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Epidural analgesia and coronary artery bypass grafting: The controversy continues
VOL 17, NO 2
APRIL 2003
EDITORIAL Epidural Analgesia and Coronary Artery Bypass Grafting: The Controversy Continues
T
HE ANESTHETIC QUEST to improve patient care while committing no harm becomes especially challenging when a clinical approach yields some benefits while risking a rare but serious complication. This dilemma applies to expanding clinical experience with epidural analgesia in cardiac surgery. Reported benefits include coronary vasodilation, improved stress response suppression, quality of analgesia and pulmonary function, as well as reduced incidences of postoperative pneumonia, renal failure, supraventricular arrhythmias, and confusion.1-7 These factors offer considerable appeal; however, anesthesiologists arguably abhor serious complications, even when rare, more than any other specialty. When pressed for an explanation, it may be that patients understand and accept surgical complications more readily than anesthetic ones. Consequently, when given the opportunity to offer patients an intervention that affords some benefits while incurring the rare but ill-defined risk of irreversible paraplegia in a fully anticoagulated unconscious patient, anesthesiologists instinctively retreat into a risk-averse comfort zone. In this issue, Canto´ et al8 bring significant additional clinical experience to this ongoing controversy. Over 7 years, Canto´ et al8 placed high thoracic (T2-3 or T1-2) epidural catheters into 714 patients undergoing coronary artery bypass graft (CABG) procedures with cardiopulmonary bypass (CPB). In contradistinction to most earlier investigations of epidural catheter placement in this clinical setting,9 they placed the catheters on the day of surgery and they evidently proceeded with both the epidural placement and the surgical procedure even after a bloody tap, which they experienced in 11 patients. The authors otherwise followed usual guidelines for epidural catheter placement and for its removal, which typically occurred on the fourth postoperative day.9-11 Using this approach in a largely unselected group of CABG patients, 75% of their patients were extubated in the operating room and there were no apparent spinal hematomas.
A recent report suggests that most anesthesiologists do not use epidural anesthesia or analgesia for cardiac surgery.12 Should this study by Canto´ et al8 and other recent studies induce more anesthesiologists to embrace epidural analgesia in this clinical setting?2-5,7 The neurologic risk remains inadequately defined and the traditional approach using general anesthesia intraoperatively and intravenous opioids for early postoperative pain management produces very favorable outcomes, so perhaps the answer is, “not yet.” As the authors note, to date, the scientific literature reports approximately 6,000 epidural catheters placed preoperatively in patients undergoing CPB without a single known occurrence of spinal hematoma.8 In most of these reports, the catheter was placed on the day preceding surgery, or if placed on the anticipated day of surgery, the procedure was delayed to another day if a bloody tap occurred.9 Neurologic injury from epidural hematoma is rare, but it has been assumed that full anticoagulation for CPB performed on the same day as catheter placement would increase risk for that complication. Canto´ et al8 apparently elected to induce general anesthesia shortly after placing a thoracic epidural catheter even if the tap was bloody, thereby relying on their coagulation history and laboratory screening procedures to ensure that the 1-hour minimum time interval between epidural puncture and heparin administration would adequately protect against epidural hematoma. The authors opine that, in patients carefully screened to exclude risk factors for epidural hematoma, any bleeding caused by the catheter insertion procedure should remit well before their 1-hour minimum period between catheter placement and heparin administration. This logic, which seems to be increasingly accepted for the lower level of hepa-
© 2003 Elsevier Inc. All rights reserved. 1053-0770/03/1702-0001$30.00/0 doi:10.1053/jcan.2003.38
Journal of Cardiothoracic and Vascular Anesthesia, Vol 17, No 2 (April), 2003: pp 151-153
151
152
