Pulmonary artery wedge pressure measurement

Catheter tip should be reasonably peripheral on fluroscopy and should not move with the cardiac systole. Pressure tracing should resemble the left atrial tracing with ‘a’ and ‘v’ waves. It is difficult to take a blood sample in a true wedge position. The sample, if withdrawn, should have a high oxygen saturation of near 100%. A catheter with only an end hole and no side holes should be used for wedging. Injection of dye into the wedge position may show a fern like pattern.