scholarly journals Potential for hypoxic gas mixture delivery using a Flexima 2 anaesthetic machine

Anaesthesia ◽  
2016 ◽  
Vol 71 (11) ◽  
pp. 1380-1381
Author(s):  
C. Turnbull ◽  
T. Dexter
Keyword(s):  
Anaesthetic Machine ◽  
Gas Mixture ◽  
Hypoxic Gas Mixture

Hyperoxia prevents hypoxia-induced bronchial hyperreactivity via a cyclooxygenase-independent mechanism

1991 ◽  
Vol 70 (2) ◽  
pp. 740-747 ◽  
Author(s):  
J. D'Brot ◽  
T. Ahmed
Keyword(s):  
Airway Responsiveness ◽  
Prior Exposure ◽  
Gas Mixture ◽  
Protective Effects ◽  
Bronchial Reactivity ◽  
Independent Mechanism ◽  
Before And After ◽  
Sham Exposure ◽  
Hypoxic Gas Mixture ◽  
Dependent Mechanism

We tested the hypothesis that prior exposure to alveolar hyperoxia prevents the hypoxia-induced enhancement of bronchial reactivity, possibly via a cyclooxygenase-dependent mechanism. In 15 sheep, specific lung resistance (sRL) was measured before and after 30 min of exposure to either air or a hypoxic gas mixture (13% O2). The sheep then inhaled 50 breaths of aerosolized 5% histamine solution (n = 9) or 10 breaths of 2.5% carbachol solution (n = 9), and measurements of sRL were repeated. On subsequent days the above protocols were repeated after a 30-min exposure to hyperoxia (O2 greater than or equal to 95%), without or after pretreatment with indomethacin (2 mg/kg). After air-sham exposure, carbachol and histamine increased mean sRL to 370 +/- 40 (SE) and 309 +/- 65% of baseline, respectively. Exposure to the hypoxic gas mixture had no effect on baseline sRL but enhanced the airway responsiveness to carbachol and histamine; mean sRL increased to 740 +/- 104 and 544 +/- 76% of baseline, respectively (P less than 0.05). Prior 30-min exposure to hyperoxia prevented the hypoxia-induced enhancement of bronchial reactivity to carbachol (sRL = 416 +/- 66% of baseline) and histamine (sRL = 292 +/- 41% of baseline) without affecting the airway responsiveness to these agents after air. Pretreatment with indomethacin did not reverse the protective effects of hyperoxia or the hypoxia-induced enhancement of bronchial reactivity. We conclude that 1) prior exposure to alveolar hyperoxia prevents the hypoxia-induced enhancement of bronchial reactivity and 2) neither the protective effects of hyperoxia nor the hypoxia-induced enhancement of bronchial reactivity is mediated via a cyclooxygenase-dependent mechanism.

Kinetics of Oxygen Uptake for Submaximal Exercise in Hyperoxia, Normoxia, and Hypoxia

1995 ◽  
Vol 20 (2) ◽  
pp. 198-210 ◽  
Author(s):  
Richard L. Hughson ◽  
John M. Kowalchuk
Keyword(s):  
Ventilatory Threshold ◽  
Binary Sequence ◽  
Submaximal Exercise ◽  
Work Rate ◽  
Oxygen Deficit ◽  
Gas Mixture ◽  
Pseudorandom Binary Sequence ◽  
Upper Limit ◽  
Kinetics Of ◽  
Hypoxic Gas Mixture

This study evaluated the dynamic response of [Formula: see text] in 6 healthy men at the onset and end of submaximal step changes in work rate during a pseudorandom binary sequence (PRBS) exercise test and during ramp incremental exercise to exhaustion while breathing three different gas mixtures. The fractional concentrations of inspired O2 were 0.14, 0.21, and 0.70 for the hypoxic, normoxic, and hyperoxic tests, respectively. Both maximal [Formula: see text] and work rate was significantly reduced in hypoxic tests compared to normoxic and hyperoxic tests. Maximal work rate was greater in hyperoxia than in normoxia. Work rate at ventilatory threshold was lower in hypoxia than in normoxia and hyperoxia but above the upper limit of exercise for the submaximal tests. Hypoxia significantly slowed the response of [Formula: see text] both at the onset and end of exercise compared to normoxia and hyperoxia. Hypoxia also modified the response to PRBS exercise, and again there was no difference between normoxia and hyperoxia. These data support the concept that [Formula: see text] kinetics can be slowed from the normoxic response by a hypoxic gas mixture. Key words: [Formula: see text]max, ventilatory threshold, oxygen deficit, pseudorandom binary sequence

