Combination of Ultra-low Dose Bupivacaine and Fentanyl for Spinal Anaesthesia in Out-patient Anorectal Surgery

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1 The Journal of International Medical Research 2008; 36: Combination of Ultra-low Dose Bupivacaine and Fentanyl for Spinal Anaesthesia in Out-patient Anorectal Surgery A GURBET, G TURKER, NK GIRGIN, H AKSU AND NH BAHTIYAR Department of Anaesthesiology and Reanimation, Faculty of Medicine, Uludag University, Bursa, Turkey This study investigated whether the addition of 25 µg fentanyl to an ultra-low (sub-anaesthetic) dose of intrathecal bupivacaine provides adequate anaesthesia for out-patient anorectal surgery, without increasing side-effects or delaying hospital discharge. Patients were randomly allocated to receive 2.5 mg 0.5% bupivacaine plus 25 µg fentanyl (group BF, n = 18) or 5 mg 0.5% bupivacaine alone (group B, n = 17). There were no significant differences in intra-operative outcomes, but mean recovery and discharge times were significantly shorter in group BF. There were no between-group differences in hypotension, bradycardia or respiratory depression and post-operative complications were comparable, apart from pruritus which was significantly more frequent in group BF. Fewer patients requested analgesic medication in the early post-operative period in group BF than in group B. In conclusion, 25 µg intrathecal fentanyl added to ultra-low dose (2.5 mg) bupivacaine provided good-quality spinal anaesthesia and reduced post-operative analgesic requirement in patients undergoing ambulatory anorectal surgery. KEY WORDS: ANORECTAL SURGERY; INTRATHECAL; BUPIVACAINE; FENTANYL; ULTRA-LOW DOSE Introduction The prevalence of minor anorectal diseases in the adult population is 4 5% and approximately 10% of cases require surgical treatment. 1 Currently, 90% of anorectal surgery is performed on an ambulatory basis. 2 Spinal anaesthesia for ambulatory surgery should be characterized by rapid onset and offset, easy administration, minimal expense, and minimal side-effects and complications. 3 High doses of intrathecal (IT) bupivacaine can, however, produce extensive sensory and motor block as well as arterial hypotension, resulting in delayed discharge from hospital. On the other hand, low dose bupivacaine is associated with a comparatively rapid recovery profile but may not provide sufficient analgesia. An alternative treatment consisting of IT administration of a combination of opioids and local anaesthetics produces a well-documented 964

2 synergistic effect without prolonged motor nerve block or delayed discharge. 4,5 Studies have shown that fentanyl in combination with low dose bupivacaine intensifies the sensory blockade and lengthens its duration without increasing the intensity of the motor blockade or prolonging recovery. 6,7 The objective of the present prospective, randomized, double-blind study was to identify whether an ultra-low (subanaesthetic) dose of IT bupivacaine in combination with 25 µg fentanyl would provide adequate anaesthesia for anorectal surgery without increasing side-effects or delaying hospital discharge. Patients and methods PATIENTS Adult patients with American Society of Anesthesiologists (ASA) scores of 1 2 who were to undergo minor anorectal surgery (for haemorrhoids, anorectal fistulas, anal fissures or pilonidal sinuses) under spinal anaesthesia were recruited for this prospective, randomized, double-blind study. Exclusion criteria included abnormal coagulation profiles, skin infections and those who did not consent to regional anaesthesia. Written informed consent was obtained from all the study participants. The study protocol was approved by the ethics committee of Uludag University. ANAESTHETIC PROTOCOLS No pre-medication was given. An intravenous infusion of ml lactated Ringer s solution was started on arrival in the operating room. All patients were monitored using non-invasive blood pressure monitoring, pulse oximetry and electrocardiography. Patients were randomly assigned to one of two spinal anaesthetic protocols: group BF received 2.5 mg 0.5% bupivacaine (0.5 ml) in 8% dextrose mixed with 25 µg fentanyl (0.5 ml), whereas group B received 5 mg 0.5% bupivacaine (1 ml) in 8% dextrose. Spinal anaesthesia was performed at the L3 L4 or L4 L5 level in the sitting position using a 27-gauge Quincke needle. After free flow of cerebrospinal fluid was observed, a total volume of 1 ml spinal solution was administered to each patient over s. Patients were moved to the prone position immediately after the block. Episodes of bradycardia (heart rate < 50 beats/min) or peri-operative hypotension (systolic blood pressure < 20% of baseline) were recorded and treated with boluses of fluid or intravenous ephedrine or atropine. SENSORY AND MOTOR BLOCKADE TESTING The quality of anaesthesia was assessed by testing for sensory and motor blockade. Sensory blockade was monitored using pin prick testing and motor block was assessed using the Bromage scale (0, full flexion of the knees and feet; 1, just able to flex knees, full flexion of feet; 2, unable to flex knees, flexion of feet; 3, unable to move legs or feet, full motor block). Sensory and motor tests were performed at 1 min intervals for the first 5 min and then every 5 min until the end of surgery. Further testing was then performed at 10-min intervals in the postanaesthesia care unit until recovery of S2 sensation. PATIENT ASSESSMENT Data regarding the highest dermatomal level of sensory blockade, the Bromage scale of motor block, time to peak level of anaesthesia, time to two-segment regression, time to S2 regression, time to urination, time to getting out of bed (ambulation) and time to discharge from hospital were recorded. 965

