Aviat Space Envir Md
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Acceleration atelectasis is the absorptional collapse of alveoli in the dependent lung due to increased accelerative forces. It is exacerbated by breathing 100% oxygen and, during +Gz exposure, by the use of an anti-G suit. Experiments were conducted on 12 subjects using simulated aerial combat maneuvers (SACM) with G profiles having peak exposures of either 4.5 G or 9 G. ⋯ Acceleration atelectasis causes symptoms of chest pain, coughing, and shortness of breath. Subjective ratings of the severity of these symptoms were obtained from the subjects, and these were much greater following the 4.5-G SACM exposures than after the 9-G runs. Acceleration atelectasis was reduced by dilution of the inspired oxygen concentration by argon and nitrogen (evaluated at 95, 82.5, 70, 50, and 20% oxygen); the addition of unassisted positive pressure at 30 mm Hg (4 kPa) to the breathing mask; or the performance of the anti-G straining maneuver (AGSM).
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Aviat Space Envir Md · Oct 1986
Pulmonary barotrauma in divers and the treatment of cerebral arterial gas embolism.
A review of case records spanning 20 years revealed 140 cases of decompression pulmonary barotrauma (PBT) in divers. There were 23 cases of uncomplicated PBT and 117 cases of cerebral arterial gas embolism (AGE), of which 58 had respiratory manifestations. Details of presentation and precipitating factors were analysed. ⋯ No cases receiving steroids relapsed. Increasing the time to treatment reduced the likelihood of cure. Comparison of treatments proved difficult and it was concluded that, although most cases would probably respond satisfactorily to 2.8 bar (2100 mm Hg) of oxygen, there were no compelling reasons for altering the current treatment practice of beginning treatment of acute cases with a 30-min period at 6.0 bar (165 fsw) before returning to 2.8 bar (60 fsw) to complete the therapy.
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Prior attempts at establishing minimal federal air ambulance regulations and standards have been unsuccessful. However, reports of poor patient medical care during transport by some air ambulance services is now forcing many states to initiate air ambulance regulations. ⋯ Minimum air ambulance regulations were then established for aircraft configuration, flight crew requirements, minimal equipment and medications, and the responsibilities of the medical director or designee for each of the three levels of medical care. We conclude that the application of a levels approach based upon the patient's medical requirements may be useful in assisting other states attempting to establish flexible but specific regulations directed at the safe transport of patients by aeromedical evacuation.
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Aviat Space Envir Md · Jun 1986
Biography Historical ArticleStrategic aeromedical evacuation: the inaugural flight.
Strategic aeromedical evacuation, a vital subsystem of the overall aeromedical airlift system, had its beginning in a confidential, poorly planned, poorly coordinated Air Transport Command flight from Karachi, Pakistan (then part of India) to Washington, DC, in January 1943. That the flight was successfully completed was due in large measure to the untiring efforts of the nurse, Second Lieutenant Elsie S. Ott, aboard the flight. ⋯ Largely through Lt. Ott's efforts, long range aeromedical evacuation was demonstrated to be a practicable method of transportation for seriously ill and wounded patients. A new dimension had been added to the overall aeromedical airlift mission.
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Central hemodynamics have been determined during stepwise decreasing LBP in head-down tilt (HDT) of -6 degrees. Measurements were performed on eight healthy volunteers using right heart catheterization. During LBNP, pressures in the right atrium, pulmonary artery, and pulmonary capillary (preload) decreased in parallel with the increase of negative pressure applied to the lower part of the body. ⋯ There was a very close correlation between stroke volume determined by thermodilution and by echocardiography. Plasma norepinephrine and dopamine tended to increase at the end of LBNP. Echocardiography proved a useful and reliable approach to hemodynamic measurement during LBNP and is recommended for analysis of hemodynamic parameters during zero G and Gz simulation.