History of APRV
John B. DownsMD, FCCM, FCCP
In 1971 a University of Florida Philosophy Professor, while driving was hit broadside by a drunk driver. He was admitted to the surgical intensive care unit, where I was the Critical Care Fellow. I had just learned to calculate right-to-left intrapulmonary shunt fraction from Jay Block, MD, the head of Pulmonary Medicine at UF. The calculation necessitated mixed venous blood, so the Chief resident in CV Surgery and I inserted the first Swan Ganz catheter ever used at UF. Arterial and venous blood samples were collected while the patient was receiving 8 cmH2O PEEP. For comparison purposes, PEEP was raised to 12 cmH2O, the maximum allowable level, and shunt decreased significantly.Surprisingly, the arterial-venous O2 content difference decreased, indicating an increase in cardiac output. It was 3AM, I was the only physician in the unit and it occurred to me that a further increase in PEEP might be beneficial. PEEP was raised to 15 cmH2O, with the same result previously observed.