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. Her pulsus paradoxus is 20 mmHg. Laboratory studies are normal. Which of the following is the best initial management of this patient?