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Results for “Altitude”

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At least 73 records · Page 4Linked to original sources

PubMed1996

Cytokines in bronchoalveolar lavage fluid in patients with high altitude pulmonary oedema at moderate altitude in Japan.

BACKGROUND: The precise mechanism of high altitude pulmonary oedema (HAPE) remains unclear. The purpose of this study was to evaluate the role of cytokines and P-selectin in the development of HAPE which occurred at moderate altitude in Japan. METHODS: The following cellular and biochemical markers and chemotactic cytokines were measured in the bronchoalveolar (BAL) fluid from four patients with HAPE at 2857-3180 m in the Japanese Alps: total proteins, albumin, lactate dehydrogenase (LDH), and interleukin (IL)-1 alpha, IL-1 beta, IL-1 receptor antagonist (ra), IL-6, IL-8, IL-10, tumour necrosis factor (TNF)-alpha, and the soluble form of P-selectin. RESULTS: At admission there were significant increases in the levels of total cells, especially macrophages and neutrophils, total protein, albumin and LDH when compared with 13 healthy individuals. Furthermore, the levels of IL-1 beta, IL-6, IL-8, and TNF-alpha were also considerably increased but returned quickly to the normal ranges or were not detected after recovery. The levels of IL-1 alpha, IL-10, and P-selectin did not change. CONCLUSIONS: These results suggest that an inflammatory process almost identical with acute respiratory distress syndrome (ARDS) may occur in HAPE, but that these changes are transient and are not associated with any increase in P-selectin levels in the BAL fluid.

Adult↗

PubMed1978

Further studies on pulmonary oedema of high altitude. Abnormal responses to hypoxia of men who had developed pulmonary oedema at high altitude.

101 Indian soldiers, 57 of whom had developed pulmonary oedema of high altitude (POHA) and 44 who had not developed this condition in spite of being at high altitudes for over 2 years, were investigated for observing the differences, if any, in their reaction to acute hypoxic stress. Each subject was made to breathe a 10% hypoxic mixture for 5 min. Haemodynamic parameters like pulmonary artery pressure (systolic, diastolic and mean), brachial artery pressure, wedge pressure, cardiac output, minute ventilation, arterial oxygen saturation and oxygen uptake before and at the end of hypoxic breathing were estimated. In addition, results of the cold pressor test were recorded and the Vd/Vt ratio was estimated. The results obtained in the present study confirmed those obtained in our previous studies. In addition, it was observed that oxygen uptake was significantly higher and oxygen saturation lower after hypoxia in the POHA subjects than in the controls. Certain parameters for screening of subjects possibly susceptible to POHA have been suggested.

Adult↗

PubMedDate not supplied

[Dynamics of biochemical indices of dog blood serum at high altitudes and on return to low altitude].

The transfer of male dogs from lowlands to an altitude of 3370 m was accompanied by hypoproteinemia and reduction of albumins and beta-globulins, stable increase of activity of alanine aminotransferase, decrease of activity of alkaline phosphatase and content of phosphate. This can be interpreted as a manifestation of adaptive changes of metabolic processes to altitude hypoxia. The return of dogs to lowlands was accompanied by the normalization of the changes during the first 20 days.

Acclimatization↗

PubMedDate not supplied

[Effect of altitude hypoxia on ultrastructure of the left ventricle of rabbit heart and the response of the myocardium to acute verapamil administration at different altitudes].

It was shown in experiments on intact male rabbits that moderate-altitude hypoxia causes over-stress of the cardiomyocyte energy-producing apparatus in unadapted animals. Acute infusion of verapamil leads to a high mortality rate among these animals, whereas among aborigines of moderate and low altitudes as well as among animals living in the planes mortality in acute verapamil infusion does not exceed 30%.

Altitude Sickness↗

PubMedDate not supplied

[Effect of chronic altitude hypoxia on the behavior of the respiratory center. Study on normal subjects living at the altitude of Mexico City (2,240 meters)].

Respiratory center (RC) output has been shown to be increased in hypoxemic Chronic Obstructive patients at sea level. In order to asses the separate role of chronic hypoxia on the RC output we studied 30 normal subjects all of them native and residents of Mexico City (altitude: 2,240 m, PaO2: 65-70 torr.). The parameters studied were: occlussion pressure (P0.1), mean inspiratory flow (Vi), and the ratio inspiratory time to total duration of the respiratory cycle (Ti/Ttot). The inspiratory impedance of the respiratory system as well as the minute ventilation (VE) and lastly to ensure isocapnic conditions, the end-tidal CO2 (PECO2), were also measured. These parameters were determined: 1) While breathing room air (RA), 2) after 30 min of breathing an inspired oxygen fraction (FiO2) of 30% and again 3) after 30 min of breathing and FiO2 of 100%. Fifteen of the subjects were studied on supine and the other 15 in the seated position. In most of the subjects the baseline (RA) values of P0.1 were found to be higher than those reported for normals at sea level. In every case, independent of body position, the P0.1 decreased (less than 0.01) to normal sea level values after 30 min of breathing O2 30%. Likewise, Vi and mechanical impedance also decreased (p less than 0.01) and no changes in Ti/Ttot were noted at this FiO2. No further changes occurred after breathing 100%. The above results show that: 1) The RC output in normal people at altitude (i.e. without mechanical abnormalities but with chronic hypoxia) is increased as compared to sea level.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

High-altitude pulmonary edema: findings at high-altitude chest radiography and physical examination.

