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

Ramirez‐Sandoval, Juan C.; Castilla-Peón, María Fernanda; Gotés-Palazuelos, José; Vázquez-García, Juan Carlos; Wagner, Michael; Merelo-Arias, Carlos A.; Vega-Vega, Olynka; Rincón-Pedrero, Rodolfo; Correa‐Rotter, Ricardo

doi:10.1089/ham.2015.0097

Cited by 14 publications

(11 citation statements)

References 24 publications

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“…It is routinely used in emergency departments, wards, intensive care and other medical situations. At high altitudes, physiological ventilation parameters like plasma bicarbonate are different 1. Pulse oximetry measurements of oxygen saturation (SpO 2 ) are lower at altitude compared with those at sea level.…”

Section: Introductionmentioning

confidence: 99%

Reference values for oxygen saturation from sea level to the highest human habitation in the Andes in acclimatised persons

Rojas-Camayo

Mejía

Callacondo

et al. 2017

Thorax

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Oxygen saturation, measured by pulse oximetry (SpO), is a vital clinical measure. Our descriptive, cross-sectional study describes SpO measurements from 6289 healthy subjects from age 1 to 80 years at 15 locations from sea level up to the highest permanent human habitation. Oxygen saturation measurements are illustrated as percentiles. As altitude increased, SpO decreased, especially at altitudes above 2500 m. The increase in altitude had a significant impact on SpO measurements for all age groups. Our data provide a reference range for expected SpO measurements in people from 1 to 80 years from sea level to the highest city in the world.

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Section: Introductionmentioning

confidence: 99%

Reference values for oxygen saturation from sea level to the highest human habitation in the Andes in acclimatised persons

Rojas-Camayo

Mejía

Callacondo

et al. 2017

Thorax

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“…Additionally, with regard to Study B, participants had to be familiar with sprinting activities and have no musculoskeletal injuries that could interfere with running activities. Additional criteria for inclusion were as follows: (1) no preceding visits to altitude above 2,000 m within 4 weeks before the investigation, (2) a moderately active lifestyle (assessed by questionnaire), (3) no history of mental or physical impairment, (4) no history of smoking, and (5) no acute infections. The study protocols were conducted in accordance with the Declaration of Helsinki.…”

Section: Methodsmentioning

confidence: 99%

Alterations in acid–base balance and high-intensity exercise performance after short-term and long-term exposure to acute normobaric hypoxic conditions

Limmer

Marées

Platen

2020

Sci Rep

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This investigation assessed the course of renal compensation of hypoxia-induced respiratory alkalosis by elimination of bicarbonate ions and impairments in anaerobic exercise after different durations of hypoxic exposure. Study A: 16 participants underwent a resting 12-h exposure to normobaric hypoxia (3,000 m). Blood gas analysis was assessed hourly. While blood pH was significantly increased, po 2 , PCO 2 , and SaO 2 were decreased within the first hour of hypoxia, and changes remained consistent. A substantial reduction in [HCO 3 − ] levels was observed after 12 h of hypoxic exposure (− 1.35 ± 0.29 mmol/L, p ≤ 0.05). Study B: 24 participants performed in a randomized, cross-over trial portable tethered sprint running (PTSR) tests under normoxia and after either 1 h (n = 12) or 12 h (n = 12) of normobaric hypoxia (3,000 m). No differences occurred for PTSR-related performance parameters, but the reduction in blood lactate levels was greater after 12 h compared with 1 h (− 1.9 ± 2.2 vs 0.0 ± 2.3 mmol/L, p ≤ 0.05). These results indicate uncompensated respiratory alkalosis after 12 h of hypoxia and similar impairment of high-intensity exercise after 1 and 12 h of hypoxic exposure, despite a greater reduction in blood lactate responses after 12 h compared with 1 h of hypoxic exposure. Hypoxia has a profound influence on acid-base balance whenever unacclimatized people ascend to high altitudes. Barometric pressure decreases with increasing altitude and, therefore, oxygen pressure in the ambient and inspired air (P I O 2) falls 1. A reduced P I O 2 leads to a decrease in arterial oxygen partial pressure (PO 2) and to hypoxemia, which stimulates the peripheral chemoreceptors to evoke carbon dioxide (CO 2) washout 2-4. Concurrently, hyperventilation occurs as an hypoxic ventilatory response during acclimatization to high altitude, CO 2 partial pressure (PCO 2) falls, and arterial pH increases according to the Henderson-Hasselbalch equation 2, 5, 6. This respiratory alkalosis is subsequently compensated by increased renal elimination of bicarbonate ions (HCO 3 −), which results in a decrease in blood bicarbonate concentration [HCO 3 − ] and arterial pH returns to normal 2, 3, 5. Metabolic compensation of respiratory alkalosis occurs after 6 h of altitude exposure and is completed after 24 h at low to moderate altitude 2, 7. This compensation is further suggested to remain incomplete after 24 h of exposure to high altitude, but is then completed after several days 1, 2, 4, 7. In contrast, lowlanders show persistent alkalosis even after 9 weeks at 5,260 m 8. Nonetheless, to the best of our knowledge, information on values of pH and [HCO 3 − ] during the first 24 h of altitude exposure is still insufficient. [HCO 3 − ] is an essential blood buffer for metabolic acids. During maximal workloads with blood lactate levels up to 15 mmol/L, there is a corresponding decrease in plasma [HCO 3 − ] levels 9. Therefore, the resulting decline in [HCO 3 − ] and blood buffer capacity in the course of adaption to altitude might signific...

