Abstract
It is estimated that labor activity at high altitudes in Chile will increase from 60,000 to 120,000 workers by the year 2020. Oxygenation of spaces improves the quality of life for workers at high geographic altitudes (<5,000 m). The aim of this study was to determine the effect of a mobile oxygen module system on cardiorespiratory and neuropsychological performance in a population of workers from Atacama Large Millimeter/submillimeter Array (ALMA, 5,050 m) radiotelescope in the Chajnantor Valley, Chile. We evaluated pulse oximetry, systolic and diastolic arterial pressure (SAP/DAP), and performed neuropsychological tests (Mini-Mental State examination, Rey-Osterrieth Complex Figure test) at environmental oxygen conditions (5,050 m), and subsequently in a mobile oxygenation module that increases the fraction of oxygen in order to mimic the higher oxygen partial pressure of lower altitudes (2,900 m). The use of module oxygenation at an altitude of 5,050 m, simulating an altitude of 2,900 m, increased oxygen saturation from 84 ± 0.8 to 91 ± 0.8% (p < 0.00001), decreased heart rate from 90 ± 8 to 77 ± 12 bpm (p < 0.01) and DAP from 96 ± 3 to 87 ± 5 mmHg (p < 0.01). In addition, mental cognitive state of workers (Mini-Mental State Examination) shown an increased from 19 to 31 points (p < 0.02). Furthermore, the Rey-Osterrieth Complex Figure test (memory) shown a significant increase from 35 to 70 (p < 0.0001). The results demonstrate that the use of an oxygen module system at 5,050 m, simulating an altitude equivalent to 2,900 m, by increasing FiO2 at 28%, significantly improves cardiorespiratory response and enhances neuropsychological performance in workers exposed to an altitude of 5,050 m.
Highlights
Exposure to high altitude has become an increasingly common event
Pulse oximetry was decreased to values of 84 ± 0.8% (p < 0.05) that represent a fall approximately 9.7% in the arterial oxygenation and heart rate was increased to values of 90 ± 8 bpm (p < 0.05) that represented an increase of 16.8%, systolic arterial pressure was increased to values of 135 ± 18 mmHg that represented an increase of 11.6%, diastolic arterial pressure was increased to values of 96 ± 3 mmHg (p < 0.05) that represented an increase of 18.5% and mean arterial pressure was increased to values of 109 ± 8 mmHg (p < 0.05) that represented an increase of 15.9% was observed in all subjects when they arrived at 5,050 m, respect of values obtained in camp base (OSF, 2,900 m)
This study is the first to assess the effect of environmental oxygen enrichment at 28% in very high altitude conditions (5,050 m) in a population of volunteers acclimatized to chronic and intermittent hypobaric hypoxia exposure for at least 4 years
Summary
Exposure to high altitude has become an increasingly common event. As many as 140 million people live at altitudes over 2,500 m (Moore, 2001). In Chile up until 1995, there were approximately 20,000 workers intermittently exposed to high altitudes for a long period of time (Jiménez, 1995), and this number is expected to increase to over 120,000 by the year 2020 (http://www.ccm.cl/wp-content/ uploads/2016/06/fuerza_laboral_de_la_gran_mineria_chilena_ 2012_2020.pdf) In these conditions, chronic intermittent hypobaric hypoxia (CIHH) constitutes a model of hypobaric hypoxic exposure previously described by several authors (Jiménez, 1995; Richalet et al, 2002; Moraga et al, 2014). Exposure to high altitude resulted in impaired sleep quality with increased periodic breathing, increased awakenings and shorter stage 3 and 4 sleep, causing low productivity and altered general well-being (Gerard et al, 2000).
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