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Abstract |
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In this prospective, randomized, double-blinded study, we assessed the efficacy of patient-controlled analgesia (PCA) for continuous interscalene analgesia after open shoulder surgery. Sixty patients were divided into three groups of 20. During a 48-h period, they received, via an interscalene catheter, a continuous infusion of 0.125% bupivacaine with sufentanil 0.1 µg/mL and clonidine 1 µg/mL at 10 mL/h in Group 1; a continuous infusion of the same solution at 5 mL/h plus PCA boluses (2.5 mL/30 min) in Group 2; and only PCA boluses (5 mL/30 min) of the same solution in Group 3. Pain scores, sensory block, supplemental analgesia, bupivacaine consumption, side effects, and satisfaction scores were recorded. At 24 and 48 h, sensory block was more frequent and pain control was significantly better in Groups 1 and 2 than in Group 3 (P < 0.001). In Group 3, larger doses of paracetamol were required. Bupivacaine consumption was significantly less in Groups 2 and 3 than in Group 1 (P < 0.001). Satisfaction was significantly higher in Groups 1 and 2 than in Group 3 (P < 0.01). Side effects were comparable in the three groups. We conclude that continuous interscalene analgesia requires a background infusion after open shoulder surgery. Because it reduces the local anesthetic consumption and allows the patients to rapidly reinforce the block shortly before physiotherapy, a basal infusion rate of 5 mL/h combined with PCA boluses (2.5 mL/30 min) is the recommended technique.
Implications: In this study, we demonstrated that continuous interscalene analgesia requires a background infusion to provide efficient pain relief after open shoulder surgery. A basal infusion of 5 mL/h combined with patient-controlled analgesia boluses (2.5 mL/30 min) seems to be the most appropriate technique.
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Introduction |
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Major shoulder surgery is often associated with severe postoperative pain, especially within the first 48 h (1). Continuous interscalene brachial plexus block is considered the gold standard for postoperative analgesia after such surgery because it provides better postoperative analgesia than a single dose block (1) or IV patient-controlled analgesia (PCA) (2,3). The continuous infusion of 0.125% bupivacaine at the rate of 0.125 mL · kg-1 · h-1 provides effective pain relief (4). However, this technique leads to administration of large volumes of local anesthetic with a potential risk of toxicity because of accumulation of the drug after prolonged periods of infusion (1), and tolerance (5). A "dose-sparing" infusion technique is thus desirable. After hand trauma surgery, a PCA technique (without background infusion) via an axillary brachial plexus catheter provides good postoperative analgesia and reduces local anesthetic consumption by 70% (5). This "dose-sparing" technique has not been described yet for brachial plexus analgesia by the interscalene route. The aim of the present study was to assess its efficacy after open shoulder surgery.
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Methods |
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After informed consent and with institutional approval, 60 American Society of Anesthesiologists class 1–3 patients scheduled for elective open shoulder surgery (rotator cuff repair, total shoulder arthroplasty) under general anesthesia were included in this study. Patients were excluded if they had contraindications to regional anesthesia (e.g., local infection, sepsis, coagulation abnormality), were aged <18 or >75 yr, weighed <50 or >100 kg, had a preexisting neurologic deficit, diabetes, severe bronchopulmonary disease, or the inability to understand pain scales or to use a PCA device.
Before induction of general anesthesia, all the patients had an interscalene block performed following Winnie’s landmarks (6). A 6-cm, 18-gauge short-beveled needle through a plastic cannula (Alphaplex® set; B. Braun-Melsungen AG, Melsungen, Germany) connected to a peripheral nerve stimulator (Anaestim MKIII; Meda, Antwerpen, Belgium) was introduced into the plexus sheath. Its position was judged adequate when a group of muscles distal to the deltoid was stimulated with a threshold stimulation <1 mA. Using a Seldinger technique, a 20-gauge catheter was threaded 4–5 cm into the plexus sheath and fixed to the skin with a tight suture. After a negative aspiration test for blood, 20 mL of 0.25% bupivacaine with epinephrine 1:200000 was injected.
General anesthesia was induced in all patients with 0.3 µg/kg sufentanil, 3–5 mg/kg thiopental, and 0.5 mg/kg atracurium IV. The trachea was intubated, and controlled ventilation was started. Anesthesia was maintained with a mixture of nitrous oxide (66%) and isoflurane (0.4%–1%) in oxygen.
