Combined Femoral and Sciatic Blocks Versus Epidural Anesthesia in Infrainguinal Surgeries, Hemodynamic Stability and Myocardial Morbidity

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1 Med. J. Cairo Univ., Vol. 84, No. 2, June: , Combined Femoral and Sciatic Blocks Versus Epidural Anesthesia in Infrainguinal Surgeries, Hemodynamic Stability and Myocardial Morbidity TAMER I. ROUK, M.Sc. and TAMER M. KHEIR, M.D. The Department of Anesthesiology, Surgical ICU and Pain Management, Faculty of Medicine, Cairo University Abstract Background: Infrainguinal surgeries for patients with peripheral vascular disease are often risky due to the nature of the surgical procedure, the associated co-morbidities (diabetes mellitus, hypertension and ischemic heart disease), and the need for efficient post-operative analgesia. Infrainguinal procedures included femoral, popliteal and infra-popliteal vascular bypass surgeries, thrombectomies, embolectomies and endarterectomies. Lower limb amputations (due to more critical ischemia or failed bypass) as well as varicose veins may be added. Using a combination of a sciatic nerve block with a femoral nerve block in these patients is a good anesthetic technique in contrary to the conventional neuraxial (spinal or epidural) anesthesia, which may be a contraindication in anticoagulated patients, septic shock and cardiovascular compromise; again spinal/epidural anesthesia usually causes evident hypotension. Aim of Work: Assessment of significance of hypotension and associated cardiac morbidity in both anesthetic techniques in this critical group of patients. Patients and Methods: We prospectively randomized 80 patients, undergoing unilateral infrainguinal surgeries, to receive either single shot combined femoral and sciatic nerve blocks or lumbar epidural anesthesia. Combined femoral sciatic block group (n=40) received isobaric bupivacaine 0.375% (femoral 20ml and sciatic 20ml) with nerve stimulator guidance. While epidural group (n=40) received isobaric bupivacaine 0.375% using loss of resistance to air technique for space detection then 5-mL aliquots were given to attain a sensory level at T 10 which is adequate for surgery. Preoperative set of cardiac biomarkers (CK, CK-MB and LDH) and ECG was obtained, intra-operative blood pressure, heart rate, dysrhythmias and any chest pain or dyspnea were observed. Post operatively, patients were observed for complications and need for ICU admission, and another set of cardiac biomarkers and ECG were repeated 24 hours later. Results: Significant blood pressure stability was observed in femoral-sciatic group, heart rate showed no difference. A significant smaller drop in cardiac biomarkers was found in epidural group (when compared with femoral-sciatic group) Correspondence to: Dr. Tamer I. Rouk, The Department of Anesthesiology, Surgical ICU and Pain Management, Faculty of Medicine, Cairo University but with no clinical symptoms or ECG changes. Only one case of ST segment depression with no clinical impact was found. Conclusion: The use of combined femoral-sciatic nerve block is superior in hemodynamic stability to conventional epidural analgesia in patients undergoing unilateral Infrainguinal surgeries. However, cardiac morbidity was clinically the same, and with no difference in the incidence of complications. Key Words: Infrainguinal surgeries Femoral-sciatic block Nerve stimulator Epidural. Introduction INFRAINGUINAL surgeries for lower limb revascularization or amputations are common. Most vascular surgical patients have advanced atherosclerotic disease and a variety of medical problems complicating the perioperative management. The type of anesthesia influences surgical stress response as well as intraoperative hemodynamic changes and may have an impact on perioperative complications. Lower-limb arterial bypass surgery is usually performed under general, spinal, or epidural anesthesia. A combined sciatic and femoral nerve block is a peripheral regional anesthesia technique used successfully for surgical procedures involving the lower extremity [1]. Patients requiring this procedure are usually either diabetics with uncontrolled sepsis of the leg or patients with peripheral vascular disease with gangrene. The patients are often quite ill and general anesthesia can be dangerous. Neuraxial (spinal or epidural) anesthesia, rather than a general anesthetic is often used but with high incidence of hypotension. An alternative technique is to perform a regional block of the affected lower limb using a combination of a sciatic nerve block with a femoral nerve block. A combination of the two blocks may 411

