The pulmonary artery (PA) (or Swan-Ganz) catheter has been like a divining rod for critical care medicine since it was adapted for bedside use some 25 years ago. Clinicians rely heavily on the device for monitoring intravascular volume and cardiac output. A recent estimate suggested that 1 million PA catheters are used each year in the United States at a cost of $2 billion.
The catheter came under fire when an article by Alfred F. Connors, Jr, MD, of Case Western Reserve University in Cleveland, and colleagues revealed higher mortality rates and higher hospitalization costs associated with its use (JAMA. 1996; 276:889-97). In August, the Food and Drug Administration (FDA) and the National Institutes of Health (NIH) convened a workshop to study the PA catheter controversy. The workshop's report contains recommendations for additional research on the safety, efficacy, and cost of the PA catheter and calls for new educational initiatives for physicians and nurses.
Connors' observational study looked at outcomes of almost 6000 patients treated at five medical centers. The authors found that, even after adjusting for severity of illness, patients who had pulmonary artery catheterization were at increased risk for death and their care required increased use of health care resources compared with patients who did not have catheterization.
Although it was not a randomized, controlled trial, the Connors study made a forceful argument against aggressive use of the PA catheter. "[The NIH-FDA workshop participants] said that this is very good level III evidence," remarked Gail Weinmann, MD, medical officer in the Division of Lung Diseases at the NIH's National Heart, Lung, and Blood Institute. The participants recommended several randomized, controlled trials as the next step. Meanwhile, a randomized trial of the PA catheter is nearing completion in Canada and data may be available within a year.
"There really are two issues: one is the catheter, and the other is how we treat septic shock," said James Klinger, MD, assistant professor of Medicine at Brown University School of Medicine in Providence, Rhode Island. He added that the Connors study raises the question: Is it the catheter or what people do with the information from the catheter that leads to the unfavorable outcome?
The Connors study could not pinpoint the factors related to PA catheter use that lead to increased mortality. The authors noted three possibilities: direct complications of the catheter, such as line sepsis or bacterial endocarditis; inappropriate application of PA catheter results; or a generally more invasive style of care, as evidenced by use of the PA catheter.
Workshop participants speculated that the proposed studies may show that the PA catheter is overused in certain subgroups of patients, such as low-risk patients having cardiac surgery. They may also reveal that prolonged use of the PA catheter by inexperienced intensive care unit (ICU) personnel might lead to the observed unfavorable outcomes. Three studies published in the past 7 years showed that a surprising number of ICU physicians could not accurately interpret PA catheter hemodynamics.
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Long Accepted, Hard To Study
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Prospective randomized, controlled studies of the PA catheter's efficacy have been problematic because clinicians have been concerned that randomization may result in their patients being placed in a group denied the PA catheter. The device became widely accepted when clinicians sought greater physiologic detail, and conventional wisdom dictated that instantaneous access to hemodynamic data would undoubtedly help a patient. However, in this era of outcomes research, invasive data collection is difficult to support without evidence that it contributes to improved morbidity or mortality.
The NIH/FDA Workshop on Pulmonary Artery Catheterization and Clinical Outcomes (PACCO) attracted dozens of clinicians who, in several clinical subgroups, debated the use of PA catheters. If the resulting recommendations are followed, clinical trials will evaluate safety, efficacy, and cost issues of right heart catheters in severe heart failure, acute respiratory distress syndrome, septic shock, and low-risk coronary artery bypass graft surgery.
"We did try to propose a very narrow set of recommendations regarding a research program. These studies are going to need to be large," said Gordon Bernard, MD, director of Medical Intensive Care in the Division of Allergy, Pulmonary, and Critical Care Medicine, at Vanderbilt University, in Nashville, Tennessee. The NIH and FDA are reviewing the workshop's findings and will determine in the next 2 months whether to support further study, according to Larry Kessler, ScD, director of the FDA's Office of Surveillance and Biometrics in the Center for Devices and Radiological Health in Rockville, Maryland.
At least one workshop participant is skeptical that further study of the PA catheter is warranted. Max Harry Weil, MD, president of the Institute of Critical Care Medicine in Palm Springs, California, argued for investment in research and development of less-invasive technologies that might eventually replace the PA catheter. "A few of us feel that money would be better spent for progress, not retrogression," he stated.
The opinion that clinicians need more education on obtaining and interpreting information from the PA catheter, however, seems to be unanimous. According to Kessler, planning for an educational curriculum is under way. "In the next 2 to 3 months we should be able to go public with a program developed by the FDA and a consortium of critical care societies."
Many workshop participants said they expect a new certification process to be a part of any forthcoming PA catheter educational programs. Although licensing the personnel responsible for cardiac catheterization was not officially recommended at the workshop, some experts saw it as implicit. Bernard said that a consensus on the issue of mandatory credentials probably will not occur for 2 to 3 years. He admitted that gaining the needed consensus from the professional societies of internal medicine, anesthesia, and surgery would be challenging, although he stated that he would support proposals for certification.
For hospital-based internists, the closest analogy for the proposed license is advanced cardiac life support (ACLS) certification. "Because of the nature of this catheter-its use crosses so many specialties-there's going to need to be a separate certification process," Bernard predicted.
While waiting for further research and initiatives from the NIH, FDA, and professional societies, critical care physicians like Bernard and Weinmann are recommending more prudent use of PA catheters. Specifically, they recommend use of a PA catheter only for specific clinical questions that cannot be answered by some other means. They also recommend removing the catheter as soon as possible. "There is a general feeling ... that the morbidity associated with the PA catheter is associated with long-term use," said Weinmann.
"There was a mentality," added Bernard, "that [the PA catheter] was part of routine monitoring like an oxygen saturation monitor or EKG leads. It's not. If I don't really know that I need it, I won't put it in."
-Paul Kefalides
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