Ventilatory parameters at rest after months of stay at 3300 m: A comparison between acclimatized lowlanders and natives at Leh

Near-Infrared Spectroscopy Monitoring of Cerebral Oxygenation and Influencing Factors in Neonates from High-Altitude Areas

BACKGROUND

Accurate detection of cerebral oxygen saturation (rSO2) may be useful for neonatal brain injury prevention, and the normal range of rSO2 of neonates at high altitude remained unclear.

OBJECTIVE

To compare cerebral rSO2 and cerebral fractional tissue oxygen extraction (cFTOE) at high-altitude and low-altitude areas in healthy neonates and neonates with underlying diseases.

METHODS

515 neonates from low-altitude areas and 151 from Tibet were enrolled. These neonates were assigned into the normal group, hypoxic-ischemic encephalopathy (HIE) group, and other diseases group. Near-infrared spectroscopy was used to measure rSO2 in neonates within 24 h after admission. The differences of rSO2, pulse oxygen saturation (SpO2), and cFTOE levels were compared between neonates from low- and high-altitude areas.

RESULTS

(1) The mean rSO2 and cFTOE levels in normal neonates from Tibet were 55.0 ± 6.4% and 32.6 ± 8.5%, significantly lower than those from low-altitude areas (p < 0.05). (2) At high altitude, neonates with HIE, pneumonia (p < 0.05), anemia, and congenital heart disease (p < 0.05) have higher cFTOE than healthy neonates. (3) Compared with HIE neonates from plain areas, neonates with HIE at higher altitude had lower cFTOE (p < 0.05), while neonates with heart disease in plateau areas had higher cFTOE than those in plain areas (p < 0.05).

CONCLUSIONS

The rSO2 and cFTOE levels in normal neonates from high-altitude areas are lower than neonates from the low-altitude areas. Lower cFTOE is possibly because of an increase in blood flow to the brain, and this may be adversely affected by disease states which may increase the risk of brain injury.

Hematologic and spirometric characteristics of Tajik and Kyrgyz highlanders in the Pamir Mountains

OBJECTIVES

In this study, we measured the hematologic and spirometric parameters of native Tajik and Kyrgyz highlanders in the Pamir Mountains to investigate adaptations to high altitude stressors.

METHODS

Hematological parameters including arterial oxygen saturation (SaO₂ ), red blood cell (RBC) counts, and hemoglobin (Hb) concentration were measured on Sarikoli Tajik (n = 80; 3100 m), Wakhi Tajik (n = 48; 3500 m), and Kyrgyz (n = 64; 3250 m) in comparison to lowland Uyghurs (n = 50; 1300 m). Spirometric parameters including forced vital capacity (FVC), the first second of forced expiration (FEV1), and forced expiratory flow between 25% and 75% (FEF25-75) were measured. We also reported mountain sickness symptoms in these highlanders and conducted a multivariate regression analysis to analyze the association between these symptoms and the measured parameters.

RESULTS

SaO₂ of Sarikoli Tajik, Wakhi Tajik, and Kyrgyz (91%-93.5%) are significantly lower than lowland Uyghurs, yet are comparable to other native highlanders at a similar altitude. RBC counts and Hb concentrations of all three highland populations are significantly increased compared to Uyghurs. FVC is lower in Sarikoli Tajik, Wakhi Tajik, and Kyrgyz (male: 3.48-3.86 L, female: 2.47-2.78 L) compared to Uyghurs. Combined with normal FEV1, elevated FEV1/FVC ratio, and FEF25-75, the spirometric patterns of these highlanders indicate restrictive lung disease. A high prevalence of mountain sickness symptoms such as headache and nausea was found in all three highland populations, and are attributed to low FVC and aging by regression analysis.

CONCLUSION

Tajik and Kyrgyz highlanders showed adaptation in SaO₂ , RBC, and Hb level, but poor performance in spirometry, which causes mountain sickness.