Effects of High Altitude on Sleep and Respiratory System and Theirs Adaptations

Abstract

High-altitude (HA) environments have adverse effects on the normal functioning body of people accustomed to living at low altitudes because of the change in barometric pressure which causes decrease in the amount of oxygen leading to hypobaric hypoxia. Sustained exposure to hypoxia has adverse effects on body weight, muscle structure and exercise capacity, mental functioning, and sleep quality. The most important step of acclimatization is the hyperventilation which is achieved by hypoxic ventilatory response of the peripheral chemoreceptors. Hyperventilation results in increase in arterial carbondioxide concentration. Altitude also affects sleep and cardiac output, which is the other determinant of oxygen delivery. Upon initial exposure to HA, the resting pulse rate increases rapidly, but with acclimatization, heart rate and cardiac output tend to fall. Another important component that leads to decrease in cardiac output is the reduction in the stroke volume with acclimatization. During sleep at HA, the levels of CO2 in the blood can drop very low and this can switch off the drive to breathe. Only after the body senses a further drop in O2 levels breathing is started again. Periodic breathing is thought to result from instability in the control system through the hypoxic drive or the response to CO2.

Time-varying signal analysis to detect high-altitude periodic breathing in climbers ascending to extreme altitude

“…Therefore, the characterization of cardiorespiratory dynamics is useful to detect physiologic effects of acclimatization. The increase in measures of PB observed with acclimatization despite a simultaneous increase in oxygen saturation is consistent with an ongoing increase in ventilatory sensitivity to hypoxia and carbon dioxide during prolonged exposure to extreme altitude [32]. Consequently, the robust automatic quantification of PBI, proposed in this study, provides a new approach to assess physiologic changes to adaptation in high altitude beyond the current analysis.…”

Overnight Polysomnographic Characteristics and Oxygen Saturation of Healthy Infants, 1 to 18 Months of Age, Born and Residing At High Altitude (2,640 Meters)

“…In addition, the lower Pa o 2 at high altitude and the compensatory increase in ventilation with Pa co 2 reduction can favor the occurrence of CA and PB. [6][7][8][33][34][35][36][37][38][39][40][41] Another intriguing result was the occurrence of obstructive respiratory events, despite the absence of any evidence of craniofacial abnormalities or enlarged adenotonsillar tissues in the upper airway in the cohort or the presence of reported snoring during the preinclusion evaluation. Th e reasons for the high occurrence of obstructive apnea are not clear.…”

“…Th is causes a compensatory increase of the ventilation with Pa co 2 reduction, favoring the occurrence of central apnea (CA) and periodic breathing (PB) during sleep. [6][7][8] Th e majority of the studies examining either the polysomnography (PSG) or the respiratory and oxygen saturation (Sp o 2 ) normative patterns during sleep in children have been conducted at sea level or at a low altitude level, and of those studies, only a few have specifi cally examined younger infants. [9][10][11][12][13][14][15][16][17][18] Furthermore, only a very small portion of these studies have used comprehensive PSG assessments, with most of them limiting their measurements and conclusions to oxyhemoglobin saturation trends.…”

What Else Could Create a Change on our Planet other than the Gravity?

“…"So as the altitude is getting higher and higher it increases the hemoglobin in the human blood [1]." That because the human body consumes and requires more oxygen.…”