2 412 Combined Femoral & Sciatic Blocks Versus Epidural Anesthesia take longer time for onset; however the cardiovascular stability and postoperative pain relief provided by these regional blocks make them worthwhile techniques to perform especially in the very sick patient [2]. This study was performed to demonstrate the difference in hypotension and myocardial morbidity between combined femoral and sciatic nerve blocks versus the conventional epidural anesthesia in patients undergoing unilateral infrainguinal surgeries. Material and Methods This study was performed in Kasr Al-Ainy Hospitals, Cairo University, between April 2012 and February 2014, after approval of Departmental Ethical Committee. Patients were asked to give an informed written consent when they were willing to take part in the study and after explanation of the possible advantages and side effects. The population included 80 patients, aged years, ASA (American Society of Anesthesiology) physical status I, II or III, scheduled for unilateral infrainguinal surgeries (femoro-popliteal bypass, popliteal embolectomy, below knee amputation, above knee amputation, and trans-metatarsal amputation). Patients were excluded if they refused consent, ASA classification >III, history of local anesthetic allergy, infection at site of injection, coagulopathy (INR >1.5, platelets less than /mm), peripheral neuropathy, patients with confusion or delirium (uncooperative with lack of communication) and patients with previous vascular anastomosis at site of femoral block injection. All patients underwent systematic preoperative assessment prior to the scheduled date of surgical intervention. Patients were instructed to fast for 6 hours before surgery. First set of cardiac biomarkers and ECG was obtained. On arrival to operative suite, and after inserting IV line in the preparation room, midazolam 1mg IV then 0.5mg increments was given slowly every 2 minutes till patient was sedated but responding to verbal stimuli. Standard monitors were applied before the regional techniques, with continuous ECG, non-invasive blood pressure and pulse oximetry (SpO 2 ). Patients were preloaded by Ringer's solution 250ml over 10min., with attention to SpO 2 (not less than 92% on room air) and basal chest auscultation. O 2 mask was applied immediately after performing blocks. Patients were randomized into two groups of 40 patients each. : Received combined femoral and sciatic nerve blocks (single shot each) with insulated 22 gauge regional needles (Stimuplex, Braun) attached to a peripheral nerve stimulator ((Life-TechTM, Model ES400, Stafford, TX, USA). The regional nerve blocks were performed using isobaric bupivacaine 0.375%. The sciatic nerve block was performed using the posterior approach of Labat, the patient was positioned laterally, with a slight forward tilt. The foot on the side to be blocked was positioned over the dependent leg so that twitches of the foot or toes easily noted. A line between the upper tip of greater trochanter and posterior superior iliac spine was connected and divided in half. A second line is drawn between the greater trochanter and the sacral hiatus. A perpendicular line is drawn from the midpoint of the original line and extended about 4-6cm in the caudad direction, until intersecting the second line at a point, that is marked as the needle entry point, an insulated 100-mm shortbevel needle was advanced at this level, and the sciatic nerve was located by a nerve stimulator (dorsiflexion or extension) and blocked by 20mL of the bupivacaine solution. Femoral nerve block was performed by using the technique described by Winnie et al., [3], where the patient was placed in supine position, a line was drawn between the anterior superior iliac spine and the pubic tubercle to identify the inguinal ligament, the femoral artery was marked, the insulated needle was advanced lateral to the artery, and the femoral nerve was located by a nerve stimulator (quadriceps contraction) and blocked by 20mL of the bupivacaine solution. Successful anesthesia was indicated by loss of pain sensation (in response to pinprick test) after 20-30min. in the foot, leg, knee and thigh, and motor power loss in the whole limb. In case of failure of the block (after sensory testing within 20-30min.), general anesthesia was induced as an alternative plan, with paying attention to patient co-morbidities, as ischemic heart disease. Induction with IV propofol 1-2mg/kg with fentanyl 1-2 microgram/kg, and atracurium 0.5mg/kg, then smooth intubation and ventilation as usual, with inhalational maintenance of anesthesia. received lumbar epidural anesthesia, in the sitting position, Tuohy needle (Braun, 18- gauge) was inserted in L4-5, or L5-S 1 space, with loss of resistance to air technique for space detection, then the catheter (Braun, 20-gauge) was inserted in the epidural space, then advanced approximately 4-6cm cephalic, and fixed by tapes on the back. The epidural block was activated by bupivacaine 0.375% in 20ml total volume, and was given in 5-mL aliquots to attain a sensory level at T 10 which is adequate for surgery. Successful anesthesia is indicated by loss of pain sensation

