A patient has been receiving a heparin sodium IV for the last three days. The patient’s most current platelet count is 65,000 x 10^3/uL; while the platelet count on admission was 350,000 x 10^3/uL. The cardiac-vascular nurse contacts the physician to:

Correct Answer: B

Rationale: A drop from 350,000 to 65,000 platelets suggests heparin-induced thrombocytopenia (HIT), an adverse reaction requiring immediate reporting and heparin cessation. A and C misinterpret the issue, and D is a subsequent step.

Correct Answer: B

Rationale: After birth, the ductus arteriosus, which shunts blood from the pulmonary artery to the aorta in the fetus, closes and becomes the ligamentum arteriosum, a fibrous remnant. The fossa ovalis is the remnant of the foramen ovale, and the other options relate to different fetal structures.

Correct Answer: D

Rationale: Venous valves prevent backflow, and the skeletal-muscle pump (contractions of skeletal muscles) aids venous return by compressing veins. Skeletal-muscle groups contribute to this pump. Venous pressure alone is low (near 0 mmHg at the venae cavae) and insufficient without these mechanisms.

Correct Answer: B

Rationale: Arteriovenous shunts (or thoroughfare channels) are metarterioles connecting arterioles to venules, bypassing capillaries to regulate blood flow (e.g., in thermoregulation or under low metabolic demand).

Correct Answer: A

Rationale: Postoperative elevation in pulse and BP is typically due to the sympathetic nervous system’s response to stress (e.g., surgery), releasing catecholamines like epinephrine, increasing heart rate and vasoconstriction. The parasympathetic system slows heart rate, infection would take longer to manifest, and pain medications often lower BP.