Questions: Following the development of left ventricular failure, a patient develops pulmonary edema. Which of the following factors accounts for the formation of this edema? Increased hydrostatic pressure in the pulmonary capillaries Increased oncotic pressure in the pulmonary capillaries Decreased hydrostatic pressure in the pulmonary capillaries Decreased pulmonary capillary permeability

The answer is the first one: Increased hydrostatic pressure in the pulmonary capillaries.

Explanation for each option:

• Increased hydrostatic pressure in the pulmonary capillaries: This is the correct answer. In left ventricular failure, the left ventricle is unable to effectively pump blood out to the systemic circulation. This leads to a backlog of blood in the left atrium and subsequently in the pulmonary veins and capillaries. The increased volume of blood in the pulmonary circulation raises the hydrostatic pressure in the pulmonary capillaries, which forces fluid out of the capillaries and into the interstitial and alveolar spaces, resulting in pulmonary edema.

• Increased oncotic pressure in the pulmonary capillaries: This is incorrect. Oncotic pressure is related to the concentration of proteins, such as albumin, in the blood. An increase in oncotic pressure would actually help retain fluid within the capillaries, opposing the formation of edema.

• Decreased hydrostatic pressure in the pulmonary capillaries: This is incorrect. A decrease in hydrostatic pressure would reduce the tendency for fluid to leave the capillaries, thus preventing edema rather than causing it.

• Decreased pulmonary capillary permeability: This is incorrect. Decreased permeability would make it harder for fluid to leave the capillaries, which would prevent edema. Pulmonary edema is more likely to occur with increased permeability, not decreased.

In summary, the formation of pulmonary edema following left ventricular failure is primarily due to increased hydrostatic pressure in the pulmonary capillaries.