Author(s)

Ivana Gritti, Clara Mauri, Stefano Defendi, Daniele Cesana, Federica Consonni, Alberto Dolci, Sabrina Luoni

Department of Biomedical and Clinical Science Luigi Sacco, University of Milan, Milan, Italy.
Hospital Luigi Sacco, University of Milan, Milan, Italy.
Roche Diagnostic SpA, Viale Stucchi 110, Milan, Italy.

Altered blood chemistry, acid-base and electrolyte are suggested determinants of sleep disturbance, with frequent arousal at high altitude even in well and long-trained altitude marathon runners. In this sample of experienced altitude marathon runners with maximal aerobic power at sea level of 61.4 ± 2.7 ml/kg^-1·min^-1 we found that pO₂ and percent of oxygen saturation (%SO₂) were lower at2050 mand3480 mthan at sea level; pO₂ was higher after 38 - 41 hours than after 30 - 31 hours of acclimatization at3480 m(P < 0.05). After ascentto3480 m%SO₂ decreased (P < 0.003). Com- pared to sea level values, pH increased at high altitude (P < 0.05) consistent with changes in pCO₂ and (P < 0.05). Nocturnal %SpaO₂ at a sleeping altitude of3480 mwas lower (P < 0.05) than at sea level. At high altitude, the percent of wake (W) time and delay falling asleep (DFA) increased, whereas non-rapid eye movement sleep (N-REM), REM sleep and total sleep time (TST) decreased (P < 0.05). Simple regression analysis disclosed a significant correlation between the changes in TST and the percent of REM sleep and the changes in %SpaO₂ recorded during sleep (P < 0.05). Simple regression analysis showed a positive correlation between the changes in pO₂ at higher altitude and the percent of W and of TST (P < 0.05). The changes in pO₂, tCO₂ and [HCO₃^-] correlated negatively and significantly with the percent of REM sleep changes at high altitude (P < 0.05). The TST changes at high altitude correlated positively with the changes in pO₂ and pH and correlated negatively with the changes in %SO₂, pCO₂, tCO₂, and [HCO₃^-] (P < 0.05). The changes in the percent of W at high altitude correlated significantly and positively with the changes in bases excess [BE] at high altitude (P < 0.05). The changes in the percent of REM sleep correlated significantly and positively with the changes in [iCa⁺⁺] and [BE] and negatively with the changes in buffered bases [BB] and [BEeffective] (P < 0.05). The change in the percent of NREM + REM sleep at high altitude correlated significantly and positively with the changes in [BE] and [BB] concentration (P < 0.05). The increase in DFA at high altitude correlated significantly and negatively with the changes in pCO₂ and significantly and negatively with the changes in [K⁺] (P < 0.05). Simple regression analysis demonstrated that the changes in pH at high altitude correlated positively and significantly with the percent of W and the DFA and negatively with the percent of changes in NREM sleep, REM sleep, NREM + REM sleep (P < 0.05). The decrease in the TST at high altitude correlated significantly and negatively with the changes in pCO₂, tCO₂, [HCO₃^-] and [K⁺] (P < 0.05). Our data demonstrate that the arterialized ear lobe techniques we used for evaluating most of the changes in blood chemistry, acid-base, electrolyte and blood lactate metabolism aresuitable for clinical and laboratory assessment and are important predictors of the quality and quantity of acclimatization and sleep at high altitude.

Clinical Investigation at High Altitude; Laboratory Investigation at High Altitude; Hematochemistry; Acid-Base Metabolism; Electrolyte Metabolism; Blood Lactate Metabolism; Hydration Status; Sleep Quality Indicators; EEG; Mountain Marathon Runners

I. Gritti, C. Mauri, S. Defendi, D. Cesana, F. Consonni, A. Dolci and S. Luoni, "Blood Chemistry, Acid-Base, Electrolyte, Blood Lactate Metabolism and Sleep at 3480 m in Mountain Marathon Runners," Journal of Behavioral and Brain Science, Vol. 3 No. 1, 2013, pp. 13-25. doi: 10.4236/jbbs.2013.31003.