PRO/CON: A Pulmonary Artery Catheter Should Be Routinely Used in All Patients Undergoing Cardiac Surgery
Peter Tassani, MD
Department of Anesthesiology
German Heart Center
As we all know, the initial use of the pulmonary artery catheter (PAC) was described more than 30 years ago by Swan and Ganz(1). To the best of my knowledge, in the field of cardiac anesthesia, there is no evidence from large, randomized trials indicating that the utilization of a PAC improves outcome. Studies with outcome as an endpoint, showing a benefit for patients, are also missing for other monitoring devices used daily (pulse oximetry, central venous pressure monitoring). The lack of a study which proves a benefit should, however, not lead to the abandonment of a very valuable diagnostic tool. In an observational study of critically ill patients (not in the cardiac operating room), the use of a PAC was associated with increased mortality(2), generating a worldwide discussion regarding the usefulness of the PAC. This study (as others) contained methodological problems, including selection bias, noncompliance by the participating physicians, and crossover from standard care to the use of a PAC. An important point of criticism regarding all studies comparing PAC with conventional monitoring is that caregivers' decisions regarding hemodynamic management in patients without a PAC will be influenced by previous clinical experiences in patients with a PAC. We all have obtained, during our time spent training and in clinical practice, useful knowledge regarding management of hemodynamic instability, from numerous experiences with utilization of PACs.
This controversy is not new: "To (PA) catheterize or not to (PA) catheterize - That is the question" was published by Lowenstein and Teplick in 1980(3) and the topic was also addressed seven years later by Weintraub and Barash(4). I recommend, however, that the PAC should be routinely used in every patient undergoing cardiac surgery. In fact, it has been previously stated in the guidelines of the American Society of Anesthesiologists Task Force on Pulmonary Artery Catheterization, that PAC monitoring of selected surgical patients can reduce perioperative complications, morbidity, and mortality(5). While there is no doubt that the hemodynamic data obtained from the PAC are of importance in at least some of our patients, I will state my arguments for placing the PAC in every patient.
The preoperative selection, namely recommendation to use the PAC in patients with low ejection fraction, is used in many centers and is based on data published in 1980 by Mangano(6). In this important publication, it was revealed that an increase in central venous pressure correlated closely with an increase in wedge pressure in patients with an ejection fraction greater than 50%, while in those with an ejection fraction lower than 40%, this was not the case(6). In my opinion, it will prove difficult, if not impossible, to decide before the operation which patient should have a PAC, as every patient can temporarily suffer from low ejection fraction or a low cardiac output syndrome immediately following cardiopulmonary bypass. Myocardial depression is also possible in every patient during the period before cardiopulmonary bypass. Early detection and aggressive therapy of any hemodynamic deterioration is essential. The occurrence of hemodynamic impairment is, in my opinion, difficult to predict based on preoperative data alone, as the course of the operation plays a major role. The absent correlation between central venous pressure and wedge pressure in many patients following cardiopulmonary bypass is not the only indication for use of the PAC. Another key issue is, that the PAC itself is not a therapeutic intervention. The PAC can help guide the therapy. Patients requiring high doses of catecholamines or vasoconstrictors are best managed using all the data from a PAC (including calculation of systemic vascular resistance and pulmonary vascular resistance) to choose and best titrate the wide variety of vasoactive drugs in the appropriate way. However, as mentioned above, a patient with a normal ejection fraction can acquire a low cardiac output syndrome at any time during the operation, which is often rather unpredictable based on the preoperative catheterization values. In the case of a smooth perioperative course, the PAC can be removed 12 to 24 hours after the operation to avoid complications from long-term usage. The delay associated with PAC placement after complications have developed may even endanger the patient. Emergency catheterization under hastily prepared "sterile" conditions may increase the risk of catheter-related sepsis significantly(7). We, therefore, routinely insert the PAC either before or immediately after induction of anesthesia under optimal conditions with an extremely low rate of complications. This is in part a result of our daily use of the PAC, leading to more than 1500 PAC insertions every year. I am convinced that under conditions of routine use by experienced cardiac anesthesiologists, the risk associated with the PAC insertion, in addition to central venous line insertion, is minimal. One should realize when discussing PAC complications, that a central venous line is usually routinely inserted in cardiac surgical patients, and that complications associated with such insertion should not be attributed to PAC-related complications.
Another aspect to consider is the education of younger colleagues. Less experienced colleagues are likely to detect hemodynamic disturbances sooner when a PAC is in place (examples include pulmonary hypertension and left ventricular failure).
Regarding PAC utilization in the intensive care unit, a randomized controlled trial (involving insertion of a PAC and implementation of therapy directed by the PAC), was published recently(8). In this investigation, 997 patients were managed with a PAC and the same number were managed without a PAC. In this large, randomized, single-blind trial, patients managed with a PAC fared no better than patients managed without a PAC. However, in this investigation, the PAC was not linked to excess mortality as reported previously by Connors and associates(2).
When intraoperative transesophageal echocardiography (TEE) is utilized, a PAC may not be required for hemodynamic management during the operation. Under these circumstances, the PAC may still be useful in the postoperative intensive care unit setting when TEE is not available. It has been reported that the extra time spent in the operating room for PAC insertion following central venous line insertion may increase cost(9). However, this data has to be interpreted with caution and cannot be transferred from one center to another. In our institution, where the time for PAC insertion is minimal in experienced hands, the extra cost is likely insignificant. In fact, the costs of a PAC are not much different from a central venous catheter in our institution. Costs must be assessed in each specific institution and weighed against potential benefits (which may even reduce the overall costs). Medicolegal aspects may also influence the decision whether or not to utilize a PAC.
In conclusion, the PAC provides assessment of cardiovascular performance in ways not otherwise available on a continuous basis, allowing a patient-adapted, optimized, hemodynamic management. Because low cardiac output syndrome is possible in every patient undergoing cardiac surgery, I recommend placement of a PAC in every patient presenting for cardiac surgery. Furthermore, we should continue to strive to develop therapeutic guidelines, based on clinically relevant hemodynamic assessment, allowing us to better manage hemodynamically unstable patients.
1. Swan H J, Ganz W, Forrester J, et al: Catheterization of the heart in man with use of a flow-directed balloon-tipped catheter. N Engl J Med 283: 447-51, 1970
2. Connors AF, Jr., Speroff T, Dawson NV, et al: The effectiveness of right heart catheterization in the initial care of critically ill patients. SUPPORT Investigators. JAMA 276: 889-97, 1996
3. Lowenstein E,Teplick R: To (PA) catheterize or not to (PA) catheterize-that is the question. Anesthesiology 53: 361-3, 1980
4. Weintraub AC, Barash PG: PRO: A pulmonary artery catheter is indicated in all patients for coronary artery surgery. J Cardiothorac Vasc Anesth 1: 358-61, 1987
5. Roizen MF: Practice guidelines for pulmonary artery catheterization. A report by the American Society of Anesthesiologists Task Force on Pulmonary Artery Catheterization. Anesthesiology 78: 380-94, 1993
6. Mangano DT: Monitoring pulmonary arterial pressure in coronary artery disease. Anesthesiology 53: 364-70, 1980
7. Mermel LA, McCormick RD, Springman SR, et al: The pathogenesis and epidemiology of catheter-related infection with pulmonary artery swan-ganz catheters: a prospective study utilizing molecular subtyping. Am J Med 91: 197S-205S, 1991
8. 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 348: 5-14, 2003
9. Spackman TN: A theoretical evaluation of cost-effectiveness of pulmonary artery catheters in patients undergoing coronary artery surgery. J Cardiothorac Vasc Anesth 8: 570-6, 1994