Design and conduct of 'Xtreme Alps' : a double-blind, randomised controlled study of the effects of dietary nitrate supplementation on acclimatisation to high altitude

The study of healthy human volunteers ascending to high altitude provides a robust model of the complex physiological interplay that emulates human adaptation to hypoxaemia in clinical conditions. Nitric oxide (NO) metabolism may play an important role in both adaptation to high altitude and response to hypoxaemia during critical illness at sea level. Circulating nitrate and nitrite concentrations can be augmented by dietary supplementation and this is associated with improved exercise performance and mitochondrial efficiency. We hypothesised that the administration of a dietary substance (beetroot juice) rich in nitrate would improve oxygen efficiency during exercise at high altitude by enhancing tissue microcirculatory blood flow and oxygenation. Furthermore, nitrate supplementation would lead to measurable increases in NO bioactivity throughout the body. This methodological manuscript describes the design and conduct of the ‘Xtreme Alps’ expedition, a double-blind randomised controlled trial investigating the effects of dietary nitrate supplementation on acclimatisation to hypobaric hypoxia at high altitude in healthy human volunteers. The primary outcome measure was the change in oxygen efficiency during exercise at high altitude between participants allocated to receive nitrate supplementation and those receiving a placebo. A number of secondary measures were recorded, including exercise capacity, peripheral and microcirculatory blood flow and tissue oxygenation. Results from this study will further elucidate the role of NO in adaption to hypoxaemia and guide clinical trials in critically ill patients. Improved understanding of hypoxaemia in critical illness may provide new therapeutic avenues for interventions that will improve survival in critically ill patients

Thermospheric density perturbations in response to substorms

We use 5 years (2001–2005) of CHAMP (Challenging Minisatellite Payload) satellite data to study average spatial and temporal mass density perturbations caused by magnetospheric substorms in the thermosphere. Using statistics from 2306 substorms to construct superposed epoch time series, we find that the largest average increase in mass density of about 6% occurs about 90 min after substorm expansion phase onset about 3 h of magnetic local time east of the onset region. Averaged over the entire polar auroral region, a mass density increase of about 4% is observed. Using a simple model to estimate the mass density increase at the satellite altitude, we find that an energy deposition rate of 30 GW applied for half an hour predominantly at an altitude of 110 km is able to produce mass density enhancements of the same magnitude. When taking into account previous work that has shown that 80% of the total energy input is due to Joule heating, i.e., enhanced electric fields, whereas 20% is due to precipitation of mainly electrons, our results suggest that the average substorm deposits about 6 GW in the polar thermosphere through particle precipitation. Our result is in good agreement with simultaneous measurements of the NOAA Polar-orbiting Operational Environmental Satellite (POES) Hemispheric Power Index; however, it is about 1 order of magnitude less than reported previously

Exercise intervention in people with cancer undergoing adjuvant cancer treatment following surgery: a systematic review

BackgroundRemaining physically active during and after cancer treatment is known to improve associated adverse effects, improve overall survival and reduce the probability of relapse. This systematic review addresses the question: is an exercise training programme beneficial in people with cancer undergoing adjuvant cancer treatment following surgery.MethodsA systematic database search of Embase, Ovid, Medline without Revisions, SPORTDiscus, Web of Science, Cochrane Library and ClinicalTrials.gov for any randomised controlled trials (RCT) or non-RCT addressing the effect of an exercise training programme in those having adjuvant cancer treatment following surgery was conducted.ResultsThe database search yielded 6489 candidate abstracts of which 94 references included the required terms. A total of 17 articles were included in this review. Exercise training is safe and feasible in the adjuvant setting and furthermore may improve measures of physical fitness and health related quality of life (HRQoL).ConclusionThis is the first systematic review on exercise training interventions in people with cancer undergoing adjuvant cancer treatment following surgery. Due to the lack of adequately powered RCTs in this area, it remains unclear whether exercise training in this context improves clinical outcomes other physical fitness and HRQoL. It remains unclear what is the optimal timing of initiation of an exercise programme and what are the best combinations of elements within an exercise training programme to optimise training efficacy. Furthermore, it is unclear if initiating such exercise programmes at cancer diagnosis may have a long-lasting effect on physically activity throughout the subsequent life course