3 Complications such as respiratory depression, nausea, vomiting and pruritus, and requests for pain relief during the early post-operative period were also noted. DATA ANALYSIS Statistical analysis was performed using SPSS version 12.0 (SPPS Inc., Chicago, IL, USA). Demographic data were analysed using the Student s t-test. Comparisons of sensory block and Bromage motor blockade scale results were made using appropriately sized contingency table analysis. Analysis of the time to peak level, time to two-segment regression, time to S2 regression, time to urination, time to ambulation and time to discharge from hospital were performed using a two-sample Student s t-test. A group size of 20 was calculated, based on 90% power, to be able to detect a 30-min difference in mean time to complete sensory recovery. A P-value < 0.05 was considered to be statistically significant. Results A total of 40 patients undergoing minor anorectal surgery under spinal anaesthesia were initially recruited to the study and randomly allocated to the two groups. Two patients in group BF and three patients in group B were then excluded on the basis of the exclusion criteria, leaving 18 who received a combination of bupivacaine and fentanyl (group BF) and 17 who received bupivacaine alone (group B). The two treatment groups were comparable with respect to age, gender, weight, height and surgical procedure (Table 1). All blocks performed in both groups were successful. The highest sensory levels achieved in the two groups are given in Table 2. There were no significant differences in the intraoperative outcomes of maximum motor blockade score, number of patients who required analgesic supplementation and number of patients who converted to general anaesthesia between the two groups (Table 2). Mean times to two-segment regression, S2 regression, ambulation, urination and discharge were significantly shorter in group BF than in group B (Table 3). There were no significant differences in the number of TABLE 1: Characteristics of patients undergoing minor anorectal surgery under spinal anaesthesia with ultra-low dose bupivacaine and fentanyl (group BF) or bupivacaine alone (group B) Characteristic (n = 18) (n = 17) Age (years) 36 ± ± 11 Gender (n) Male Female 5 6 Weight (kg) 68 ± ± 9 Height (cm) 168 ± ± 11 Type of surgery (n) Haemorrhoidectomy 8 9 Fistulectomy 6 3 Pilonidal cyst excision 3 3 Anal polypectomy 1 2 Values given are the mean ± SD or number of patients (n). No statistically significant between-group differences. 966

4 TABLE 2: Intra-operative outcomes in patients undergoing minor anorectal surgery under spinal anaesthesia with ultra-low dose bupivacaine and fentanyl (group BF) or bupivacaine alone (group B) Intra-operative outcome (n = 18) (n = 17) Highest level of sensory block T9 (T4 L1) T8 (T3 T11) Maximum motor blockade score a 2 (1 3) 2 (2 3) Analgesic supplementation 3 5 Conversion to general anaesthesia 0 0 a Bromage scale (0, full flexion of the knees and feet; 1, just able to flex knees, full flexion of feet; 2, unable to flex knees, flexion of feet; 3, unable to move legs or feet, full motor block). No statistically significant between-group differences. Values given are the median and range or number of patients. TABLE 3: Recovery and home discharge times in patients undergoing minor anorectal surgery under spinal anaesthesia with ultra-low dose bupivacaine and fentanyl (group BF) or bupivacaine alone (group B) Time (min) Measure (n = 18) (n = 17) Two-segment regression 36 ± 11** 48 ± 9 S2 regression 56 ± 21* 72 ± 19 Ambulation 110 ± 30* 136 ± 32 Urination 126 ± 25* 154 ± 35 Home discharge 172 ± 28* 205 ± 43 Values given are the mean ± SD. ** P < 0.01 and * P < 0.05 versus group B. TABLE 4: Post-operative side-effects and complications in patients undergoing minor anorectal surgery under spinal anaesthesia with ultra-low dose bupivacaine and fentanyl (group BF) or bupivacaine alone (group B) Side-effect/complication (n = 18) (n = 17) Nausea 2 (11.1%) 2 (11.8%) Vomiting 0 0 Pruritus 8 (44.4%)* 1 (5.9%) Headache 1 (5.5%) 0 Backache 1 (5.5%) 2 (11.8%) Analgesic supplementation required 2 (11.1%)* 7 (41.2%) Values given are number (percentage) of patients. * P < 0.05 versus group B. 967

