Table 2

Relationship between daytime EtCO2, daytime SpO2 and sleep variables at baseline (130 m) and altitude (3500 m)

130 m3500 m
EtCO2=38–47 mm HgDaytime EtCO2=31–40 mm Hg
R2p ValueβRangeR2p ValueβRange
Daytime SpO2 (%)0.320.1−0.56197–1000.650.009−0.80685–92
Mean overnight SpO2 (%)–980.400.066−0.63580–89
Minimum overnight SpO2 (%)0.460.0460.67584–940.380.078−0.61560–82
Number of desaturations/hour overnight0.750.003−0.8650––49.3
Number of central apnoeas/hour overnight0.780.002−0.8820–1.70.450.047−0.6730.3–9.5
% total sleep time spent in periodic breathing0.760.017−0.7630–−0.1590–17.5
  • EtCO2, end-tidal partial pressure of carbon dioxide; SpO2, haemoglobin oxygen saturation from pulse oximeter.