Pulmonary artery catheter: Does the problem lie in the users?

Squara P, Bennett D, Perret C. Chest 2002; 121:2009-15

Reviewer: K.W. Tim Park, MD
Beth Israel Deaconess Medical Center
Boston, MA

Introduction: Since its introduction, pulmonary artery catheters (PAC) are estimated to have been used in > 45 million patients. However, with increasing call for evidence-based medicine and cost control, the wisdom of PAC use in critically ill patients has been challenged. Four studies, all arguably with methodological flaws, found that PAC use was associated with greater mortality (1-4). The reasons for this paradoxical finding might have been from incorrect data acquisition from PAC, insufficient theoretical knowledge of hemodynamics, and inadequate data analysis and reasoning as well as the fact that patients with PAC might have been sicker than those without it (4). PAC may have fewer adverse effects in the hands of clinicians who follow guidelines and are proficient in interpreting PAC data (5,6). This study examines the proficiency in PAC data analysis among practitioners who use PAC in their everyday practice.

Methods: Four hundred seventeen physicians, including 91 anesthesiologists, attending the annual meetings of the European Society of Critical Care, the French Language Society of Critical Care, and the Society of Critical Care Medicine in 1997-98 participated in the study. First, they were asked what were the most important hemodynamic parameter(s) one could obtain from a PAC. They were then presented a clinical scenario of a patient with history of hypertensive cardiomyopathy, experiencing acute hypertensive pulmonary edema. The clinical presentation included the patient's past history, current problem with on-the-field treatment, and initial vital signs in the emergency room, with findings of a chest X-ray, arterial blood gas (ABG), and transthoracic echocardiography (TTE). They were then given the data from PAC and arterial blood gas 2, 14, and 27 hours after hospital admission. After the initial clinical presentation and then after each set of PAC data, the participants were asked what treatment options they would recommend. The recommendations of the participants were compared to those of an expert panel and were classified as acceptable or potentially harmful by the panel.

Results: Cardiac output was believed to be the most important parameter by the vast majority of participants, followed by wedge pressure, mixed venous saturation, and pulmonary artery pressure. Among cardiologists, the order of importance was wedge pressure, cardiac output, pulmonary artery pressure, and mixed venous saturation.

Before the presentation of the PAC data, there was considerable variability in the initial treatment suggested by the participants. Only 38 % of the participants not on the expert panel suggested acceptable treatment options, which were recommended by 100 % of the panel members. More than 35 % of the non-panel participants suggested potentially harmful treatment options. After presentation of the PAC data, participants' agreement among themselves and with the expert panel increased. However, the proportion of participants suggesting at least one potentially harmful treatment remained > 15 % after the first set of PAC data, > 10 % after the second set of PAC data, and at 10 % after the third set of PAC data.

Discussion and Comments: The PAC parameters that study participants considered important are all parameters that cannot be obtained with a central venous line (CVL) alone. The participants in the study saw an incremental benefit of a PAC over a CVL.

It is notable that whereas the "experts" were able to make the correct diagnosis and choose the correct treatment options based on clinical presentation alone, the non-panel participants who were probably more representative of the overall PAC user population than the experts were not uniformly able to come up with beneficial treatment options with clinical presentation alone. The presentation included the finding of transthoracic echocardiography, which should have provided information on the patient's volume status and ventricular function. In fact, however, despite the echocardiographic data, more than 35 % of the study participants recommended potentially harmful treatment options in the absence of PAC data.

After PAC data was provided, the concordance among the participants and between the participants and the experts improved and the participants picked beneficial treatment options more often. This would suggest that PAC data provided an incremental benefit in evaluating the hemodynamic status of the patient and that clinical examination and laboratory findings (chest X-ray, ABG, and TTE) were not sufficient. This result is consistent with previous studies that showed that PAC data are more accurate than clinical assessment in evaluating the hemodynamic status (7,8) and that PAC leads to major changes in therapeutic strategies (8-10).

Even with PAC data, however, a significant % of study participants recommended potentially harmful treatment options. This was not an error in PAC data collection, but rather an error in judgment in using the data. Any potential benefit of a PAC would be attenuated by such errors in judgment in using the data obtained with a PAC. This finding underscores the importance of educating and perhaps even credentialing the physicians and other care providers involved in obtaining and interpreting information from a PAC.

References:
1. Connors A, Speroff T, Dawson N, et al. The effectiveness of right heart catheterization in the initial care of critically ill patients. J Am Med Assoc 1996; 276:889-918
2. Gore J, Goldberg R, Spodick D, et al. A community-wide assessment of the use of pulmonary artery catheters in patients with acute myocardial infarction. Chest 1987; 92:721-7
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4. Zion MM, Balkin J, Rosenmann D, et al. Use of pulmonary artery catheterization with acute myocardial infarction: analysis of experience in 5,841 patients in the SPRINT registry. Chest 1990; 98:1331-5
5. American Society of Anesthesiologists task force on pulmonary artery catheterization: practice guidelines for pulmonary artery catheterization. Anesthesiology 1993; 78:380-94
6. European Society of Intensive Care Medicine expert panel. The use of the pulmonary artery catheter. Intensive Care Med 1991; 17:1-7
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