Which of the following changes best describes the path physiology involved in the production of pulmonary edema in patients with congestive heart failure?
B. Widespread endothelial damage
C. Increased hydrostatic pressure
D. Increased vascular permeability
Answer.
C. Increased hydrostatic pressure
Edema is the
accumulation of excess fluid in the interstitial tissue or body cavities. It
may be caused by inflammation (inflammatory edema) or it may be due to
abnormalities involving the Starling forces acting at the capillary level
(noninflammatory edema or hemodynamic edema). Inflammatory edema is caused by
increased capillary permeability, which is the result of vasoactive mediators
of acute inflammation. An exudate is inflammatory edema fluid resulting from
increased capillary permeability. It is characterized by a high protein
content, much cellular debris, and a specific gravity greater than 1.020. Pus
is an inflammatory exudate containing numerous leukocytes and cellular debris.
In contrast, transudates result either from increased intravascular hydrostatic
pressure or from decreased osmotic pressure. They are character- ized by a low
protein content and a specific gravity of <1.012. Non- inflammatory edema is
the result of abnormalities of the hemodynamic (Starling) forces acting at the
level of the capillaries. Increased hydrostatic pressure may be caused by
arteriolar dilation, hypervolemia, or increased venous pressure.
