Anesthesia and Outcome

From Survey of Current Issues in Surgical Anesthesia, sponsored by the Anesthesiology Institute, Cleveland Clinic Foundation, November 15-19, 2008, Daytona Beach, FL

Educational Objectives

The goals of this program are to increase knowledge of the impact of anesthetic choice on outcome after lower ex­tremity total joint replacement and in aortic surgery. After hearing and assimilating this program, the clinician will be better able to:

1.   Review techniques for reducing thromboembolic complications after elective lower extremity joint replace­ment.

2.   Analyze the impact of anesthetic choice and technique on perioperative blood loss, cognitive function, risk for infection, peripheral nerve injury, and peripheral blood flow.

3.   Discuss the outcome studies about the use of epidural anesthesia and/or analgesia in aortic surgery.

4.   Explain the transient interest in combined epidural/general technique for aortic repair.

5.   Recognize the potential role of epidural cooling in thoracoabdominal aortic repair.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and planning commit­tee members to disclose relevant financial relationships within the past 12 months that might create any personal con­flicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the faculty and planning commit­tee reported nothing to disclose.

Acknowledgments

Drs. Tetzlaff and Schoenwald spoke in Daytona Beach, FL, at Survey of Current Issues in Surgical Anesthesia, held November 15-19, 2008, and sponsored by the Anesthesiology Institute, Cleveland Clinic Foundation, Cleveland, OH. The Audio-Digest Foundation thanks the speakers and the Cleveland Clinic Foundation for their cooperation in the production of this program.

Regional Anesthesia vs General Anesthesia for Lower Extremity Joint Replacement

John E. Tetzlaff, MD, Professor of Anesthesiology, Cleveland Clinic Lerner College of Medicine of Case West­ern Reserve University, and Vice Chair for Education, Anesthesiology Institute, Cleveland Clinic, Cleveland, OH

Early studies: Modig et al, 1980  —  60 patients with elective total hip replacement (THR); randomized to receive ei­ther general anesthesia (GA) or epidural anesthesia (EA) with continuous lumbar epidural (CLE) for postoperative pain control; noted that virtually every criterion in hypothesis proven; substantial reduction in popliteal deep ve­nous thrombosis (DVT), femoral DVT, combined calf-thigh clot, pulmonary embolism, and intraoperative blood loss (BL) in EA group; Modig et al, 1983  —  elective THR with same randomization as first study; measured blood flow (BF) in microcirculation using plethysmography; noted improved microvascular BF in EA group and same substantial reduction in BL; improved calf BF during and after surgery with EA and postoperative analgesia; Modig et al, 1986  —  94 patients randomized for elective THR; same criteria; venogram and lung scan added for all pa­tients, rather than waiting for symptoms; by overt measurement, decreased DVT rate (>50%) and PE rate (10% vs 33%) with EA; ³50% reduced BL in hip surgery patients who had EA in operating room; study of spinal anesthesia (SA) and GA in THR  —  85 patients; anesthetic technique selected by anesthesia provider; no randomization; 4 SA vs 33 GA required transfusion; lower hemoglobin in SA; urinary stasis equivalent; >50% decrease in DVT with SA; Covert study  —  hip surgery; reduction in BL and DVT consistent with above study; lower O₂ saturation in GA; greater incidence of early confusion with GA; benefits of regional anesthesia (RA) for thromboembolic complica­tions include improved regional BF, improved fibrinolysis, decreased platelet hyperactivity, maintenance of endog­enous anticoagulants, and decreased endothelial cell activity

DVT after joint replacement: large number of patients; not randomized for anesthetic technique; all had pharmaco­logic DVT prophylaxis; no difference in DVT for RA vs GA; observational study by Sharrock  —  showed sub­stantial reduction in DVT and reduced pulmonary embolism with CLE (2 deaths due to aspiration in CLE group; likely preventable); Sharrock et al speculated on reasons; looked carefully at 441 THR patients with EA; DVT rate related to duration of surgery; increased DVT with prolonged surgery; reduced with vasopressor use (possi­bly due to either reduced BF or  lowered mean arterial blood pressure [BP]); subsequent study by Sharrock  —  total knee replacement (TKR); randomized to GA or EA; samples taken preoperatively, intraoperatively, and postoperatively; looked at wide variety of activity in coagulation system; unable to demonstrate difference be­tween groups

