Wilderness & Environmental Medicine

The aim of this investigation was to assess the changes of atrial volumes during and after prolonged high-altitude exposure, in relation to extracellular and total body water and plasma levels of atrial natriuretic peptide (ANP). The estimation of extracellular and total body water was obtained by bioelectrical impedance measurement in seven healthy male subjects aged 24.7 years (range 23-28). These were members of a Himalayan expedition (Pumori, 7135 m). Measurements were taken before departure, after 1 and 4 weeks at altitude over 5000 m, and upon return to sea level. In the same phases, right and left atrial volumes were determined by 2D-echocardiography and blood samples were drawn for ANP by radioimmunoassay.

At high altitude, body fluid depletion, as shown by reduction of extracellular and total body water, was related to reduction of left atrial volume, whereas the right atrium did not show any significant change. Upon return to sea level, the persistence of reduced extracellular and total body water went along with the persistence of decreased left atrial volume. Despite the wide variability in plasma levels of ANP among subjects, a clear-cut reduction was observed in all subjects after 4 weeks at high altitude, and a significant (p < .01) correlation was found between ANP concentrations and left atrial volumes, considering the subjects in all phases of research.

During prolonged high altitude exposure, progressive reduction of left atrial volume reflects body fluid depletion; after 4-week exposure, circulating ANP levels decrease concomitant with left atrial volume reduction.

Objective: Ascent to high altitude may be associated with changes in heart rate and systolic blood pressure, resulting in greater cardiac work. In elderly individuals with coronary artery disease, these changes may lead to myocardial ischemia. We studied an elderly population to assess the incidence of myocardial ischemia and the effect on the electrocardiogram (ECG) during a visit to moderate altitude.

Design: Inception cohort study.

Setting: Vail, Colorado (2500 m).

Participants: Members and spouses of the Tenth Mountain Division reunion.

Interventions: Resting 12-lead ECGs and blood pressures were obtained daily for 4 days.

Results: Ninety-seven subjects participated (77 men and 20 women) with a mean age of 69.8 ± 4.4 years. Twenty-one percent of our subjects had some manifestation of coronary artery disease. On arrival, 59 (61%) of the ECGs were normal, 1 (1%) borderline, and 37 (38%) abnormal. No new ST-T-wave abnormalities clearly indicative of myocardial ischemia during the altitude stay were found. When compared to baseline ECGs recorded previously in 56 of our subjects, 8 (14%) had P-wave vector changes probably related to pulmonary hypertension. Cardiac work as estimated by the heart rate-blood pressure double product was increased by 13% at rest.

Conclusions: Despite an increase in cardiac work, no new ST-T-wave abnormalities clearly indicative of myocardial ischemia were present on arrival or during the next 4 days at altitude. Despite a high prevalence of ECG abnormalities and probable coronary artery disease in these elderly subjects, ascent to moderate altitude did not appear to precipitate myocardial ischemia in subjects with asymptomatic coronary artery disease (New York Heart Association Class I).

Nineteen current makes of sports glasses and six older types of sunglasses were tested for spectral UV transmission. Transmissions in the UVB range (280–320 nm) were less than 10⁻⁴; all glasses therefore offered 100% protection against keratitis. Transmissions of UVA radiation (320–400 nm) varied greatly. All makes transmitted varying small amounts of cataract effective UVA radiation, but the effectiveness for cataract is less than 0.15% in the UVA range. If lateral incident radiation is shielded, sports glasses protect against ocular damage from solar UV radiation even in a very bright environment.

We performed a retrospective study of the behavior of lost dementia of Alzheimer's type (DAT) patients who became the subjects of organized search and rescue efforts. We compared the DAT patients' behavior to the behavior of elderly lost victims who possessed normal cognitive abilities. Data for both populations were from the Virginia Department of Emergency Services lost-subject database. We found that normal elderly individuals on average traveled a greater straight-line distance (2.56 km) from the point last seen (PLS) than did DAT patients (0.88 km). The median straight-line distance from the PLS was the same for both populations (0.8 km). The mortality rate for DAT patients was 19%. Mortality was caused by hypothermia, dehydration, and drowning. No fatalities were found among DAT patients when they were located within 24 h. A mortality rate of 46% was found for patients requiring more than 24 h to locate. This 24-h survivability window suggests that lost DAT patients require an immediate and aggressive search response.

More than 25 years after the discovery of the 2 main African Paragonimus species, P. africanus and P. uterobilateralis, the snails' first intermediate hosts, which harbour rediae and cercariae as well as these larval stages, remain yet unknown.

In the present study, the authors describe microcercous cercariae and rediae with the characteristics of the genus Paragonimus from land snails of the Achatinidae family caught in a forest zone of Cameroon where P. africanus is endemic. The results corroborate Sachs and Cumberlidge's findings in a P. uterobilateralis focus in Liberia and indicate that for both African Paragonimus species, the first intermediate host should probably be land snails rather than fresh water snails.