In response to concerns about the benefits and safety of PAC, the NHLBI and the Food and Drug Administration (FDA) co-sponsored a workshop in August 1997 entitiled "Pulmonary Artery Catheterization and Clinical Outcomes (PACCO)". The purpose of the workshop was to provide an objective assessment of the state-of-the-science of PAC and its various uses. Experts in critical care, pulmonary medicine, cardiovascular medicine, surgery, pediatric cardiology, nursing, biostatistics, ethics, and medical economics identified several important clinical areas as priorities for clinical trials; persistent/refractory congestive heart failure (NYHA class IV) received top priority to test whether a PAC-directed treatment strategy achieves a better and less costly long-term outcome compared to a non-invasive treatment strategy. In addition to providing data on outcome, hospital utilization, and costs, the study would have additional benefits. For example, it would provide a clear benchmark for testing other technologies, now in developmental stages, that could supplant PAC in the future. Finally, the study would provide the basis for developing competency requirements for physicians, nurses, and others who insert and use pulmonary artery catheters, which was a strong recommendation of the PACCO Workshop.