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          RESUMEN Introducción. La adaptación a grandes altitudes implica cambios evolutivos que conllevan respuestas adaptativas, como a la hipoxia. Los andinos desarrollaron fenotipos eritroides diferentes en relación con otras poblaciones a gran altitud que pueden variar dependiendo la altitud. Objetivo. Determinar las variaciones fenotípicas de hemoglobina (Hb), saturación de oxígeno (SpO2), P50 y lactato en andinos bolivianos con radicatorias entre 400, 4000 y 5000 msnm. Material y métodos. Estudio descriptivo transversal de tipo prospectivo. Se recolectó sangre venosa periférica de andinos bolivianos (n=124) nacidos a 4000 m, pero con radicatoria en altitudes diferentes (400 m, 4000 m, 5000 m), así como de aquellos con eritrocitosis patológicas. Adicionalmente, se recolectó muestras de europeos residentes a 4000 m (n=11). Se realizó estudios de hemograma, oximetría y gasometría. La P50 fue calculada con fórmula de Lichtman. Resultados. Los andinos sanos, comparados entre distintas altitudes, reflejaron aumento de Hb al ser mayor la altitud (p: 0,001), empero disminución de SpO2 (p: 0,001) y P50 (p: 0,001); sin variaciones en lactato. Los europeos a 4000 m, en relación con andinos a la misma altitud, presentaron Hb incrementada (p: 0,01), SpO2 y P50 sin variaciones, pero lactato significativamente aumentado (p: 0,001). Los pacientes con eritrocitosis comparados con sujetos sanos, a 4000 m y 5000 m respectivamente, presentaron Hb aumentada (p: 0,001); SpO2 disminuida (p: 0,001); P50 sin variaciones, pero lactato incrementado (p: 0,01). El lactato elevado en sujetos a 5000 m con eritrocitosis fue llamativo (1,7 mmol/L). Conclusiones. Las variaciones fenotípicas observadas entre andinos en diferentes altitudes constituyen una expresión de una adaptación parcial a la altura.

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          ABSTRACT Introduction. Human adaptation to high altitude involves evolutionary changes leading adaptive responses, such as to hypoxia. Andeans developed different erythroid phenotypes in relation to other populations at high altitude, which can vary depending on the altitude. Objective. To determine the phenotypic variations of hemoglobin (Hb), oxygen saturation (SpO2), P50 and lactate in Bolivian Andeans residing between 400, 4000 or 5000 masl. Material and methods. Prospective cross-sectional descriptive study. Peripheral venous blood from Bolivian Andeans (n=124) born at 4000 m, but residing at different altitudes (400 m, 4000 m, 5000 m), likewise from those with pathological erythrocytosis were collected. Additionally, samples from Europeans residing at 4000 m (n=11) were collected. CBC, oximetry and blood gas studies were performed. P50 was calculated using the Lichtman formula. Results. Healthy Andeans, compared between different altitudes, reflected an increased Hb (p: 0.001), but a decreased SpO2 (p: 0.001) and P50 (p: 0.001) as the altitude was higher; without variations in lactate. Europeans at 4000 m, related to Andeans at the same altitude, presented increased Hb (p: 0.01), SpO2 and P50 without variations, but significantly increased lactate (p: 0.001). Patients with erythrocytosis compared to healthy subjects, at 4000 m and 5000 m respectively, depicted increased Hb (p: 0.001); decreased SpO2 (p: 0.001); P50 without changes, but increased lactate (p: 0.01). Increased lactate in subjects with erythrocytosis at 5000 m was remarkable (1.7 mmol/L). Conclusion. The phenotypic variations observed among Andeans residing at different altitudes constitute an expression of partial adaptation to altitude.

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          Most cited references24

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          Hemoglobin-oxygen affinity in high-altitude vertebrates: is there evidence for an adaptive trend?

          Jay Storz (2016)
          In air-breathing vertebrates at high altitude, fine-tuned adjustments in hemoglobin (Hb)-O2affinity provide an energetically efficient means of mitigating the effects of arterial hypoxemia. However, it is not always clear whether an increased or decreased Hb-O2affinity should be expected to improve tissue O2delivery under different degrees of hypoxia, due to the inherent trade-off between arterial O2loading and peripheral O2unloading. Theoretical results indicate that the optimal Hb-O2affinity varies as a non-linear function of environmental O2availability, and the threshold elevation at which an increased Hb-O2affinity becomes advantageous depends on the magnitude of diffusion limitation (the extent to which O2equilibration at the blood-gas interface is limited by the kinetics of O2exchange). This body of theory provides a framework for interpreting the possible adaptive significance of evolved changes in Hb-O2affinity in vertebrates that have colonized high-altitude environments. To evaluate the evidence for an empirical generalization and to test theoretical predictions, I synthesized comparative data in a phylogenetic framework to assess the strength of the relationship between Hb-O2affinity and native elevation in mammals and birds. Evidence for a general trend in mammals is equivocal, but there is a remarkably strong positive relationship between Hb-O2affinity and native elevation in birds. Evolved changes in Hb function in high-altitude birds provide one of the most compelling examples of convergent biochemical adaptation in vertebrates.
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            Oxygen transport by hemoglobin.