rin-induced anticoagulation used for noncardiac vascular surgery, appears equally valid regardless of the heparin dose. Heparin does not dissolve clots that have already formed, but rather prevents the formation of new ones, and 1 hour is clearly sufficient to arrest venous bleeding (by far the most likely source) induced by an 18-gauge Tuohy needle in patients who lack a bleeding diathesis. As an analogy, assume that an intravenous cannulation attempt using a 16-gauge needle perforates a vein while failing to place the cannula into the vein, thus creating the proverbial “blown IV.” Even without applying pressure, the bleeding stops in a matter of minutes. The important distinction is that the blown IV is unlikely to induce a clinically significant complication even if it should cause a 100-mL hematoma, whereas a much smaller epidural hematoma can induce spinal cord compression. Consequently, it would have been preferable for Canto´ et al to delay induction of general anesthesia for an hour after any bloody tap. This approach would have permitted neurologic evaluation of the lower extremities after any venous hematoma reached its maximal size. That the authors experienced no apparent neurologic complications in their 11 bloody taps offers insufficient reassurance. It is also surprising that the authors observed blood only 11 times in 714 epidural catheter insertions for an incidence of 1.5%. Previous reports suggest that the expected incidence of blood vessel puncture during a mixture of spinal, epidural, and caudal blocks is 2.3% to 4.5%.13 Although Canto´ et al8 studied an impressive number of patients and report impressive results, the study design raises some concerns. That it took 7 years for them to accumulate 714 patients raises concern about the impact of the expected evolution of clinical practice on clinical outcomes. The authors reported some important procedural changes that occurred over that period, but it is likely that many more actually transpired, some of which may have impacted clinical outcomes. More importantly, the study lacks a control group. Observational studies do have merit, but their clinical outcomes cannot be easily assessed without the benefits of a simultaneous control group and random patient assignment. For example, the observed mortality of 7.8% exceeded the expected figure of 6.2%. This difference apparently did not reach statistical significance, but the use of a historical multicenter database to assess expected mortality is far less compelling than a simultaneous randomly assigned study population would have been. The neurologic evaluation by Canto´ et al8 was somewhat cursory; it could have missed significant sensory deficits and subtle motor deficits, which may serve as initial signs of an epidural hematoma, for which rapid diagnosis and treatment are essential.14 The absence of follow-up after discharge from the hospital also raises the possibility of undetected subtle neurologic deficits. In this context, it would be wise to remember that only after nearly a quarter century of cardiac surgery was the importance of acute and long-term neuropsychologic deficits after CPB appreciated. It took that long because clinicians and investigators were not looking carefully for something that was undoubtedly present and clinically significant. Clearly, paraplegia is not subtle; however, it is only the most obvious and severe clinical manifestation of spinal cord compression. Similarly, hemiplegia is only the most obvious and severe manifestation among a broad spectrum of neurologic abnormalities
GLENN P. GRAVLEE
that cerebrovascular occlusion can cause. Resolving uncertainties about the safety and potential advantages of epidural anesthesia and analgesia in cardiac surgery will require additional prospective clinical trials with more complete postoperative neurologic examinations and longer follow-up, although admittedly this task will be daunting. Other practical issues merit consideration by those who may seek to apply the techniques of Canto et al8 to their clinical practice. Their incremental style of testing the epidural catheter location and establishing epidural blockade while inducing anesthesia and placing intravenous and monitoring catheters took approximately 45 to 60 minutes after completing placement of the epidural catheter. Even in the author’s clinical practice in a teaching institution in which the onset time of cardiac surgical procedures is less than dazzling, this much time could not be dedicated to epidural catheter placement, testing, and dosing without incurring the wrath of surgical colleagues and the operating room efficiency “police.” The authors used intravenous ketorolac or acetaminophen in addition to the epidural infusion of ropivacaine and fentanyl. Presumably, this was done to address the pain from the leg incision(s) used for saphenous vein harvesting. Aside from minor concerns about the hemostatic implications of ketorolac, it could reasonably be asked if the effort and risk of placing a high thoracic epidural catheter are worth it when the