- Email: [email protected]
Con: Is the Pulmonary Artery Catheter Dead?
Con: Is the Pulmonary Artery Catheter Dead? Glenn S. Murphy, MD, and Jeffery S. Vender, MD
T
HE PULMONARY ARTERY CATHETER (PAC) was introduced into clinical practice in 1970. Since that time, over 1,500 articles and abstracts have been published that examined the role of the PAC in the management of the critically ill patient. Despite an extensive body of literature relating to the effects of PAC monitoring on outcomes, there remains uncertainty about appropriate PAC applications in the perioperative and critical care settings. Controlled clinical trials have shown that PAC utilization improves, worsens, or has no impact on morbidity or mortality.1-3 Although the risks and benefits of PAC monitoring have not been clearly defined in the literature, surveys suggest that the majority of clinicians believe that the hemodynamic data provided by the PAC is useful in guiding therapy and improving outcomes.4,5 It is the belief of the authors that the beneficial effects of PAC monitoring are most likely to be obtained when the PAC is used in the appropriate patient, for the appropriate situation, in the appropriate setting, in a timely manner. This review will examine the limitations of the available scientific evidence and provide expert and personal opinion on the clinical utility of the PAC. CLINICAL TRIALS: PACS AND OUTCOMES
Despite three decades of intensive clinical research, there is still vigorous debate about the benefits and risks of PAC monitoring. This controversy has been further fueled by the recent publication of 4 large-scale well-designed clinical trials showing no clear benefits to PAC monitoring.6-9 Unfortunately, interpretation of most of the published studies is significantly limited by important flaws in study design. A recent systematic critique of randomized controlled trials revealed a low quality of overall study design (mean Chalmer score of 40 on a scale of 1-100).10 These important limitations include but are not limited to the following11: 1. Inadequate sample size to assess important outcomes: clinically relevant outcome measures (major morbidity and mortality) should be assessed in PAC trials in order to determine effectiveness. Unfortunately, most published trials have been too small to detect differences in these outcomes. For example, major morbidity (stroke and renal failure) and mortality occur in 1% to 4% of cardiac surgical patients.12 To show a statistically significant effect of PAC monitoring on major outcomes, a trial of several thousand patients would be required. However, the 2 randomized studies of PACs in cardiac surgical patients enrolled only 226 and 403 patients.13,14 2. Lack of randomization: the belief among clinicians that PAC monitoring improves outcomes complicates the conduct of randomized trials. A small minority of clinical trials have been randomized studies, and only 7 of the publications in the setting of cardiovascular surgery have been randomized.13-19 3. Lack of standardization of therapies based on PAC information: the PAC is simply a monitor and will not independently alter outcomes unless coupled with appropriate therapy. Therapeutic interventions initiated by the PAC can potentially benefit or harm the patient
and should be independently validated. To appropriately interpret the findings from a PAC trial, strict protocols predicated on evidence-based medicine should be used to define therapeutic goals and the interventions used to achieve them. The implementation of protocols will reduce the recognized variability of care related to PAC data. Such protocols are rarely used in PAC studies. 4. Uncertainty relating to hemodynamic goals needed to improve outcomes: the PAC allows the clinician to measure cardiac output, intracardiac filling pressures, mixed venous oxygen saturation, derived hemodynamic parameters such as systemic and pulmonary artery resistance, and ejection fraction. Optimization of these indices may improve outcomes in critically ill patients. However, the optimal value of these various parameters has not been independently determined at the present time (ie, a cardiac index of ⬎3 L/min/m2 or ⬎4 L/min/m2, a wedge pressure of 15 mmHg or 18 mmHg). 5. Uncertainty as to which therapeutic intervention is most important in impacting outcomes: patients receiving PACs typically receive more fluids (to raise wedge pressures), more inotropes (to increase cardiac index), and more vasoactive medications (to raise or lower systemic vascular resistance) than control patients.3 At the present time, it is uncertain which therapeutic intervention, initiated by the PAC, produces the greatest beneficial effects on patient outcomes. 