2-47. PULMONARY EDEMA
a. Pulmonary edema is an abnormal accumulation of fluid in the lungs. The
most common cause of pulmonary edema is cardiac disease. When the pulmonary
blood vessels receive more blood from the right heart than the left heart is able to
receive in return, pulmonary congestion occurs. Pulmonary edema is the end result of
unrelieved pulmonary congestion. The congested pulmonary capillaries leak fluid into
the nearby air spaces. As the pulmonary edema progresses, the escaping fluid mixes
with alveolar air and a frothy sputum is produced, churning and gurgling with each
respiration. This causes the characteristic "death rattle" associated with severe
pulmonary edema. Fluid build-up in the lungs prevents air from entering the alveoli,
causing severe hypoxia.
b. Treatment involves measures to improve ventilation and oxygenation and
reduce lung congestion. The patient should be positioned in an upright position to
decrease venous return to the right heart, thereby decreasing the right ventricular output
to the lungs. Oxygen is used to relieve dyspnea and hypoxia. Administration of
morphine in small doses will decrease the anxiety and dyspnea. Diuretics are used to
decrease the fluid volume if necessary. Since pulmonary edema is a result of an
imbalance between the left and right heart, treatment will also include those therapies
and medications necessary to stabilize the heart dysfunction.
2-48. PNEUMOTHORAX AND HEMOTHORAX
a. Pneumothorax is defined as the presence of air in the pleural space.
This condition may occur after thoracentesis or pleural biopsy.
(2) It may also occur secondary to mechanical ventilation when use of
excessive pressures results in tissue rupture. When there is a rupture of lung tissue
(alveoli or visceral pleura), a "spontaneous" pneumothorax is said to have occurred.
(3) Chest trauma, such as a puncture or missile wound, allows air to enter
the pleural space, also causing pneumothorax.
b. When air enters the pleural space through a hole in the lungs, the tissue
around the edges of the hole acts as a valve, allowing air to enter the pleural space, but
not to escape. This condition is called a tension pneumothorax because there is a build
up of pressure (tension) within the pleural space. This pressure, if unrelieved, will
cause lung compression and eventual collapse. Additionally, the mediastinum may be
displaced, causing disrupted circulation.
(1) Tension pneumothorax may occur when there is a wound in the lung
that does communicate with the exterior of the body. For example, a fractured rib may
be pushed inward, tearing the lung and the surrounding pleura. Air can now escape
from the lung, but is trapped in the pleural space.