An 85-year-old woman is admitted to the hospital due to suspected acute pyelonephritis. On arrival, blood pressure is 100/80 mm Hg, pulse is 102/min, and respirations are 16/min with normal oxygen saturation. An internal jugular venous catheter is being placed for fluid resuscitation and antibiotics. During the procedure, the patient becomes restless and has shortness of breath. Repeat blood pressure is 80/50 mm Hg, pulse is 122/min and regular, and respirations are 30/min. Oxygen saturation is 85% on room air. Pupils are equal and reactive to light. The trachea is midline, and there is no stridor. Breath sounds are equal and normal. Neurological examination reveals no gross motor or sensory deficit. While being evaluated, the patient develops pulseless electrical activity. Which of the following is the most likely diagnosis?

Question

An 85-year-old woman is admitted to the hospital due to suspected acute pyelonephritis.  On arrival, blood pressure is 100/80 mm Hg, pulse is 102/min, and respirations are 16/min with normal oxygen saturation.  An internal jugular venous catheter is being placed for fluid resuscitation and antibiotics.  During the procedure, the patient becomes restless and has shortness of breath.  Repeat blood pressure is 80/50 mm Hg, pulse is 122/min and regular, and respirations are 30/min.  Oxygen saturation is 85% on room air.  Pupils are equal and reactive to light.  The trachea is midline, and there is no stridor.  Breath sounds are equal and normal.  Neurological examination reveals no gross motor or sensory deficit.  While being evaluated, the patient develops pulseless electrical activity.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec25c8_d854_6916_bc81_7fdc11c53dc3_MD0003_00 This patient who developed rapid decompensation and cardiac arrest following central venous catheter placement most likely experienced a venous air embolism (VAE). VAE results from the introduction of air into the venous circulation; potential causes include trauma, certain surgeries (eg, neurosurgical, otolaryngological), central venous catheters, and pulmonary barotrauma. A small VAE often causes minimal sequelae, traveling to the pulmonary capillaries where it can diffuse into the alveoli without consequence. However, a large VAE (eg, >50 mL) can lodge in the right ventricle to cause right ventricular outflow tract obstruction or lodge within the pulmonary arterioles to obstruct pulmonary blood flow. Affected patients usually develop sudden-onset dyspnea and respiratory distress, often accompanied by obstructive shock (with hypotension and tachycardia) that can lead to cardiac arrest (eg, pulseless electrical activity). As with thrombotic pulmonary embolism, hypoxemia can result from dead space ventilation and ventilation-perfusion mismatching due to obstructed pulmonary blood flow. Air embolism can also affect the arterial circulation, most commonly due to trauma or neurosurgical procedures. Manifestations of arterial air embolism include stroke and myocardial infarction (due to cerebral or coronary microarterial occlusion, respectively), the latter of which can lead to rapid cardiac arrest. (Choice A) Acute respiratory distress syndrome (ARDS) involves the development of diffuse pulmonary edema; patients usually experience relatively gradual (eg, over 1-2 hr) decompensation. VAE can sometimes precipitate ARDS by triggering endothelial damage and inflammation; however, this patient's normal breath sounds (absence of crackles) and abrupt decompensation are not consistent with ARDS. (Choice C) Cardiac tamponade is a potential cause of obstructive shock, but it would be unlikely to cause sudden ventilation-perfusion mismatching and hypoxemia. (Choice D) Tension pneumothorax can cause obstructive shock by cutting off venous return to the right atrium; however, unilaterally absent breath sounds are expected. (Choice E) Upper airway obstruction (eg, due to an expanding hematoma with tracheal compression) would cause hypoxemia and respiratory distress; however, stridor is also expected. Educational objective: Venous air embolism results from the introduction of a large volume of air (eg, >50 mL) into the venous circulation; it can occur in the setting of trauma, certain surgeries (eg, neurosurgical), central venous catheter manipulation, or pulmonary barotrauma. The air can obstruct blood flow in the right ventricular outflow tract or pulmonary arterioles, leading to hypoxemia, obstructive shock, and cardiac arrest. References: Venous air embolism: clinical and experimental considerations. (http://www.ncbi.nlm.nih.gov/pubmed/1643897)

An 85-Year-Old Woman Is Admitted to the Hospital Due to Suspected