Journal of wilderness medicine最新文献

There are over 1000 species of fresh and saltwater catfish worldwide, many of them venomous. Toxicity results from both the classically described venom, delivered when a spine punctures the victim, and a more recently elucidated skin toxin found over the entire surface of the catfish. Although systemic sequelae including death have been reported, symptoms are usually limited to the involved extremity and respond within hours to supportive therapy. We report a case of toxicity resulting from occupational exposure to the coral catfish, Plotatus lineatus.

Acute mountain sickness (AMS) describes a constellation of symptoms that is usually self-limited and benign. However, it may impair judgement and physical abilities at high altitudes and interfere with the pleasure of recreational activities. Severe cases may be fatal. Acclimatization is an effective prevention, but is not always practical or possible. Therefore, pharmacologic prophylaxis of AMS is an active area of research.

This study used meta-analytic techniques to evaluate the published literature regarding pharmacologic prophylaxis of AMS with acetazolamide and dexamethasone. Twenty eligible reports were located via a computer-assisted search, reference lists and review articles. Dependent measures for this study were the percentage of patients with AMS and the percentage of patients with specific symptoms associated with AMS.

An effect size (ES) is the standardized mean difference between experimental and control groups or the conversion from the point-biserial correlation between treatment and effect and allows integration of the results of independent studies. In this study, a negative ES indicates that the prophylaxis regimen exerted a protective effect; the greater the magnitude of the ES the greater its effect. The overall average weighted ES was −0.59 (95% confidence interval (CI) = −0.41 to −0.77) when both drugs’ results were pooled. The average weighted ES for studies comparing acetazolamide to placebo was −0.61 and it was −0.32 for studies comparing dexamethasone to placebo. The average ES was −0.38 when all of the reported symptoms were pooled together.

This report confirms the effectiveness of pharmacologic prophylaxis against AMS with acetazolamide or dexamethasone. Acetazolamide appears to be more effective, but inconsistencies in dexamethasone dosing, environmental conditions, and rate of ascent confound interpretation. This meta-analysis points out areas for future research.

Pulmonary artery hypertension is a common occurrence in mammals exposed to high altitude, yet little is known about the response of cold-acclimated animals. To study this problem pulmonary arterial pressure (Ppa), systemic blood pressure (Psa) and the ratio of Ppa/Psa in cold-acclimated rats (CA, 8 weeks, 6 °C, n = 11) during exposure to low oxygen (10% O₂) were measured by direct catheter methods and compared with those of controls raised at 22 °C (C, n = 10). There was no difference between CA and C in values of Ppa at a normal oxygen level (20.9% O₂). When rats were exposed to 10% O₂ Ppa increased significantly in C, while the increase in CA was not significant. The weights of the total ventricle (TV), right ventricle (RV) and left ventricle (LV) in the CA animals were increased significantly above the C values. The ratio of RV weight (RVW) to LV weight (LVW), however, was higher in C than in CA. During exposure to low oxygen, Psa did not change between the two groups. The ratio of Ppa/Psa was increased significantly in both groups when exposed to hypoxia. There were no significant differences in hematological measurements, including hematocrit (Ht), blood viscosity (CP) and red blood cells (RBC) between the CA and the C. It was concluded that the animals exposed to cold over a long period had no right ventricular hypertrophy (RVH) and the response to hypoxia in Ppa was lower in CA than that in C. The depression in hypoxic pulmonary vasoconstriction in CA may be caused by the decrease of RVW/LVW.

In an attempt to assess the physiological changes that occur in a patient suffering from the sickle cell disease (SCD) and living permanently at a high altitude, hematological parameters (hemoglobin concentration, RBC count, reticulocyte count, MCH, MCHC, MCV, Hb S, F and A₂ levels) and biochemical parameters (serum bilirubin, erythrocyte 2,3-DPG, serum iron, TIBC and haptoglobin levels) were measured in patients with two sickle cell syndromes (homozygous Hb SS and heterozygous Hb S/β°-thalassemia) matched with Hb AA normal controls living at an altitude of 3000m. These parameters were compared with values obtained in similar groups of subjects residing at sea level.

Our results confirm that normal controls permanently residing at altitude have higher hemoglobin concentrations and erythrocyte 2,3-DPG levels than do normal counterparts living at sea level. Patients with SCD living permanently at high altitude show a marked increase in 2,3-DPG levels with little or no change in hemoglobin concentration. Normal serum iron and total iron binding capacity (TIBC) levels in our patients exclude iron deficiency as a possible reason for the poor expected erythropoietic response to altitude. We suggest that the marked rise in 2,3-DPG may be an important aid to oxygen delivery to tissues of SCD patients living at high altitude.

Pit vipers are the predominant venomous serpents of Central and South America. Their bites cause substantial local tissue destruction and other morbidity and if untreated cause significant mortality. Primary treatment is with intravenous equine derived antivenom.

Thirty-eight cases of nonfreezing cold injury (NFCI) occurring during a peacetime military exercise are reported. NFCI occurred in 11% of exposed persons. All cases were classified as moderate, mild or minimal. The racial and smoking histories of the population were retrospectively studied. The incidence of NFCI among black subjects did not differ from that among non-blacks. There was a trend towards increased incidence among smokers (14%) versus nonsmokers (9%) (p=0.09). We conclude that NFCI remains a significant threat for expeditions in cold wet climates. Positive smoking history, but not black race, tended to increase individual risk for NFCI.