Travel Reference
In-Depth Information
No treatment is available, nor does a need to treat exist. Most high-altitude retinal hem-
orrhages absorb in a week or two. Nevertheless, persons with very large hemorrhages or
macular bleeding should descend to a lower elevation since further exposure may worsen
the condition.
At high altitude less oxygen is present in the bloodstream. Because the retina and brain
require a constant amount of oxygen, one of the responses to a lower oxygen saturation
is an increase in the flow of blood to these vital structures. Elsewhere in the body, arter-
ies have muscular coats to deal with flow increases, but the retinal vessels are designed
to remain clear and not obstruct light signals with big, beefy muscles. Instead, they have
delicate support cells (pericytes) that surround the vessels. These pericytes are sensitive to
damage from lack of oxygen and can rupture in high-flow situations. The result is leaking
of blood into the retina (retinal hemorrhaging). Such hemorrhages also occur with severe
carbon monoxide poisoning and severe hypoxia from other causes at sea level.
High-Altitude Peripheral Edema
Swelling of the feet and hands may occur during or after ascent to high altitude. Con-
siderable swelling of the face and eyelids is often present in the morning. This edema is
usually accompanied by a decrease in urine output but may not be associated with symp-
toms of AMS. Although this condition sometimes is a nuisance, it is harmless and clears
up within a few days.
Almost identical edema and fluid retention can develop following strenuous exertion
near sea level, which makes it difficult to assign it to altitude alone. Salty foods and salt
tablets should be avoided because an increased sodium intake aggravates the condition.
Neverthelessahighfluidintakeisnecessarytoavoiddehydration.Itisironicthattheblood
may be concentrated due to edema and the body may be dehydrated despite the fluid in the
tissues.Acetazolamide givenforacutemountainsicknessmaydiminishtheedemathrough
itsmilddiureticaction.Someexpertsgiveasmalldoseofthestrongdiureticfurosemideto
help this condition; this should be done with caution.
Nutrition at Altitude
Almost all extreme-altitude climbers lose weight during a climb. Losses of as much as
forty pounds occur in a few individuals. Since these individuals usually are physically fit
withlittleexcessbodyfat,mostoftheweightlossisfrommuscle.Thecauseofsuchweight
loss is not well understood.
The maintenance ofadequate foodandwater intake isdifficult at extreme altitudes. Ap-
petites are poor, and high-altitude climbers usually eat and drink much less than they need.
Atleastsomeofthefatigueandweaknessexperiencedatsuchaltitudesisduetoinadequate
nutrition, dehydration, and possibly potassium loss accompanying high energy expendit-
ure.
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