3 Tamer I. Rouk & Tamer M. Kheir 413 (in response to pinprick test) up to the level of the umbilicus and motor power loss in both lower limbs (failure to elevate the leg off the table). Top up injections 5ml of the same preparation were given every 40-45min. to maintain anesthesia. At the end of surgery the epidural catheter was removed carefully, a sterile piece of gauze was applied and taped on the puncture site, or left for 6 hours if heparin is used (in bypass and embolectomy). Intra-operatively, onset of sensory and motor block sufficient to start the surgical procedure was recorded, with maximum 30min. failure to attain analgesia at this time is considered failure, and general anesthesia was induced. Also patients were closely monitored for hemodynamics, HR and NIBP after bupivacaine injection was done after: 5min. = T1, 10min. = T2, 15 min. = T3, 20min. = T4, 30min, = T5, 45min. = T6, 60min. = T7, 90min. = T8, 120min. = T9. Complications as dysrhythmias, shivering, nausea and vomiting, itching or local anesthetic toxicity were observed. Post-operatively, patients were discharged to the recovery room for 15min., then they were transferred to the ward (or to intensive care unit ICU if indicated), then patients were followed-up, any further complication (back pain, headache, femoral or gluteal pain and swelling suspecting hematoma) were observed within the first 24 hours postoperatively, another set of cardiac biomarkers and ECG was obtained 24 hours later. Statistical analysis: Obtained data were presented as mean ± SD, ranges, numbers and percentages as appropriate. Nominal variables were analyzed using Chi-squared ( χ 2 ) test or Fischer exact test as appropriate. Continuous variables were analyzed using unpaired Student's t-test or univariate two-group repeated measures mixed-design analysis of variance (ANOVA) with post hoc Dunnett's test as appropriate. Nominal and non-normally distributed variables were analyzed using Mann- Whitney U-test. Statistical calculations were performed using Microsoft Office Excel 2007 and SPSS (Version 17, 2008). p-value <0.05 was considered statistically significant. Results Eighty patients were enrolled in this study after signing informed consent; they were randomly allocated into two groups: had combined femoral and sciatic nerve block (nerve stimulator guided) (40 patients), and had epidural anesthesia (40 patients). Three patients were excluded from the study after randomization due to outstanding preoperative CK levels (mostly due to dead muscles in ischemic limb) to avoid misleading skewing results. All data analyses were performed after exclusion of these cases. So were 39 cases and were 38 cases, total number was 77 cases. Demographic data (age, gender, and smoking) showed no significant difference between groups (Table 1). Table (1): Demographic data of patients within groups. Group A Group B Total p- value Age (years): 63 (±9.9) 58.4 (± 10.8) 0.05 Mean (±SD) Males: 23 (59%) 20 (52.6%) Females: 16 (41%) 18 (47.4%) Smokers: 15 (38.5%) 13 (34.2%) ASA classification of patients was random as shown in (Table 2). Table (2): ASA classification of patients within each group. ASA I 3 (7.7%) 0 (0%) 3 Total ASA II 21 (53.8%) 18 (47.4%) 39 ASA III 15 (38.5%) 20 (52.6%) 35 Total 39 (100%) 38 (100%) 77 Distribution of medical diseases (diabetes, hypertension, renal impairment, hepatic impairment, bronchial asthma, ischemic heart disease and stroke) is shown in (Table 3), with count and % within group for every disease. Table (3): Count and percentage of medical diseases in each group. Medical co-morbidities Total count (% within all cases) Diabetes mellitus 25 (64.1 %) 24 (63.2%) 49 (63%) Hypertension 22 (56.4%) 15 (39.5%) 37 (48%) Renal impairment 2 (5.1%) 0 (0%) 2 (2.6%) Hepatic impairment 0 (0%) 2 (5.3%) 2 (2.6%) Bronchial asthma 2 (5.1%) 2 (5.3%) 4 (5.2%) Ischemic heart disease 9 (23.1) 5 (13.2%) 14 (18.2%) Stroke 2 (5.1%) 2 (5.3%) 4 (5.2%)