6. Inappropriate patient populations receiving a PAC: low-risk patients are unlikely to derive benefits from PAC monitoring. In this patient population, the risks of PACs likely outweigh the benefits, and differences in mortality are unlikely to be observed. In a trial of critically ill patients, the use of a PAC was associated with increased mortality rates in patients with a lower severity of illness score while reducing mortality in the most severely ill.20 A recently published databased analysis of 53,312 trauma patients revealed no beneficial effects of PAC monitoring on mortality in low-risk patients.21 In contrast, PAC use was associated with a significant survival benefit in patients with advanced age or increased injury severity. In the setting of cardiac surgery, 3 of the 5 prospective PAC trials studied low-risk patients.13,14,22
From the Department of Anesthesiology, Evanston Northwestern Healthcare, Northwestern University Feinberg School of Medicine, Evanston, IL. Address reprint requests to Glenn S. Murphy, MD, Department of Anesthesiology, Evanston Northwestern Healthcare, 2650 Ridge Avenue, Evanston, IL 60201. E-mail: [email protected] © 2007 Elsevier Inc. All rights reserved. 1053-0770/07/2101-0029$32.00/0 doi:10.1053/j.jvca.2006.11.001 Key words: pulmonary artery catheter, utcomes, invasive monitoring
Journal of Cardiothoracic and Vascular Anesthesia, Vol 21, No 1 (February), 2007: pp 147-149
147
148
MURPHY AND VENDER
7. Lack of standardization (and breadth) of user knowledge: PAC data must be properly obtained and interpreted by knowledgeable clinicians to ensure the delivery of appropriate therapeutic interventions. Surveys of critical care physicians, intensive care unit nurses, and cardiac anesthesiologists have shown significant deficiencies in clinicians’ ability to interpret PAC data.23-25 The inability of physicians and nurses to correctly interpret information from the PAC can result in inappropriate analysis of the data, leading to improper therapies and potential adverse outcomes. Few of the clinical trials examining the efficacy of PAC monitoring have attempted to qualitatively or quantitatively examine the experience and cognitive skills of all caregivers using the PAC in the study. Because of significant deficiencies in the quality of the scientific evidence, it is difficult to determine the effectiveness of PAC monitoring in influencing outcomes in surgical and medical patients. Despite the recent publication of large-scale randomized trials,6-9 many questions remain unanswered. In particular, what are the appropriate or optimal endpoints of care using a PAC? What are the treatment strategies guided by PAC data that are most likely to benefit outcomes? What role does user experience and knowledge play in determining outcomes? Until these questions are answered, it will be difficult to draw meaningful conclusions from the scientific literature about the benefits and risks of PAC monitoring. EXPERT OPINION
A review of the evidence from clinical trials does not provide clear support for or against the use of PAC in the management of the critically ill patient. In the absence of this information, important insights can be obtained from expert opinion. The American Society of Anesthesiologists reconvened the Task Force on Pulmonary Artery Catheterization in 2000.3 The Task Force concluded that available evidence from published research provided incomplete information about PAC effectiveness. Expert opinion of the Task Force was assessed using a formal group consensus process. It was the opinion of the task force that “PA catheter monitoring of selected surgical patients can reduce the incidence of perioperative complications, primarily by providing immediate access to critical hemodynamic data. The expert opinion of the Task Force is that access to these data for selected indications and settings, coupled with accurate interpretation and appropriate treatment tailored to hemodynamic status, can reduce perioperative mortality and morbidity.”3 A similar opinion was expressed by the Pulmonary Artery Consensus Conference sponsored by the Society of Critical Care Medicine.2 It was the collective opinion of the Consensus Conference participants that management guided by the PAC may be beneficial for critically ill medical patients (myocardial infarction with shock, refractory CHF, and sepsis) and high-risk surgical patients. The participants concluded that clinicians should weigh the risks and benefits of the PAC on a case-by-case basis and that there was no basis for a moratorium for PAC use at this time. The opinions of practicing anesthesiologists in the United States and Canada about appropriate PAC applications were assessed in a recent survey.26 Fiftythree percent of respondents rated the PAC as not appropriate
