WHAT THIS REPORT ADDS:

• Although PA catheters may not harm patients, there is little evidence that they improve outcomes; however, there is still no consensus as to whether routine use of PA catheters in the ICU should be abandoned.

ORLANDO, FLA—Pulmonary artery (PA) catheters are widely used in ICUs for continuous hemodynamic monitoring. These catheters were initially intended as a diagnostic tool, but since their introduction, they have often been used to guide treatment decisions.

In 1996, a study by Connors et al[1] found an increased risk of mortality in critically ill patients who had had a PA catheter inserted. It had also become clear that many physicians and nurses did not have sufficient education—in how to insert the PA catheter and also in how to read and interpret data from the device. This spurred the FDA and the National Heart, Lung, and Blood Institute to issue a consensus statement calling for randomized clinical trials of PA catheters and education of medical personnel.[2]

Those studies are now being published. Thus, at this year’s annual meeting of the American College of Chest Physicians, three speakers presented their views on PA catheterization and its risks, benefits, and future.[3-5]

PA CATHETER IS INACCURATE, UNSAFE

Stephen O. Heard, MD, Chair of the Department of Anesthesiology at UMass Memorial Medical Center in Worcester, Massachusetts, noted that a good monitor will warn members of the health care team early on when patients are in trouble.[3] The PA catheter, however, is inaccurate, and its data are often poorly interpreted, mainly because many personnel remain unfamiliar with its use.

Compared with echocardiography or the end-diastolic volume index, argued Dr. Heard, the PA catheter performs poorly. After insertion the device may “migrate” to other arterial zones and as a result give erroneous readings, unbeknownst to the physicians and nurses who are monitoring the patient’s condition. All too often, he noted, treatment decisions are made based on the faulty readings.

Even when the PA catheter is correctly placed and properly functioning, Dr. Heard said, many physicians and nurses still have not had enough training in its use. Thus, data interpretation is highly variable among medical personnel—even when they are all looking at the same reading.

Aside from the problem of data interpretation, the procedure required to implant a PA catheter carries its own risks. Dr. Heard pointed out that studies have shown an increased risk of pulmonary embolism, hemorrhage, pneumothorax, hemothorax, and arterial puncture associated with right heart catheterization.

These shortcomings might be surmounted, of course, if use of the PA catheter could clearly be shown to improve patient outcomes. Yet, this has not been done.

For example, a recently published study by Richard et al[6] included 676 patients who were hospitalized in the ICU for shock and/or ARDS. These patients were randomly assigned to receive either a PA catheter or standard care. In both groups, treatment decisions were left to the physicians. The end points were mortality at 14, 28, and 90 days.

Richard et al found that use of a PA catheter was not associated with increased mortality or a rise in the complication rate. However, it was not associated with improved outcomes, either.

“I think that we should limit the use of the PA catheter,” said Dr. Heard. He proposed several alternative methods of measuring cardiac output, the most viable being transpulmonary thermodilution (using lithium indicator dilution) and esophageal Doppler echocardiography.

ECHOCARDIOGRAPHY IS THE BEST ALTERNATIVE

“Echocardiography can take the place of the PA catheter,” agreed Olivier L. Axler, MD, who is affiliated with the Cardiology Department of Centre Hospitalier Territorial, in Noumea, New Caledonia.[4] Like Dr. Heard, Dr. Axler pointed out that the available literature has shown either an increased risk of mortality with use of the PA catheter or no benefit at all—especially in high-risk patients.

Echocardiography is the best alternative to the PA catheter, said Dr. Axler. It is stronger and faster than a PA catheter for diagnosing acute disease. Transthoracic echocardiography, for example, can be performed in five minutes in the emergency department and readily detects problems such as pulmonary emboli, he observed.

Dr. Axler proposed that every ICU have both an echocardiographic machine and a trained echocardiologist on staff.

THE PA CATHETER IS VALUABLE

Howard Belzberg, MD, countered that in many hospitals, having an echocardiographic machine and a trained echocardiologist in every ICU is simply not feasible.[5] He defended the PA catheter, pointing out that it is a monitoring and diagnostic tool and should not be subjected to evaluation as a therapeutic tool. “We reach the wrong conclusions when we ask the wrong questions,” he argued.

“When you are performing multiple interventions on an ICU patient, you must monitor them continually to see the effects of therapy,” said Dr. Belzberg, who is an Associate Professor of Clinical Surgery and the Associate Director of the Surgical ICU at the University of Southern California Medical Center in Los Angeles. The only way to achieve this type of continuous monitoring, he maintained, is through the use of a PA catheter.

As for criticisms of the PA catheter, said Dr. Belzberg, therapeutic end points and lack of efficacy are not valid arguments. Because therapeutic end points and lack of efficacy are measures of therapy, not of diagnosis or monitoring, they are not relevant, said Dr. Belzberg. Accuracy is the most important diagnostic end point, he stressed. Reliability—to be able to reproduce results on a continual basis, and spot trends—is the most important monitoring end point.

It’s not that the catheter is wrong, it’s the people who are using it, argued Dr. Belzberg. “We have to recognize that this is a complex tool,” he said. “Even with normal patients, you’ll see very dramatic variations between the respiratory cycles. We have to train our residents to look on and evaluate things on an ongoing basis.”

—Gale Jurasek

References
1. Connors AF, Speroff T, Dawson NV, et al. The effectiveness of right heart catheterization in the initial care of critically ill patients. SUPPORT Investigators. JAMA. 1996;276:889-897.
2. Bernard GR, Sopko G, Cerra F, et al. Pulmonary artery catheterization and clinical outcomes: National Heart, Lung, and Blood Institute and Food and Drug Administration Workshop Report. JAMA. 2000;283:2568-2572.
3. Heard SO. Grand rounds: A critical evaluation of the pulmonary artery catheter: Can we measure cardiac output by other means? Presented at: annual meeting of the American College of Chest Physicians; October 30, 2003; Orlando, Fla.
4. Axler OL. Current controversies in critical care: Echocardiography takes the place of the pulmonary artery catheter. Presented at: annual meeting of the American College of Chest Physicians; October 28, 2003; Orlando, Fla.
5. Belzberg H. Current controversies in critical care: Do pulmonary artery catheters still have a role? Presented at: annual meeting of the American College of Chest Physicians; October 28, 2003; Orlando, Fla.
6. Richard C, Warszawski J, Anguel N, et al, for the French Pulmonary Artery Catheter Study Group. Early use of the pulmonary artery catheter and outcomes in patients with shock and acute respiratory distress syndrome: a randomized controlled trial. JAMA. 2003; 290:2713-2720.

Return to table of contents