Efectividad de un entrenamiento cardiorrespiratorio, muscular y ventilatorio en el rendimiento aeróbico de pacientes hemodializados / Effectiveness of a cardiorespiratory, muscular and ventilatory training program in the aerobic performance of hemodialysis patients

Resumen Introducción: la enfermedad renal crónica terminal provoca fatiga y debilidad muscular progresiva, que afecta no solo la muscula tura de extremidades, sino también la respiratoria. Existen diversos estudios de entrenamiento combinado en pacientes dializados, pero sin incluir trabajo respiratorio. Por esto, el presente estudio pretende determinar la efectividad de un entrenamiento combinado aeróbico, de resistencia de miembro inferior y de resistencia muscular inspiratoria, en el rendimiento aeróbico de pacientes hemodializados. Materiales y métodos: ensayo clínico aleatorizado que incluyó ll pacientes hemodializados del Hospital Base Valdivia. Fueron divididos en dos grupos, uno sometido a un programa de entrenamiento con ejercicio aeróbico, de resistencia muscular de miembros inferiores y de musculatura inspiratoria (ARM+V) (n=6), y el otro, a un programa de entrenamiento con ejercicio aeróbico y de resistencia muscular de miembros inferiores (ARM) (n=5). La intervención fue realizada durante 8 semanas evaluando el rendimiento pre y post intervención de capacidad aeróbica (TM6M), fuerza inspiratoria máxima (Carefore Airlift NIF-gauge®) y función pulmonar (Sibelmed Datospir Micro Spirometer 120D®) en ambos grupos. Resultados: el grupo ARM+V obtuvo mejoras significativas (p<0,05) en el rendimiento del TM6M (p=0,027) y PIM (p=0,001); así mismo el grupo ARM mejoró en el TM6M (p=0,022) y PIM (p=0,002) y en la espirometría se mostró una disminución significativa en VEF1 (p=0,004), CVF (p=0,005) y VEF1/CVF (p=0,038). Conclusión: ambos entrenamientos fueron efectivos en la mejora del rendimiento aeróbico, pero el grupo jARM+V obtuvo mejoras significativamente superiores en este ítem. Ninguno de los dos entrenamientos obtuvo mejoras en los valores espirométricos.

Abstract Introduction: End stage kidney disease causes fatigue and progressive muscle weakness, which affects not only the muscles of extremities, but also the respiratory. There are several studies of combined training in dialysis patients, but not including respiratory work. Therefore, the present study aims to determine the effectiveness of an aerobic, lower limb resistance and inspiratory muscle resistance combined training in the generation of changes in aerobic performance of patients undergoing hemodialysis. Material and methods: Randomized controlled trial which included 11 hemodialysis patients from Valdivia's Central Hospital. The sample was divided in two groups, the first one included: an aerobic, lower limbs and inspiratory muscle training (ARM+V) (n=6) and the second one included an aerobic and lower limbs muscle training (ARM) (n=5). The training was performed during 8 weeks and three variables were measured in both groups pre and post intervention, inspiratory muscle strength (Carefore Airlift NIF-gauge®), aerobic endurance (6MWT) and pulmonary function (Sibelmed Datospir Micro Spirometer 120D®). Results: ARM+V group obtained significant improvements (p<0.05) in 6MWT performance (p=0.027) and MIP (p=0,001). Likewise performance improved in 6MWT (p=0.022) and MIP (p=0.002) at ARM group, but decreased in spirometry values: FEV1 (p=0.004), FVC (p=0.005) and FEV1/FVC (p=0,038). Conclusion: Both training protocols were effective in the aerobic endurance improvement, however the patients in the ARM+V group presented better changes than the ARM group. Neither of the two training programs improved pulmonary function.

Determinants of ventilation and pulmonary artery pressure during early acclimatization to hypoxia in humans.

Pulmonary ventilation and pulmonary arterial pressure both rise progressively during the first few hours of human acclimatization to hypoxia. These responses are highly variable between individuals, but the origin of this variability is unknown. Here, we sought to determine whether the variabilities between different measures of response to sustained hypoxia were related, which would suggest a common source of variability. Eighty volunteers individually underwent an 8-h isocapnic exposure to hypoxia (end-tidal P(O2)=55 Torr) in a purpose-built chamber. Measurements of ventilation and pulmonary artery systolic pressure (PASP) assessed by Doppler echocardiography were made during the exposure. Before and after the exposure, measurements were made of the ventilatory sensitivities to acute isocapnic hypoxia (G(pO2)) and hyperoxic hypercapnia, the latter divided into peripheral (G(pCO2)) and central (G(cCO2)) components. Substantial acclimatization was observed in both ventilation and PASP, the latter being 40% greater in women than men. No correlation was found between the magnitudes of pulmonary ventilatory and pulmonary vascular responses. For G(pO2), G(pCO2) and G(cC O2), but not the sensitivity of PASP to acute hypoxia, the magnitude of the increase during acclimatization was proportional to the pre-acclimatization value. Additionally, the change in G(pO2) during acclimatization to hypoxia correlated well with most other measures of ventilatory acclimatization. Of the initial measurements prior to sustained hypoxia, only G(pCO2) predicted the subsequent rise in ventilation and change in G(pO2) during acclimatization. We conclude that the magnitudes of the ventilatory and pulmonary vascular responses to sustained hypoxia are predominantly determined by different factors and that the initial G(pCO2) is a modest predictor of ventilatory acclimatization.

