Soru

An emergency medical team brings a female in her early thirties to the resuscitation bay following a brief loss of consciousness at her workplace. Upon arrival, the patient is lethargic and complains of profound weakness, lightheadedness, and difficulty breathing. She reports recovering from a severe viral upper respiratory tract infection two weeks ago but otherwise has no chronic medical conditions.

Her temperature is $37.2^\circ\text{C}$ ($99.0^\circ\text{F}$), pulse is $128$/min, respirations are $26$/min, and blood pressure is $78/48$ mmHg. When assessed during normal inhalation, her systolic blood pressure drops to $62$ mmHg.

Physical evaluation reveals marked distension of the external jugular veins while she is positioned at a $45$-degree angle. Auscultation of the chest demonstrates clear lung fields bilaterally without rhonchi or crepitations. Cardiac auscultation reveals a regular, rapid rhythm with significantly distant and muffled heart sounds. An electrocardiogram shows sinus tachycardia with low-voltage QRS complexes and beat-to-beat variation in QRS amplitude.

Which of the following is the most appropriate immediate next step in the management of this patient?