In the recovery room, the correct position of the interscalene catheter was confirmed by a sensory block (reduced or loss of temperature sense assessed by using an ether-soaked swab) involving at least one major nerve distribution (axillary, musculocutaneous, median, ulnar, radial) of the arm. Patients were then divided into three groups of 20 in a randomized manner using a computer-generated list of random permutations. During the first 48 h postoperatively, Group 1 received, through the interscalene catheter, a continuous infusion of 0.125% bupivacaine with sufentanil 0.1 µg/mL and clonidine 1 µg/mL at the rate of 10 mL/h; Group 2 received a continuous infusion of the same solution at the rate of 5 mL/h plus boluses of 2.5 mL with a lockout time of 30 min; and Group 3 received only boluses of 5 mL of the same solution with a lockout time of 30 min. To blind the study, patients in Group 1 also had access to PCA.
If pain was not adequately controlled (pain score >30 on the visual analog scale [VAS; ranging from 0 = no pain to 100 = worst pain imaginable]), patients received 1 g of IV propacetamol (Prodafalgan®; Upsamedica s.a., Brussels, Belgium) followed by 10–20 mg of IM piritramide, a synthetic µ-agonist opioid (Dipidolor®; Janssen Pharmaceutica, Beerse, Belgium), if pain remained unchanged after 30 min.
Pain at rest and on movement (VAS), and sensory block in the major nerve distributions of the arm were assessed 4, 24, and 48 h after the operation. Supplemental analgesia, bupivacaine consumption, side effects, and satisfaction score (using a VAS ranging from 0 = not satisfied to 100 = entirely satisfied) at the end of the study period, were recorded. All data were collected by an anesthesiologist who was neither involved in the administration of anesthesia nor in the patient care in the recovery room.
A power analysis suggested that 18 patients would need to be enrolled in the study groups to provide a 95% chance of detecting a 50% reduction in the consumption of bupivacaine at the 0.01 level of significance. Data from the three groups were compared by using analysis of variance and least significant difference test or by using 
2 analysis when appropriate. A P value <0.05 was considered significant.
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Results |
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Population data are presented in Table 1. They were comparable in all groups. In the recovery room, sensory block in at least one of the major nerve distributions of the arm was observed in all patients.
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The VAS scores at rest and on movement, and supplemental analgesia are presented in Table 2. significantly different compared with Groups 1 and 2.\. In the immediate postoperative period (4 h), both scores were comparable in the three groups. At 24 and 48 h postoperatively, they were significantly lower in Groups 1 and 2 when compared with Group 3. In Group 3, a significantly higher mean dose of propacetamol was required. The need for opioid supplementation was comparable in all groups.
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When compared with Group 1, bupivacaine consumption was significantly lower in Groups 2 and 3 (516 ± 85, 331 ± 59, and 139 ± 115 mg/48h [P < 0.001], in Groups 1, 2, and 3, respectively). Moreover, Group 3 consumed significantly less bupivacaine than Group 2. The use of PCA was significantly less frequent in Group 1 than in Groups 2 and 3 (12 ± 18, 37 ± 48, and 72 ± 96 demands/48h [P = 0.02], in Groups 1, 2, and 3 respectively).
Sensory block in the major nerve distributions of the arm is presented in Table 3. In the immediate postoperative period (4 h), no difference was noted among the groups. When compared with Group 3, reduced or loss of temperature sensation in the distribution of the axillary and musculocutaneous nerves was significantly more frequent in Groups 1 and 2 at 24 and 48 h. This was also noted for the median, ulnar, and radial nerves but only in Group 1 at 48 h.
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Side effects and technical problems are presented in Table 4. No statistically significant difference was noted among the groups. However, hoarseness, Horner’s syndrome, and motor blockade were more frequent in Group 1 than in Groups 2 and 3. These side effects as well as clinical phrenic paresis (difficult deep breathing with mild dyspnea) confirmed by radiograph, were observed only during the immediate postoperative period (4 h), never later (24 or 48 h).
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All kinked catheters were caused by dressing. This problem was rapidly resolved in all patients, so that the analgesic regimen was never stopped for more than 20–30 min.
When compared with Group 3, satisfaction score at 48 h was significantly higher in Groups 1 and 2 (88 ± 10, 85 ± 13, and 72 ± 16 [P < 0.001], respectively, in Groups 1, 2, and 3).
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Discussion |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
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Major shoulder surgery is often associated with severe postoperative pain, especially within the first 48 hours (1). This not only causes patient discomfort but also compromises the intensive postoperative rehabilitation necessary for a good functional result. Continuous interscalene brachial plexus block is a reliable and effective method of providing postoperative pain relief after such surgery (1,2,7,8), and is more efficient than intramuscular opioid (1), IV PCA (2,3), or single injection block (1).
