Polysomnography in bolivian children native to high altitude compared to children native to low altitude

Study Objectives: To compare polysomnographic parameters in high altitude (HA) native Andean children with low altitude (LA) native peers in order to explain the nocturnal oxyhemoglobin saturation (SpO₂) instability reported in HA native children and to study the effect on sleep quality. Methods: Ninety-eight healthy children aged 7-10 y and 13-16 y were recruited at LA (500 m) or HA (3,650 m) above sea level. Physical examination was undertaken and genetic ancestry determined from salivary DNA to determine proportion of European ancestry, a risk factor for poor HA adaptation. Attended polysomnography was carried out over 1 night for 58 children at their resident location. Results: Of 98 children recruited, 85 met inclusion criteria, 58 of 85 (68.2%) completed polysomnography, of which 56 were adequate for analysis: 30 at LA (17 male) and 26 at HA (16 male). There were no altitude differences in genetic ancestry, but a high proportion of European admixture (median 50.6% LA; 44.0% HA). SpO₂ was less stable at HA with mean 3% and 4% oxygen desaturation indices greater (both P <0.001) than at LA. This was not explained by periodic breathing. However, more obstructive hypopnea was observed at HA (P <0.001), along with a trend toward more central apnea (P = 0.053); neither was explained by clinical findings. There was no difference in sleep quality between altitudes. Conclusions: HA native Andean children have more respiratory events when scoring relies on SpO₂ desaturation due to inherent SpO₂ instability. Use of American Academy of Sleep Medicine scoring criteria may yield false-positive results for obstructive sleep-disordered breathing at HA.