An analysis of commercially recommended profiles for normobaric preacclimatization

2021 ◽  
Vol 14 (1) ◽  
pp. 25-29
Author(s):  
Markus Tannheimer ◽  
Raimund Lechner
Keyword(s):  
Gas Mixture ◽  
Slow Increase ◽  
Helicopter Flight ◽  
Hypoxic Training ◽  
Base Camp ◽  
Hypoxic Gas Mixture ◽  
Healthy Persons ◽  
At Home

Introduction: Normobaric hypoxic training (NHT) for preacclimatization at home has found its way into commercial expedition mountaineering. Portable NH-generators produce a normobaric hypoxic gas mixture that can be inhaled using breathing masks at rest or during exercise or it can be pumped into lightweight tents for sleeping. These devices can be rented from commercial companies. Materials and methods: Prior to an expedition to Manaslu (8163 m) NHT was used for preacclimatization over a period of 10 days. Our regimen involved a greater increase in sleeping altitude (10 nights to reach 5400 m) than recommended by the rental company (30 nights to reach 3900 m). Results: No incidents occurred during NHT. Our regimen induced sufficient acclimatization to Manaslu Base Camp (4900 m), as evidenced by the fact that none of the expedition members suffered from AMS although they reached base camp within 2 days from Kathmandu – by helicopter flight to 3500 m and a one day walk the next day. Eight days after leaving Kathmandu, camp III was reached at 6850 m. Conclusions: At natural altitudes above 2500 m an increase of sleeping altitude should not exceed 300-500 m per day. Below 2500 m, there are no restrictions. It is therefore unclear why the company recommends such a slow increase in sleeping altitude. In our opinion, it is not necessary for healthy persons to start with a sleeping altitude below 2500 m. In contrast to natural altitudes, NH exposure can be instantly stopped if symptoms occur. Therefore, it seems safe to expose healthy persons to more liberal normobarichypoxic conditions.

scholarly journals METABOLIC CHANGES IN HUMANS UPON LONG-TERM CONTAINMENT IN AN ARGON-BASED HYPOXIC GAS MIXTURE

2018 ◽  
Vol 4 (2) ◽  
pp. 7-14
Author(s):  
A. O. Ivanov ◽  
V. S. Petrov ◽  
E. N. Bezkishkiy ◽  
A. Yu. Yeroshenko ◽  
N. V. Kochubeychik ◽  
...  
Keyword(s):  
Cholesterol Metabolism ◽  
Venous Blood ◽  
Gas Mixture ◽  
Atherogenicity Index ◽  
Gradual Accumulation ◽  
The Subject ◽  
Male Subjects ◽  
Oxidized Products ◽  
Hypoxic Gas Mixture

The objective of the present study was an in-depth assessment of the main human metabolic parameters upon longterm (60 days) containment in a normobaric argon-based hypoxic gas mixture (AHGM) for checking the possibility to develop gas media able to reduce the risk of ignitions and fires in inhabited sealed objects, such as submarines. Study group included six male subjects aged 20 to 51 years and found to be fit for sea trips lasting for up to 90 days. Continuing containment in the test medium comprising 30–35% V/V argon, 13,3–14,5% V/V oxygen, and up to 0,8% V/V, the rest being nitrogen, lasted for 60 days. During this time the subject were engaged in typical physical activities and operator routines. Venous blood samples were taken before, every 15 days in the course of, and 5 days after containment. This regimen has been found to be associated with the gradual accumulation of under-oxidized products of carbohydrate, protein and cholesterol metabolism in the blood and with increasing atherogenicity index. Adaptation to this regimen was manifested as decreases in the magnitudes of the above changes suggesting that metabolism may be tuned to increase body tolerance to hypoxia. Within 5 days after containment, virtually complete normalization of parameters studied was observed. The data confirm that it is possible to make gas mixtures for improving fire safety of inhabited sealed objects, in particular submarines.

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