Ischemic strokes were the most common type, and altitude-related polycythemia was identified as the most significant risk factor.94 Travel to high altitude is contraindicated for a 90-day period post stroke or transient ischemic attack. Following this period, decisions about the safety of high altitude exposure and/or necessary treatment at altitude must be made based on each individual’s clinical situation and the physician’s estimation of stroke risk.12 Migraine sufferers do not appear to be buy Roxadustat at increased risk of developing altitude sickness.95 However, altitude exposure is a clinically recognized trigger for migraines and the severity of headaches

may increase at altitude.12,22,95,96 Furthermore, Murdoch described a migraine sufferer whose migraine presentation changed drastically at altitude to include focal neurological deficits.96 Migraine sufferers can safely travel to high altitude, albeit with the caution that migraine frequency, severity, and character may be altered. There is little information available on the effects of anemia at altitude, and the risk of altitude-related illness in this cohort has not been established.

Hackett states that patients with iron deficiency anemia appear to acclimatize well to high altitude.22 Pollard and Murdoch report that hemoglobin concentrations of 14 to 18 g/dL are optimal for high altitude acclimatization.30 Patients with anemia can expect to have reduced exercise capacity find more Loperamide at altitude. Anemia should be corrected prior to high altitude travel43 and premenopausal women may benefit from iron supplementation while at altitude if their ferritin stores are low.97 Exposure to altitudes above 2,000 m has been associated with a high incidence of vaso-occlusive sickle cell crisis or splenic infarcts in patients with sickle cell disease (HbSS or HbSC) or sickle cell trait (HbAS).1,22,98 Travel to altitude is contraindicated for people with sickle cell disease.22,31,98 Splenic

crisis is the most frequent risk associated with exposure to hypobaric hypoxia in people with sickle cell trait.99,100 Furthermore, severe exertion has been associated with sickle cell crisis and sudden death in this patient cohort.101,102 Thiriet and colleagues suggest that although individuals with sickle cell trait are capable of intense exercise at high altitude, their performance is diminished.103 Although some experts do not recommend absolute activity or altitude restrictions in patients with sickle cell trait,2 others1 have advised that altitude should be avoided. Should they decide to travel to altitude, people with sickle cell trait should be informed of the risks and instructed to avoid over-exertion, to maintain adequate hydration, and to minimize heat stress.102,104,105 Individuals who are deconditioned should be exceptionally cautious in exerting themselves at altitude.102 Patients may be unaware of their sickle cell status prior to traveling.