Mediastinal Air-Fluid Level and Respiratory FailureAn 80-year-old woman was evaluated in the emergency room for a two-day history of passing blood in the stool. She had a history of sigmoid resection for an adenocarcinoma two years previously. A peripheral intravenous line and a left subclavian catheter were placed, and she was taken to the radiology department for a chest film (Fig 1). While sitting for the roentgenogram, she suddenly became hypotensive and unresponsive. She responded quickly to assisted ventilation with oxygen via an anesthesia bag, and was transferred to the intensive care unit. An electrocardiogram showed sinus tachycardia with atrial premature complexes and right bundle branch block. Arterial blood gas levels with the patient breathing oxygen at 4 L/min by nasal cannula showed: Pa02, 66 mm Hg; PaC02, 42 mm Hg; and pH, 7.40. http://www.cheap-asthma-inhalers.com/

Diagnosis: Pulmonary air embolism
The initial chest film in the upright position shows the left subclavian catheter and an air-fluid level within the pulmonary outflow tract and left main pulmonary artery. A film taken later the same day (Fig 2) shows that the air is no longer present, but that diffuse pulmonary infiltrates have developed. A pulmonary artery catheter was also placed. The initial measurements included systemic blood pressure, 115/60 mm Hg; pulmonary artery pressure, 20/16 mm Hg; pulmonary artery wedge pressure, 4 mm Hg; and cardiac index, 2.25 L/min/m2. She improved with supportive care and was discharged from the hospital six days later.
Air embolism is a recognized complication of central intravenous catheterization. Air may enter the circulation whenever the venous pressure is subatmos-pheric, or if air is introduced under positive pressure. This is a relatively common occurrence during neurosurgical procedures, especially in the sitting position. Venous air embolism may occur less frequently during a variety of procedures, including surgery of the head and neck, thoracic or cardiovascular surgery, transthoracic needle aspiration, or during obstetric procedures.

Figure 1

Figure 1

Figure 2

Figure 2