            Hemoglobin (Hb) constitutes a vital link between ambient O2 availability and aerobic metabolism by transporting oxygen (O2) from the respiratory surfaces of the lungs or gills to the O2-consuming tissues. The amount of O2 available to tissues depends on the blood-perfusion rate, as well as the arterio-venous difference in blood O2 contents, which is determined by the respective loading and unloading O2 tensions and Hb-O2-affinity. Short-term adjustments in tissue oxygen delivery in response to decreased O2 supply or increased O2 demand (under exercise, hypoxia at high altitude, cardiovascular disease, and ischemia) are mediated by metabolically induced changes in the red cell levels of allosteric effectors such as protons (H(+)), carbon dioxide (CO2), organic phosphates, and chloride (Cl(-)) that modulate Hb-O2 affinity. The long-term, genetically coded adaptations in oxygen transport encountered in animals that permanently are subjected to low environmental O2 tensions commonly result from changes in the molecular structure of Hb, notably amino acid exchanges that alter Hb's intrinsic O2 affinity or its sensitivity to allosteric effectors. Structure-function studies of animal Hbs and human Hb mutants illustrate the different strategies for adjusting Hb-O2 affinity and optimizing tissue oxygen supply. © 2012 American Physiological Society. Compr Physiol 2:1491-1539, 2012.
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              The utility of venous lactate to triage injured patients in the trauma center.

              Field triage criteria for trauma patients results in over-triage rates of 30% to 50% to achieve under-triage rates of 10%. This large number of patients may stress trauma center resources. Elevated arterial lactate (ALAC) levels have been shown to be a marker of serious injury but the need for arterial sampling limits the utility of the determination. The goal of this study was: 1) to determine the correlation between venous lactate (VLAC) and ALAC; 2) to determine whether VLAC could identify those patients with serious injuries; and 3) to compare an elevated VLAC level against standard triage criteria (STC) in their ability to identify major injury. Arterial and venous samples for blood gas and lactate analyses were obtained in 375 patients within 10 minutes of patient arrival to the trauma center. Arterial and venous samples were drawn within 2 minutes of each other, placed on ice, and analyzed within 10 minutes of sampling. The location of sampling was left to physician discretion. Data collected included injury mechanism, demographics, admission vital signs, emergency department disposition, length of stay, and injury severity scores (ISS). Admission to the ICU, need for emergency operation, length of stay, and death were noted. Emergency medical service staff were queried to determine which standard triage criteria (STC) were fulfilled. The mean ALAC was 3.11 mmol/L (SD 3.45, 95% confidence interval [CI] 2.67 to 3.55) and mean VLAC was 3.43 mmol/L (SD 3.41, 95% CI 2.96 to 3.90). There was no significant difference between ALAC and VLAC. The correlation between ALAC and VLAC was 0.94 (95% CI 0.94 to 0.96, p = 0.0001). An elevated VLAC predicted moderate to severe injury and there was a significant association between an increased lactate and maximum Abbreviated Injury Score (AIS) of 4 and 5 (ANOVA, F = 8.26, p or =2 mmol/L had significantly increased relative risks of ISS > or = 13, death, admission to the ICU, and length of stay > 2 days. In comparison with STC, a VLAC > or = 2 mmol/L decreased undertriage in patients with ISS > or = 13 by one half (11% versus 24%) for patients with ISS > or = 13 and decreased over-triage by 28% (46% versus 64%). These data were most pronounced for patients injured in motor vehicle collisions. VLAC is an excellent approximation for ALAC. A VLAC > or = 2 mmol/L appears to predict an ISS > or = 13, the need for ICU resources, and prolonged hospital stays. VLAC was significantly better than STC in all patients and was most useful in victims of blunt trauma, especially motor vehicle collisions.

                Author and article information

                Revista Médica La Paz
                Rev. Méd. La Paz
                Colegio Médico de La Paz (La Paz, , Bolivia )
                : 29
                : 1
                : 20-26
                [1] La Paz La Paz orgnameUniversidad Mayor de San Andrés orgdiv1Facultad de Medicina orgdiv2Unidad de Biología Celular Bolivia
                [2] Potosí orgnameCentro de Salud Chorolque Bolivia
                S1726-89582023000100020 S1726-8958(23)02900100020

                This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

                : 05 September 2022
                : 18 November 2022
                Page count
                Figures: 0, Tables: 0, Equations: 0, References: 24, Pages: 7

                SciELO Bolivia

                ARTÍCULO ORIGINAL

                fenotipo,Erythrocytosis,High altitude,adaptation,phenotype,Eritrocitosis,altura,adaptación,P50


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