Twenty-five male volunteers underwent chest radiography at 550 m above sea level (baseline) and at 4,559 m at 6, 18, and 42 hours after arrival. Nine had a history of high-altitude pulmonary edema (HAPE). Starting by 6 hours and independent of the consecutive presence of HAPE, the diameters of the central pulmonary arteries increased by 10%-30% at 4,559 m. At 18 hours and, increasingly, at 42 hours, radiographic evidence of HAPE developed in eight subjects: six with previously documented HAPE and two without. Radiographic signs of HAPE were most severe peripherally, and morphologic characteristics were compatible with permeability and/or overperfusion edema and normal pulmonary venous pressure. Extensive radiographic findings were accompanied by discrete pulmonary rales, and chest radiography proved valuable in detecting HAPE in subjects with normal findings of lung auscultation. This study demonstrates a significant individual susceptibility of lowland residents with a history of HAPE to develop HAPE, resulting in a recurrence rate of 66%.

Adult↗

PubMed1989

[Sperm count and seminal biochemistry of high altitude inhabitants and patients with chronic altitude sickness].

Semen analysis has been studied in 9 healthy adult males from sea level (150 m), age 19-32 years old and 15 healthy males from high altitude (NA), 9 from Cerro de Pasco (4,300 m) and 6 from Morococha (4,540 m), ages 19-45 years old. Five patients with chronic mountain sickness (MMC), whose ages ranged from 23 to 52 years old were also studied. The volume and motility were similar in NA and MMC, however both were below than in sea level subjects, but still in the normal range; the number of spermatozoa per 1 ml was lower at sea level than in NA and MMC, although the total number was higher at sea level due to the higher semen volume. Fructose at sea level was 356 +/- 53 mg/100 ml (mean +/- S.E.) which is similar to NA 237 +/- 45 whereas a MMC was significantly lower, 142 +/- 60. Citric acid was lower at sea level than in NA and MMC. Na, K and Cl, were similar among the three groups. The lower concentration of fructose in MMC parallels the decreased testicular function already found in these groups. However it is worthy to point out that the fertility is preserved in all the groups. The normal reproductive function in MMC is against the concept that this process occurs as a consequence of environmental disadaptation.

Adult↗

PubMed1995

Effects of long-term acclimatization in lowlanders migrating to high altitude: comparison with high altitude residents.

The physiological response to submaximal and maximal exercise was assessed in lowlanders and Tibetans at low (500 m above sea level) and high altitude (HA, 3,680 m). The times spent at HA by the lowland migrators was 8 days (n = 60), 7 months (n = 60, same group), 15 months (n = 29) and 27 months (n = 29). After the 15-month stay at HA, the maximal oxygen uptake (VO2max) and maximal heart rate of the lowland migrators almost reached those of the HA native residents (Tibetans, n = 57), but their total work capacity and the gross efficiency (eta) of mechanical work remained lower than those of the Tibetans. The rate of VO2max achieved at 90 W by the Tibetans was lower than that of the lowland migrators. It was concluded that, at HA, the lowlanders regained much of the aerobic capacity which they had lost initially. However, they did not attain the same gross mechanical efficiency as the Tibetans, who seemed to be at an advantage in respect of work at HA.

Acclimatization↗

PubMed2002

Selected contribution: High-altitude natives living at sea level acclimatize to high altitude like sea-level natives.

Sea-level (SL) natives acclimatizing to high altitude (HA) increase their acute ventilatory response to hypoxia (AHVR), but HA natives have values for AHVR below those for SL natives at SL (blunting). HA natives who live at SL retain some blunting of AHVR and have more marked blunting to sustained (20-min) hypoxia. This study addressed the question of what happens when HA natives resident at SL return to HA: do they acclimatize like SL natives or revert to the characteristics of HA natives? Fifteen HA natives resident at SL were studied, together with 15 SL natives as controls. Air-breathing end-tidal Pco(2) and AHVR were determined at SL. Subjects were then transported to 4,300 m, where these measurements were repeated on each of the following 5 days. There were no significant differences in the magnitude or time course of the changes in end-tidal Pco(2) and AHVR between the two groups. We conclude that HA natives normally resident at SL undergo ventilatory acclimatization to HA in the same manner as SL natives.

Adaptation, Physiological↗

PubMed1976

[Altitude adaptation. Part II. Altitude adaptation as a problem of human biology. I. Growth)].

There are 3 main components influencing the mean stature of high altitude natives. The lower mean birthweight, which seems to result from the impossibility of complete adaptation during the last trimenon of gestation, which cannot be fully compensated during life. The general protein deficiency, or the habits of nutrition which are not comparable with the food-composition in industry-nations may be important. A definitive undernourishment has not been observed in those nations with longtime adaptation to the available food since generations, but several deficiencies of substances which specially influence growth, cannot be outruled. We also have to recognize the generally lower mean stature of the population in whole (South America Indians), that means of the both parents of a child. In the presence of low gene flow from one to the other generation this may influence also individual body measurement.

Acclimatization↗

PubMed1964