Indirect Measurements of Acceleration Atelectasis and the Role of Inspired Oxygen Concentrations

2021 ◽  
Vol 92 (10) ◽  
pp. 780-785
Author(s):  
Ross D. Pollock ◽  
Sonny D. Gates ◽  
Jeremy J. Radcliffe ◽  
Alec T. Stevenson
Keyword(s):  
Vital Capacity ◽  
Symptom Reporting ◽  
Hypoxic Exposure ◽  
Gas Composition ◽  
Respiratory Resistance ◽  
Indirect Measurements ◽  
Symptom Reports ◽  
Inspired Oxygen ◽  
Oxygen Concentrations

BACKGROUND: A growing number of symptom reports suggestive of acceleration atelectasis in fast jet aircrew have raised the question as to whether traditional guidelines on inspired gas composition remain valid. The aim of this study was to assess the effects of inspired O2 concentration on the development of acceleration atelectasis when wearing modern anti-G garments. METHODS: There were 14 nonaircrew subjects who completed 5 centrifuge exposures to +5 Gz lasting 90 s. During exposures subjects breathed a gas mixture containing 21, 35, 45, 60, or 75% O2. To assess the extent of atelectasis post-Gz, forced inspiratory vital capacity (FIVC), regional FIVC (EITFIVC), shunt, respiratory resistance, reactance, and compliance and peripheral O2 saturation during a hypoxic exposure were measured. RESULTS: Compared with baseline, FIVC was not statistically significantly altered. EITFIVC was 14.4% lower after the 75% O2 exposure only with a greater symptom reporting with higher FIO2 in some individuals. A significantly greater shunt (3>6%) followed the 60 and 75% O2 exposures. O2 concentration during Gz had no effect on respiratory resistance, reactance, compliance, or hypoxemia. DISCUSSION: There is evidence of mild acceleration atelectasis present when breathing 60% O2, particularly in susceptible individuals, with 75% O2 causing more obvious physiological compromise. An inspired oxygen concentration of <60% will prevent the majority of individuals from developing acceleration atelectasis. Pollock RD, Gates SD, Radcliffe JJ, Stevenson AT. Indirect measurements of acceleration atelectasis and the role of inspired oxygen concentrations. Aerosp Med Hum Perform. 2021; 92(10):780785.

scholarly journals What is the Role of Absorption Atelectasis in the Genesis of Perioperative Pulmonary Collapse?

1995 ◽  
Vol 23 (6) ◽  
pp. 691-696 ◽  
Author(s):  
C. J. Joyce ◽  
A. B. Baker
Keyword(s):  
Nitrous Oxide ◽  
Significant Role ◽  
Lung Volume ◽  
Underlying Mechanism ◽  
Gas Absorption ◽  
Experimental Results ◽  
Inspired Oxygen ◽  
Oxygen Concentrations

During anaesthesia the combination of breathing at low lung volume, the administration of nitrous oxide and high inspired oxygen concentrations produces conditions that favour absorption atelectasis. Measures such as adding nitrogen to the inspired mixture and avoiding high inspired oxygen concentrations would reduce the amount of perioperative atelectasis if gas absorption was important in the genesis of perioperative pulmonary collapse. Experimental results demonstrate that these measures do not protect against atelectasis. This indicates that absorption atelectasis does not play a significant role in the genesis of perioperative pulmonary collapse. Compression atelectasis may be the underlying mechanism.