resulting analgesia will predictably exclude 1 of the 2 surgical incision sites. Although empirically it seems that chest pain from a median sternotomy should be more intense than leg pain from saphenous vein harvesting, clinical experience suggests that postoperative CABG patients may complain more about leg pain than chest pain. The authors clearly achieved impressive fast-track extubation outcomes, yet their median lengths of stay were 48 hours for the intensive care unit (ICU) and 8 days for hospitalization. Accomplishing extubation on the operating table after surgery does not appear to improve overall fast-track outcomes15; thus, clinicians should not obsess over achieving this goal. Canto´ et al appropriately point out that their ICU and hospital lengths of stay had more to do with local cultural and environmental factors than with patient clinical progress, which echoes the multicenter experience of Butterworth et al.16 Nevertheless, a potential opportunity to demonstrate an economic advantage to postoperative epidural analgesia was unfortunately lost as a result of circumstances beyond the authors’ control. Canto´ et al8 are to be commended for reporting this large series, although many important issues remain unresolved. These authors point out that the approximately 6,000 reported cases in which thoracic epidural catheters were placed before cardiac surgery without a single instance of paraplegia probably confers a maximum risk of 1 in 2,000 cases (minimum risk 1 in 150,000).8,9 Nevertheless, as clinicians, the task of balancing risks and benefits in the clinical setting of median sternotomy with CPB still exists. Assessing the neurologic risk remains difficult in the face of the “zero numerator” problem9,14,17 and, perhaps equally importantly, in the presence of potentially inadequate neurologic evaluations. Little improvement in short-term or long-term clinical outcomes has yet been shown from the use of epidural analgesia in cardiac surgery, but the recent report of Scott et al5 supports improved pulmonary and
EDITORIAL
153
renal outcomes. Fast-tracking with early extubation and early ICU and hospital discharge are readily attainable even without epidural analgesia.15 Indeed, current outcomes using conventional analgesia are so favorable that many if not most anesthesiologists and cardiac surgeons might eschew thoracic epidural catheters for CABG even if they could be confident that the actual risk of neurologic injury approximated the current minimum estimated risk of 1 in 150,000 procedures. Placed in the context of existing knowledge, what conclusions should be drawn from the added voluminous experience of Canto´ et al8? Although thoracic epidural catheter insertion for patients undergoing CABG with CPB should not be viewed as irrational, routine selection of this approach still seems inadvisable. While awaiting more prospective studies with control groups and random patient assignment, it seems reasonable to consider epidural analgesia in patients undergoing CABG with CPB who lack preoperative epidural hematoma risk factors and who have one or more of the following conditions: (1) ongoing myocardial ischemia with anticipated incomplete surgical revascularization; (2) tenuous pulmonary function that is
likely to impair postoperative ventilatory weaning, or (3) chronic opioid dependency from either substance abuse or from chronic pain disturbances in which postoperative pain will likely be difficult to manage with intravenous opioids. Even patients having these clinical conditions will most often fare well without epidural analgesia, so it would also be reasonable to try conventional intravenous opioid therapy first while reserving epidural analgesia for those who manifest postoperative difficulties with myocardial ischemia, ventilator weaning, or pain management. This approach offers the appeal of reestablishing coagulation competence and consistent wakefulness before placing the epidural catheter, but also risks the still unproven possibility that an ounce of prevention (eg, epidural analgesia for perioperative myocardial ischemia reduction or preemptive analgesia) will be worth a pound of cure. Glenn P. Gravlee, MD Professor, Department of Anesthesiology The Ohio State University College of Medicine and Public Health Columbus, OH
