Aviat Space Envir Md
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Aviat Space Envir Md · Jul 1998
Estimated individual annual cosmic radiation doses for flight crews.
Individual annual cosmic radiation doses for fulltime airline crewmembers were calculated for 12 consecutive months using data from flight profiles and previously reported cosmic radiation intensity measurements at various altitudes. ⋯ The calculated individual doses reflect the type of aircraft flown and the amount of flight time. The calculated doses are lower than those received by simply assuming constant radiation exposure at all altitudes during flight. Annual individual doses are well below the maximum 5 mSv x a(-1) allowed by the national laws.
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An experiment on the relationship between aeromedical color vision screening test performance and performance on color-dependent tasks of Air Traffic Control Specialists (ATCS) was replicated to expand the database supporting the job-related validity of 13 FAA-accepted screening tests. ⋯ The aeromedical screening tests were generally acceptable in terms of selecting individuals who did not make errors on ATCS color tests, but several tests had high false alarm rates. High job-related validity, in the vicinity of 0.90, was confirmed for several aeromedical color vision tests used for ATCS screening.
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Aviat Space Envir Md · Jun 1998
Case ReportsAltitude-induced migraine headache secondary to pravastatin: case report.
A 46-yr-old airline captain with many exposures to altitude chamber, fighter, and airliner flight developed migraine-type headaches after exposure to cabin altitudes above 6,000 feet. He had no prior history of chronic headaches or migraine. Symptoms began within days of starting pravastatin for hypercholesterolemia, but had not occurred during 4 yr of treatment with lovastatin. ⋯ Although the HMG-CoA reductase inhibitors are reported to be associated with increased occurrence of headache, the mechanism is poorly understood. Migraine headaches may be triggered in previously asymptomatic individuals by unique combinations of trigger factors. However, there have been no prior reports of migraine headaches triggered by the combined exposure to pravastatin and reduced barometric pressure.
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Aviat Space Envir Md · Apr 1998
Hypercapnic ventilatory response in humans before, during, and after 23 days of low level CO2 exposure.
Alterations in ventilation and the chemoreceptor response to CO2 during 23 d of 1.2% inspired CO2 were studied in four male subjects. Resting ventilation (VE), tidal volume (VT), respiratory frequency (fR), inspired and end tidal O2 and CO2 and the hypercapnic ventilatory response (HCVR) measured by CO2 rebreathing were measured once before entering the chamber, on days 2, 5, 11, and 22 of CO2 exposure, and one day after. Resting VE slightly increased (5%) on day 2 of exposure and significantly increased (22%) by day 5 followed by a progressive decrease to pre-chamber levels by day 22 and on the first day of recovery. ⋯ The VE60 decreased by approximately 32% and 16% on day 2 and 5, respectively, then returned within pre-exposure range for the remainder of the exposure and during recovery. During the early phase and one day after the exposure the HCVR was right shifted. One day after exposure chemoreceptor sensitivity to elevated CO2 was increased but, the B was right shifted resulting in a reduced HCVR below PCO2 of 60 mmHg and a greater HCVR above 60 mmHg.
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Aviat Space Envir Md · Apr 1998
An abrupt zero-preoxygenation altitude threshold for decompression sickness symptoms.
The altitude threshold for decompression sickness (DCS) symptoms has been variously described as being 18,000 ft (5,487 m) to above 25,000 ft (7,620 m). Safety and efficiency of aerospace operations require more precise determination of the DCS threshold. ⋯ A 5% threshold for DCS symptoms was concluded to be 20,500 ft under the conditions of this study. The abrupt increase in DCS symptoms, with zero-preoxygenation exposure above 21,200 ft implies a need for reconsideration of current USAF and FAA altitude exposure guidance.