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Introduction: Limited information is available on blood pressure (BP) behavior in workers exposed to chronic intermittent hypoxia (CIH), and even less is known regarding effects of CIH on 24-h ambulatory BP in those affected by arterial hypertension at sea level (SL). The aims of this study were to assess clinic and 24-h ambulatory BP at SL and at high altitude (HA; 3,870 m above SL) in workers exposed to CIH, and to compare BP response to HA exposure between normotensive and hypertensive workers.Methods: Nineteen normotensive and 18 pharmacologically treated hypertensive miners acclimatized to CIH were included, whose work was organized according to a “7 days-on−7 days-off” shift pattern between SL and HA. All measurements were performed on the second and seventh day of their HA shift and after the second day of SL sojourn.Results: Compared to SL, 24-h systolic BP (SBP) and diastolic BP (DBP) increased at HA [+14.7 ± 12.6 mmHg (p < 0.001) and +8.7 ± 7.2 mmHg (p < 0.001), respectively], and SBP nocturnal fall decreased consistently (−4.1 ± 9.8%; p < 0.05) in all participants, with hypertensives showing higher nocturnal DBP than normotensives (p < 0.05) despite the current therapy. Also, heart rate (HR) nocturnal fall tended to be reduced at HA. In addition, the 24-h SBP/DBP hypertension threshold of ≥130/80 mmHg was exceeded by 39% of workers at SL and by 89% at HA. Clinic HR, SBP, and DBP were significantly higher on the second day of work at HA compared with SL, the increase being more pronounced for SBP in hypertensives (p < 0.05) and accompanied by, on average, mild altitude sickness in both groups. These symptoms and the values of all cardiovascular variables decreased on the seventh day at HA (p < 0.05) regardless of CIH exposure duration.Conclusion: Long history of work at HA according to scheduled CIH did not prevent the occurrence of acute cardiovascular changes at HA during the first days of exposure. The BP response to HA tended to be more pronounced in hypertensive than in normotensive workers despite being already treated; the BP changes were more evident for 24-h ambulatory BP. Twenty-four-hour ABP monitoring is a useful tool for an appropriate evaluation of BP in CIH workers.

During the last decades, the number of lowland children exposed to high altitude (HA) has increased drastically. Several factors may influence the development of illness after acute HA exposure on children and adolescent populations, such as altitude reached, ascent velocity, time spent at altitude and, especially, their age. The main goal of this study was to evaluate the resting cardiorespiratory physiological and submaximal exercise responses under natural HA conditions by means of the six-minute walking test (six MWT). Secondly, we aimed to identify the signs and symptoms associated with acute mountain sickness (AMS) onset after acute HA exposure in children and adolescents. Forty-two children and adolescents, 18 boys and 24 girls aged from 11 to 15 years old, participated in this study, which was performed at sea level (SL) and during the first 42 h at HA (3330 m). The Lake Louise score (LLS) was recorded in order to evaluate the evolution of AMS symptoms. Submaximal exercise tests (six MWT) were performed at SL and HA. Physiological parameters such as heart rate, systolic and diastolic blood pressure, respiratory rate and arterialized oxygen saturation were measured at rest and after ending exercise testing at the two altitudes. After acute HA exposure, the participants showed lower arterial oxygen saturation levels at rest and after the submaximal test compared to SL (p &lt, 0.001). Resting heart rate, respiratory rate and diastolic blood pressure presented higher values at HA (p &lt, 0.01). Moreover, heart rate, diastolic blood pressure and dyspnea values increased before, during and after exercise at HA (p &lt, 0.01). Moreover, submaximal exercise performance decreased at HA (p &lt, 0.001). The AMS incidence at HA ranged from 9.5% to 19%, with mild to moderate symptoms. In conclusion, acute HA exposure in children and adolescent individuals produces an increase in basal cardiorespiratory parameters and a decrement in arterial oxygen saturation. Moreover, cardiorespiratory parameters increase during submaximal exercise at HA. Mild to moderate symptoms of AMS at 3330 m and adequate cardiovascular responses to submaximal exercise do not contraindicate the ascension of children and adolescents to that altitude, at least for a limited period of time.

