PubMed · 14191629
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R LEFRANCOIS, P PASQUIS. 1964-10-17. [HYPOXIA].. https://pubmed.ncbi.nlm.nih.gov/14191629/
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This study assessed changes in forest cover in a mountain watershed in central Nepal between 1976 and 2000 by comparing classified satellite images coupled by GIS analyses, and examined the association of forest change with major physiographic, economic, and local forest governance parameters. The results showed an increase in forested area (forest plus shrublands) by 7.6% during 1976-2000. Forest dynamism (changes including improvement, deterioration, gain, and loss) was highest in low-elevation, south-facing and less-steep slopes that were closer to roads. Proportionately the highest net improvement and gain to forested area also took place in those locations. Forest degradation occurred at twice the rate of improvement in high elevation areas (> 2300 m). Forests located in urban and semiurban areas (i.e., a market-oriented economy) experienced a proportionately higher amount of net improvement and gain than forests in rural areas (i.e., a subsistence economy). Among the three governance arrangements, proportionately the highest net improvement and gain took place in semigovernment forests (forested area legally under the forest department but with de facto control and claim of ownership by local communities and/or municipality) followed by formalized community forests (including leasehold). Government forests, which were mostly found in the southern high mountains and had virtually open access, remained relatively stable during the study period. Over 50% of the watershed forests have not come under community-based management despite favorable policy and more than two decades of government intervention with continuous donor support. The findings indicate that the present "one size fits all" approach of community forest handover policy in Nepal needs rethinking to accommodate biophysical and socioeconomic variations across the country.
OBJECTIVE: To describe the response to exercise of normal subjects and patients with chronic obstructive pulmonary disease (COPD) in Bogota, Colombia (altitude: 2640 m; atmospheric pressure: 560 mm Hg) and compare it with data published on COPD patients at sea level. Healthy people increase their minute ventilation to attenuate hypoxemia (PaCO2: 30 mm Hg; PaO2: 63 mm Hg). MATERIAL AND METHOD: A descriptive study was carried out on healthy subjects and COPD patients. Exercise limitation was determined by an incremental test on a cycle ergometer. RESULTS: The study enrolled 16 healthy subjects and 25 COPD patients (forced expiratory volume in 1 second: 43.3% [SD 13%]). Minute ventilation at rest was greater in COPD patients compared with healthy subjects, it was not adequately sustained during exercise, and there was a reduction in peak oxygen uptake (53.0% [15%]). At peak exercise, inspiratory capacity decreased (-0.62 [0.34] L), the ratio of minute ventilation to maximal voluntary ventilation increased, and severe hypoxemia occurred (PaO2: 49.9 [9.9] mm Hg). There was significant correlation between hypoxemia and the percentage of predicted peak oxygen uptake (r=0.60), leg fatigue (r=-0.62), percentage of predicted peak inspiratory capacity (r=0.61), and the percentage of predicted peak tidal volume (r=0.49). Minute ventilation at rest was shown to be higher, there was a greater reduction in the inspiratory capacity during exercise, and hypoxemia was more severe at rest and during exercise for patients with COPD in Bogota, compared with those at sea level. CONCLUSIONS: Patients with COPD living in Bogota were shown to have lower tolerance to exercise evidenced by ventilatory limitation and severe hypoxemia. Increased minute ventilation at rest, greater reduction in inspiratory capacity, and severity of hypoxemia during exercise were the main differences between COPD in Bogota and at sea level.
The effects of different volumes of fluid resuscitation on traumatic hemorrhagic shock in unacclimated rats to high altitude were investigated. Seventy-eight Wistar rats were transported to LaSa, Tibet, 3760 meters above sea level, and traumatic hemorrhagic shock was induced by right-femur fracture plus bleeding to 45 mmHg of mean arterial pressure (MAP) for 1 h under the anesthesia of sodium pentobarbital (40 mg/kg, i.p.). Experiments were conducted in two series. In series I, 36 rats were equally divided into six groups: sham-operated, untreated (traumatic shock without fluid infusion), and with lactated Ringer's resuscitation (LR) of 1.0, 1.5, 2.0 or 3.0 times the shed blood (1, 1.5, 2, 3 vol LR group). MAP, left intraventricular systolic pressure, the maximal change rate of intraventricular pressure rise or decline (+/-dp/dtmax), the maximal physiological velocity of contractile element shortening, and the area of left intraventricular pressure-dp/dt vector loop (Lo) were observed at 30, 60, 90, and 120 min and the blood gases were determined at 30 and 120 min after resuscitation. Meanwhile the survival time was observed after the observation period. In series II, 42 rats were used to observe the effects of different volumes of fluid resuscitation on water content of lung and brain and hematocrit. One and 1.5 vol LR resuscitation significantly lifted MAP, left intraventricular systolic pressure, +dp/dtmax, and Lo, partially improved the blood gases and significantly prolonged the survival time. Although 2 and 3 vol of LR resuscitation caused apparent hemodilution and lung edema, they only partially improved hemodynamic parameters. Meanwhile 2 and 3 vol of LR resuscitation decreased the survival time. These results suggest that 1 and 1.5 vol of LR resuscitation can effectively resuscitate traumatic hemorrhagic shock at high altitude. More than two volumes of LR resuscitation would deteriorate the resuscitation outcome.