Travel Reference
In-Depth Information
Rarely the tear in the lung behaves like a valve, allowing air to enter the pleural space
but not leave, which causes the pressure within the space to build rapidly. The pressure
collapses the lung and can shift the heart and its surrounding structures (the mediastinum)
toward the opposite side of the chest. If untreated, this disorder, called “tension pneumo-
thorax” because the air is under increased pressure, may cause shock and result in death
Pneumothorax should be suspected when unexplained shortness of breath appears sud-
denly in an otherwise healthy, active person—particularly in the setting of trauma to the
chest. Sometimes the onset is associated with sudden pain. The diagnosis is confirmed
when breath sounds cannot be heard over the entire lung on the affected side. A tension
pneumothorax should be suspected when shortness of breath is severe and the person is
fighting for air. Lips and fingernails are usually purple (cyanotic). Sometimes the trachea
just above the sternum is shifted to the side away from the pneumothorax; the point where
the heart is felt may be shifted in the same direction.
Notreatmentisneededunlessatensionpneumothoraxdevelops.Thenthepressuremust
be relieved by inserting a needle or tube into that side of the chest, a simple procedure that
may be life saving, but should be done only by a physician except in desperate circum-
stances. This procedure is discussed in greater detail in
Chapter 9: Chest Injuries
.
Individuals withaspontaneous pneumothorax needtorestforaweekorlongeruntil the
“leak” in the lung tissue has healed, as it usually does. Increasing the altitude, even pass-
ively as in an aircraft, worsens the pneumothorax. Descent improves it. Persons who have
had one episode of spontaneous pneumothorax are more vulnerable to others. They may
consider surgery to try to eliminate the condition.
VENOUS THROMBOSIS AND PULMONARY EMBOLISM
Blood clots in the veins of the legs (or rarely the arms)—venous thrombosis—are not un-
common and may result in serious complications. Blood clots in the large central veins of
thethighandpelvis—deep venousthrombosis—may breakoffandtravelthroughtheheart
tothelungs,producingpulmonaryembolism.Theclots(emboli)obstructthearteriesinthe
lung (pulmonary arteries) and reduce blood flow through that organ, which interferes with
the exchange of oxygen and carbon dioxide. Extensive embolism or obstruction of a major
pulmonary artery, such as the artery to an entire lung, can be immediately fatal. Ascent to
high altitude increases the risk of venous thrombosis and pulmonary embolism.
Anincreasedtendencyofthebloodtoclot(increasedcoagulability)andslowingoreven
cessation of blood flow in the veins (stasis) favor the development of venous thrombosis.
Factors that increase the coagulability or stasis of blood are:
Dehydration, which causes the blood to become thicker and more viscous
An increase in the number of red blood cells due to high altitude, a normal mechanism
of acclimatization that also increases the viscosity of blood
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