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Increased success rate with infraclavicular brachial plexus block using a dual-injection technique
Original Contributions Increased Success Rate with Infraclavicular Brachial Plexus Block Using a Dual-Injection Technique J. Rodrı´guez, MD, PhD,* M. Ba´rcena, MD,* J. Lagunilla, MD,* J. A´lvarez, MD, PhD† Department of Anesthesiology, Complexo Hospitalario Universitario de Santiago, Santiago de Compostela, Spain
*Staff Anesthesiologist †Assistant Professor of Anesthesiology; Head of Department of Anesthesiology Address correspondence to Dr. Rodrı´guez at the Servicio de Anestesiologı´a y Reanimacio´n. Hospital Clı´nico Universitario de Santiago, Travesı´a da Choupana, s.n. 15706, Santiago de Compostela, Spain. E-mail: [email protected] Received for publication April 22, 2003; revised manuscript accepted for publication August 7, 2003. Journal of Clinical Anesthesia 16:251–256, 2004 © 2004 Elsevier Inc. All rights reserved. 360 Park Avenue, South, New York, NY 10010
Study Objective: To test the hypothesis that dual injection of the local anesthetic in coracoid infraclavicular brachial plexus block might enhance both sensory and motor block for anesthesia of the upper limb when compared with a single-injection technique. Design: Comparative, prospective, randomized, investigator-blinded study. Setting: University-affiliated hospital. Patients: 60 patients scheduled for surgery of the hand, forearm, or elbow. Interventions: Patients were randomly assigned to receive either a coracoid infraclavicular block guided by nerve stimulator with a single injection technique (Group 1) or a dual-injection technique (Group 2). Injection of 40 mL 1.5% mepivacaine was made after eliciting one evoked motor response in the upper limb with a nerve stimulator for coracoid infraclavicular block in Group 1 and injection of two separate doses of 20 mL 1.5% mepivacaine after elicitation of two motor responses in Group 2. Measurements: Assessment of sensory and motor block in the upper limb 5 and 20 minutes after the end of the injection of the local anesthetic. The time needed to elicit the second response and to inject the second dose of local anesthetic was also recorded. Main Results: Significantly higher rates of sensory block to pinprick on the distributions of axillary, musculocutaneous, radial, ulnar, and medial cutaneous of the forearm nerves were found in Group 2 at 20 minutes. Significantly higher rates of motor block for arm, wrist, and hand movements were found in Group 2 at 20 minutes. Conclusions: Dual injection of local anesthetic guided by nerve stimulator increases the efficacy of coracoid block when compared with a single injection of the same dose of local anesthetic. © 2004 by Elsevier Inc. Keywords: Anesthesia, techniques; nerve stimulation; brachial plexus; infraclavicular.
Introduction Single-injection coracoid infraclavicular brachial plexus block produces an inconsistent anesthesia of the upper limb, with a low success rate in the distributions of axillary, radial, musculocutaneous and medial cutaneous of the arm nerves.1 The technique of multiple injections of local anesthetic guided by nerve stimulation has been shown to increase the number of blocked nerve 0952-8180/04/$–see front matter doi:10.1016/j.jclinane.2003.08.006
Original Contributions
distributions of the upper limb when compared with the corresponding similar approach with single-injection techniques in axillary2– 4 and interscalene5 approaches for brachial plexus anesthesia. In a similar fashion, a shorter onset time was observed with both sciatic6 and femoral7 nerve blocks when multistimulation was used. Recently, Gaertner et al.8 found that triple injection of the local anesthetic guided by nerve stimulation increased the quality of the motor and sensory block obtained by a coracoid brachial plexus block. To our knowledge, the efficacy of double injection in nerve stimulator-guided coracoid block has not been compared with a singleinjection technique to date. The aim of this study was to investigate whether the technique of dual injection of local anesthetic guided by nerve stimulation could enhance the efficacy of sensory and motor block after a coracoid infraclavicular brachial plexus block.