REFERENCES 1. Blomberg SG, Emanuelson H, Kvist H, et al: Effects of thoracic epidural anesthesia and central hemodynamics in patients with unstable angina pectoris. Anesthesiology 73:840-847, 1990 2. Tenling A, Joachimsson PO, Tyden H, et al: Thoracic epidural analgesia as an adjunct to general anaesthesia for cardiac surgery: Effects on pulmonary mechanics. Acta Anaesthesiol Scand 44:10711076, 2000 3. Stenseth R, Bjella L, Berg EM, et al: Effects of thoracic epidural analgesia on pulmonary function after coronary artery bypass surgery. Eur J Cardiothorac Surg 10:859-865, 1996 4. Liem TH, Hasenbos MA, Booij LH, et al: Coronary artery bypass grafting using two different anesthetic techniques: Part 2: Postoperative outcome. J Cardiothorac Vasc Anesth 6:156-161,1992 5. Scott NB, Turfrey DJ, Ray DAA, et al: A prospective randomized study of the potential benefits of thoracic epidural anesthesia and analgesia in patients undergoing coronary artery bypass grafting. Anesth Analg 93:528-535, 2001 6. Toft P, Jorgensen A: Continuous thoracic epidural analgesia for the control of pain in myocardial infarction. Intensive Care Med 13: 388-389, 1987 7. Moore CM, Cross MH, Desborough JP, et al: Hormonal effects of thoracic extradural analgesia for cardiac surgery. Br J Anaesth 75:387393, 1995 8. Canto M, Sanchez MJ, Casas MA, et al: Thoracic epidural analgesia in coronary artery bypass graft surgery: Seven years’ experience. J Cardiothorac Vasc Anesth 17:154-159, 2003
9. Ho A M-H, Chung DC, Joynt GM: Neuraxial blockade and hematoma in cardiac surgery: Estimating the risk of a rare adverse event that has not (yet) occurred. Chest 117:551-555, 2000 10. Vandermeulen EP, Van Aken H, Vermylen J: Anticoagulants and spinal-epidural anesthesia. Anesth Analg 79:1165-1177, 1994 11. Horlocker TT, Wedel DJ, Schroeder DR, et al: Preoperative antiplatelet therapy does not increase the risk of spinal hematoma associated with regional anesthesia. Anesth Analg 80:303-309, 1995 12. Goldstein S, Dean D, Kim SJ, et al: A survey of spinal and epidural techniques in adult cardiac surgery. J Cardiothorac Vasc Anesth 15:158-168, 2001 13. Concepcion M: Acute complications and side effects of regional anesthesia, in Brown DA (ed): Regional Anesthesia and Analgesia. Philadelphia, PA, Saunders, 1996, pp 446-461 14. Castellano JM, Durbin Jr CG: Epidural analgesia and cardiac surgery: Worth the risk? Chest 117:305-307, 2000 15. Cheng DCH: Fast-track cardiac surgery pathways: Early extubation, process of care, and cost containment. Anesthesiology 88:14291433, 1998 16. Butterworth J, James R, Prielipp RC, et al: Do shorter-acting neuromuscular blocking drugs or opioids associate with reduced intensive care unit or hospital length of stay after coronary artery bypass grafting? Anesthesiology 88:1437-1446, 1998 17. O’Connor CJ, Tuman KJ: Epidural anesthesia and analgesia for coronary artery bypass graft surgery: Still forbidden territory? Anesth Analg 93:523-525, 2001
APRIL 2003
EDITORIAL Epidural Analgesia and Coronary Artery Bypass Grafting: The Controversy Continues
T
HE ANESTHETIC QUEST to improve patient care while committing no harm becomes especially challenging when a clinical approach yields some benefits while risking a rare but serious complication. This dilemma applies to expanding clinical experience with epidural analgesia in cardiac surgery. Reported benefits include coronary vasodilation, improved stress response suppression, quality of analgesia and pulmonary function, as well as reduced incidences of postoperative pneumonia, renal failure, supraventricular arrhythmias, and confusion.1-7 These factors offer considerable appeal; however, anesthesiologists arguably abhor serious complications, even when rare, more than any other specialty. When pressed for an explanation, it may be that patients understand and accept surgical complications more readily than anesthetic ones. Consequently, when given the opportunity to offer patients an intervention that affords some benefits while incurring the rare but ill-defined risk of irreversible paraplegia in a fully anticoagulated unconscious patient, anesthesiologists instinctively retreat into a risk-averse comfort zone. In this issue, Canto´ et al8 bring significant additional clinical experience to this ongoing controversy. Over 7 years, Canto´ et al8 placed high thoracic (T2-3 or T1-2) epidural catheters into 714 patients undergoing coronary artery bypass graft (CABG) procedures with cardiopulmonary bypass (CPB). In contradistinction to most earlier investigations of epidural catheter placement in this clinical setting,9 they placed the catheters on the day of surgery and they evidently proceeded with both the epidural placement and the surgical procedure even after a bloody tap, which they experienced in 11 patients. The authors otherwise followed usual guidelines for epidural catheter placement and for its removal, which typically occurred on the fourth postoperative day.9-11 Using this approach in a largely unselected group of CABG patients, 75% of their patients were extubated in the operating room and there were no apparent spinal hematomas.