Our study confirmed such efficacy when a background infusion of local anesthetic was used. Indeed, except for the immediate postoperative period, the PCA technique (bolus of five milliliters with a lockout time of 30 minutes) did not maintain effective sensory block (Table 3) or pain relief. Moreover, patients in Group 3 had a significantly lower satisfaction score. These results are in contrast with those obtained by Iskandar et al. (5). In their study, the PCA technique (bolus of 0.1 mL/kg with a lockout time of one hour) via an axillary brachial plexus catheter provided a postoperative analgesia as good as the continuous infusion technique, reduced local anesthetic consumption, and increased patient satisfaction. These conflicting results can be partially explained by the type of surgery performed (the intensity of pain after hand trauma varies widely), and the use of a less dilute bupivacaine solution. However, if 0.25% bupivacaine adequately controls pain, it also produces major motor nerve block (9). That is why we prefer using a 0.125% bupivacaine solution.
In accordance with the concept of "balanced analgesia" advocated by Kehlet (10), sufentanil and clonidine were included in our continuous infusion. When added to the local anesthetic solution, sufentanil reduces the onset time of the block1 and clonidine prolongs duration of both anesthesia and analgesia (11) after a single-shot brachial plexus block. Unpublished data support the same effects during continuous peripheral nerve block. This observation must be confirmed by a large randomized study.
The underlying mechanism of action of clonidine on peripheral nerves is not known. Two mechanisms of action may be proposed: the first supposes a clonidine-mediated activation of postsynaptic adrenergic receptors leading to local vasoconstriction (12), thus prolonging local anesthesia by decreasing the systemic absorption of the local anesthetic. However, at least two studies (13,14) comparing the vasoconstrictor effects of clonidine with those of epinephrine in peripheral nerve block, showed that clonidine does not evoke local vasoconstriction. The second possible mechanism involves a local anesthetic action of clonidine. Compared with procaine, clonidine is equipotent in inhibiting impulse propagation on the frog sciatic nerve (15). When applied on the rabbit cornea, it is approximately 140 times more potent as a surface anesthetic than procaine (15). This might indicate that C fibers or A
fibers, which exclusively innervate the rabbit cornea, are especially sensitive to clonidine. Butterworth and Strichartz (16) hypothesized that analgesia seen after neuraxial application of clonidine might result from the direct inhibition of impulse conduction in primary afferent nerve fibers. From the results of their study on rat sciatic nerves, they speculate that part of the efficacy of 
2-adrenergic agonists at producing analgesia after their regional injection may result from their "local anesthetic" actions on A and, especially, C fibers. Gaumann et al. (14) examined the local anesthetic effects of clonidine and its interaction with lidocaine on the C fiber compound action potential of the isolated rabbit vagus nerve. They showed an enhancing effect of a small dose of clonidine on lidocaine-evoked inhibition of C fiber action potential. The authors concluded that this effect might explain the clinical observation that clonidine prolongs the action of local anesthetics in peripheral nerve blocks.
In the present study, the continuous infusion of 0.125% bupivacaine at the rate of 10 mL/h provided effective pain relief. This confirmed the results obtained by Pere (4). However, this technique leads to administration of large volumes of local anesthetic with a potential risk of toxicity because of accumulation of the drug after prolonged periods of infusion (1), and tolerance (17). Moreover, although not reaching statistical significance, a higher incidence of hoarseness, Horner’s syndrome, and motor weakness in the arm was observed in this group.
Reducing the background infusion of 0.125% bupivacaine by half (five mL/h) associated with the use of small size (2.5 milliliters) PCA boluses provided excellent pain relief, no side effects (except for motor weakness in one patient), and a 36% reduction in the local anesthetic consumption. Moreover, as expressed by the patients, this technique allowed rapid reinforcement of the block shortly before a shoulder physiotherapy session. Similar results have been obtained by Borgeat et al. (2); however, they observed motor blockade in 35% of patients. This could be explained by the use of 0.15% bupivacaine, a larger (three to four milliliters) PCA bolus size, and a reduced lockout time (20 minutes) in their study.
Single-shot interscalene brachial plexus block is associated with ipsilateral hemidiaphragmatic paresis in all patients (18). During continuous block, the paresis is frequent [as high as 75% (19)] and often persists until the end of the infusion (9). Patients with an interscalene infusion of 0.125% bupivacaine had less deterioration of diaphragmatic function than did patients who were given an infusion of 0.25% bupivacaine (4). Nevertheless, two of our patients presented clinical phrenic paresis (difficult deep breathing with mild dyspnea) that required oxygen by mask. Thus, continuous interscalene brachial plexus block, even in small doses, cannot be recommended for patients with severe respiratory dysfunction.
In this study, the use of PCA technique was uncomplicated, but, the small number of patients does not permit us to make definitive conclusions about its relative safety.
In conclusion, our study demonstrated that continuous interscalene brachial plexus block requires a background infusion to provide efficient pain relief after open shoulder surgery. Because it reduces the local anesthetic consumption while allowing the patients to rapidly reinforce the block shortly before physiotherapy, a basal infusion rate of five mL/h of 0.125% bupivacaine combined with PCA boluses (2.5 milliliters; lockout time: 30 minutes) is the recommended infusion technique.
