Bicarbonate Values for Healthy Residents Living in Cities Above 1500 Meters of Altitude: A Theoretical Model and Systematic Review

Abstract

Abstract

Ramirez-Sandoval, Juan C., Maria F. Castilla-Peón, José Gotés-Palazuelos, Juan C. Vázquez-García, Michael P. Wagner, Carlos A. Merelo-Arias, Olynka Vega-Vega, Rodolfo Rincón-Pedrero, and Ricardo Correa-Rotter. Bicarbonate values for healthy residents living in cities above 1500 m of altitude: a theoretical model and systematic review. High Alt Med Biol. 17:85–92, 2016.—Plasma bicarbonate (HCO₃⁻) concentration is the main value used to assess the metabolic component of the acid–base status. There is limited information regarding plasma HCO₃⁻ values adjusted for altitude for people living in cities at high altitude defined as 1500 m (4921 ft) or more above sea level. Our aim was to estimate the plasma HCO₃⁻ concentration in residents of cities at these altitudes using a theoretical model and compare these values with HCO₃⁻ values found on a systematic review, and with those venous CO₂ values obtained in a sample of 633 healthy individuals living at an altitude of 2240 m (7350 ft). We calculated the PCO₂ using linear regression models and calculated plasma HCO₃⁻ according to the Henderson–Hasselbalch equation. Results show that HCO₃⁻ concentration falls as the altitude of the cities increase. For each 1000 m of altitude above sea level, HCO₃⁻ decreases to 0.55 and 1.5 mEq/L in subjects living at sea level with acute exposure to altitude and in subjects acclimatized to altitude, respectively. Estimated HCO₃⁻ values from the theoretical model were not different to HCO₃⁻ values found in publications of a systematic review or with venous total CO₂ measurements in our sample. Altitude has to be taken into consideration in the calculation of HCO₃⁻ concentrations in cities above 1500 m to avoid an overdiagnosis of acid–base disorders in a given individual.