Rate of Pulmonary Artery Catheterization Shows Significant Decline

WHITE RIVER JUNCTION, Vt., July 24 -- Pulmonary artery catheterization decreased by 65% for all medical admissions in the U.S., from 1993 through 2004, researchers reported.

During that time, catheter use declined from 5.66 to 1.99 per 1,000 medical admissions, possibly because of evidence that this invasive procedure did not reduce mortality, according to a study published in the July 25 issue of the Journal of the American Medical Association.

After the pulmonary artery catheter (also known as the Swan-Ganz catheter) became available as a diagnostic tool in 1970, it became a hallmark of critical-care practice and was widely used until the mid-1980s when its benefits were first challenged, said Renda S. Wiener, M.D., and H. Gilbert Welch, M.D., of the Veterans Affairs Medical Center here, and Dartmouth Medical School.

In 1996, a multicenter observational study suggested an increase in mortality with pulmonary artery catheterization, and an accompanying editorial called for a moratorium on its use until a randomized trial could be conducted, Drs. Wiener and Welch wrote.

To determine trends in the use of the procedure, the researchers did a time-trend analysis of national estimates from all states contributing to the Nationwide Inpatient Sample, beginning in 1993.

Hospital admissions for patients age 18 or older were assessed, with primary analysis focused on medical admissions and a secondary analysis on surgical admissions.

Pulmonary artery catheterization was identified by procedure codes in the International Classification of Diseases, Ninth Revision describing pulmonary artery or wedge-pressure monitoring, measurement of mixed venous blood gases, or monitoring of cardiac output by oxygen consumption or other technique.

From 1993 through 2004, annual pulmonary artery catheterization use per 1,000 medical admissions decreased by 65% from 5.66 to 1.99 (risk ratio [RR], 0.35; 95% confidence interval [CI], 0.29-0.42).

Among patients who died during hospitalization, a group whose

disease severity may be consistent across time, the relative decline was similar (67%), decreasing from 54.7 to 18.1 per 1,000 deaths (RR, 0.33; CI, 0.28-0.38), the researchers said.

Also similar was a 63% decline in use among surgical patients

(RR, 0.37; 95% CI, 0.25-0.49).

A significant change in trend occurred after the 1996 study suggested increased mortality with the procedure, Drs. Wiener and Welch noted.

Among common diagnoses associated with pulmonary artery catheterization, the decline was most prominent for myocardial infarction, for which use decreased by 81% (RR, 0.19; CI, 0.15-0.23), and least prominent for septicemia, for which use decreased by 54% (RR, 0.46; CI, 0.38-0.54).

Sensitivity analyses suggested that the findings were not related to a change in procedure-coding practice, the researchers said.

They noted several study limitations, including a possible undercount of catheterization use, possibly becoming more substantial over time.

Furthermore, the investigators noted, the data provided incomplete information on the indication for the catheter's use. The diagnostic categories used in the study were based on the primary diagnosis at discharge, a record that may at times be driven more by reimbursement interests than clinical relevance.

Drs. Wiener and Welch said they were surprised to find that teaching hospitals were 43% more likely to do pulmonary artery catheterization than non-teaching hospitals, noting that one possibility might be the more inclusive definition of teaching hospitals used in 2004.

Nevertheless, they said, the national decrease in the use of the procedure suggests that many physicians have responded appropriately to the evidence that it does not reduce mortality.

In an accompanying editorial, Gordon D. Rubenfeld, M.D., of the University of Toronto, and colleagues wrote that hospitals should consider several options to address the increasingly rare procedure of pulmonary artery catheterization.

For example, they advised centers doing only a few procedures to consider not doing any, or at least allowing only a small number of skilled clinicians to do the procedure.

Consider other hemodynamic monitoring tools, the editorialists suggested, but remain skeptical until convincing data are available.

No one would consider using a new drug without some evidence that it improves patient outcome, they wrote. It is tempting to apply a different set of standards to diagnostic, screening, and monitoring technology, which is expected only to provide accurate information or to change the choice of treatments.

"The 40-year story of the pulmonary artery catheter is nearing its end. It is a cautionary tale of rapid adoption and slow evaluation of a monitoring device that, when used correctly, provides exquisitely detailed physiological data that, regrettably, does not appear to benefit patients," Dr. Rubenfeld and his colleagues concluded.

The editorial authors had no financial disclosures to report.