Facilitation by intracellular carbonic anhydrase of Na+ -HCO3- co-transport but not Na+ / H+ exchange activity in the mammalian ventricular myocyte.

Carbonic anhydrase enzymes (CAs) catalyse the reversible hydration of CO2 to H+ and HCO3- ions. This catalysis is proposed to be harnessed by acid/base transporters, to facilitate their transmembrane flux activity, either through direct protein-protein binding (a 'transport metabolon') or local functional interaction. Flux facilitation has previously been investigated by heterologous co-expression of relevant proteins in host cell lines/oocytes. Here, we examine the influence of intrinsic CA activity on membrane HCO3- or H+ transport via the native acid-extruding proteins, Na+ -HCO3- cotransport (NBC) and Na+ / H+ exchange (NHE), expressed in enzymically isolated mammalian ventricular myocytes. Effects of intracellular and extracellular (exofacial) CA (CAi and CAe) are distinguished using membrane-permeant and -impermeant pharmacological CA inhibitors, while measuring transporter activity in the intact cell using pH and Na+ fluorophores. We find that NBC, but not NHE flux is enhanced by catalytic CA activity, with facilitation being confined to CAi activity alone. Results are quantitatively consistent with a model where CAi catalyses local H+ ion delivery to the NBC protein, assisting the subsequent (uncatalysed) protonation and removal of imported HCO3- ions. In well-superfused myocytes, exofacial CA activity is superfluous, most likely because extracellular CO2/HCO3- buffer is clamped at equilibrium. The CAi insensitivity of NHE flux suggests that, in the native cell, intrinsic mobile buffer-shuttles supply sufficient intracellular H+ ions to this transporter, while intrinsic buffer access to NBC proteins is restricted. Our results demonstrate a selective CA facilitation of acid/base transporters in the ventricular myocyte, implying a specific role for the intracellular enzyme in HCO3- transport, and hence pHi regulation in the heart.

Spanish translation and validation of four short pelvic floor disorders questionnaires.

INTRODUCTION AND HYPOTHESIS: Globally, Spanish is the primary language for 329 million people; however, most urogynecologic questionnaires are available in English. We set out to develop valid Spanish translations of the Questionnaire for Urinary Incontinence Diagnosis (QUID), the Three Incontinence Questions (3IQ), and the short Pelvic Floor Distress Inventory (PFDI-20) and Pelvic Floor Impact Questionnaire (PFIQ-7). METHODS: The TRAPD method (translation, review, adjudication, pretesting, and documentation) was used for translation. Eight native Spanish-speaking translators developed Spanish versions collaboratively. These were pretested with cognitive interviews and revised until optimal. For validation, bilingual patients at seven clinics completed Spanish and English questionnaire versions in randomized order. Participants completed a second set of questionnaires later. The Spanish versions' internal consistency and reliability and Spanish-English agreement were measured using Cronbach's alpha, weighted kappa, and intraclass correlation coefficients. RESULTS: A total of 78 subjects were included; 94.9 % self-identified as Hispanic and 73.1 % spoke Spanish as their primary language. The proportion of per-item missing responses was similar in both languages (median 1.3 %). Internal consistency for Spanish PFDI-20 subscales was acceptable to good and for PFIQ-7 and QUID excellent. Test-retest reliability per item was moderate to near perfect for PFDI-20, substantial to near perfect for PFIQ-7 and 3IQ, and substantial for QUID. Spanish-English agreement for individual items was substantial to near perfect for all questionnaires (kappa range 0.64-0.95) and agreement for PFDI-20, PFIQ-7, and QUID subscales scores was high [intraclass correlation coefficient (ICC) range 0.92-0.99]. CONCLUSIONS: We obtained valid Spanish translations of the PFDI-20, PFIQ-7, QUID, and 3IQ. These results support their use as clinical and research assessment tools in Spanish-speaking populations.

Optimal hemoglobin concentration and high altitude: a theoretical approach for Andean men at rest.

The beneficial role of erythrocytosis for O2 transport has been questioned by evidence from bloodletting and hemodilution research as well as by studies suggesting the existence of an "optimal" hematocrit (Hct) or hemoglobin concentration ([Hb]) value. To assess to what extent erythrocytosis is beneficial in Andean men at high altitude, we examined and discussed optimal [Hb] using a mathematical approach by modeling the mixed (mean) venous Po2 (Pv(O2)) and arterial O2 content, considering for both the relation between [Hb] and arterial Po2. Relations of [Hb] to other physiological variables such as cardiac output and convective arterial O2 transport were also discussed, revealing the importance of Pv(O2) in this model. Our theoretical analysis suggests that increasing [Hb] allows increase and maintenance of Pv(O2) with only moderate declines in arterial Po2 as a consequence of moderate increases in altitude, reaching its maximum at the optimal [Hb] of 14.7 g/dl. Our analysis also shows that [Hb] corresponding to high arterial O2 content and O2 transport values is apparently not quite advantageous for improvement of oxygenation. Furthermore, chronic mountain sickness is discussed as an insightful example of the effects of excessive erythrocytosis at high altitude.