Society. Effect of exercise on cerebral perfusion in humans at high altitude. J Appl Physiol 99: 699 -706, 2005. First published May 26, 2005 doi:10.1152/japplphysiol.00973.2004.-The effects of submaximal and maximal exercise on cerebral perfusion were assessed using a portable, recumbent cycle ergometer in nine unacclimatized subjects ascending to 5,260 m. At 150 m, mean (SD) cerebral oxygenation (rSO2%) increased during submaximal exercise from 68.4 (SD 2.1) to 70.9 (SD 3.8) (P Ͻ 0.0001) and at maximal oxygen uptake (V O2 max) to 69.8 (SD 3.1) (P Ͻ 0.02). In contrast, at each of the high altitudes studied, rSO2 was reduced during submaximal exercise from 66.2 (SD 2.5) to 62.6 (SD 2.1) at 3,610 m (P Ͻ 0.0001), 63.0 (SD 2.1) to 58.9 (SD 2.1) at 4,750 m (P Ͻ 0.0001), and 62.4 (SD 3.6) to 61.2 (SD 3.9) at 5,260 m (P Ͻ 0.01), and at V O2 max to 61.2 (SD 3.3) at 3,610 m (P Ͻ 0.0001), to 59.4 (SD 2.6) at 4,750 m (P Ͻ 0.0001), and to 58.0 (SD 3.0) at 5,260 m (P Ͻ 0.0001). Cerebrovascular resistance tended to fall during submaximal exercise (P ϭ not significant) and rise at V O2 max, following the changes in arterial oxygen saturation and end-tidal CO 2. Cerebral oxygen delivery was maintained during submaximal exercise at 150 m with a nonsignificant fall at V O2 max, but at high altitude peaked at 30% of V O2 max and then fell progressively at higher levels of exercise. The fall in rSO2 and oxygen delivery during exercise may limit exercise at altitude and is likely to contribute to the problems of acute mountain sickness and highaltitude cerebral edema. maximal oxygen uptake; cerebral oxygenation; cerebral blood flow; cerebrovascular resistance; cerebral oxygen delivery ALTERED CEREBRAL FUNCTION on ascent to altitude was part of the first description of mountain sickness in 1913 (40), and acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) have been shown to be potentially serious clinical conditions that may occur on acute exposure to altitudes above 2,500 -3,000 m. Exercise at altitude causes further decreases in arterial oxygenation and so may exacerbate cerebral hypoxia. However, the fall in arterial saturation that occurs during exercise at high altitude (14) might not affect cerebral oxygenation to the same extent as it does in peripheral tissues due to a compensatory increase in cerebral blood flow (24). Nevertheless, avoidance of strenuous exercise during ascent, and on arrival at altitude, is standard advice for reducing the risk of AMS and HACE. Evidence from clinical studies is conflicting. Higher AMS symptom scores were found in subjects exercising four times a day for 30 min at 50% of their altitude-specific maximal oxygen consumption (V O 2 max ), compared with no exercise, in a chamber study at simulated altitude of 4,800 m (41). Another study of mountaineers, however, showed that physical fitness and exercise intensity during ascent to 4,559 m were of minor importance for the development of AMS (3). It is also possible that other neurological conditions falling outside the usual def...

Acute kidney injury (AKI) after any type of intervention negatively impacts mortality, length of hospitalization, and perhaps long-term survival. In the case of endovascular aneurysm repair (EVAR), the incidence of AKI ranges from 1% to 23% for elective and emergency procedures and is lower compared to open repair. The pathophysiology of AKI in EVAR is complex: contrast-induced nephropathy, renal microembolization, and acute tubular necrosis are all implicated. Prevention strategies include hydration, ischemic preconditioning, regional anesthesia, and pharmacological agents. There is no level I evidence regarding the prevention of AKI in EVAR, so this review sought to examine the mechanisms and prevention strategies for this potentially fatal complication.

Deep frostbite is a thermal injury associated with significant morbidity. Historically, this has been associated with military personnel; however, increasingly it is becoming an injury that afflicts the civilian population. The use of intravenous iloprost or intra-arterial thrombolytics has led to promising tissue salvage. This article provides an up-to-date understanding of frostbite pathophysiology, classification, prevention, and management. It also highlights the role of telemedicine in optimizing patient outcomes. To further the understanding of optimal frostbite management, larger, likely multicenter, high-quality trials are required. An international frostbite register would facilitate data gathering.

The Wilderness Medical Society convened an expert panel to develop a set of evidence-based guidelines for the prevention and treatment of frostbite. We present a review of pertinent pathophysiology. We then discuss primary and secondary prevention measures and therapeutic management. Recommendations are made regarding each treatment and its role in management. These recommendations are graded on the basis of the quality of supporting evidence and balance between the benefits and risks or burdens for each modality according to methodology stipulated by the American College of Chest Physicians. This is an updated version of the original guidelines published in