USMLE Step 3 - Question 42

A 70 year old female with a history of coronary artery disease, hypertension, arthritis, and breast cancer presents with dyspnea on exertion and dizziness slowly progressing over the past 2 weeks. She denies any chest pains. Her blood pressure is 80/40, heart rate 120, respirations 24, and oxygen saturation 88% on room air. Physical exam revealed pulmonary rales at the left lung base, distant heart sounds, and elevated jugular venous pressures especially with inspiration. Laboratory studies are normal. An arterial line is inserted and a strip is below (top) along with the inspirometer strip (bottom). Which of the following is the best initial management of this patient?

pulsus

A. Intravenous fluids

B. Intravenous beta-blockers

C. Cardiac surgical consultation

D. Coronary angiography

This patient has cardiac tamponade. Remember that the right-sided heart chambers are the lowest pressure chambers, thus as intrapericardial pressure rises, these chambers will be first compressed. Also recall that right sided heart pressures reflect "preload" which is determined by 2 things: 1) intravenous volume (hydration status) and 2) venous tone (dilated vs constricted). Giving fluids will allow the right ventricle to fill better and increase preload will improve the blood pressure. Nitroglycerine decreases preload by venodilating. Eventually pericardiocentesis would be needed.

Key phrase: "Pulsus paradoxus" which is present in cardiac tamponade reflects a decrease in systolic blood pressure with inspiration of more than 12 mmHg. Pulsus paradoxus also occurs in severe asthma or COPD exacerbations.