Ultrasound Case 2: Unexplained tachycardia and dyspnea

Ultrasound Case 2
A 64 year-old man has tachycardia and dyspnea. Why?
You are called late at night by the surgical ward to the bedside of a 64 year-old male who is post-op day 2 for reversal of an ileostomy, following a right hemicolectomy for colon cancer 6 months previously. He has been tachycardic and short of breath for the past two hours. Surgery was uneventful, and a diet was started earlier in the day. He has no significant history outside of the colon cancer. He was given a dose of furosemide an hour ago, and has had an output of 300 cc’s since. Physical examination reveals an alert and cooperative elderly man in moderate respiratory distress. Auscultation reveals decreased air entry at both bases with a few crackles, mild accessory muscle use, and no paradoxical breathing. Abdomen is moderately distended but non-tender. Calves are supple, heart sounds are irregular without gross murmur. Vital signs:
Atrial fibrillation, pulse 130-160
BP 115/60
RR 24
Oxygen saturation 91% on 4 liters nasal cannula
Bedside Ultrasound: Case2: Left lower quadrant scan. Case2: Left subcostal coronal scan. [polldaddy poll=7380571] Give your answer in the box above, then read the discussion for Ultrasound Case 2. Case courtesy of the Critical Care & Ultrasound Institute, excerpted from 50 Cases in Bedside Ultrasound, by Dr. P. Steinmetz and P. Rola, available in the Apple Store.