Aviat Space Envir Md
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Aviat Space Envir Md · Sep 2013
Intracranial pressure and optic nerve sheath diameter as cephalic venous pressure increases in swine.
Nontraumatic, nonhydrocephalic increases in intracranial pressure (ICP) are often difficult to diagnose and may underlie spaceflight-related visual changes. This study looked at the utility of a porcine animal model of increasing cephalic venous pressure to mimic acute changes in ICP and optic nerve sheath diameter (ONSD) from cephalic venous fluid shifts observed during spaceflight. ⋯ Increases in SVCP result in ICP changes that are well correlated with alteration in ONSD. These changes are consistent with observed ONSD changes monitored during spaceflight.
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Aviat Space Envir Md · Sep 2013
Sensorineural hearing loss incidence among U.S. military aviators between 1997 and 2011.
Noise-induced hearing loss is the most common cause of sensorineural hearing loss (SNHL) in military aviation. Few published studies compare SNHL rates between fixed and rotary-wing military pilots. The study's objective was to determine whether a difference in mean annual SNHL incidence rate exists between fixed and rotary wing aviators in the U.S. Army, Navy, Air Force, and Marines. ⋯ The average annual incidence rate of SNHL between 1997-2011 was higher for fixed than for rotary-wing aviators, and higher for U.S. Army and Air Force than Navy and Marine aviators. An examination of hearing conservation programs and engineering controls may be warranted.
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The major causes of in-flight fatal incapacitation in civil pilots are acute coronary events, new onset idiopathic epilepsy, and physiological problems. Less than 1% of all air accidents are due to sudden incapacitaion. The problem with acute coronary disease is very serious when occurring during critical stages of the flight, such as takeoff or landing, rather than during the cruising phase. ⋯ The normal aorta contains collagen, elastin, and smooth muscle cells that form the vessel wall. Degenerative changes lead to breakdown of the collagen, elastin, and smooth muscle, and an increase in basophillic ground substance with the formation of cysts and accumulation of mucopolysaccharide. Medical incapacitation in the cockpit is rare. The leading causes of fatal in-flight incapacitation are myocardial infarction, cardiac arrhythmias, and epileptic seizures; cystic medial necrosis is very rare and no similar cases were found in the aviation literature.
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Aviat Space Envir Md · Sep 2013
A sensitive shock index for real-time patient assessment during simulated hemorrhage.
Shock index [SI = the ratio of heart rate (HR) to systolic arterial pressure (SAP)] is a metric used to diagnose patients at risk of impending hemorrhagic shock. We hypothesized that a metric called the compensatory reserve index (CRI), derived using computer modeling with continuous feature extraction from arterial waveforms, would provide an earlier indicator of cardiovascular instability than SI during progressive central hypovolemia. ⋯ CRI provided a significantly earlier indicator of impending hemodynamic decompensation than SI > or = 0.9 during progressive LBNP. These results support the notion that the CRI represents an improved 'shock index' as an indicator of impending hemorrhagic shock compared to standard vital signs.