Intermittent exposure to high-altitude work: nocturnal hypoxemia sea-level anthropometric and biochemical markers

Abstract Introduction Workers native to sea level and employed in Chilean Andes mines (3800–4500 m) experience Chronic Intermittent Hypobaric Hypoxia (CIHH) due to 7-day high-altitude shifts alternating with 7-day sea-level rest. Hypobaric hypoxia can exacerbate Sleep-Disordered Breathing (SDB), raising cardiovascular risk. Evaluating miners before altitude exposure may help identify SDB risk factors. We described nocturnal respiratory alterations during CIHH and the anthropometric and biological characteristics measured at sea level. Method In this Cross-sectional study, nocturnal oximetry was performed in miners during high-altitude shifts. Blood samples, blood pressure, and anthropometric data were collected at sea level before ascent. Oxygen Desaturation Index (ODI) ≥ 15/h and time spent with SpO 2 < 85% were used as markers of SDB. Results Over 36 months, 762 workers underwent nocturnal oximetry; 30 were female, mean age 45 ± 11 years, mean BMI 27 ± 3 kg/m². 203 workers had ODI ≥ 15/h, and 559 showed nocturnal saturation < 85% at altitude. Those with higher ODI had higher BMI, total cholesterol, triglycerides, uric acid, and blood pressure at sea level. Lowest SpO₂ values were described in miners with highest BMI, uric acid, and blood pressure. BMI remained the principal independent correlate of SDB. Conclusion Obesity may represent a marker of vulnerability to nocturnal hypoxemia in workers exposed to CIHH Preventive strategies—such as nutritional improvement, sleep apnea screening, and appropriate treatment—are essential to improve health and working conditions under CIHH.