CALGARY, ALBERTA—More than one million pulmonary artery catheters (PACs) are placed each year in the United States; associated costs exceed $2 billion. Yet, the benefits of PACs have never been clearly demonstrated, and their use remains controversial.

In recent years, some data have even suggested that the devices increase mortality. Adding fuel to the flames is a recent study by James Dean Sandham, MD, and colleagues, which examined PAC use in 1,994 elderly patients who received intensive care after major surgery.[1] All the patients in this study were considered high risk, with an American Society of Anesthesiologists (ASA) risk classification of III or IV.

Although the study did not link PAC use to increased mortality, PAC-guided management appeared to be no more beneficial than standard postoperative care without catheterization. “Perioperative PAC use is therefore not routinely indicated in ASA III and IV patients,” said Dr. Sandham, a Professor of Critical Care Medicine at the University of Calgary in Alberta. Whether the study results can be generalized to other critically ill patients is uncertain, however.

POSTOPERATIVE CARE

Seven years ago, a study by Connors et al[2] brought the debate over PACs to the forefront when it reported that the devices increased mortality, length of hospital stay, and costs. Many experts criticized both this study and subsequent ones, however; among the problems cited were selection bias and physician noncompliance. The trial by Sandham et al was specifically designed to circumvent many of the problems that had plagued earlier studies. For example, by focusing on surgical patients, the investigators could define the start of the critical illness. “Our patients were going to have a critical event at a known point in time,” acknowledged Dr. Sandham.

The patients in the study, who had a mean age of about 72, underwent urgent or elective major abdominal, thoracic, vascular, or hip-fracture surgery at one of 19 Canadian centers. Preoperatively, the patients were randomized to receive standard postoperative care without a PAC or postoperative management with a PAC. The protocol explicitly stated that patients assigned to standard care could not be given a PAC unless the principal investigator was contacted; they could, however, receive a central venous catheter.

In the PAC group, the catheters were inserted before surgery. Postoperative management was aimed at the following therapeutic goals: oxygen delivery index, 550 to 600 mL/min/m2; cardiac index, 3.5 to 4.5 L/min/m2; mean arterial pressure, 70 mm Hg; pulmonary-capillary wedge pressure, 18 mm Hg; heart rate, less than 120 beats/min; and hematocrit, greater than 27%. In order of priority, the suggested therapies to achieve these goals were fluid loading, inotropic agents, vasodilators, vasopressors, and blood transfusion.

Thromboprophylaxis with low-dose subcutaneous heparin was recommended for all patients before and after surgery. Follow-up duration averaged one year.

MORBIDITY AND MORTALITY

At baseline, the two groups were similar in vital capacity, forced expiratory volume in one second, and hemoglobin, bilirubin, and creatinine concentrations. They were also similar in their risk of cardiac events.

A comparable number of patients in both groups (about 5%) did not receive the planned therapy; in most cases, this was because an operating room or ICU bed was not available or informed consent was withdrawn. However, 24 patients in the standard care group were eventually given PACs, and in five patients in the PAC group the catheters failed to work properly. The calculations for in-hospital mortality (the primary outcome) and length of hospital stay were based on intention-to-treat analysis and included all randomized patients; the other assessments included only the patients who actually underwent surgery.

Both the PAC and the standard care groups had a median hospital stay of 10 days. They also had similar in-hospital mortality rates (7.8% vs 7.7%), six-month survival (87.4% vs 88.1%), and 12-month survival (83% vs 83.9%). Adjustment for baseline variables did not change these findings markedly; furthermore, subgroup analysis of in-hospital mortality produced comparable results, regardless of whether the variable studied was age, sex, type of surgery, ASA risk class, or New York Heart Association functional class.

Except for pulmonary embolism, which occurred more often in the PAC group, postoperative morbidity was similar in the two groups. Catheter-related complications developed in 15 of the patients given PACs and in five of the 769 patients in the standard care group who received a central venous catheter. The increased incidence of pulmonary embolism in the PAC group may have resulted from the fact that fewer of these patients had received thromboprophylaxis.

“These findings should affect patient care,” asserted Polly E. Parsons, MD, in an editorial.[3] Indeed, they confirm the results of several recent nonrandomized studies of PACs in high-risk surgical patients. Dr. Parsons, Professor of Medicine at the University of Vermont College of Medicine in Burlington, agrees with Dr. Sandham’s assertion that routine perioperative PAC use is not warranted in such patients. However, she and Dr. Sandham both caution that it is premature to extrapolate this study’s results to other critically ill patients.

Dr. Sandham’s study has substantially advanced research in critical care, Dr. Parsons believes, because it clearly demonstrates that physicians will allow their patients to be randomized to standard care rather than PAC use. The study also illustrates the feasibility of large multicenter trials of pulmonary artery catheterization. “These accomplishments represent milestones … that would not have been possible less than two decades ago,” Dr. Parsons concluded.

—Timothy Begany

References
1. Sandham JD, Hull RD, Brant RF, et al. A randomized, controlled trial of the use of pulmonary-artery catheters in high-risk surgical patients. N Engl J Med. 2003;348:5-14.
2. Connors AF Jr, Speroff T, Dawson NV, et al. The effectiveness of right heart catheterization in the initial care of critically ill patients. JAMA. 1996;276:889-897.
3. Parsons PE. Progress in research on pulmonary-artery catheters. N Engl J Med. 2003;348:66-68.

Return to table of contents