Use of low molecular weight heparin (LMWH; Lovenox): studies in early 1990s suggested that LMWH effective in preventing DVT; perceived to have reduced impact on coagulation, and, therefore, RA not problematic; study from Europe  —  included dose of LMWH, 40 mg once daily; involved 5000 SA, 1100 single-shot EA, and 150 maintained with epidural catheter (>24 hr); no neurologic complications, although superficial infection reported by surgeons in 31 of 6288 cases (double rate of superficial epidural wound hematoma after joint replacement); European study of 8400 patients  —  does not specifically report DVT rate, but does indicate low risk for epidural hematoma; United States study of LMWH and RA management  —  showed uncertain response in routine pro­thrombin time (PT) and partial thromboplastin time (PTT); in first 5 yr, 14 cases of epidural hematoma reported (risk identified by manufacturer); before consensus guideline reached, total of 64 cases reported (probably under­reported); majority of cases originally  associated with placement of epidural needle; subsequently attributed to removal of catheter; in patients receiving RA, exercise considerable vigilance when using LMWH; guideline rec­ommends waiting 12 hr after administration of LMWH before removing catheter

Bleeding: study of 41 THR patients  —  randomized to either GA or EA; statistically significant decrease in number re­quiring transfusion with heterologous blood in EA group; study of 538 geriatric hip fracture patients  —  randomized to GA or SA; technique not specified; no difference in 28-day mortality, although mortality increased when surgery delayed >24 hr, patient had coronary artery disease (CAD) or preexisting dementia, lived in nursing home, or was catabolic (as determined by serum proteins)

Mental status: study of hip fracture patients >60 yr of age  —  randomized to GA or SA; cognitive function measured preoperatively and at 3 mo postoperatively; found no difference in outcome; early hospitalization possibly associ­ated with more confusion in geriatric patients with lower O₂ saturation

Postoperative infection: retrospective study (Fernandez et al, 1992)  —  combination of 376 spinal surgery and lower extremity knee replacement patients; compared outcomes with autologous blood, heterologous blood, or both; ho­mologous blood significantly increased infection rate by 25% to 30%; Murphy et al (1991) —limited in design (no defined transfusion triggers); elective THR; received 2 to 3 units of homologous or autologous blood; recipients of homologous blood had significantly higher rate of postoperative infections, greater need for antibiotics, and re­quired 2.5 to 3.0 extra postoperative hospital days; study of 31 orthopedic patients  —  received SA, GA, or no sur­gery; looked at neutrophil biocidal activity by extracting neutrophils from blood and incubating with Staphylococcus aureus; neutrophils from SA patients killed twice as many bacteria in first hour, and higher activity than GA group maintained in second hour; SA group also showed increased neutrophil cell membrane activity; re­sults duplicated in small study of THR patients

Urinary retention: Petersen et al  —  60 male patients; slightly higher urinary tract infection rate if urinary retention; no focus on anesthetic technique; McQueen  —  same hypothesis; 100 patients for TKR or THR; randomized to EA or GA technique; in EA group, pain scores substantially better, substantial reduction in BL and transfusion, but in­creased urinary retention and increased pruritus

Peripheral nerve injury: Mayo Clinic orthopedic surgeons  —investigated whether postoperative epidural delays di­agnosis of peroneal nerve injury; studied 361 patients entered in database over 1 yr; found 8 cases of peroneal palsy (2.2% rate); 4 of 8 had CLE, other 4 had GA; potential for delay in diagnosis, but avoidable via modification of RA technique; subgroups at greater risk for peroneal nerve injury; valgus deformity and valgus knee >15°, patients re­ceiving pneumatic tourniquet for >120 min, and those with preexisting neuropathy at substantially increased risk; case report of infected nonunion of tibia  —  patient had intraoperative and postoperative EA, maintained with 0.125% bupivacaine at modest rate; pain and neurologic deficit noted; compartment exploration on postoperative day 3 noted necrotic lateral compartment; sustained disability from missed diagnosis; concluded that recognition delayed by EA; complete removal of bladder in lithotomy position  —  received EA and GA intraoperatively (0.125% bupivacaine with fentanyl); left calf pain noted in postanesthesia care unit (PACU); early diagnosis fol­lowed with compartment pressure measurement and immediate fasciotomy; other than scar, outcome normal

