A central venous catheter that revealed a vascular paradox

A 60-year-old man with insignificant past medical history, was admitted to the intensive care unit with acute respiratory failure following community-acquired pneumonia. On admission, he was haemodynamically stable in sinus rhythm, febrile and neurologically intact with no focal neurological findings. Under mechanical ventilation, the ratio of arterial oxygen (PaO2) to fractional inspired oxygen concentration (FiO2) was 100. An antibiotic regime...