Oxygen Plus Pressure Plus Time: The Etiology of Bronchopulmonary Dysplasia

PEDIATRICS ◽  
1975 ◽  
Vol 55 (1) ◽  
pp. 44-50
Author(s):  
Alistair G. S. Philip
Keyword(s):  
Bronchopulmonary Dysplasia ◽  
Positive Pressure Ventilation ◽  
Underlying Disease ◽  
Assisted Ventilation ◽  
Positive Pressure ◽  
The Relationship ◽  
Inspired Oxygen ◽  
Oxygen Concentrations

Ten infants developed the chronic pulmonary syndrome designated bronchopulmonary dysplasia, following artificial (assisted) ventilation using a volume-regulated positive-pressure respirator. Despite previous reports implicating elevated oxygen concentrations for prolonged periods of time, only two infants required more than 80% oxygen for more than 24 hours, and only one infant required 60% oxygen for more than 100 hours. "Immature" lungs when exposed to inspired oxygen concentrations over 40% for as little as three days via positive-pressure ventilation may develop bronchopulmonary dysplasia. The role of the underlying disease and the relationship with Wilson-Mikity syndrome remain uncertain.

Endothelium-derived relaxing factor activity in rat lung during hypoxic pulmonary vascular remodeling

1993 ◽  
Vol 74 (3) ◽  
pp. 1061-1065 ◽  
Author(s):  
L. Zhao ◽  
D. E. Crawley ◽  
J. M. Hughes ◽  
T. W. Evans ◽  
R. J. Winter
Keyword(s):  
Hypoxic Pulmonary Vasoconstriction ◽  
Hypoxic Exposure ◽  
Control Group ◽  
Pulmonary Vascular Remodeling ◽  
Relaxing Factor ◽  
Pulmonary Vasoconstriction ◽  
O2 Concentration ◽  
Pulmonary Arterial ◽  
Endothelium Derived Relaxing Factor

We have investigated the role of endothelium-derived relaxing factor in modulating hypoxic pulmonary vasoconstriction by inhibiting its synthesis with the false substrate NG-monomethyl-L-arginine (L-NMMA) in the isolated blood-perfused lungs of Wistar rats after chronic hypoxia (CH, fractional inspiratory O2 concentration 10%) for 15 h, 2 days, and 7 days. Lungs were perfused with blood of normal hematocrit at constant flow (18 ml/min) ventilated with 1) 95% air-5% CO2 (normoxia) and 2) 2% O2–5% CO2-93% N2 (hypoxia) and were studied in the absence and presence of L-NMMA (30 and 300 microM) or L-arginine (L-Arg, 1 and 6 mM) in separate groups. Pulmonary arterial pressure (Ppa) rose incrementally with hypoxic exposure (all P < 0.05 vs. normoxic control group). Hypoxic pulmonary vasoconstriction (HPV) was markedly reduced after 15 h and 2 days of CH: the mean increases in Ppa (delta Ppa) in hypoxia were 15.3, 3.5, 3.8, and 13.6 mmHg in control rats and rats exposed to 15 h (P < 0.05 vs. control and 7 days of CH), 2 days (P < 0.001 vs. control and 7 days of CH), and 7 days of CH, respectively. Ppa in control rats and rats exposed to 15 h, 2 days, and 7 days of CH were 137, 179, 184, and 166% of control, respectively, after 30 microM L-NMMA (all P < 0.05 when expressed as percent change vs. no L-NMMA). Similar augmentation in HPV was seen after 30 microM L-NMMA, with all hypoxic groups having a greater response than control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals THE ROLE OF OXYGEN IN THE REGULATION OF ERYTHROPOIESIS. DEPRESSION OF THE RATE OF DELIVERY OF NEW RED CELLS TO THE BLOOD BY HIGH CONCENTRATIONS OF INSPIRED OXYGEN 12

1949 ◽  
Vol 28 (6 Pt 2) ◽  
pp. 1544-1564 ◽  
Author(s):  
John C. Tinsley ◽  
Carl V. Moore ◽  
Reubenia Dubach ◽  
Virginia Minnich ◽  
Moises Grinstein
Keyword(s):  
Red Cells ◽  
High Concentrations ◽  
Inspired Oxygen

scholarly journals The Role of Pressure and Duration of Dive on Lung Physiology in Professional and Non-Professional Divers