in low-risk patients undergoing cardiovascular surgery. In contrast, 74% of respondents strongly agreed that use of the PAC is appropriate in patients with ventricular impairment. In conclusion, it is the opinion of “experts” and practicing anesthesiologists that the PAC has a beneficial role in the management of critically ill patients. PERSONAL OPINION
It is the belief of the authors that the routine use of PACs in low-risk patients is unwarranted. In this setting, the risks of invasive monitoring outweigh the potential benefits. Patients with extreme mortality risks or pathophysiologic processes unresponsive to therapeutic interventions (ie, ruptured thoracic aneurysm) are also unlikely to derive benefits. The PAC must also be used in the appropriate situations to influence outcomes. Alterations in clinical management and outcomes are more likely to be observed in a patient with poor ventricular function undergoing major cardiac surgery compared with the same patient undergoing a laparoscopic cholecystectomy. In addition, clinicians using PAC monitoring should be experienced in technical skills relating to catheter placement and maintenance and should show competence in data interpretation and application. Finally, the PAC must be placed and therapies initiated before irreversible tissue injury occurs! Timeliness of interventions is likely of critical importance in determining efficacy of care and eventual outcomes. Early goal-directed therapy before admission to the intensive care unit resulted in significant reductions in mortality in patients with severe sepsis or septic shock when compared with a group randomized to standard therapy.27 There is likely a window of time during which the data derived from the PAC can impact decision making and thereby morbidity and mortality. Unfortunately, many studies have significant delays in PAC management relating to the onset of pathophysiologic trespass. The authors acknowledge that the scientific evidence does not clearly show that PAC monitoring reduces major morbidity and mortality. It is important to note, however, that there is limited (if any) evidence that any monitoring technology used in the operating room or intensive care unit settings has a definitive mortality benefit. Clinicians believe that pulse oximetry and capnography are valuable perioperative monitors, yet there is no evidence from large-scale randomized trials showing improvements in major outcomes with these standard monitors. Transesophageal echocardiography is a valuable monitor of cardiac structure and function that is frequently used by cardiac anesthesiologists and intensivists. However, there are no published randomized trials showing an obvious reduction in mortality after TEE application. A review of the literature reveals an absence of high-quality “evidence-based” data supporting any commonly used monitoring devices (eg, invasive radial arterial catheters, central venous catheters, and pulse oximetry). As a result of the numerous limitations relating to the scientific evidence, physicians must depend on “expert opinion” to determine the role of the PAC in their clinical practice. We agree with the opinion of the Task Force that the PAC, by providing immediate access to critical hemodynamic data and allowing for prompt treatment with fluids or medications, can reduce morbidity and mortality.3 These benefits, however, will only be derived when the PAC is used in the
PRO AND CON
149
appropriate patient (high-risk medical or surgical patients), for the appropriate situation (conditions likely to respond to therapies such as fluids and vasoactive medications), in the appropriate setting (by experienced and knowledgeable clinicians in a timely manner). It is the belief of the authors that the most
important issues with the PAC are related to caregiver understanding and appropriate and timely utilization of the technology. Additional well-designed clinical trials that address and use the correct questions and endpoints, are needed to define the role of the PAC in the management of the critically ill patient.
