Our stroke teams should be looking at this for air transport to stroke centers. It would be good to know at what altitude they were traveling at. Plane vs. helicopter?
http://www.alphagalileo.org/ViewItem.aspx?ItemId=159035&CultureCode=en
A study that simulated the effects of reduced barometic pressure
(hypobaria) experienced by patients with traumatic brain injury (TBI)
evacuated by air showed that prolonged hypobaria significantly worsened
long-term cognitive and neurological outcomes. Maintaining normal oxygen
levels did not affect the poorer outcomes after hypobaric exposure, and
multiple exposures or use of 100% oxygen further worsened the effects
in the rats studied, as described in an article published in Journal of
Neurotrauma, a peer-reviewed journal from Mary Ann Liebert, Inc.,
publishers (http://www.liebertpub.com/). The article is available free
to download on the Journal of Neurotrauma
(http://online.liebertpub..com/doi/full/10.1089/neu.2015.4189) website
until January 2, 2016.
In "Simulated Aeromedical Evacuation Exacerbates Experimental Brain
Injury (http://online.liebertpub.com/doi/full/10.1089/neu.2015.4189),"
Alan Faden, MD led a team of researchers from the Center for Shock,
Trauma and Anesthesiology Research (STAR), University of Maryland School
of Medicine, Baltimore, in designing a study that simulated the
prolonged hypobaria that a soldier with TBI would experience if
evacuated by air from the battlefield. The researchers examined the
effects on learning, memory, movement, and depressive-like behaviors in
rats with induced TBI exposed to 6 hours of hypobaria 24 hours after
injury. Some rats were exposed to a second 10-hour hypobaric period 72
hours after injury.
Based on the results of this study, the
authors suggest several approaches to limit the negative effects of
hypobaric exposure following TBI, including delaying air transport,
increasing cabin pressurization to reduce barometric effects, having
specialized enclosures to individualize pressurization, or changing
supplemental oxygenation protocols.
In the Editorial "Hidden
Perils of the 'Wild Blue Yonder' after Traumatic Brain Injury
(http://online.liebertpub.com/doi/full/10.1089/neu.2015.4329)," Patrick
M. Kochanek, MD, MCCM and Hülya Bayir, MD, University of Pittsburgh, PA,
describe the study as "a valuable and timely exploratory report that
takes an early step in addressing a largely unrecognized gap in the
pre-clinical and clinical literatures-a gap that is highly relevant to
combat casualty care, but also to some cases of civilian trauma." The
study authors "appear to have identified a new secondary injury pathway
after TBI to add to the list of hypoxemia, hypotension, hyponatremia,
hyperthermia, hypertension, hypervolemia, namely, hypobaria that needs
to be characterized and prevented to maximize outcomes after TBI-even if
patients need to travel into the wild blue yonder."
John T.
Povlishock, PhD, Editor-in-Chief of Journal of Neurotrauma and
Professor, Medical College of Virginia Campus of Virginia Commonwealth
University, Richmond, notes that, "the Journal is exceptionally pleased
to report this well done and provocative study that probes important
questions relevant to the current standard of combat casualty care
during aeromedical evacuation. The reported studies conducted in
traumatically brain injured rodents illustrate the damaging consequences
of sustained hypobaric exposure, while demonstrating the concomitant
adverse consequences associated with the use of 100% oxygen. While
additional studies are needed to further refine the overall
interpretation of this study, the published work raises the important
implication that hypobaria should be considered a potential secondary
insult in traumatically brain injured patients."
http://online.liebertpub.com/doi/abs/10.1089/neu.2015.4189
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