Recovery of embolized albumin microspheres from the pulmonary microvasculature using a wedged balloon-tipped catheter.
This study was performed to determine if particulate material within the pulmonary vascular bed could be sampled by aspirating blood from a wedged pulmonary artery catheter. 99mTechnetium-labeled albumin microspheres (20 micrometers) were injected and embolized into the precapillary pulmonary vasculature of 6 critically ill and 4 routine diagnostic catheterization patients. Recovery of the particulates was demonstrated by comparing the gamma radioactivity of the wedge blood sample obtained to that of mixed venous blood. The degree of success in the recovery corresponded to the height of the oxygen tension of the wedge blood sample (PWO2). This suggests that the PWO2 may be a useful marker of successful sampling of the pulmonary microvascular bed during wedge aspiration. In wedge samples obtained serially, peak yield of the microspheres was obtained within the first 10 ml whereas peak oxygen tension was obtained at 20 ml of total aspiration volume. Wedge aspiration has promise as a sampling method for microembolized particulates in the investigation of acute pulmonary microvascular diseases.