A recent report suggests that most anesthesiologists do not use epidural anesthesia or analgesia for cardiac surgery.12 Should this study by Canto´ et al8 and other recent studies induce more anesthesiologists to embrace epidural analgesia in this clinical setting?2-5,7 The neurologic risk remains inadequately defined and the traditional approach using general anesthesia intraoperatively and intravenous opioids for early postoperative pain management produces very favorable outcomes, so perhaps the answer is, “not yet.” As the authors note, to date, the scientific literature reports approximately 6,000 epidural catheters placed preoperatively in patients undergoing CPB without a single known occurrence of spinal hematoma.8 In most of these reports, the catheter was placed on the day preceding surgery, or if placed on the anticipated day of surgery, the procedure was delayed to another day if a bloody tap occurred.9 Neurologic injury from epidural hematoma is rare, but it has been assumed that full anticoagulation for CPB performed on the same day as catheter placement would increase risk for that complication. Canto´ et al8 apparently elected to induce general anesthesia shortly after placing a thoracic epidural catheter even if the tap was bloody, thereby relying on their coagulation history and laboratory screening procedures to ensure that the 1-hour minimum time interval between epidural puncture and heparin administration would adequately protect against epidural hematoma. The authors opine that, in patients carefully screened to exclude risk factors for epidural hematoma, any bleeding caused by the catheter insertion procedure should remit well before their 1-hour minimum period between catheter placement and heparin administration. This logic, which seems to be increasingly accepted for the lower level of hepa-
© 2003 Elsevier Inc. All rights reserved. 1053-0770/03/1702-0001$30.00/0 doi:10.1053/jcan.2003.38
Journal of Cardiothoracic and Vascular Anesthesia, Vol 17, No 2 (April), 2003: pp 151-153
151
152
rin-induced anticoagulation used for noncardiac vascular surgery, appears equally valid regardless of the heparin dose. Heparin does not dissolve clots that have already formed, but rather prevents the formation of new ones, and 1 hour is clearly sufficient to arrest venous bleeding (by far the most likely source) induced by an 18-gauge Tuohy needle in patients who lack a bleeding diathesis. As an analogy, assume that an intravenous cannulation attempt using a 16-gauge needle perforates a vein while failing to place the cannula into the vein, thus creating the proverbial “blown IV.” Even without applying pressure, the bleeding stops in a matter of minutes. The important distinction is that the blown IV is unlikely to induce a clinically significant complication even if it should cause a 100-mL hematoma, whereas a much smaller epidural hematoma can induce spinal cord compression. Consequently, it would have been preferable for Canto´ et al to delay induction of general anesthesia for an hour after any bloody tap. This approach would have permitted neurologic evaluation of the lower extremities after any venous hematoma reached its maximal size. That the authors experienced no apparent neurologic complications in their 11 bloody taps offers insufficient reassurance. It is also surprising that the authors observed blood only 11 times in 714 epidural catheter insertions for an incidence of 1.5%. Previous reports suggest that the expected incidence of blood vessel puncture during a mixture of spinal, epidural, and caudal blocks is 2.3% to 4.5%.13 Although Canto´ et al8 studied an impressive number of patients and report impressive results, the study design raises some concerns. That it took 7 years for them to accumulate 714 patients raises concern about the impact of the expected evolution of clinical practice on clinical outcomes. The authors reported some important procedural changes that occurred over that period, but it is likely that many more actually transpired, some of which may have impacted clinical outcomes. More importantly, the study lacks a control group. Observational studies do have merit, but their clinical outcomes cannot be easily assessed without the benefits of a simultaneous control group and random patient assignment. For example, the observed mortality of 7.8% exceeded the expected figure of 6.2%. This difference apparently did not reach statistical significance, but the use of a historical multicenter database to assess expected mortality is far less compelling than a simultaneous randomly assigned study population would have been. The neurologic evaluation by Canto´ et al8 was somewhat cursory; it could have missed significant sensory deficits and subtle motor deficits, which may serve as initial