5 episodes of hypotension, bradycardia or respiratory depression requiring treatment between the two groups (data not shown). The number of patients experiencing nausea, vomiting, headache or backache was comparable in the two groups, but pruritus was significantly more frequent in group BF (Table 4). Additionally, significantly fewer patients requested analgesic medication in the early postoperative period in group BF than in group B (Table 4). Discussion The results of the present study indicate that, for out-patient anorectal surgery, IT administration of 25 µg fentanyl combined with an ultra-low dose of bupivacaine provides good-quality spinal anaesthesia and reduces the need for early post-operative analgesic supplementation. Furthermore, this protocol is well suited for the out-patient setting because it is associated with rapid recovery of full motor power, sensory function and bladder function. This suggests a potential synergism between fentanyl and bupivacaine. The IT administration of opioids selectively decreases nociceptive afferent input from Aδ and C fibres without affecting dorsal root axons or somatosensory evoked potentials. 8 Lipophilic opioids, such as fentanyl, have a favourable clinical profile with fast onset, modest duration (1 4 h) and little risk of delayed respiratory depression. The recommended safe effective dose of IT fentanyl is µg. Numerous clinical studies have demonstrated that IT fentanyl does not prolong the duration of motor blockade. 9,10 In an attempt to modify anaesthesia for ambulatory surgery, several investigators have evaluated IT fentanyl in combination with smaller doses of spinal local anaesthetic. In a randomized, double-blind study involving gynaecological laparoscopy, Chilvers et al. 11 compared 0, 10 and 25 µg doses of fentanyl as an IT adjunct to hypobaric lignocaine (20 mg) spinal anaesthesia. They found improved intraoperative analgesia and prolonged sensory block, but no difference in motor recovery or time to discharge, in the 25 µg fentanyl group compared with the 0 and 10 µg fentanyl groups. Singh et al. 12 reported similar results with the addition of IT fentanyl (25 µg) to spinal hyperbaric bupivacaine (13.5 mg) in patients undergoing lower extremity and genitourinary procedures. In addition, Ben- David et al. 6 found increased duration of sensory block without prolonged motor blockade or recovery for ambulatory discharge with 10 µg fentanyl added to low dose (5 mg) hyperbaric bupivacaine for knee arthroscopy. All these findings are consistent with the present results that 25 µg fentanyl added to ultra-low dose (2.5 mg) IT bupivacaine neither increased the intensity of motor block nor prolonged the discharge time for anorectal surgery in the ambulatory setting. In contrast to our findings, however, Ben-David et al. 6 found significantly increased duration of two-segment regression and S2 regression with 10 µg IT fentanyl added to 3 ml 0.17% bupivacaine. This might be explained by protocol differences since the present study used ultralow dose (2.5 mg) IT bupivacaine with 25 µg IT fentanyl. Comparing different doses of fentanyl (7.5, 10 and 12.5 µg) added to a fixed dose (5 mg, 0.17%) of bupivacaine, Goel et al. 13 found that 12.5 µg fentanyl provided better surgical anaesthesia and increased reliability of the block in minor urological procedures than 7.5 or 10 µg fentanyl. As the spinal bupivacaine dose in the present study is lower than in that of Goel et al., µg fentanyl was used to 968

