OBJECTIVE: To clarify the issues related to the use of the pulmonary artery catheter within a rational clinical perspective. RESULTS: Barriers include a) increased patient risk of pulmonary artery catheter placement; b) ability to measure similar variables via central venous catheterization, echocardiography, or other less invasive techniques; c) increased cost; d) inaccurate measurements; e) incorrect interpretation and application of pulmonary artery catheter-derived variables; and f) lack of proven benefit of pulmonary artery catheter use in the overall management of patients. INTERPRETATION: a) The risks are mainly due to insertion of a central catheter, not a pulmonary artery catheter; b) continuous monitoring of left ventricular filling pressures, pulmonary vascular pressures, and mixed venous oxygen saturation is a unique feature; c) additional costs are minimal relative to the cost of intensive care; d) measurement errors require ongoing programmatic educational efforts; e) pulmonary artery catheter-derived data need to be used within the context of a defined treatment protocol; and f) no monitoring device, no matter how simple or sophisticated, will improve patient-centered outcomes unless coupled with a treatment that, itself, improves outcome. CONCLUSION: A treatment protocol for the use of pulmonary artery catheter-derived variables is proposed that could serve as a basis for a prospective clinical trial.