4 414 Combined Femoral & Sciatic Blocks Versus Epidural Anesthesia After performing the regional block in both groups, the mean time ( ±SD) of onset of surgical anesthesia varied significantly between the groups, it was 22.8 (±4.8) min for, and 13.8 ( ±3.5) min for, with p.value <0.001, as shown in (Table 4). Table (4): Comparing time of onset of surgical anesthesia between both groups, with p.value. Onset of surgical anesthesia in minutes: Mean (± SD) p-value 22.8 (±4.8) 13.8 (±3.5) <0.001 MABP ± SD T 1 T2 T3 T4 T5 T6 T7 T8 T9 T10 Time of recording Operative time in ranged from 35 to 210min., with mean (±SD): 74.2 (±39.3), while in it was 30 to 180min., with mean ( ±SD): 79.3 (±36.4), which was non-significant. Intra-operatively, tracing of heart rate showed no statistical difference between both groups throughout the operative time, as shown in Fig. (1). Mean HR ± SD T 1 T2 T3 T4 T5 T6 T7 T8 T9 T10 Time of recording Fig. (1): Intra-operative trend of Heart Rate (HR) in both groups. However, tracing of Mean Arterial Blood Pressure (MABP) Fig. (2) showed significant statistical difference between groups at 15, 20, 30, 45, 60 and 90min. (T 3, 4, 5, 6, 7, 8 and 9), with p.value range , with lower MABP readings in. No local anesthetic toxicity, dysrhythmias, allergy, hypertension, itching or back pains were recorded in all patients within the observation time (24h). A small number of peri-operative complications included non-significant difference in hypotension, significant difference with shivering between groups, failure (with induction of general anesthesia), bradycardia, headache, nausea and vomiting, and hematoma formation (Table 5). Fig. (2): Intra-operative trend of Mean Arterial Blood Pressure (MABP) in both groups. Table (5): Count and (% of complications within each group, with p.value. p- value Hypotension 4 (10.3%) 10 (26.3%) 0.68 Failure (with 6 (15.4%) 2 (5.3%) 0.14 induction of GA) Bradycardia 0 (0%) 1 (2.6%) 0.30 Shivering 0 (0%) 7 (18.4%) Headache 0 (0%) 1 (2.6%) 0.30 Nausea and vomiting 0 (0%) 1 (2.6%) 0.30 Hematoma formation 1 (2.6%) 0 (0%) 0.32 After 24 hours post-operative, ECG changes occurred only in one case (1.3%) in the form of ST segment depression in lead II, III avf. This was in, with p.value of 0.30 (non-significant), and resolved on follow-up. When comparing pre-and post-operative cardiac biomarkers for each group separately, the drop was statistically significant in when comparing pre-and post operative CK (with p.value 0.035) and pre-and post operative CK-MB (with p.value 0.010), but not in LDH in this group, and not in at all (Tables 6-8). Table (6): Pre-operative with post-operative CK within every group, with p.value within the group. Pre. CK: Mean (±SD) (±149) (±128.8) Post. CK: Mean (±SD) (±68.9) (±133.4) p.value Table (7): Pre-operative with post-operative CK-MB within every group, with p.value within the group. Pre. CK. MB: Mean (±SD) 23.7 (±4.5) 22.8 (± 10) Post. CK. MB: Mean ( ±SD) 21.9 (±2.2) 22.7 (± 11.6) p.value

5 Tamer I. Rouk & Tamer M. Kheir 415 Table (8): Pre-operative with post-operative LDH within every group, with p.value within the group. Pre. LDH: Mean (±SD) (±260) (±153.5) Post. LDH: Mean (±SD) 405 (±249.6) 377 (±138.2) p.value Of all 77 patients, only five patients (6.4%) were admitted to ICU post-operatively, four in, and one in, with non-significant p.value between groups. Discussion The present study showed that combined femoral-sciatic block for infrainguinal surgeries is a good anesthesia plan when compared with conventional lumbar epidural anesthesia, as regards to less hypotension and cardiac morbidity, but with more time for onset than the conventional epidural anesthesia. Nerve stimulator was selected as a method of femoral and sciatic nerves localization in our study as well as in many other studies [1,2,4-6]. In contrary to the more expensive and advanced U/S used in Al-Zahrani et al., 2015 study [7]. The number of patients in the present study was 80 cases divided into 2 groups, this was the case in Horasanli et al., study [4] who used the same number of cases, while other studies included 60 patients or less. There was some clinical heterogeneity among the studies. For example, Al-Zahrani et al., 2015 [7] used U/S guided continuous femoral nerve block combined with sciatic nerve block versus epidurals, Papiol et al., [8] used epidural analgesia versus femoral or femoral-sciatic nerve blocks, Barrington et al., 2005 [9] compared continuous femoral nerve blockade or epidural analgesia (both associated with spinal anesthesia). There was also variation in the drug, additives, and doses used. The aim of the anesthetic techniques in our study was more intra-operative hemodynamic stability and less cardiac morbidity. The onset of regional blocks adequate for surgery in the present study was 22.8 ( ±4.8) min. in