signs of an epidural hematoma, for which rapid diagnosis and treatment are essential.14 The absence of follow-up after discharge from the hospital also raises the possibility of undetected subtle neurologic deficits. In this context, it would be wise to remember that only after nearly a quarter century of cardiac surgery was the importance of acute and long-term neuropsychologic deficits after CPB appreciated. It took that long because clinicians and investigators were not looking carefully for something that was undoubtedly present and clinically significant. Clearly, paraplegia is not subtle; however, it is only the most obvious and severe clinical manifestation of spinal cord compression. Similarly, hemiplegia is only the most obvious and severe manifestation among a broad spectrum of neurologic abnormalities
GLENN P. GRAVLEE
that cerebrovascular occlusion can cause. Resolving uncertainties about the safety and potential advantages of epidural anesthesia and analgesia in cardiac surgery will require additional prospective clinical trials with more complete postoperative neurologic examinations and longer follow-up, although admittedly this task will be daunting. Other practical issues merit consideration by those who may seek to apply the techniques of Canto et al8 to their clinical practice. Their incremental style of testing the epidural catheter location and establishing epidural blockade while inducing anesthesia and placing intravenous and monitoring catheters took approximately 45 to 60 minutes after completing placement of the epidural catheter. Even in the author’s clinical practice in a teaching institution in which the onset time of cardiac surgical procedures is less than dazzling, this much time could not be dedicated to epidural catheter placement, testing, and dosing without incurring the wrath of surgical colleagues and the operating room efficiency “police.” The authors used intravenous ketorolac or acetaminophen in addition to the epidural infusion of ropivacaine and fentanyl. Presumably, this was done to address the pain from the leg incision(s) used for saphenous vein harvesting. Aside from minor concerns about the hemostatic implications of ketorolac, it could reasonably be asked if the effort and risk of placing a high thoracic epidural catheter are worth it when the resulting analgesia will predictably exclude 1 of the 2 surgical incision sites. Although empirically it seems that chest pain from a median sternotomy should be more intense than leg pain from saphenous vein harvesting, clinical experience suggests that postoperative CABG patients may complain more about leg pain than chest pain. The authors clearly achieved impressive fast-track extubation outcomes, yet their median lengths of stay were 48 hours for the intensive care unit (ICU) and 8 days for hospitalization. Accomplishing extubation on the operating table after surgery does not appear to improve overall fast-track outcomes15; thus, clinicians should not obsess over achieving this goal. Canto´ et al appropriately point out that their ICU and hospital lengths of stay had more to do with local cultural and environmental factors than with patient clinical progress, which echoes the multicenter experience of Butterworth et al.16 Nevertheless, a potential opportunity to demonstrate an economic advantage to postoperative epidural analgesia was unfortunately lost as a result of circumstances beyond the authors’ control. Canto´ et al8 are to be commended for reporting this large series, although many important issues remain unresolved. These authors point out that the approximately 6,000 reported cases in which thoracic epidural catheters were placed before cardiac surgery without a single instance of paraplegia probably confers a maximum risk of 1 in 2,000 cases (minimum risk 1 in 150,000).8,9 Nevertheless, as clinicians, the task of balancing risks and benefits in the clinical setting of median sternotomy with CPB still exists. Assessing the neurologic risk remains difficult in the face of the “zero numerator” problem9,14,17 and, perhaps equally importantly, in the presence of potentially inadequate neurologic evaluations. Little improvement in short-term or long-term clinical outcomes has yet been shown from the use of epidural analgesia in cardiac surgery, but the recent report of Scott et al5 supports improved pulmonary and
EDITORIAL
153
