Answer to Question 1
A
Peripheral vasodilation results in decreased venous return. This decreases intravascular volume and the development of relative hypovolemia. Decreased venous return results in decreased stroke volume and a fall in cardiac output.
Answer to Question 2
D
A contusion manifests initially as a hemorrhage followed by alveolar and interstitial edema. The edema can remain rather localized in the contused area or can spread to other lung areas. Inflammation affects alveolar-capillary units. As more units are affected by inflammation, further pathophysiologic events can occur, including decreased compliance, increased pulmonary vascular resistance, and decreased pulmonary blood flow. These processes result in a ventilationperfusio n imbalance that results in progressive hypoxemia and poor ventilation over a 24- to 48-hour period.