femoral-sciatic group and 13.8 ( ±3.5) min. in epidural group, which was statistically significant. This was in contrary to Davies et al., 2004 study [5], in which time (range) was 13 (8-18.5) min. in epidural group and 12.5 ( ) min. in nerve block group, which was not significant. This may be attributed to the different dose used (bupivacaine 0.375% in a volume of 30ml for the femoral component and 25ml for the sciatic component). Intra-operative stable mean arterial blood pressure (at 15-90min. post-injection of local anesthesia) in the femoral-sciatic block group was significant when compared with the epidural group, in consistency with Fowler et al., [10] systematic review and meta-analysis of randomized trials (eight studies with total 510 patients) [10], who found that hypotension occurred more frequently in patients who received an epidural more than femoral-sciatic block, and Yazigi et al., [1] who did combined femoral-sciatic block, nerve stimulator guided, on 25 patients having femoro-popliteal bypass surgeries and they found minimal hemodynamic changes in combined femoral-sciatic block anesthesia. In contrast to our results, Al-Zahrani et al., [7] performed ultrasound guided combined continuous femoral block with single shot sciatic blocks (n=25) versus epidural infusion (n=25) for post-operative analgesia following unilateral total knee arthroplasty (both groups received general anesthesia after the regional techniques), and found no significant difference in the mean arterial pressure or the heart rate in the first 72 hours, Horasanli et al., 2010, [4] who used combined lumbar plexusfemoral block (n=40) versus epidural anesthesia (n=40) for total knee arthroplasty, stated that changes in arterial blood pressure and heart rate were not different between the two groups, and Davies et al., [5] who compared combined femoral and sciatic nerve blocks (n=30)versus epidural (n=29) for post-operative analgesia following knee arthroplasty (both groups received general anesthesia), found that hypotension was a frequent finding with no significant difference in both groups at the 24h assessment (this was attributed by the author to possibility of hypovolemia in the patients). The smaller number of patients of these studies should be considered. Fortunately, no significant cardiac morbidity was noticed in the present study in both groups, apart from one case (1.3%) in epidural group showed reversible ST segment depression 24 hours post operative with no chest pain or elevated cardiac biomarkers. However, in Yazigi et al., study [1], there was one case of 25 patients (4%) who showed 2 episodes of intra-operative ST segment depression on the monitor of 1.5mm magnitude and for total duration of 6 minutes, and another one case (4%) of postoperative ventricular tachycardia that responded

6 416 Combined Femoral & Sciatic Blocks Versus Epidural Anesthesia to cardioversion. Zaric et al., 2006 [6] compared epidural (n=23) with combined continuous femoralsciatic block (n=26) for post-operative analgesia following total knee arthroplasty, where 2 patients of epidural group (8.6) were complicated; one developed rapid Atrial Fibrillation (AF) and the other developed acute myocardial infarction and was transferred to specialized cardiology center, but this was statistically non significant. No major complications (local anesthetic toxicity, dysrhythmias, angina, myocardial infarction, allergy, back pain or itching) were recorded in the present study, and also no mortality was present. Only 7 cases (18.4%) of shivering occurred in epidural group which was statistically significant but clinically non significant, and hypotension (with need for ephedrine bolus) in 4 cases (10.3%) of femoral-sciatic block group, and 10 cases (26.3%) of epidural group, this was statistically not significant, but may be clinically significant in our geriatric population. In Yazigi et al., 2005 study [1], two of 25 patients (8%) required small doses of ephedrine (6 and 9mg) during surgery. A small incidence of failure to achieve adequate anesthesia for surgery (with need for induction of general anesthesia) was recorded in 6 cases (15.4%) of femoral-sciatic group, and 2 cases (5.3%) of epidural group which was statistically not significant. Failed cases may be attributed to individual skill in block performance, and may be decreased by using U/S for performing the nerve blocks in future studies. Al-Zahrani et al., [7] reported failure of catheter placement in two of 28 cases (7%) of epidural group and one in 28 cases (3.5%) of combined femoral-sciatic group, inspite using U/S guidance for nerve blocks. In Horasanli et