6 provide longer sensory anaesthesia without increasing discharge duration. The most consistent side-effect in the present study was pruritus in patients receiving IT fentanyl, although in most cases it was mild and did not require treatment. In other studies the side-effects of IT fentanyl have been shown to be dose-related. 14 Respiratory depression is a known complication of spinal opioids; 15 this may be problematic with higher doses, as reported in a volunteer study. 16 In the present study, however, there were no clinical manifestations of respiratory depression with a fentanyl dose of 25 µg. Additionally, Varrassi et al. 17 reported that 25 µg IT fentanyl in elderly patients did not lead to respiratory depression. Urinary retention is a significant sideeffect of hydrophilic spinal opioids, however lipophilic opioids such as fentanyl appear to have a more favourable urinary profile. Liu et al. 18 found no increase in time to first void in a volunteer study using 20 µg IT fentanyl. Similarly, Ben-David et al. 6 reported no significant difference in time to urination with the addition of 10 µg IT fentanyl for out-patient knee arthroscopy. In the present study, 25 µg fentanyl with low-dose bupivacaine reduced the length of time required for the return of bladder function compared with 5 mg bupivacaine alone. The present study also demonstrated that 25 µg IT fentanyl reduced the analgesic requirement without increasing episodes of nausea or vomiting. These findings were comparable with those of Singh et al., 12 who used 25 µg IT fentanyl for lower extremity or genitourinary surgery, and Belzarena, 14 who used 0.5 or 0.75 µg/kg IT fentanyl for caesarean delivery. In conclusion, 25 µg IT fentanyl added to ultra-low dose (2.5 mg) bupivacaine prolonged the duration of sensory spinal block and reduced the analgesic requirement during the early post-operative period without increasing the incidence of opioidrelated side-effects, except pruritus, or delaying hospital discharge in patients undergoing ambulatory anorectal surgery. Conflicts of interest The authors had no conflicts of interest to declare in relation to this article. Received for publication 3 April 2008 Accepted subject to revision 11 April 2008 Revised accepted 6 August 2008 Copyright 2008 Field House Publishing LLP References 1 Li S, Coloma M, White PF, et al: Comparison of the costs and recovery profiles of three anesthetic techniques for ambulatory anorectal surgery. Anesthesiology 2000; 93: Smith LE: Ambulatory surgery for anorectal diseases: an update. South Med J 1986; 79: Maroof M, Khan RM, Siddique M, et al: Hypobaric spinal anaesthesia with bupivacaine (0.1%) gives selective sensory block for ano-rectal surgery. Can J Anaesth 1995; 42: Maves TJ, Gebhart GF: Antinociceptive synergy between intrathecal morphine and lidocaine during visceral and somatic nociception in the rat. Anesthesiology 1992; 76: Wang C, Chakrabarti MK, Whitwam JG: Specific enhancement by fentanyl of the effects of intrathecal bupivacaine on nociceptive afferent but not on sympathetic efferent pathways in dogs. Anesthesiology 1993; 79: Ben-David B, Soloman E, Levin H, et al: Intrathecal fentanyl with small-dose dilute bupivacaine: better anesthesia without prolonging recovery. Anesth Analg 1997; 85: Choi DH, Ahn HJ, Kim MH: Bupivacainesparing effect of fentanyl in spinal anesthesia for caesarean delivery. Reg Anesth Pain Med 2000; 25: Gudaityte J, Marchertiene I, Pavalkis D: Anesthesia for ambulatory anorectal surgery. 969

7 Medicina (Kaunas) 2004; 40: Hunt CO, Naulty JS, Bader AM, et al: Perioperative analgesia with subarachnoid fentanyl bupivacaine for cesarean delivery. Anesthesiology 1989; 71: Akerman B, Arweström E, Post C: Local anesthetics potentiate spinal morphine antinociception. Anesth Analg 1988; 67: Chilvers CR, Vaghadia H, Mitchell GW, et al: Small-dose hypobaric lidocaine fentanyl spinal anesthesia for short duration outpatient laparoscopy. II. Optimal fentanyl dose. Anesth Analg 1997; 84: Singh H, Yang J, Thornton K, et al: Intrathecal fentanyl prolongs sensory bupivacaine spinal block. Can J Anaesth 1995; 42: Goel S, Bhardwaj N, Grover VK: Intrathecal fentanyl added to intrathecal bupivacaine for day case surgery: a randomized study. Eur J Anaesthesiol 2003; 20: Belzarena SD: Clinical effects of intrathecally administered fentanyl in patients undergoing cesarean section. Anesth Analg 1992; 74: Etches RC, Sandler AN, Daley MD: Respiratory depression and spinal opioids. Can J Anaesth 1989; 36: Lu JK, Schafer PG, Gardner TL, et al: The dose response pharmacology of intrathecal sufentanil in female volunteers. Anesth Analg 1997; 85: Varrassi G, Celleno D, Capogna G, et al: Ventilatory effects of subarachnoid fentanyl in the elderly. Anaesthesia 1992; 47: Liu S, Chiu AA, Carpenter RL, et al: Fentanyl prolongs lidocaine spinal anesthesia without prolonging recovery. Anesth Analg 1995; 80: Author s address for correspondence Assistant Professor Alp Gurbet Department of Anaesthesiology and Reanimation, Faculty of Medicine, Uludag University, Bursa Turkey. agurbet@uludag.edu.tr 970