2020 ◽  
Vol 40 (2) ◽  
pp. 103-112
Author(s):  
Jerry Indra Setiawan ◽  
Suradi Suradi ◽  
Yusup Subagio Sutanto
Keyword(s):  
Vital Capacity ◽  
Cross Sectional Study ◽  
Professional Group ◽  
Sectional Study ◽  
Test Statistic ◽  
Cross Sectional ◽  
Lung Physiology ◽  
Significant Difference ◽  
Normally Distributed

Backgrounds: Professional divers have a greater lung volume than non-professional divers in higher force vital capacity (FVC) and force expiratory flow in 1 second (FEV1) values. The purpose of this study is to analyse the effect of pressure and duration of diving on changes in lung physiology in professional divers and non-professional divers. Methods: This is a cross sectional study on the personnel of the Indonesian Navy Dislambair Koarmada II Surabaya and RSAL personnel of dr. Ramelan Navy Hospital in Lakesla Surabaya in March-April 2019. Samples was collected with purposive sampling. This study used unpaired subjects with the independent t-test statistic analysis if the data is normally distributed and the Mann-Whitney U test if the data is not normally distributed Results: There was a significant difference in the professional divers group compared to non-professional divers group in the values of FVC (P=0.042) and FEV1 (P=0.040) at 1.3 ATA for 10 minutes and the FEV1 (P=0.049) for 20 minutes. No significant differences in FVC (P=0.092) at 1.3 ATA pressure for 20 minutes. There were no significant differences in FVC (P=0.865), FEV1 (P=0.659) at 1.5 ATA pressure for 10 minutes and FVC (P=0.858) and FEV1 (P=0.857) for 20 minutes. Conclusions: The different pressure in non-professional group could reduce the FEV1 value. There was a difference in the FVC value of the professional diver group and non-professional divers at a pressure of 1.5 ATA for 10 minutes. (J Respir Indo. 2020; 40(2): 103-12)

scholarly journals First In-Situ Measurements of Plume Chemistry at Mount Garet Volcano, Island of Gaua (Vanuatu)

2020 ◽  
Vol 10 (20) ◽  
pp. 7293
Author(s):  
Joao Lages ◽  
Yves Moussallam ◽  
Philipson Bani ◽  
Nial Peters ◽  
Alessandro Aiuppa ◽  
...  
Keyword(s):  
High Temperature ◽  
Emission Rates ◽  
Gas Composition ◽  
Gas Analyzer ◽  
Total Volatile ◽  
Volcanic Gas ◽  
So2 Flux ◽  
Gas Chemistry

Recent volcanic gas compilations have urged the need to expand in-situ plume measurements to poorly studied, remote volcanic regions. Despite being recognized as one of the main volcanic epicenters on the planet, the Vanuatu arc remains poorly characterized for its subaerial emissions and their chemical imprints. Here, we report on the first plume chemistry data for Mount Garet, on the island of Gaua, one of the few persistent volatile emitters along the Vanuatu arc. Data were collected with a multi-component gas analyzer system (multi-GAS) during a field campaign in December 2018. The average volcanic gas chemistry is characterized by mean molar CO2/SO2, H2O/SO2, H2S/SO2 and H2/SO2 ratios of 0.87, 47.2, 0.13 and 0.01, respectively. Molar proportions in the gas plume are estimated at 95.9 ± 11.6, 1.8 ± 0.5, 2.0 ± 0.01, 0.26 ± 0.02 and 0.06 ± 0.01, for H2O, CO2, SO2, H2S and H2. Using the satellite-based 10-year (2005–2015) averaged SO2 flux of ~434 t d−1 for Mt. Garet, we estimate a total volatile output of about 6482 t d−1 (CO2 ~259 t d−1; H2O ~5758 t d−1; H2S ~30 t d−1; H2 ~0.5 t d−1). This may be representative of a quiescent, yet persistent degassing period at Mt. Garet; whilst, as indicated by SO2 flux reports for the 2009–2010 unrest, emissions can be much higher during eruptive episodes. Our estimated emission rates and gas composition for Mount Garet provide insightful information on volcanic gas signatures in the northernmost part of the Vanuatu Arc Segment. The apparent CO2-poor signature of high-temperature plume degassing at Mount Garet raises questions on the nature of sediments being subducted in this region of the arc and the possible role of the slab as the source of subaerial CO2. In order to better address the dynamics of along-arc volatile recycling, more volcanic gas surveys are needed focusing on northern Vanuatu volcanoes.

