease in total sleeping time and arterial oxygen saturation as well as an increase of the heart rate (HF) on 4500 m compared to 3500 m. No statistically significant difference in the AHI and frequency of Arousals could be seen although there is a obvious difference in mean AHI for the different groups. Central hypopneas changed to central apneas with the higher altitude.

	3500 m		4500 m
	Mean	Stdv.	Mean	Stdv
TST	417 min	± 45,5 min	325,17 min	± 85,8 min
SaO 2	84,8%	± 2,7%	76,8%	± 3,5%
HR	69,2bpm	± 8,3bpm	78,6bpm	± 10,1bpm
AHI	44,1	± 37,6	68,6	± 48,3

Conclusion: Sleep overnight in increasing simulated altitude at the cut off from moderate to high altitude goes along with decreasing oxygen saturation at a higher HF and reduced TST but AHI's are individually too different in a sample of nine individuals in each altitude group to show a statistically significant difference.