REFERENCES 1. 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 283: 2568-2572, 2000 2. Pulmonary Artery Consensus Conference: Consensus Statement. Pulmonary Artery Catheter Consensus Conference Participants. Crit Care Med 25:910-924, 1997 3. Practice guidelines for pulmonary artery catheterization. An updated report by the American Society of Anesthesiologists Task Force on Pulmonary Artery Catheterization. Anesthesiology 99:988-1014, 2003 4. Trottier SJ, Taylor RW: Physicians’ attitudes toward and knowledge of the pulmonary artery catheter: Society of Critical Care Medicine membership survey. New Horiz 5:201-206, 1997 5. Chernow B: Pulmonary artery floatation catheters: A statement by the American College of Chest Physicians and the American Thoracic Society. Chest 111:261-262, 1997 6. Sandham JD, Hull RD, Brant RF, et al: Canadian Critical Care Trials Group. A randomized controlled trial of the use of pulmonary artery catheters in high risk surgical patients. N Engl J Med 348:5-14, 2003 7. The Escape Investigators and Escape Study Coordinators: Evaluation of congestive heart failure and pulmonary artery catheterization effectiveness. JAMA 294:1625-1633, 2005 8. Harvey S, Harrison DA, Singer M, et al: Assessment of clinical effectiveness of pulmonary artery catheters in the management of patients in intensive care (PAC-MAN): A randomized trial. Lancet 366:472-477, 2005 9. The National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network: The pulmonaryartery versus central venous catheter to guide treatment of acute lung injury. N Engl J Med 354:2213-2224, 2006 10. Ivanov R, Allen J, Sandham D, et al: Pulmonary artery catheterization: A narrative and systematic critique of randomized controlled trials and recommendations for the future. New Horiz 5:268-276, 1997 11. Murphy GS, Nitsun M, Vender JS: Is the pulmonary artery catheter of utility?, in Van Aken H, Fleisher L (eds): Best Practice and Research Clinical Anesthesiology (vol 19). Philadelphia, PA, Elsevier, 2005 12. Gummert JF, Funkat A, Beckmann A, et al: Cardiac surgery in Germany during 2005: A report on behalf of the German Society of Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 54:362371, 2006 13. Pearson KS, Gomez MN, Moyers JR, et al: A cost/benefit analysis of randomized invasive monitoring for patients undergoing cardiac surgery. Anesth Analg 69:336-341, 1989
14. Polonen P, Ruokonen E, Hippelainen M, et al: A prospective, randomized study of goal-oriented hemodynamic therapy in cardiac surgical patients. Anesth Analg 90:1052-1059, 2000 15. Isaacson IJ, Lowdon JD, Berry AJ, et al: The value of pulmonary artery and central venous monitoring in patients undergoing abdominal aortic reconstructive surgery: A comparative study of two selected, randomized groups. J Vasc Surg 12:754-760, 1990 16. Joyce WP, Provan JL, Ameli FM, et al: The role of central hemodynamic monitoring in abdominal aortic surgery. A prospective randomized study. Eur J Vasc Surg 4:633-636, 1990 17. Berlauk JF, Abrams JH, Gilmour IJ, et al: Preoperative optimization of cardiovascular hemodynamics improves outcome in peripheral vascular surgery. A prospective, randomized clinical trial. Ann Surg 214:289-299, 1991 18. Valentine RJ, Duke ML, Inman MH, et al: Effectiveness of pulmonary artery catheters in aortic surgery: A randomized trial. J Vasc Surg 27:203-212, 1998 19. Bender JS, Smith-Meek MA, Jones CE: Routine pulmonary artery catheterization does not reduce morbidity and mortality of elective vascular surgery. Results of a prospective, randomized trial. Ann Surg 226:229-237, 1997 20. Chittock DR, Dhingra VK, Ronco JJ, et al: Severity of illness and risk of death associated with pulmonary artery catheter use. Crit Care Med 32:911-915, 2004 21. Friese RS, Shafi S, Gentilello LM: Pulmonary artery catheter use is associated with reduced mortality in severely injured patients: A National Trauma Data Bank analysis of 53,312 patients. Crit Care Med 34:1597-1601, 2006 22. Stewart RD, Psyhojos T, Lahey SJ, et al: Central venous catheter use in low-risk coronary artery bypass grafting. Ann Thorac Surg 66:1306-1311, 1998 23. Iberti TJ, Fischer EP, Leibowitz AB, et al: A multicenter study of physicians’ knowledge of the pulmonary artery catheter. JAMA 264:2928-2932, 1990 24. Burns D, Burns D, Shively M: Critical care nurses’ knowledge of pulmonary artery catheters. Am J Crit Care 5:49-54, 1996 25. Jacka MJ, Cohen MM, To T, et al: Pulmonary artery occlusion pressure estimation: How confident are anesthesiologists? Crit Care Med 30:1197-1203, 2002 26. Jacka MJ, Cohen MM, To T, et al: The appropriateness of the pulmonary artery catheter in cardiovascular surgery. Can J Anaesth 49:276-282, 2002 27. Rivers E, Nguyen B, Havstad S, et al: Early goal-directed therapy in the treatment of severe sepsis and septic shock. N Engl J Med 345:1368-1377, 2001