The Stocks Suction Bullet

1978 ◽  
Vol 6 (3) ◽  
pp. 185-199 ◽  
Author(s):  
D. R. Kerr ◽  
J. B. Vonwiller ◽  
N. Abrahams
Keyword(s):  
Positive Pressure Ventilation ◽  
Positive Pressure ◽  
Suction Catheter ◽  
Suction Pressure ◽  
Pressure Limit ◽  
Experimental Apparatus ◽  
Peak Pressures ◽  
Inspired Oxygen ◽  
Ventilator Settings ◽  
Oxygen Concentrations

The Stocks suction bullet is a device allowing maintenance of positive pressure ventilation, continuous distending pressure and high inspired oxygen concentrations during tracheal toilet in intubated patients. The effectiveness of this device was studied using an experimental apparatus and a dummy lung to represent neonates being treated with either C.P.A.P. or I.P.P.V. and P.E.E.P. By using appropriate combinations of suction catheter type and size, bullet lumen size, ventilator settings and suction pressure limit, it was possible to maintain during suctioning ventilation peak pressures between 50% and 100% of presuction levels and continuous distending pressures (P.E.E.P. or C.P.A.P.) at or in excess of 80% of presuction levels.

Role of sex hormones in development of chronic mountain sickness in rats

1994 ◽  
Vol 77 (1) ◽  
pp. 427-433 ◽  
Author(s):  
L. C. Ou ◽  
G. L. Sardella ◽  
J. C. Leiter ◽  
T. Brinck-Johnsen ◽  
R. P. Smith
Keyword(s):  
Gender Differences ◽  
Pulmonary Hypertension ◽  
High Altitude ◽  
Sex Hormones ◽  
Systolic Pressure ◽  
Female Rats ◽  
Hypoxic Exposure ◽  
Chronic Mountain Sickness ◽  
Mountain Sickness

After chronic exposure to hypoxia, Hilltop Sprague-Dawley rats developed excessive polycythemia and severe pulmonary hypertension and right ventricular (RV) hypertrophy, signs consistent with human chronic mountain sickness; however, there were gender differences in the magnitude of the polycythemia and susceptibility to the fatal consequence of chronic mountain sickness. Orchiectomy and ovariectomy were performed to evaluate the role of sex hormones in the gender differences in these hypoxic responses. After 40 days of exposure to simulated high altitude (5,500 m; barometric pressure of 370 Torr and inspired Po2 of 73 Torr), both sham-gonadectomized male and female rats developed polycythemia and had increased RV peak systolic pressure and RV hypertrophy. The hematocrit was slightly but significantly higher in males than in females. Orchiectomy did not affect these hypoxic responses, although total ventricular weight was less in the castrated high-altitude rats. At high altitude, the mortality rates were 67% in the sham-operated male rats and 50% in the castrated animals. In contrast, ovariectomy aggravated the high-altitude-associated polycythemia and increased RV peak systolic pressure and RV weight compared with the sham-operated high-altitude female rats. Both sham-operated control and ovariectomized females suffered negligible mortality at high altitude. The present study demonstrated that 1) the male sex hormones play no role in the development of the excessive polycythemia, pulmonary hypertension, and RV hypertrophy during chronic hypoxic exposure or in the associated high mortality and 2) the female sex hormones suppressed both the polycythemic and cardiopulmonary responses in vivo during chronic hypoxic exposure.

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