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Acknowledgments |
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The authors are grateful to F. Veyckemans, MD, for his valuable criticism of the manuscript and his comments.
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Footnotes |
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1 Singelyn FJ, Contreras V, Lefebvre B, et al. Adding sufentanil to mepivacaine results in faster but not prolonged anesthesia and analgesia after brachial plexus blockade [abstract]. Anesthesiology 1993;79:A832.
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References |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
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- Tuominen M, Pitkanen M, Rosenberg PH. Postoperative pain relief and bupivacaine plasma levels during continuous interscalene brachial plexus block. Acta Anaesthesiol Scand 1987;31:276–8.[Web of Science][Medline]
- Borgeat A, Schäppi B, Biasca N, Gerber C. Patient-controlled analgesia after major shoulder surgery: patient-controlled interscalene analgesia versus patient-controlled analgesia. Anesthesiology 1997;87:1343–7.[Web of Science][Medline]
- Riedl V, Buchfelder A, Kellermann W, Schwender D. Patient-controlled analgesia versus continuous interscalenar plexus blockade: effectivity of the postoperative pain management after open shoulder surgery [abstract]. Br J Anaesth 1997;78:A417.
- Pere P. The effect of continuous interscalene brachial plexus block with 0.125% bupivacaine plus fentanyl on diaphragmatic motility and ventilatory function. Reg Anesth 1993;18:93–7.[Web of Science][Medline]
- Iskandar H, Rakotondriamihary S, Dixmérias F, et al. Analgésie par bloc axillaire continu après chirurgie des traumatismes graves de la main: auto-administration versus injection continue. Ann Fr Anesth Réanim 1998;17:1099–103.[Web of Science][Medline]
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Winnie A. Interscalene brachial plexus block. Anesth Analg 1970;49:455–66.
[Free Full Text] - Tuominen M, Haasio J, Hekali R, Rosenberg PH. Continuous interscalene brachial plexus block: clinical efficacy, technical problems and bupivacaine plasma concentrations. Acta Anaesthesiol Scand 1989;33:84–8.[Web of Science][Medline]
- Haasio J, Tuominen M, Rosenberg PH. Continuous interscalene brachial plexus block during and after shoulder surgery. Ann Chir Gynaecol 1990;79:103–7.[Web of Science][Medline]
- Pere P, Pitkänen M, Rosenberg PH, et al. Effect of continuous interscalene brachial plexus block on diaphragm motion and on ventilatory function. Acta Anaesthesiol Scand 1992;36:53–7.[Web of Science][Medline]
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Kehlet H. Surgical stress: the role of pain and analgesia. Br J Anaesth 1989;63:189–95.
[Free Full Text] - Singelyn FJ, Gouverneur JM, Robert A. A minimum dose of clonidine added to mepivacaine prolongs the duration of anesthesia and analgesia after axillary brachial plexus block. Anesth Analg 1996;83:1046–50.[Abstract]
- Langer S, Duval N, Massingham R. Pharmacologic and therapeutic significance of alpha-adrenoreceptor subtypes. J Cardiovasc Pharmacol 1985;7:1–8.[Web of Science][Medline]
- Eledjam JJ, Deschodt J, Viel E, et al. Brachial plexus block with bupivacaine: effects of added alpha-adrenergic agonists— comparison between clonidine and epinephrine. Can J Anaesth 1991;38:870–5.[Web of Science][Medline]
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Gaumann D, Brunet P, Jirounek P. Clonidine enhances the effects of lidocaine on C-fiber action potential. Anesth Analg 1992;74:719–25.
[Abstract/Free Full Text] - Starke K, Wagner J, Schürmann HJ. Adrenergic neuron blockade by clonidine: comparison with guanethidine and local anesthetics. Ther 1972;195:291–308.
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Butterworth JF, Strichartz GR. The 2-adrenergic agonists clonidine and guanfacine produce tonic and phasic block of conduction in rat sciatic nerve fibers. Anesth Analg 1993;76:295–301.[Web of Science][Medline]
- Gaumann D, Lennon R, Wedel D. Continuous axillary block for postoperative pain management. Reg Anesth 1988;13:77–82.[Web of Science]
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Urmey W, Talts K, Sharrock N. One hundred percent incidence of hemidiaphragmatic paresis associated with interscalene brachial plexus anesthesia as diagnosed by ultrasonography. Anesth Analg 1991;72:498–503.
[Abstract/Free Full Text] - Tuominen M, Tarkkila P. Diaphragmatic motion during continuous interscalene brachial plexus block. Reg Anesth 1995;20:543–4.[Web of Science][Medline]
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