T
HE PULMONARY ARTERY CATHETER (PAC) was introduced into clinical practice in 1970. Since that time, over 1,500 articles and abstracts have been published that examined the role of the PAC in the management of the critically ill patient. Despite an extensive body of literature relating to the effects of PAC monitoring on outcomes, there remains uncertainty about appropriate PAC applications in the perioperative and critical care settings. Controlled clinical trials have shown that PAC utilization improves, worsens, or has no impact on morbidity or mortality.1-3 Although the risks and benefits of PAC monitoring have not been clearly defined in the literature, surveys suggest that the majority of clinicians believe that the hemodynamic data provided by the PAC is useful in guiding therapy and improving outcomes.4,5 It is the belief of the authors that the beneficial effects of PAC monitoring are most likely to be obtained when the PAC is used in the appropriate patient, for the appropriate situation, in the appropriate setting, in a timely manner. This review will examine the limitations of the available scientific evidence and provide expert and personal opinion on the clinical utility of the PAC. CLINICAL TRIALS: PACS AND OUTCOMES
Despite three decades of intensive clinical research, there is still vigorous debate about the benefits and risks of PAC monitoring. This controversy has been further fueled by the recent publication of 4 large-scale well-designed clinical trials showing no clear benefits to PAC monitoring.6-9 Unfortunately, interpretation of most of the published studies is significantly limited by important flaws in study design. A recent systematic critique of randomized controlled trials revealed a low quality of overall study design (mean Chalmer score of 40 on a scale of 1-100).10 These important limitations include but are not limited to the following11: 1. Inadequate sample size to assess important outcomes: clinically relevant outcome measures (major morbidity and mortality) should be assessed in PAC trials in order to determine effectiveness. Unfortunately, most published trials have been too small to detect differences in these outcomes. For example, major morbidity (stroke and renal failure) and mortality occur in 1% to 4% of cardiac surgical patients.12 To show a statistically significant effect of PAC monitoring on major outcomes, a trial of several thousand patients would be required. However, the 2 randomized studies of PACs in cardiac surgical patients enrolled only 226 and 403 patients.13,14 2. Lack of randomization: the belief among clinicians that PAC monitoring improves outcomes complicates the conduct of randomized trials. A small minority of clinical trials have been randomized studies, and only 7 of the publications in the setting of cardiovascular surgery have been randomized.13-19 3. Lack of standardization of therapies based on PAC information: the PAC is simply a monitor and will not independently alter outcomes unless coupled with appropriate therapy. Therapeutic interventions initiated by the PAC can potentially benefit or harm the patient
and should be independently validated. To appropriately interpret the findings from a PAC trial, strict protocols predicated on evidence-based medicine should be used to define therapeutic goals and the interventions used to achieve them. The implementation of protocols will reduce the recognized variability of care related to PAC data. Such protocols are rarely used in PAC studies. 4. Uncertainty relating to hemodynamic goals needed to improve outcomes: the PAC allows the clinician to measure cardiac output, intracardiac filling pressures, mixed venous oxygen saturation, derived hemodynamic parameters such as systemic and pulmonary artery resistance, and ejection fraction. Optimization of these indices may improve outcomes in critically ill patients. However, the optimal value of these various parameters has not been independently determined at the present time (ie, a cardiac index of ⬎3 L/min/m2 or ⬎4 L/min/m2, a wedge pressure of 15 mmHg or 18 mmHg). 