High altitude is an extreme environment that challenges human beings exposed because of work, recreational activities, or habitat. Exposure to hypobaric hypoxia results in physiological adaptations in response to the geography and the associated extreme environmental conditions. These acclimatization responses can be diverse and result from evolutionary changes and comorbidities. In this context, this review aims to identify the available evidence on the effects of high altitude on blood pressurefrom the physiological to clinical aspects at rest and during exerciseand the underlying mechanisms and possible clinical implications of acute and chronic intermittent hypoxia.La gran altitud es un ambiente extremo que impone fuertes desafíos para el ser humano que se expone por actividades laborales, recreativas o que vive en esta condición. La exposición a hipoxia hipobárica genera una serie de adaptaciones fisiológicas dadas por el entorno geográfico y las condiciones ambientales extremas asociadas. Estas respuestas de aclimatación pueden ser heterogéneas, siendo el resultado de cambios evolutivos y de la existencia de comorbilidades o patologías asociadas. En este contexto, el objetivo de este artículo es identificar la evidencia científica acerca de los efectos de la altitud geográfica en la presión arterial, desde los aspectos fisiológicos a las implicaciones clínicas en reposo y ejercicio. Asimismo, se abordan los mecanismos subyacentes y las posibles implicaciones clínicas en hipoxia aguda e hipoxia intermitente crónica.

High altitude (HA) exposure may affect human health and performance by involving the body timing system. Daily variations of melatonin may disrupt by HA exposure, thereby possibly affecting its relations with a metabolic parameter like the respiratory quotient (RQ). Sea level (SL) volunteers (7 women and 7 men, 21.0 ± 2.04 y) were examined for daily changes in salivary melatonin concentration (SMC). Sampling was successively done at SL (Antofagasta, Chile) and, on acute HA exposure, at nearby Caspana (3,270 m asl). Saliva was collected in special vials (Salimetrics Oral Swab, United Kingdom) at sunny noon (SMCD) and in the absence of blue light at midnight (SMCN). The samples were obtained after rinsing the mouth with tap water and were analyzed for SMC by immunoassay (ELISA kit; IBL International, Germany). RQ measurements (n = 12) were realized with a portable breath to breath metabolic system (OxiconTM Mobile, Germany), between 8:00 PM and 10:00 PM, once at either location. At SL, SMCD, and SMCN values (mean ± SD) were, respectively, 2.14 ± 1.30 and 11.6 ± 13.9 pg/ml (p < 0.05). Corresponding values at HA were 8.83 ± 12.6 and 13.7 ± 16.7 pg/ml (n.s.). RQ was 0.78 ± 0.07 and 0.89 ± 0.08, respectively, at SL and HA (p < 0.05). Differences between SMCN and SMCD (SMCN–SMCD) strongly correlate with the corresponding RQ values at SL (r = -0.74) and less tight at HA (r = -0.37). Similarly, mean daily SMC values (SMC) tightly correlate with RQ at SL (r = -0.79) and weaker at HA (r = -0.31). SMCN–SMCD, as well as, SMC values at SL, on the other hand, respectively, correlate with the corresponding values at HA (r = 0.71 and r = 0.85). Acute exposure to HA appears to loosen relations of SMC with RQ. A personal profile in daily SMC variation, on the other hand, tends to be conserved at HA.

