In which type of water would a submersion injury cause the patient's fluid to be drawn from the vascular space into the alveoli, impairing alveolar ventilation and resulting in hypoxia?

 

The correct answer is B. Hypertonic saltwater.

Choice A rationale: Hypotonic saltwater would not cause significant fluid shifts into the alveoli. Instead, it would cause cells to swell due to the lower concentration of solutes outside the cells.

Choice B rationale: Hypertonic saltwater causes fluid to be drawn from the vascular space into the alveoli due to the higher concentration of solutes in the water compared to the body's cells. This can impair alveolar ventilation and result in hypoxia.

Choice C rationale: Hypotonic freshwater would cause cells to swell and potentially burst due to the lower concentration of solutes outside the cells, but it would not specifically cause fluid to be drawn into the alveoli.

Choice D rationale: Hypertonic freshwater is not a common classification for drowning water. Freshwater is typically hypotonic compared to body fluids, and it would not cause the same fluid shift as hypertonic saltwater.

Choice A rationale:

Purpura refers to purple or red discolorations on the skin caused by bleeding underneath the skin. It is larger than petechiae and ecchymosis and could be a sign of a more serious underlying condition. Petechiae are small, red or purple dots that appear on the skin due to minor bleeding from broken capillaries. In the context of leukemia and thrombocytopenia (low platelet count), petechiae are common due to impaired clotting mechanisms.

Choice B rationale:

Bruising occurs due to damage to blood vessels underneath the skin, resulting in the leakage of blood into the surrounding tissues. Bruises are typically larger than petechiae and can occur with various conditions, including trauma. In this case, the small 1-mm red macules are more indicative of petechiae.

Choice D rationale:

Ecchymosis refers to a larger area of subcutaneous bleeding or bruising. It is larger than both petechiae and purpura and often results from more significant trauma or bleeding disorders. The description of multiple 1-mm red macules is characteristic of petechiae rather than ecchymosis.