Page 250 - 2023 SMOG Digital

ALTITUDE PHYSIOLOGY AND

PATIENT TRANSFER

ALTITUDE CONCERNS FOR AEROMEDICAL TRANSFERS:
• Gas expansion occurs as altitude above sea level increases. Gas volume doubles at
18,000ft mean sea level (½ sea level atmospheric pressure) and increases 25% from
5,000ft-10,000ft. This will typically not affect the operational ceiling for the UH-60
Blackhawk during Aeromedical Evacuation operations. Certain conditions and
precautions to note:
 Air embolism/Decompression illness–This is the only absolute
contraindication to transport of patients at altitude. These patients should be
transferred at sea level or in an A/C capable of cabin pressurization to sea
level.
 Pneumothorax–There is little risk of developing a tension PTX due to gas
expansion from altitude during typical aeromedical evacuation flights in rotary-
wing A/C. However, altitude should be limited when possible to <5,000ft MSL.
If mission requirements mandate higher altitudes, the use of aeromedical
evacuation platforms with pressurized cabins should be considered as
applicable and tactically capable. Prophylactic chest tubes (for altitude-related
concerns) are recommended for any flights above 10,000ft mean sea level.
 Gastric distention–Gas expansion does increase the risk of vomiting and,
therefore, aspiration. Therefore, all patients with decreased LOC should have
an NG/OG tube placed prior to transfer.
 Head injury–As with PTX, there is little concern of altitude related elevation of
elevated ICP in head injured patients although penetrating intracranial or
maxillofacial injuries may set conditions for an entrapped-gas phenomenon
with adverse clinical consequences. Any evidence of elevated ICP should
result in treatment per guideline. Altitude restrictions do not differ from those
listed for PTX. Constant vigilance should be maintained for evidence of
elevation of ICP.
 Eye injury–Penetrating eye injuries or surgeries may introduce air into the
globe. Again, the altitudes obtained for rotary-wing A/C does not pose a risk of
elevating the IOP during normal operations.
 Gas filled equipment–Medical equipment with gas filled bladders also may
suffer from interference at high-altitudes. Primarily, endotracheal tube cuffs
and pressure bags which should be evaluated at altitude by testing the
pressure of the exterior bladder or filled with air. If able, utilize manometer to

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