5. Uncertainty as to which therapeutic intervention is most important in impacting outcomes: patients receiving PACs typically receive more fluids (to raise wedge pressures), more inotropes (to increase cardiac index), and more vasoactive medications (to raise or lower systemic vascular resistance) than control patients.3 At the present time, it is uncertain which therapeutic intervention, initiated by the PAC, produces the greatest beneficial effects on patient outcomes. 6. Inappropriate patient populations receiving a PAC: low-risk patients are unlikely to derive benefits from PAC monitoring. In this patient population, the risks of PACs likely outweigh the benefits, and differences in mortality are unlikely to be observed. In a trial of critically ill patients, the use of a PAC was associated with increased mortality rates in patients with a lower severity of illness score while reducing mortality in the most severely ill.20 A recently published databased analysis of 53,312 trauma patients revealed no beneficial effects of PAC monitoring on mortality in low-risk patients.21 In contrast, PAC use was associated with a significant survival benefit in patients with advanced age or increased injury severity. In the setting of cardiac surgery, 3 of the 5 prospective PAC trials studied low-risk patients.13,14,22
From the Department of Anesthesiology, Evanston Northwestern Healthcare, Northwestern University Feinberg School of Medicine, Evanston, IL. Address reprint requests to Glenn S. Murphy, MD, Department of Anesthesiology, Evanston Northwestern Healthcare, 2650 Ridge Avenue, Evanston, IL 60201. E-mail: [email protected] © 2007 Elsevier Inc. All rights reserved. 1053-0770/07/2101-0029$32.00/0 doi:10.1053/j.jvca.2006.11.001 Key words: pulmonary artery catheter, utcomes, invasive monitoring
Journal of Cardiothoracic and Vascular Anesthesia, Vol 21, No 1 (February), 2007: pp 147-149
147
148
MURPHY AND VENDER
7. Lack of standardization (and breadth) of user knowledge: PAC data must be properly obtained and interpreted by knowledgeable clinicians to ensure the delivery of appropriate therapeutic interventions. Surveys of critical care physicians, intensive care unit nurses, and cardiac anesthesiologists have shown significant deficiencies in clinicians’ ability to interpret PAC data.23-25 The inability of physicians and nurses to correctly interpret information from the PAC can result in inappropriate analysis of the data, leading to improper therapies and potential adverse outcomes. Few of the clinical trials examining the efficacy of PAC monitoring have attempted to qualitatively or quantitatively examine the experience and cognitive skills of all caregivers using the PAC in the study. Because of significant deficiencies in the quality of the scientific evidence, it is difficult to determine the effectiveness of PAC monitoring in influencing outcomes in surgical and medical patients. Despite the recent publication of large-scale randomized trials,6-9 many questions remain unanswered. In particular, what are the appropriate or optimal endpoints of care using a PAC? What are the treatment strategies guided by PAC data that are most likely to benefit outcomes? What role does user experience and knowledge play in determining outcomes? Until these questions are answered, it will be difficult to draw meaningful conclusions from the scientific literature about the benefits and risks of PAC monitoring. EXPERT OPINION
A review of the evidence from clinical trials does not provide clear support for or against the use of PAC in the management of the critically ill patient. In the absence of this information, important insights can be obtained from expert opinion. The American Society of Anesthesiologists reconvened the Task Force on Pulmonary Artery Catheterization in 2000.3 The Task Force concluded that available evidence from published research provided incomplete information about PAC effectiveness. Expert opinion of the Task Force was assessed using a formal group consensus process. It was the opinion of the task force that “PA catheter monitoring of selected surgical patients can reduce the incidence of perioperative complications, primarily by providing immediate access to critical hemodynamic data. The expert opinion of the Task Force is that access to these data for selected indications and settings, coupled with accurate interpretation and appropriate treatment tailored to hemodynamic status, can reduce perioperative mortality and morbidity.”3 A similar opinion was expressed by the Pulmonary Artery Consensus Conference sponsored by the Society of Critical Care Medicine.2 It was the collective opinion of the Consensus Conference participants that management guided by the PAC may be beneficial for critically ill medical patients (myocardial infarction with shock, refractory CHF, and sepsis) and high-risk surgical patients. The participants concluded that clinicians should weigh the risks and benefits of the PAC on a case-by-case basis and that there was no basis for a moratorium for PAC use at this time. The opinions of practicing anesthesiologists in the United States and Canada about appropriate PAC applications were assessed in a recent survey.26 Fiftythree percent of respondents rated the PAC as not appropriate