Background Acute exposure to high‐altitude hypobaric hypoxia induces a blood pressure rise in hypertensive humans, both at rest and during exercise. It is unclear whether this phenomenon reflects specific blood pressure hyperreactivity or rather an upward shift of blood pressure levels. We aimed at evaluating the extent and rate of blood pressure rise during exercise in hypertensive subjects acutely exposed to high altitude, and how these alterations can be counterbalanced by antihypertensive treatment. Methods and Results Fifty‐five subjects with mild hypertension, double‐blindly randomized to placebo or to a fixed‐dose combination of an angiotensin‐receptor blocker (telmisartan 80 mg) and a calcium‐channel blocker (nifedipine slow release 30 mg), performed a cardiopulmonary exercise test at sea level and after the first night's stay at 3260 m altitude. High‐altitude exposure caused both an 8 mm Hg upward shift ( P P P P Conclusions In hypertensive subjects exposed to high altitude, we observed a hypoxia‐driven upward shift and steepening of the blood pressure response to exercise. The effect of the combination of telmisartan/nifedipine slow release outweighed these changes and was associated with better muscle oxygen delivery. Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 01830530.

Background: Limited evidence exists on blood pressure (BP) responses to exercise in hypertensive subjects exposed to high altitude, and on the effects of antihypertensive treatment in this setting. We aimed to asses BP response to submaximal exercise in hypertensive lowlanders acutely exposed to high altitude, and the effects of a calcium antagonist–angiotensin receptor blocker combination in this condition. Methods: 89 mild-hypertensive participants in HIGHCARE-ANDES study performed a six-minute walk test in 3 conditions: at sea-level off-treatment; at sea-level after 6 weeks of double-blind treatment with telmisartan 80mg + slow release nifedipine 30 mg or with placebo; on the first full day of permanence at 3260 m altitude under randomized treatment. Results: The distance walked in 6 min was reduced by about 10% at high altitude in both groups (p b 0.001) without treatment-related differences. Systolic BP increased at altitude in both groups, remaining lower on telmisartan/nifedipine than on placebo both before and after exercise (p b 0.001).The exercise-induced increase in systolic BP at altitude was blunted by active treatment as compared to placebo (+32.0 ± 19.8 vs +41.9 ± 23.3 mm Hg, p b 0.05). Diastolic BP was unchanged from sea-level to altitude in both groups, showing lower values on telmisartan/nifedipine than on placebo before and after exercise (p b 0.01). Oxygen saturation was similarly reduced in both groups before exercise at altitude, but after exercise it was higher on telmisartan/nifedipine than on placebo. Conclusions: In mild hypertensives, acute exposure to high altitude enhances the BP response to exercise. Such an enhanced response is effectively reduced by telmisartan/nifedipine combination therapy, without affecting exercise performance.

Blood pressure increases during acute exposure to high altitude in healthy humans. However, little is known on altitude effects in hypertensive subjects or on the treatment efficacy in this condition. Objectives of High Altitude Cardiovascular Research (HIGHCARE)–Andes Lowlanders Study were to investigate the effects of acute high-altitude exposure on 24-hour ambulatory blood pressure in hypertensive subjects and to assess antihypertensive treatment efficacy in this setting. One hundred untreated subjects with mild hypertension (screening blood pressure, 144.1±9.8 mm Hg systolic, 92.0±7.5 mm Hg diastolic) were randomized to double-blind placebo or to telmisartan 80 mg+modified release nifedipine 30 mg combination. Twenty-four–hour ambulatory blood pressure monitoring was performed off-treatment, after 6 weeks of treatment at sea level, on treatment during acute exposure to high altitude (3260 m) and immediately after return to sea level. Eighty-nine patients completed the study (age, 56.4±17.6 years; 52 men/37 women; body mass index, 28.2±3.5 kg/m 2 ). Twenty-four–hour systolic blood pressure increased at high altitude in both groups (placebo, 11.0±9 mm Hg; P P P Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT01830530.

Acute exposure to high altitude induces a blood pressure (BP) rise in healthy humans [(1)][1]. Arterial hypertension is associated both with enhanced BP response to exercise and with increased sympathetic discharge in hypoxic conditions [(2,3)][2], which may increase the risk of adverse consequences