renal outcomes. Fast-tracking with early extubation and early ICU and hospital discharge are readily attainable even without epidural analgesia.15 Indeed, current outcomes using conventional analgesia are so favorable that many if not most anesthesiologists and cardiac surgeons might eschew thoracic epidural catheters for CABG even if they could be confident that the actual risk of neurologic injury approximated the current minimum estimated risk of 1 in 150,000 procedures. Placed in the context of existing knowledge, what conclusions should be drawn from the added voluminous experience of Canto´ et al8? Although thoracic epidural catheter insertion for patients undergoing CABG with CPB should not be viewed as irrational, routine selection of this approach still seems inadvisable. While awaiting more prospective studies with control groups and random patient assignment, it seems reasonable to consider epidural analgesia in patients undergoing CABG with CPB who lack preoperative epidural hematoma risk factors and who have one or more of the following conditions: (1) ongoing myocardial ischemia with anticipated incomplete surgical revascularization; (2) tenuous pulmonary function that is
likely to impair postoperative ventilatory weaning, or (3) chronic opioid dependency from either substance abuse or from chronic pain disturbances in which postoperative pain will likely be difficult to manage with intravenous opioids. Even patients having these clinical conditions will most often fare well without epidural analgesia, so it would also be reasonable to try conventional intravenous opioid therapy first while reserving epidural analgesia for those who manifest postoperative difficulties with myocardial ischemia, ventilator weaning, or pain management. This approach offers the appeal of reestablishing coagulation competence and consistent wakefulness before placing the epidural catheter, but also risks the still unproven possibility that an ounce of prevention (eg, epidural analgesia for perioperative myocardial ischemia reduction or preemptive analgesia) will be worth a pound of cure. Glenn P. Gravlee, MD Professor, Department of Anesthesiology The Ohio State University College of Medicine and Public Health Columbus, OH
REFERENCES 1. Blomberg SG, Emanuelson H, Kvist H, et al: Effects of thoracic epidural anesthesia and central hemodynamics in patients with unstable angina pectoris. Anesthesiology 73:840-847, 1990 2. Tenling A, Joachimsson PO, Tyden H, et al: Thoracic epidural analgesia as an adjunct to general anaesthesia for cardiac surgery: Effects on pulmonary mechanics. Acta Anaesthesiol Scand 44:10711076, 2000 3. Stenseth R, Bjella L, Berg EM, et al: Effects of thoracic epidural analgesia on pulmonary function after coronary artery bypass surgery. Eur J Cardiothorac Surg 10:859-865, 1996 4. Liem TH, Hasenbos MA, Booij LH, et al: Coronary artery bypass grafting using two different anesthetic techniques: Part 2: Postoperative outcome. J Cardiothorac Vasc Anesth 6:156-161,1992 5. Scott NB, Turfrey DJ, Ray DAA, et al: A prospective randomized study of the potential benefits of thoracic epidural anesthesia and analgesia in patients undergoing coronary artery bypass grafting. Anesth Analg 93:528-535, 2001 6. Toft P, Jorgensen A: Continuous thoracic epidural analgesia for the control of pain in myocardial infarction. Intensive Care Med 13: 388-389, 1987 7. Moore CM, Cross MH, Desborough JP, et al: Hormonal effects of thoracic extradural analgesia for cardiac surgery. Br J Anaesth 75:387393, 1995 8. Canto M, Sanchez MJ, Casas MA, et al: Thoracic epidural analgesia in coronary artery bypass graft surgery: Seven years’ experience. J Cardiothorac Vasc Anesth 17:154-159, 2003
9. Ho A M-H, Chung DC, Joynt GM: Neuraxial blockade and hematoma in cardiac surgery: Estimating the risk of a rare adverse event that has not (yet) occurred. Chest 117:551-555, 2000 10. Vandermeulen EP, Van Aken H, Vermylen J: Anticoagulants and spinal-epidural anesthesia. Anesth Analg 79:1165-1177, 1994 11. Horlocker TT, Wedel DJ, Schroeder DR, et al: Preoperative antiplatelet therapy does not increase the risk of spinal hematoma associated with regional anesthesia. Anesth Analg 80:303-309, 1995 12. Goldstein S, Dean D, Kim SJ, et al: A survey of spinal and epidural techniques in adult cardiac surgery. J Cardiothorac Vasc Anesth 15:158-168, 2001 13. Concepcion M: Acute complications and side effects of regional anesthesia, in Brown DA (ed): Regional Anesthesia and Analgesia. Philadelphia, PA, Saunders, 1996, pp 446-461 14. Castellano JM, Durbin Jr CG: Epidural analgesia and cardiac surgery: Worth the risk? Chest 117:305-307, 2000 15. Cheng DCH: Fast-track cardiac surgery pathways: Early extubation, process of care, and cost containment. Anesthesiology 88:14291433, 1998 16. Butterworth J, James R, Prielipp RC, et al: Do shorter-acting neuromuscular blocking drugs or opioids associate with reduced intensive care unit or hospital length of stay after coronary artery bypass grafting? Anesthesiology 88:1437-1446, 1998 17. O’Connor CJ, Tuman KJ: Epidural anesthesia and analgesia for coronary artery bypass graft surgery: Still forbidden territory? Anesth Analg 93:523-525, 2001