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. 2016 Jun;17(2):93-100.
doi: 10.1089/ham.2015.0084.

Increased Cardiometabolic Risk and Worsening Hypoxemia at High Altitude

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Free PMC article

Increased Cardiometabolic Risk and Worsening Hypoxemia at High Altitude

Catherine H Miele et al. High Alt Med Biol. .
Free PMC article

Abstract

Miele, Catherine H., Alan R. Schwartz, Robert H. Gilman, Luu Pham, Robert A. Wise, Victor G. Davila-Roman, Jonathan C. Jun, Vsevolod Y. Polotsky, J. Jaime Miranda, Fabiola Leon-Velarde, and William Checkley. Increased cardiometabolic risk and worsening hypoxemia at high altitude. High Alt Med Biol. 17:93-100, 2016.-Metabolic syndrome, insulin resistance, diabetes, and dyslipidemia are associated with an increased risk of cardiovascular disease. While excessive erythrocytosis is associated with cardiovascular complications, it is unclear how worsening hypoxemia of any degree affects cardiometabolic risk factors in high-altitude populations. We studied the relationship between daytime resting oxyhemoglobin saturation and cardiometabolic risk factors in adult participants living in Puno, Peru (3825 m above sea level). We used multivariable logistic regression models to study the relationship between having a lower oxyhemoglobin saturation and markers of cardiometabolic risk. Nine hundred and fifty-four participants (mean age 55 years, 52% male) had information available on pulse oximetry and markers of cardiometabolic risk. Average oxyhemoglobin saturation was 90% (interquartile range 88%-92%) and 43 (4.5%) had excessive erythrocytosis. Older age, decreased height-adjusted lung function, and higher body mass index (BMI) were associated with having an oxyhemoglobin saturation ≤85%. When adjusting for age, sex, socioeconomic status, having excessive erythrocytosis, and site, we found that each 5% decrease in oxyhemoglobin saturation was associated with a higher adjusted odds of metabolic syndrome (OR = 1.35, 95% CI: 1.07-1.72, p < 0.04), insulin resistance as defined by homeostasis model assessment-insulin resistance (HOMA-IR) >2 mass units (OR = 1.29, 95% CI: 1.00-1.67, p < 0.05), hemoglobin A1c ≥6.5% (OR = 1.66, 95% CI: 1.09-2.51, p < 0.04), and high sensitivity C-reactive protein (hs-CRP) ≥3 mg/L (OR = 1.46, 95% CI: 1.09-1.96, p < 0.01). In high-altitude populations in Puno, Peru, a higher BMI and lower pulmonary function were associated with lower resting daytime oxyhemoglobin saturation. Lower resting oxyhemoglobin saturation, in turn, was associated with higher odds of having multiple unfavorable cardiometabolic factors. Worsening hypoxia of any degree in high-altitude dwellers may be an independent risk factor for cardiovascular disease.

Keywords: altitude; diabetes; hypoxemia; insulin resistance; metabolic syndrome.

Figures

<b>FIG. 1.</b>
FIG. 1.
Relationship between oxyhemoglobin saturation and either age or BMI. We plotted the mean oxyhemoglobin saturation by deciles of age and BMI, respectively, and stratified by sex. Numbers in the x-axis represent the starting value of each decile. The graphs show a dose-response relationship with age or BMI corresponding to an incrementally lower oxyhemoglobin saturation, in both men and women. BMI, body mass index.
<b>FIG. 2.</b>
FIG. 2.
Odds ratio of metabolic syndrome based on 5% decrease in oxyhemoglobin saturation. We plotted the odds ratios and 95% confidence intervals for every 5% increase in oxyhemoglobin saturation. Relationship between oxyhemoglobin saturation and age and BMI in men and women. We plotted the mean oxyhemoglobin saturation for each 1 year or 1 kg/m2 increased in age and BMI, respectively. This was done for men and woman independently. The graphs show a dose–response with increased age and BMI corresponding to incremental decreased oxyhemoglobin saturation. BMI, body mass index.

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