Segmental pulmonary angiography in the critically-ill patient using a flow-directed catheter.

Selective pulmonary angiography was performed using a flow-directed, balloon-tipped catheter in 20 consecutive intensive care unit patients requiring heart catheterizations on the right side for hemodynamic monitoring. No morbidity was encountered from this procedure. Adequate quality balloon-occlusion angiographs were obtained with a portable chest roentgenogram in 17 (85 percent) but appeared normal in only 12 (60 percent), seriously limiting the usefulness of this technique in the diagnosis of occult pulmonary embolisms. With this technique, the catheter tip was found to be in a segmental pulmonary artery anterior to the left atrium (zone I) in 30 percent of the patients. From these findings, we conclude that not infrequently the catheter tip was situated in zone I anterior to the left atriums. Slective pulmonary angiography using a flow-directed, balloon-tipped catheter proved useful in demonstrating the precise location of the catheter tip. When this is the case, the catheter tip should be relocated to a segment below the left atrium (zone III) in patients requiring positive end-expiratory pressure because the "wedge" pressure measured in zone I may not accurately reflect left atrial pressure.