Editorial: Onward and upward (p. 1)

As the Journal embarks on its 15^th year of publication, we take stock and look to the future.

Sightings, Edited by John W. Severinghaus (p. 4)

Clinician's Corner, Edited by Andrew Luks

Managing moderate and severe pain in mountain rescue

Pain in mountain accidents is often a severe and difficult problem, and frequently it is undertreated. Ellerton et al (p. 8) provide a broad concensus statement.

Scientific Articles

Peripheral chemoreceptor responsiveness and hypoxic pulmonary vasoconstriction in humans

Albert and Swenson (p. 15) present an important and novel study of the relation between the ventilatory response to hypoxia and hypoxic pulmonary vasoconstriction in 15 human volunteers. They found that in general the two responses are inversely correlated with the result that a large peripheral chemoreceptor response to hypoxia tends to limit hypoxic pulmonary vasoconstriction. This finding has many implications including the pathogenesis of high altitude pulmonary edema.

Time course variations in the mechanisms by which cerebral oxygen delivery is maintained on exposure to hypoxia/altitude

Oxygen delivery to the brain is a critical factor in tolerance to high altitude. Many previous studies of cerebral blood flow have relied on transcranial Doppler measurements which give the velocity of flow in the middle cerebral artery. However a new important finding by Imray and colleagues (p. 21) is that the caliber of the artery, rather than blood velocity, is the major contributor to increased oxygen delivery in early hypoxia. During long-term exposure, increases in the velocity of blood flow become increasingly important.

Prevalence of acute mountain sickness at 3500 m within and between families: A prospective cohort study

Kriemler and her many colleagues (p. 28) measured the prevalence of acute mountain sickness (AMS) based on the Lake Louise score in 87 children, 70 adolescents, and 155 parents after a fast ascent to 3450 m. AMS prevalence was lower in children than in adolescents and adults on the first day but not the second. Familial clustering of AMS explained 25% to 50% of its variability.

Dental problems and emergencies of trekkers—epidemiology and prevention. Results of the ADEMED-Expedition 2008

Dental problems have not received much attention in people trekking at high altitude. Küpper and colleagues (p. 39) carried out a survey of dental problems in 309 trekkers at an altitude of 3550 m in the Anapurna region of Nepal. 16.5% had dental problems potentially treatable with a first aid kit. Oral hygiene was worse than at home and trekkers who had seen a dentist up to 6 months before the trek had fewer problems. Gum bleeding, dental pain, lost fillings, and fractured teeth were the main findings.

Meta-analysis of clinical efficacy of Sildenafil, a phosphodiesterase type-5 inhibitor on high-altitude hypoxia and its complications

Phosphodiesterase type 5 inhibitors such as Sildenafil are known to reduce pulmonary artery pressure under some conditions. Xu and colleagues (p. 46) carried out an extensive meta-analysis to examine the effects of short-term use of the drug for pulmonary hypertension at high altitude and acute mountain sickness. It was found that although there was a reduction in pulmonary artery systolic pressure, there are no beneficial effects on arterial oxygen saturation, cardiac contractility or acute mountain sickness.

The effect of climbing Mount Everest on spleen contraction and increase in hemoglobin concentration during breath holding and exercise

Spleen contraction can improve exercise performance by adding red cells to the circulation. In this study by Engan and colleagues (p. 52) spleen volume was measured by ultrasound and hemoglobin concentration in eight climbers before and after acclimatization during an ascent of Mt. Everest. Splenic contraction was stimulated by breath-holding and exercise. Spleen volume after both breath-holding and exercise was less after the climb.

Brief Reports

Deep accidental hypothermia with core temperature below 24°C presenting with vital signs. A case report and review of the literature

Pasquier and colleagues (p. 58) report the case of a woman aged 53 who had a core temperature of less than 24°C but preserved vital signs. They then searched the literature for similar cases and found 22 with a median core temperature of 22 °C. Vital signs were present but often minimal. 20 patients survived with an excellent neurological outcome.

Altitude is positively correlated to race time during the marathon

Although it might be expected that marathon times would increase with altitude, this has not formally been analyzed. Lara and coworkers (p. 64) reviewed the race times of 16 marathons performed at altitudes from sea level to 2800 m. Finishing time was positively correlated with altitude for both males and females. Each increase of 1000 m above sea level increased race time by an average of 10.8% in men and 12.3% in women.

Case Reports

Repeated pre-syncope from increased inspired CO₂ in a background of severe hypoxia

Fan and Kayser (p. 70) describe an interesting course of events in a healthy young man who was breathing 10% oxygen. When carbon dioxide was added to the inspired gas he developed pre-syncope symptoms including hypotension and a large reduction in middle cerebral artery velocity in diastole while systolic flow was maintained. It was speculated that the mechanism was impaired compensatory sympathetic activity to the hypocapnia.

Mt. Everest & Makalu cold injury amputation: 40 years on

Cold injury of the extremities is common among climbers at high altitude. Morrison and coworkers (p. 78) studied a 62-year-old alpinist 40 years after his attempt to reach the summits of Makalu (8481 m) and Everest (8848 m) during which he had amputations of some fingers and toes. It was found that after 40 years, rates of rewarming after a cold stress of both fingers and toes were generally not different between previously injured and non-injured digits.

Late hyperbaric oxygen treatment of cilioretinal artery occlusion with non-ischemic central retinal vein occlusion secondary to high altitude

Gokce and coworkers (p. 84) describe a previously healthy 48-year-old woman who was exposed to an altitude of 2540 m for one month and developed occlusion of the cilioretinal artery. She was treated with hyperbaric oxygen therapy and made a good recovery.

Meeting Report

Report of proceedings of Birmingham Medical Research Expeditionary Society (BMRES) Altitude Medicine Conference on 22nd Nov 2013 at the Birmingham Medical Institute, Birmingham UK

Thomas and Booth (p. 89) describe a one-day meeting organized by the Birmingham Medical Research Expeditionary Society during which various aspects of high altitude and biology were discussed.

Nepalese Mountain Rescue Development Project

Large numbers of people trek and climb in Nepal particularly in the Khumbu area. However mountain rescue operations are poorly developed. Thapa and colleagues (p. 91) make important recommendations.

Letters to the Editor

Isolated generalized tonic-clonic seizure at high altitude in a young male trekker with a positive family history of seizures

Hennis and colleagues (p. 93) report the case of an 18-year-old man with a family history of seizures who developed a tonic-clonic seizure at an altitude of 4250 m at the Everest Base Camp.

Portable hyperbaric chamber and management of hypothermia and frostbite: An evident utilization

Cauchy and colleagues (p. 95) propose a change in the management of hypothermia and cold injury at high altitude. They suggest that in addition to the usual fast-warming protocol, the patient should be placed in a portable hyperbaric chamber if the altitude exceeds 3500 m.