in low-risk patients undergoing cardiovascular surgery. In contrast, 74% of respondents strongly agreed that use of the PAC is appropriate in patients with ventricular impairment. In conclusion, it is the opinion of “experts” and practicing anesthesiologists that the PAC has a beneficial role in the management of critically ill patients. PERSONAL OPINION
It is the belief of the authors that the routine use of PACs in low-risk patients is unwarranted. In this setting, the risks of invasive monitoring outweigh the potential benefits. Patients with extreme mortality risks or pathophysiologic processes unresponsive to therapeutic interventions (ie, ruptured thoracic aneurysm) are also unlikely to derive benefits. The PAC must also be used in the appropriate situations to influence outcomes. Alterations in clinical management and outcomes are more likely to be observed in a patient with poor ventricular function undergoing major cardiac surgery compared with the same patient undergoing a laparoscopic cholecystectomy. In addition, clinicians using PAC monitoring should be experienced in technical skills relating to catheter placement and maintenance and should show competence in data interpretation and application. Finally, the PAC must be placed and therapies initiated before irreversible tissue injury occurs! Timeliness of interventions is likely of critical importance in determining efficacy of care and eventual outcomes. Early goal-directed therapy before admission to the intensive care unit resulted in significant reductions in mortality in patients with severe sepsis or septic shock when compared with a group randomized to standard therapy.27 There is likely a window of time during which the data derived from the PAC can impact decision making and thereby morbidity and mortality. Unfortunately, many studies have significant delays in PAC management relating to the onset of pathophysiologic trespass. The authors acknowledge that the scientific evidence does not clearly show that PAC monitoring reduces major morbidity and mortality. It is important to note, however, that there is limited (if any) evidence that any monitoring technology used in the operating room or intensive care unit settings has a definitive mortality benefit. Clinicians believe that pulse oximetry and capnography are valuable perioperative monitors, yet there is no evidence from large-scale randomized trials showing improvements in major outcomes with these standard monitors. Transesophageal echocardiography is a valuable monitor of cardiac structure and function that is frequently used by cardiac anesthesiologists and intensivists. However, there are no published randomized trials showing an obvious reduction in mortality after TEE application. A review of the literature reveals an absence of high-quality “evidence-based” data supporting any commonly used monitoring devices (eg, invasive radial arterial catheters, central venous catheters, and pulse oximetry). As a result of the numerous limitations relating to the scientific evidence, physicians must depend on “expert opinion” to determine the role of the PAC in their clinical practice. We agree with the opinion of the Task Force that the PAC, by providing immediate access to critical hemodynamic data and allowing for prompt treatment with fluids or medications, can reduce morbidity and mortality.3 These benefits, however, will only be derived when the PAC is used in the
PRO AND CON
149
appropriate patient (high-risk medical or surgical patients), for the appropriate situation (conditions likely to respond to therapies such as fluids and vasoactive medications), in the appropriate setting (by experienced and knowledgeable clinicians in a timely manner). It is the belief of the authors that the most
important issues with the PAC are related to caregiver understanding and appropriate and timely utilization of the technology. Additional well-designed clinical trials that address and use the correct questions and endpoints, are needed to define the role of the PAC in the management of the critically ill patient.
