Sleep-related hypoxaemia and excessive erythrocytosis in Andean high-altitude natives

Abstract

To determine whether nocturnal hypoxaemia contributes to the excessive erythrocytosis (EE) in Andean natives, standard polysomnographies were performed in 10 patients with EE and in 10 controls (mean haematocrit 76.6 ¡ 1.3% and 54.4 ¡ 0.8%, respectively) living at an altitude of 4,380 m. In addition, the effect of O 2 administration for 1 h prior to sleep, and the relationship between the hypoxic/ hypercapnic ventilatory response and the apnoea/hypopnoea index (AHI) during sleep were studied.Awake arterial oxygen saturation (Sa,O 2 ) was significantly lower in patients with EE than in controls (83.7¡0.3% versus 85.6¡0.4%). In both groups, the mean Sa,O 2 significantly decreased during sleep (to 80.0¡0.8% in EE and to 82.8¡0.5% in controls). The mean Sa,O 2 values remained significantly lower in patients with EE than in controls at all times of the night, and patients with EE spent significantly more time than the controls with an Sa,O 2 of v80%. There were no differences between the two groups in the number and duration of the apnoeas/hypopnoeas. None of these variables were affected by O 2 administration. In both groups the AHI positively correlated with the hypercapnic ventilatory response.Andean natives undergo minor respiratory disorders during sleep. The reduction in oxygen saturation found in subjects with excessive erythrocytosis was small, yet consistent and potentially important, as it remained below the threshold known for the increase in erythropoietin stimulation. This may be an important factor promoting erythropoiesis, but its relevance needs to be further explored.

Cerebrovascular Responses to Hypoxia and Hypocapnia in Ethiopian High Altitude Dwellers

“…Not only do Peruvians hyperventilate in response to high altitude hypoxia, but they are also at increased risk of periodic breathing and apnoea, particularly during sleep, 26,27 which may be attributable to their reduced cerebral reactivity to The cerebral reactivity to hypocapnia during hypoxia was greater in Ethiopians than Peruvians when tested at high altitude ( †PϽ0.05). After descent to low altitude, responses were significantly reduced in all 3 groups (*PϽ0.05; **PϽ0.01).…”

Serum testosterone levels and excessive erythrocytosis during the process of adaptation to high altitudes

“…Hypoventilation, particularly during sleep, appears to be the dominant cause of hypoxaemia in patients with CMS. 32 One characteristic of this disease is excessive erythrocytosis (EE). 28 The prevalence of EE increases with age in men 33 and women.…”

“…However, in the case of CMS, causation due to an increased number of apnoeic events has not been proven. 32 Moreover, no studies have been conducted in humans during the daytime to show an association between ventilation and testosterone levels at HA. The classic ventilatory blunting of healthy high-altitude natives 24 does not necessarily result in lower SpO 2 .…”

Caregiver perception of sleep-disordered breathing-associated symptoms in children of rural Andean communities above 4000 masl with chronic exposure to biomass fuel

“…Sleep apnea symptoms are more prevalent among people residing at high altitude [13,14], which also become apparent among individuals residing at low altitudes but traveling to the highlands [15,16]. It is therefore possible that the extremely high prevalence of sleep-disordered breathing symptoms found in the current survey merely reflects the adverse interactions jointly imposed on the respiratory system by the chronic and permanent exposure to biomass fuel combustion and high altitude.…”