al., 2010 study [4], failure in one patient (2.5%) of the epidural group and three patients (7.5%) of the combined lumber plexus-sciatic block group occurred and required general anesthesia. Other rare incidents in the present study were: One case of headache (2.6%), one case of bradycardia (2.6%) and one case of nausea and vomiting (2.6%) were in epidural group and were properly managed. While only one case of small femoral hematoma (2.6%) occurred in femoral-sciatic group and managed conservatively. All these were statistically non significant. Zaric et al., [6] observed statistically significant urinary retention in the epidural group on the day of surgery and the first postoperative day. Only 5 cases needed post-operative ICU admissions in our study, 4 cases (10.2%) in femoralsciatic group, and one (2.6%) in epidural group, which was statistically non-significant. All these admissions were not due to intra-operative anesthetic complications or due to need for analgesia; they were planned for ICU pre-operatively due to: - Cardiac conditions (two cases with pre-operative pathological Q in ECG with recent myocardial infarction 4 month and 5 month ago, and one case with mild basal crepitations) but with no hemodynamic changes intraoperatively. - Septic limb with post-operative development of septic shock (2 cases) with need for inotropic support in the ICU. In Yazigi et al., study [1], all patients were admitted to ICU as a routine due to the nature of their vascular bloody surgeries. This was not recorded in other similar studies. Future thoughts: Further studies concerning the same comparison groups may be done but using the more accurate but expensive ultrasound guidance for nerve blocks, to avoid the high failure rate and prolonged technique time in the present study. Also different local anesthetic preparation (e.g. adding opioids) may be used for better analgesia efficacy and duration. And more parameters can be assessed: Patient satisfaction rate, change in morphine consumption rate and serum level of stress hormones. Conclusion: Combined femoral-sciatic nerve blocks can be used as a good anesthesia plan for unilateral infrainguinal surgeries, providing more cardiovascular stability when compared to conventional lumbar epidural anesthesia. The introduction of ultrasound guided regional anesthesia is a promising advance, increasing the success rate and safety of these peripheral nerve blocks. References 1- YAZIGI A., MADI-GEBARA S., HADDAD F., HAYECK G. and TABET G.: Combined Sciatic and Femoral Nerve Blocks for Infrainguinal Arterial Bypass Surgery: A Case Series. Journal of Cardiothoracic and Vascular Anesthesia, 19 (2): pp , BADDOO H.K.: A preliminary report on the use of peripheral nerve blocks for lower limb amputations. Ghana Med. J., 43: 24-8, pp , WINNIE A.P., RAMAMURTHY S. and DURRANI Z.: The inguinal paravascular technique of lumbar plexus anesthesia: The 3-in-1 block. Anesth. Analg., 52: , 1973.

7 Tamer I. Rouk & Tamer M. Kheir HORASANLI E., GAMLI M., PALA Y., EROL M., SA- HIN F. and DIKMEN B.: A comparison of epidural anesthesia and lumbar plexus-sciatic nerve blocks for knee surgery. Clinics, 65 (1): pp , DAVIES A.F., SEGAR E.P., MURDOCH J., WRIGHT D.E. and WILSON I.H.: Epidural infusion or combined femoral and sciatic nerve blocks as perioperative analgesia for knee arthroplasty. British Journal of Anaesthesia, 93 (3): pp , ZARIC D., BOYSEN K., CHRISTIANSEN C., CHRIS- TIANSEN J., STEPHENSEN S. and CHRISTENSEN B.: A Comparison of Epidural Analgesia With Combined Continuous Femoral-Sciatic Nerve Blocks After Total Knee Replacement. Anesth. Analg., 102: pp , AL-ZAHRANI T., DOAIS K.S., ALJASSIR F., ALSHAYGY I., ALBISHI W. and TERKAWI A.S.: Randomized Clinical Trial of Continuous Femoral Nerve Block Combined with Sciatic Nerve Block Versus Epidural Analgesia for Unilateral Total Knee Arthroplasty. The Journal of Arthroplasty, 30: pp , PAPIOL S., MONSEGUR C.J., VIVES B.E., CESPE- DOSA G.A., VILARNAU B.R., PÉREZ M.A. and VILLÉN E.F.: Epidural analgesia versus femoral or femoral-sciatic nerve block after total knee replacement: Comparison of efficacy and safety. Rev. Esp. Anestesiol. Reanim., 56 (1): pp , BARRINGTON M.J., OLIVE D., LOW K., SCOTT D.A., BRITTAIN J. and CHOONG P.: Continuous Femoral Nerve Blockade or Epidural Analgesia After Total Knee Replacement, A Prospective Randomized Controlled Trial. Anesth. Analg., 101: pp , FOWLER S.J., SYMONS J., SABATO S. and MYLES P.S.: Epidural analgesia compared with peripheral nerve blockade after major knee surgery, a systematic review and meta-analysis of randomized trials. British Journal of Anaesthesia, 100 (2): pp , 2008.