Early identification of wound infection: understanding wound odour

Malodorous wounds can be distressing for patients and their families, negatively impacting on quality-of-life outcomes. For health professionals malodorous wounds can also cause distress manifesting in feelings of disgust when faced with a wound emitting an unpleasant or repulsive odour. There has been investigation into the management of controlling odour particularly in relation to fungating wounds. However, there is limited research that explores techniques for early identification and recognition of wound odours that may be indicative of infection. Electronic nose technology has received some attention, but to date has not been integrated into either diagnostics of infection in wounds or education of health professionals to prepare them for the realities of clinical practice

Concepts in hypoxia reborn

The human fetus develops in a profoundly hypoxic environment. Thus, the foundations of our physiology are built in the most hypoxic conditions that we are ever likely to experience: the womb. This magnitude of exposure to hypoxia in utero is rarely experienced in adult life, with few exceptions, including severe pathophysiology in critical illness and environmental hypobaric hypoxia at high altitude. Indeed, the lowest recorded levels of arterial oxygen in adult humans are similar to those of a fetus and were recorded just below the highest attainable elevation on the Earth's surface: the summit of Mount Everest. We propose that the hypoxic intrauterine environment exerts a profound effect on human tolerance to hypoxia. Cellular mechanisms that facilitate fetal well-being may be amenable to manipulation in adults to promote survival advantage in severe hypoxemic stress. Many of these mechanisms act to modify the process of oxygen consumption rather than oxygen delivery in order to maintain adequate tissue oxygenation. The successful activation of such processes may provide a new chapter in the clinical management of hypoxemia. Thus, strategies employed to endure the relative hypoxia in utero may provide insights for the management of severe hypoxemia in adult life and ventures to high altitude may yield clues to the means by which to investigate those strategies

Characteristics of medium-scale travelling ionospheric disturbances observed near the Antarctic Peninsula by HF radar

We present a survey of medium-scale traveling ionospheric disturbances (MSTIDs) observed by a Super Dual Auroral Radar Network HF radar located in the Falkland Islands between May 2010 and April 2011. The radar has a field of view that overlooks the Antarctic Peninsula, a known hot spot of gravity wave activity. We present observations of radar ground-backscatter data, in which the signatures of MSTIDs are manifested as structured enhancements in echo power. Observed periods were in the range 30–80 min, corresponding to frequencies of 0.2–0.6 mHz. Wavelengths were generally in the range 200–800 km and phase speeds in the range 100–300 m s−1. These values are within the ranges typically associated with medium-scale gravity waves. We find a primary population of northward (equatorward) propagating MSTIDs, which demonstrate an association with enhanced solar wind-magnetosphere coupling and a smaller, westward propagating population, that could be associated with atmospheric gravity waves excited by winds over the Andean and Antarctic Peninsula mountains or by the high winds of the Antarctic Polar Vortex

Exercise rehabilitation following intensive care unit discharge for recovery from critical illness:executive summary of a Cochrane Collaboration systematic review

Skeletal muscle wasting and weakness are major complications of critical illness and underlie the profound physical and func-\ud tional impairments experienced by survivors after discharge from the intensive care unit (ICU). Exercise-based rehabilitation\ud has been shown to be bene\ud fi\ud cial when delivered during ICU admission. This review aimed to determine the effectiveness of\ud exercise rehabilitation initiated after ICU discharge on primary outcomes of functional exercise capacity and health-related\ud quality of life. We sought randomized controlled trials, quasi-randomized controlled trials, and controlled clinical trials compar-\ud ing an exercise intervention commenced after ICU discharge vs. any other intervention or a control or\ud ‘\ud usual care\ud ’\ud programme\ud in adult survivors of critical illness. Cochrane Central Register of Controlled Trials, Medical Literature Analysis and Retrieval Sys-\ud tem Online (MEDLINE), Excerpta Medica Database, and Cumulative Index to Nursing and Allied Health Literature databases\ud were searched up to February 2015. Dual, independent screening of results, data extraction, and quality appraisal were per-\ud formed. We included six trials involving 483 patients. Overall quality of evidence for both outcomes was very low. All studies\ud evaluated functional exercise capacity, with three reporting positive effects in favour of the intervention. Only two studies\ud evaluated health-related quality of life and neither reported differences between intervention and control groups. Meta-\ud analyses of data were precluded due to variation in study design, types of interventions, and selection and reporting of out-\ud come measurements. We were unable to determine an overall effect on functional exercise capacity or health-related quality\ud of life of interventions initiated after ICU discharge for survivors of critical illness. Findings from ongoing studies are awaited.\ud Future studies need to address methodological aspects of study design and conduct to enhance rigour, quality, and synthesis