Postoperative rehabilitation: outcome study of 262 elective THRs  —  randomized to standard GA or EA; postopera­tive pain control involved GA plus intravenous (IV) patient-controlled analgesia (PCA) with morphine or EA plus 0.1% bupivacaine with fentanyl; in CLE group, patients walked stairs unassisted 1 day sooner than GA group and achieved 90° flexion of hip significantly earlier; no difference in length-of-stay; study of 45 elective TKRs  —  GA vs EA; pain treated with opioids, CLE, or 3-in-1 block; patients receiving RA had substantially lower pain scores overall, including during active rehabilitation, 10° greater knee flexion at postoperative day 7, and shorter hospital stay; additional study comparing GA and RA in elective TKR found peripheral nerve block perhaps superior to lumbar epidural; length-of-stay decreased by £20% and pain scores reduced by £2% in RA group

Epidural Anesthesia and Aortic Surgery

Peter K. Schoenwald, MD, Faculty, Department of General Anesthesiology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University; Staff Anesthesiologist and Associate Director, Anesthesiology Residency, Center for Anesthesiology Education, Anesthesiology Institute, Cleveland Clinic, Cleveland, OH

Impetus for using EA as main intraoperative analgesic in combination with GA:  endovascular aortic surgery performed with increasing frequency; finding that surgeries can be completed with EA and mild sedation; epidural also option for postoperative analgesia; in aortic surgery, consider epidural catheter to cool spinal cord for preserva­tion and thoracic aneurysm repair; literature indicates EA can yield better outcomes (improves postoperative pul­monary function; decreases hypercoagulability; decreases morbidity and mortality, particularly cardiac morbidity and mortality)

Stress response to surgery and trauma: stress response may be protective in trauma, but probably maladaptive for surgery; injury results in direct chemical response; cytokines released into bloodstream travel to brain and release compounds indicative of stress response; neuroendocrine response includes sympathetic and sensory afferent im­pulses; chemical mediators of importance include epinephrine, norepinephrine, cortisol, aldosterone, and renin-al­dosterone system; net result includes changes in coagulability, immune system, metabolism, cardiovascular system; effects on heart include increase in heart rate, BP, and inotropy; shift in O₂ supply and demand could result in isch­emia; ischemic response seen in patients with advanced or clinical CAD, however,  also induced in asymptomatic patients with subclinical disease; Hertzer performed coronary angiography in 1000 patients for peripheral vascular reconstruction; found high proportion of patients had CAD (60%, advanced or severe CAD; 25%, severe correct­able CAD); of those with aortic aneurysms, 34% had severe CAD and of those, 31% had correctable lesions; se­vere, inoperable CAD increases markedly with age, but »50% have severe, correctable CAD; significant proportion of patients with diabetes and hypertension have severe CAD

Concept of stress-free surgery: cardiac morbidity most common medical complication of patients undergoing non­cardiac surgery; evidence indicates relationship between myocardial ischemia and postoperative myocardial events; perioperative cardiac events associated with high mortality (approaching 60%); if stress response eliminated, possi­ble to decrease morbidity and mortality, particularly due to cardiac complications; epidural analgesia demonstrated to ameliorate neuroendocrine response to surgery

Benefits of EA in abdominal aortic aneurysm (AAA) repair: positive pulmonary effects, including maintenance of lung volume, functional residual capacity (FRC), and vital capacity; decreased pulmonary morbidity; positive ef­fects on gut motility; others include less impact on coagulation system, decreased BL, and superior pain control and patient satisfaction

Yeager study (1987): evaluation of effects of EA and analgesia on morbidity in high-risk surgical patients; subse­quently criticized for small sample size, mix of surgical procedures (aortic surgery one subset), and inconsistent postoperative epidural management; randomized, controlled trial; in EA group, light GA plus epidural for intraop­erative management; epidural continued postoperatively for pain control; in control group, GA delivered by 1 of 3 methods; parenteral narcotics given postoperatively; outcomes measured included clinical outcome, endocrine re­sponse, and cost; results  —  EA group had no mortality vs 4 deaths in control, »50% fewer complications, less car­diovascular failure, fewer major infections, lower initial cortisol levels, and lower hospital costs

