Aviat Space Envir Md
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Aviat Space Envir Md · Feb 2000
Case ReportsPulmonary cyst and cerebral arterial gas embolism in a hypobaric chamber: a case report.
This is a report of an aircrew member who suffered a serious physiological incident in the form of pulmonary barotrauma and cerebral arterial gas embolism during hypobaric chamber training, and who subsequently was shown to have a cyst in the upper lobe of the left lung. The likely origin of the cyst is discussed, as well as the aeromedical disposition following thoracotomy and apical segmentectomy to remove the cyst.
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Aviat Space Envir Md · Dec 1999
Comparative StudyDo standard monitoring sites affect true brain temperature when hyperthermia is rapidly induced and reversed.
Accurate measurements of brain and core temperatures during warming and cooling of the whole organism, accidentally or therapeutically, are important for studies of thermoregulation and cerebral insults and resuscitation. ⋯ In normal dogs and monkeys, rectal, esophageal and nasopharyngeal temperatures are almost identical with brain temperatures; but during rapid external warming or cooling, brain temperature is reflected in nasopharyngeal temperature, somewhat in higher esophageal temperature, but not in even higher rectal temperature. For clinical monitoring during temperature changes, one should use primarily esophageal temperature and, if feasible, brain (epidural) temperature as well.
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Aviat Space Envir Md · Nov 1999
Immersion of distal arms and legs in warm water (AVA rewarming) effectively rewarms mildly hypothermic humans.
Active rewarming of hypothermic victims for field use, and where transport to medical facilities is impossible, might be the only way to restore deep body temperature. In active rewarming in warm water, there has been a controversy concerning whether arms and legs should be immersed in the water or left out. Further, it has been suggested in the Royal Danish Navy treatment regime, that immersion of hands, forearms, feet, and lower legs alone might accomplish rapid rates of rewarming (AVA rewarming). ⋯ The extremity rewarming procedure was experienced by the subjects as the most comfortable as the rapid rise in deep body temperature shortened the period of shivering. During the extremity rewarming procedures the rectal temperature lagged considerably behind the esophageal and aural canal (via indwelling thermocouple) temperatures. Thus large gradients may still exist between body compartments even though the heart is warmed.
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Aviat Space Envir Md · Sep 1999
Short hypobaric hypoxia and breathing pattern: effect of positive end expiratory pressure.
The ventilatory effects of a 5-cm H2O positive end expiratory pressure (PEEP) and its influence on the breathing pattern during short hypoxic exposure both at rest and during physical exercise were studied. There were 22 healthy subjects who were submitted to normoxia and to 4-h of hypoxia in a hypobaric chamber (4500 m, PB = 589 hPa) both at rest and during an 8-min cycle ergometer exercise (100 W) without and with a 5 cm H2O PEEP. The results show that hypoxia compared with normoxia induces increases in tidal volume (VT) (+28.5%, p < 0.05 at rest; and +19.4%, p < 0.01 at 100 W) and in respiratory frequency (f) at 100 W (p < 0.05), and significant decreases in inspiratory (tI) (p < 0.05 at rest and at 100 W), and expiratory (tE) durations (p < 0.05 at 100 W). ⋯ However, PEEP does not alter the breathing pattern in hypoxia since VT/tI and tI/tt are unchanged. Heart rate and arterial O2 saturation are also unaffected by PEEP. In conclusion, this study shows that a 4-h hypoxia modifies ventilatory parameters and mean inspiratory flow (VT/tI) at rest and during exercise (100 W), whereas a 5-cm H2O PEEP does not alter the breathing pattern despite changes in ventilatory parameters are observed.
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Aviat Space Envir Md · Aug 1999
Comparative StudyPositive pressure generation by pneumatic and electronic O2 regulators: a bench experimental evaluation.
The introduction of advanced anti-G protection into agile fast fighter aircraft may result in the regular use of positive pressure breathing (PPB) for G protection by aircrew. Since PPB results in an external additional work of breathing (WoB), we compared the mechanical performance of the pneumatic and electronic O2 regulators designed for "Mirage 2000" and "Rafale" aircraft. ⋯ We concluded that the electronic control of mask pressure is relatively efficient but that the device would be improved by placing the site of the pressure measurement into the mask.