Objective Variations in definitions, scores, and methodologies have created differences in the results and conclusions obtained from studies on mountaineering and climbing sports injuries and illnesses; this has made interstudy comparisons difficult or impossible. To develop a common, simple, and sport-specific scoring system to classify injuries and illnesses in mountaineering and climbing studies; such retrospective scoring would facilitate the analysis and surveillance of their frequencies, severity and fatalities, and outcomes of any treatment. Methods The UIAA (The International Mountaineering and Climbing Federation) makes recommendations, sets policy, and advocates on behalf of the climbing and mountaineering community internationally through its various commissions. Using a nominal group consensus model approach, a working group was formed during the UIAA Medical Commission's meeting in Adršpach – Zdoňov, in the Czech Republic, 2008. This group critically examined climbing and other relevant literature for various methodological approaches in measuring injury incident rates and severity, including data sources, and produced a working document that was later edited and ratified by all members of the UIAA Medical Commission. Results Definitions of injury location, injury classification, and fatality risk are proposed. Case fatality, time-related injury risk, and a standardized metric climbing difficulty scale are also defined. Conclusions The medical commission of the UIAA recommends the use of the described criteria and scores for future research in mountaineering and climbing sports in order to enable robust and comprehensive interstudy comparisons and epidemiological analysis.

Our field study provides novel data on nocturnal oxygen saturation, breathing patterns, and ventilation at very high altitude. It demonstrates that periodic breathing increases during acclimatization over 2 weeks at altitudes greater than 3,730 m, despite improved oxygen saturation consistent with a progressive increase in loop gain of the respiratory control system. Clinical trial registered with www.clinicaltrials.gov (NCT00514826).

Little is known about the ocular and cerebral blood flow during exposure to increasingly hypoxic conditions at high altitudes. There is evidence that an increase in cerebral blood flow resulting from altered autoregulation constitutes a risk factor for acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) by leading to capillary overperfusion and vasogenic cerebral edema. The retina represents the only part of the central nervous system where capillary blood flow is visible and can be measured by noninvasive means. In this study we aimed to gain insights into retinal and choroidal autoregulatory properties during hypoxia and to correlate circulatory changes to symptoms of AMS and clinical signs of HACE. This observational study was performed within the scope of a high-altitude medical research expedition to Mount Muztagh Ata (7,546 m). Twenty seven participants underwent general and ophthalmic examinations up to a maximal height of 6,800 m. Examinations included fundus photography and measurements of retinal and choroidal blood flow, as well as measurement of arterial oxygen saturation and hematocrit. The initial increase in retinal blood velocity was followed by a decrease despite further ascent, whereas choroidal flow increase occurred later, at even higher altitudes. The sum of all adaptational mechanisms resulted in a stable oxygen delivery to the retina and the choroid. Parameters reflecting the retinal circulation and optic disc swelling correlated well with the occurrence of AMS-related symptoms. We demonstrate that sojourns at high altitudes trigger distinct behavior of retinal and choroidal blood flow. Increase in retinal but not in choroidal blood flow correlated with the occurrence of AMS-related symptoms.

Investigations studying the secretion of EPO (erythropoietin) in response to acute hypoxia have produced mixed results. Further, the errors associated with the various methods used to determine EPO are not well documented. The purpose of the current study was to determine the EPO response of 17 trained male subjects to either an acute bout of normobaric hypoxia (Hy; n = 10) or normoxia (Con; n = 7). A secondary aim was to determine the error associated with the measurement of EPO. After baseline tests, the treatment group (Hy) underwent a single bout of hypoxic exposure (F(I(O(2))) approximately 0.148; 3100 m) consisting of a 90-min rest period followed by a 30-min exercise phase (50% V(O)(2max)). Venous blood samples were drawn pre (0 min) and post (120 min) each test to assess changes in plasma EPO (DeltaEPO). The control (Con) group was subjected to the same general experimental design, but placed in a normoxic environment (F(I(O(2))) approximately 0.2093). The Hy group demonstrated a mean increase in EPO [19.3 (4.4) vs. 24.1 (5.1) mU/mL], p < 0.04, post 120 min of normobaric hypoxia. The calculated technical error of measurement for EPO was 2.1 mU/mL (9.8%). It was concluded that an acute bout of hypoxia, has the capacity to elevate plasma EPO. This study also demonstrates that the increase in EPO accumulation was 2 times greater than the calculated measurement of error.

Key pointsr A physiological response to increase microcirculatory oxygen extraction capacity at high altitude is to recruit capillaries. r In the present study, we report that high altitude-induced sublingual capillary recruitment is an intrinsic mechanism of the sublingual microcirculation that is independent of changes in cardiac output, arterial blood pressure or systemic vascular hindrance.r Using a topical nitroglycerin challenge to the sublingual microcirculation, we show that high altitude-related capillary recruitment is a functional response of the sublingual microcirculation as opposed to an anatomical response associated with angiogenesis.r The concurrent presence of a low capillary density and high microvascular reactivity to topical nitroglycerin at sea level was found to be associated with a failure to reach the summit, whereas the presence of a high baseline capillary density with the ability to further increase maximum recruitable capillary density upon ascent to an extreme altitude was associated with summit success.Abstract A high altitude (HA) stay is associated with an increase in sublingual capillary total vessel density (TVD), suggesting microvascular recruitment. We hypothesized that microvascular recruitment occurs independent of cardiac output changes, that it relies on haemodynamic changes within the microcirculation as opposed to structural changes and that microcirculatory function is related to individual performance at HA. In 41 healthy subjects, sublingual handheld vital microscopy and echocardiography were performed at sea level (SL), as well as at 6022 m Matthias Peter Hilty has found that, during his education and throughout his board certification in General Internal Medicine and Intensive Care Medicine, his main interests lie in the foundations of human physiology, in addition to their application in clinical practice. Studies of the response of the macro-and microcirculation to critical illness and high altitude environments have lead to his high appreciation of the contrast between witnessing cardiovascular pathophysiology during field studies, in laboratory settings and at the bedside. Hoping to support the upcoming challenge to translate these findings to clinical use, Dr Hilty is applying advanced computational techniques for the objective assessment of a patient's microcirculation. M. P. Hilty and othersJ Physiol 597.10 (C2) and 7042 m (C3), during ascent to 7126 m within 21 days. Sublingual topical nitroglycerin was applied to measure microvascular reactivity and maximum recruitable TVD (TVD NG ). HA exposure decreased resting cardiac output, whereas TVD (mean ± SD) increased from 18.81 ± 3.92 to 20.92 ± 3.66 and 21.25 ± 2.27 mm mm −2 (P < 0.01). The difference between TVD and TVD NG was 2.28 ± 4.59 mm mm −2 at SL (P < 0.01) but remained undetectable at HA. Maximal TVD NG was observed at C3. Those who reached the summit (n = 15) demonstrated higher TVD at SL (P < 0.01), comparable to TVD NG in non-summiters (n = 21) at SL and in both groups at C2. Recruitment of sublingu...