Tuman study (1991): effects of EA and analgesia on coagulation and outcome after major vascular surgery; more ho­mogeneous population (45% aortic surgery); larger study group; 3 groups, including GA plus thoracic EA followed by postoperative epidural for pain control, GA plus on-demand narcotics postoperatively, and nonvascular control; 120 patients prospectively randomized; also examined effect of epidural on coagulability; findings  —  vascular pa­tients hypercoagulable on thromboelastography, and hypercoagulability attenuated with epidural; EA group had fewer thrombotic events and reduced rates of cardiovascular, infectious, and overall postoperative complications; intensive care unit stay reduced with EA

Baron study (1991): combined EA and GA vs GA alone for AAA surgery; goal to determine whether addition of thoracic epidural intraoperatively to GA alters postoperative mortality; 173 patients; results did not demonstrate benefit from EA; criticized because postoperative analgesic techniques not controlled or randomized

Three additional AAA surgery studies: utilized EA; found that addition of EA resulted in no difference in outcome parameters; 2001 study looked at >1000 patients from Veterans Affairs hospitals; 4 operative procedure types; GA plus postoperative parenteral opioids vs EA plus light GA and postoperative epidural morphine; in aggregate, no difference in mortality or major complications; when aortic surgery analyzed alone, significant reduction in death and major complications

Meta-analysis: Rigg looked at high-risk patients undergoing major surgery; compared EA plus GA and postopera­tive EA vs GA plus postoperative parenteral opioids; eligibility required one of several comorbidities; results  —  low mortality in both groups, with no significant difference; only respiratory failure occurred less frequently with EA; lower pain scores in first 3 days with EA; further analysis by Peyton showed no difference among 3 subgroups

Hall study: reviewed meta-analysis of RA vs GA in cardiovascular patients; conclusion  —  earlier studies used older surgical techniques and anesthetics than those in current usage, and data therefore invalid; supposition that RA de­creases morbidity and mortality after major surgery remains unproven

Additional comments: abandonment of EA as primary intraoperative anesthetic; no clear-cut benefit in literature; more hypotension with EA; Cambria showed marked decrease in neurologic deficits with use of epidural cooling for spinal cord protection, but difficult to reproduce his data; cooling protects spinal cord, but increase in CSF pres­sure decreases perfusion and potentially detrimental; use in endovascular AAA repair

Suggested Reading

Baron JF et al: Combined epidural and general anesthesia versus general anesthesia for abdominal aortic surgery. Anesthe­siology 75:611, 1991; Beattie WS et al: Epidural analgesia reduces postoperative myocardial infarction: a meta-analysis. Anesth Analg 93:853, 2001; Bergqvist D et al: Risk of combining low molecular weight heparin for thromboprophylaxis and epidural or spinal anesthesia. Semin Thromb Hemost 19:147, 1993; Cambria RP et al: Clinical experience with epidu­ral cooling for spinal cord protection during thoracic and thoracoabdominal aneurysm repair. Covert CR, Fox GS: Anaes­thesia for hip surgery in the elderly. Can J Anaesth 36:311, 1989; Davis FM et al: Prospective, multi-centre trial of mortality following general or spinal anaesthesia for hip fracture surgery in the elderly. Br J Anaesth 59:1080, 1987; Grass JA: The role of epidural anesthesia and analgesia in postoperative outcome. Anesthesiol Clin North America 18:407, 2000; Hertzer NR et al: Coronary artery disease in peripheral vascular patients. A classification of 1000 coronary angiograms and results of surgical management. Ann Surg 199:223, 1984; J Vasc Surg 25:234, 1997; Modig J et al: Thromboembolism after total hip replacement: role of epidural and general anesthesia. Anesth Analg 62:174, 1983; Peyton PJ et al: Periopera­tive epidural analgesia and outcome after major abdominal surgery in high-risk patients. Anesth Analg 96:548, 2003; Rigg JR et al: MASTER Anaethesia Trial Study Group. Epidural anaesthesia and analgesia and outcome of major surgery: a ran­domised trial. Lancet 359:1276, 2002; Rodgers A et al: Reduction of postoperative mortality and morbidity with epidural or spinal anaesthesia: results from overview of randomised trials. BMJ 321:1493, 2000; Sharrock NE et al: Changes in mortality after total hip and knee arthroplasty over a ten-year period. Anesth Analg 80:242, 1995; Tuman KJ et al: Effects of epidural anesthesia and analgesia on coagulation and outcome after major vascular surgery. Anesth Analg 73:696, 1991; Yeager MP et al: Epidural anesthesia and analgesia in high-risk surgical patients. Anesthesiology 66:729, 1987.