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“…The expected range of normal described above is applicable to sea level. For altitudes above 1500 m (4921 ft), the limits of normal have to incorporate the low serum [TCO 2 ] values reflective of chronic hypocapnia and hypobicarbonatemia consequent to the prevailing hypoxemia (10,11).…”

Section: Normal Range Of Serum [Tco 2 ]mentioning

confidence: 99%

Re-Evaluation of the Normal Range of Serum Total CO2 Concentration

Kraut

Madias

2018

CJASN

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A reliable determination of blood pH, PCO, and [HCO] is necessary for assessing the acid-base status of a patient. However, most acid-base disorders are first recognized through abnormalities in serum total CO concentration ([TCO]) in venous blood, a surrogate for [HCO]. In screening patients on the basis of serum [TCO], we have been concerned about the wide limits of normal for serum [TCO], 10-13 mEq/L, reported by many clinical laboratories. Indeed, we have encountered patients with serum [TCO] values within the lower or upper end of the normal range of the reporting laboratory, who subsequently were shown to have a cardinal acid-base disorder.Here, we present a patient who had a serum [TCO] within the lower end of the normal range of the clinical laboratory, which resulted in delayed diagnosis of a clinically important "hidden" acid-base disorder. To better define the appropriate limits of normal for serum [TCO], we derived the expected normal range in peripheral venous blood in adults at sea level from carefully conducted acid-base studies. We then compared this range, 23 to 30 mEq/L, to that reported by 64 clinical laboratories, 2 large commercial clinical laboratories, and the major textbook of clinical chemistry. For the most part, the range in the laboratories we queried was substantially different than that we derived and that published in the textbook, with some laboratories reporting values as low as 18-20 mEq/L and as high as 33-35 mEq/L. We conclude that the limits of values of serum [TCO] reported by clinical laboratories are very often inordinately wide and not consistent with the range of normal expected in healthy individuals at sea level. We suggest that the limits of normal of serum [TCO] at sea level be tightened to 23-30 mEq/L. Such correction will ensure recognition of the majority of "hidden" acid-base disorders.

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

Cited by 14 publications

References 24 publications

Reference values for oxygen saturation from sea level to the highest human habitation in the Andes in acclimatised persons

Reference values for oxygen saturation from sea level to the highest human habitation in the Andes in acclimatised persons

Alterations in acid–base balance and high-intensity exercise performance after short-term and long-term exposure to acute normobaric hypoxic conditions

Re-Evaluation of the Normal Range of Serum Total CO2 Concentration

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