REFERENCES 1. 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 283: 2568-2572, 2000 2. Pulmonary Artery Consensus Conference: Consensus Statement. Pulmonary Artery Catheter Consensus Conference Participants. Crit Care Med 25:910-924, 1997 3. Practice guidelines for pulmonary artery catheterization. An updated report by the American Society of Anesthesiologists Task Force on Pulmonary Artery Catheterization. Anesthesiology 99:988-1014, 2003 4. Trottier SJ, Taylor RW: Physicians’ attitudes toward and knowledge of the pulmonary artery catheter: Society of Critical Care Medicine membership survey. New Horiz 5:201-206, 1997 5. Chernow B: Pulmonary artery floatation catheters: A statement by the American College of Chest Physicians and the American Thoracic Society. Chest 111:261-262, 1997 6. Sandham JD, Hull RD, Brant RF, et al: Canadian Critical Care Trials Group. A randomized controlled trial of the use of pulmonary artery catheters in high risk surgical patients. N Engl J Med 348:5-14, 2003 7. The Escape Investigators and Escape Study Coordinators: Evaluation of congestive heart failure and pulmonary artery catheterization effectiveness. JAMA 294:1625-1633, 2005 8. Harvey S, Harrison DA, Singer M, et al: Assessment of clinical effectiveness of pulmonary artery catheters in the management of patients in intensive care (PAC-MAN): A randomized trial. Lancet 366:472-477, 2005 9. The National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network: The pulmonaryartery versus central venous catheter to guide treatment of acute lung injury. N Engl J Med 354:2213-2224, 2006 10. Ivanov R, Allen J, Sandham D, et al: Pulmonary artery catheterization: A narrative and systematic critique of randomized controlled trials and recommendations for the future. New Horiz 5:268-276, 1997 11. Murphy GS, Nitsun M, Vender JS: Is the pulmonary artery catheter of utility?, in Van Aken H, Fleisher L (eds): Best Practice and Research Clinical Anesthesiology (vol 19). Philadelphia, PA, Elsevier, 2005 12. Gummert JF, Funkat A, Beckmann A, et al: Cardiac surgery in Germany during 2005: A report on behalf of the German Society of Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 54:362371, 2006 13. Pearson KS, Gomez MN, Moyers JR, et al: A cost/benefit analysis of randomized invasive monitoring for patients undergoing cardiac surgery. Anesth Analg 69:336-341, 1989
14. Polonen P, Ruokonen E, Hippelainen M, et al: A prospective, randomized study of goal-oriented hemodynamic therapy in cardiac surgical patients. Anesth Analg 90:1052-1059, 2000 15. Isaacson IJ, Lowdon JD, Berry AJ, et al: The value of pulmonary artery and central venous monitoring in patients undergoing abdominal aortic reconstructive surgery: A comparative study of two selected, randomized groups. J Vasc Surg 12:754-760, 1990 16. Joyce WP, Provan JL, Ameli FM, et al: The role of central hemodynamic monitoring in abdominal aortic surgery. A prospective randomized study. Eur J Vasc Surg 4:633-636, 1990 17. Berlauk JF, Abrams JH, Gilmour IJ, et al: Preoperative optimization of cardiovascular hemodynamics improves outcome in peripheral vascular surgery. A prospective, randomized clinical trial. Ann Surg 214:289-299, 1991 18. Valentine RJ, Duke ML, Inman MH, et al: Effectiveness of pulmonary artery catheters in aortic surgery: A randomized trial. J Vasc Surg 27:203-212, 1998 19. Bender JS, Smith-Meek MA, Jones CE: Routine pulmonary artery catheterization does not reduce morbidity and mortality of elective vascular surgery. Results of a prospective, randomized trial. Ann Surg 226:229-237, 1997 20. Chittock DR, Dhingra VK, Ronco JJ, et al: Severity of illness and risk of death associated with pulmonary artery catheter use. Crit Care Med 32:911-915, 2004 21. Friese RS, Shafi S, Gentilello LM: Pulmonary artery catheter use is associated with reduced mortality in severely injured patients: A National Trauma Data Bank analysis of 53,312 patients. Crit Care Med 34:1597-1601, 2006 22. Stewart RD, Psyhojos T, Lahey SJ, et al: Central venous catheter use in low-risk coronary artery bypass grafting. Ann Thorac Surg 66:1306-1311, 1998 23. Iberti TJ, Fischer EP, Leibowitz AB, et al: A multicenter study of physicians’ knowledge of the pulmonary artery catheter. JAMA 264:2928-2932, 1990 24. Burns D, Burns D, Shively M: Critical care nurses’ knowledge of pulmonary artery catheters. Am J Crit Care 5:49-54, 1996 25. Jacka MJ, Cohen MM, To T, et al: Pulmonary artery occlusion pressure estimation: How confident are anesthesiologists? Crit Care Med 30:1197-1203, 2002 26. Jacka MJ, Cohen MM, To T, et al: The appropriateness of the pulmonary artery catheter in cardiovascular surgery. Can J Anaesth 49:276-282, 2002 27. Rivers E, Nguyen B, Havstad S, et al: Early goal-directed therapy in the treatment of severe sepsis and septic shock. N Engl J Med 345:1368-1377, 2001