Material and Methods After approval of the Ethics Committee (Comite´ E´ tico de Ensayos Clı´nicos de Galicia) and obtaining written informed consent from each patient, 60 patients undergoing surgery on the upper limb were randomly assigned to receive an infraclavicular block guided by a nerve stimulator (Multistim; Pajunk, Geisingen, Germany) with a single-injection technique (Group 1) or with a dualinjection technique (Group 2). Randomization was performed by means of a computer-generated randomization list. For the infraclavicular block, a perpendicular coracoid approach was used.1 To perform the block, patients were requested to flex their arm with their forearm and hand lying over the torso. The puncture site was located 1 cm below and 1 cm medial to the coracoid process and the needle was inserted perpendicularly to the table with the patient in the supine position. All blocks were performed with 40 mL plain 1.5% mepivacaine. The current output of the nerve stimulator was initially set at an output of 2 mA with a frequency of stimulation of 2 Hz and a duration of pulse of 0.1 msec. A 22-gauge, 800-mm long stimulating needle (Pajunk) was introduced perpendicularly to the patient’s body and advanced until the elicitation of a motor response of the upper limb. A satisfactory response to nerve stimulation was considered when the motor response could be elicited with a current intensity equal to or below 0.5 mA. In Group 1, 40 mL of local anesthetic was injected in a single bolus after the first location of the brachial plexus. In Group 2, 20 mL of local anesthetic was injected after the first location of the brachial plexus, and the remaining 20 mL was injected after the second location. To achieve this second location, the needle was withdrawn to the subcutaneous tissue, the nerve stimulator was reset at an output of 2 mA, and the needle was advanced again perpendicularly toward the brachial plexus until a new nerve location was achieved with further reduction of the intensity of stimulation below 0.5 mA. If the first stimulation had produced a response corresponding to the lateral or medial cord (musculocutaneous, median, or ulnar 252
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nerves) the needle was withdrawn and reintroduced. The needle was again directed perpendicularly at a point 0.5 cm cranial to the first puncture site to locate the posterior cord. Conversely, if the first stimulation had produced a response corresponding to the posterior cord (radial or axillary nerves), the needle was withdrawn and reintroduced perpendicularly at a point located 0.5 cm caudal to the first puncture site. The procedure for location of the medial or lateral cord was reinitiated. No specific search to stimulate a certain nerve element was made in any group. The time needed to elicit the second response and to inject the second dose of local anesthetic was also recorded. Brachial plexus block was assessed 5 and 20 minutes after the end of the injection of the total dose of local anesthetic (time zero) by a study-blinded investigator. Sensory block was assessed in the following nerve distributions: axillary, musculocutaneous, radial, median, ulnar, medial cutaneous of forearm, and medial cutaneous of the arm. Sensory block was assessed by the pinprick method with an 18-gauge long bevel needle, using the following scale: 0 points ⫽ pinprick perceived as painful, 1 point ⫽ analgesia to pinprick (tactile sensation), and 2 points ⫽ anesthesia to pinprick (no perception). Motor block was assessed for flexion and extension of the elbow, flexion and extension of the wrist, flexion and extension of the fingers, and adduction of the thumb, using the following scale: 0 points ⫽ no paresis, 1 point ⫽ paresis, and 2 points ⫽ complete paralysis. Additionally, global scores for both sensory block (minimum, 0 points; maximum, 14 points) and motor block (minimum, 0 points; maximum, 14 points) were calculated basing on the sum of the individual scores obtained (see scales above). Specific search was addressed to side effects and complications such as hoarseness, Horner’s syndrome, dyspnea, vascular puncture, and hematoma formation. For the sample size calculation, we postulated that using dual stimulation would provide an increase from 50% to 85% in the rate of sensory block (analgesia and anesthesia) on any nerve distribution compared with single stimulation. Based on this, we calculated a sample size of 27 patients per group to achieve a statistical power of 0.8 with an ␣ of 0.05. Statistical analysis consisted of 2 test for gender, sensory block, and motor block; Student’s t-test for demographic quantitative variables, and Wilcoxon rank sum test for sensory and motor block global scores. A p-value ⱕ 0.05 was considered significant.
Results Groups were similar in terms of age, height, weight, and gender (Table 1). One of the patients in Group 2 could not be evaluated at 5 minutes. The elicited motor responses are shown in Table 1. The time interval between the end of the first injection and the end of the second injection was 209 ⫾ 114 seconds (means ⫾ SD). In Group 1, the brachial plexus was located with an intensity of 0.46 ⫾ 0.07 mA (means ⫾ SD). In Group 2, the first location was achieved with an intensity of 0.5 ⫾ 0 mA and the second location was achieved with 0.5 ⫾ 0.1 mA.
Is dual-injection enough?: Rodrı´guez et al.
Table 1. Demographic Characteristics of Both Groups, Motor Responses Elicited by Nerve Stimulation, and Type of Surgery
Gender (M/F) Age (yr) Weight (kg) Height (cm)
Single Stimulation (n ⴝ 30)
Dual Stimulation (n ⴝ 30)
p-Value
12/18 52 ⫾ 14 69 ⫾ 12 161 ⫾ 7.8
17/13 53 ⫾ 19 71 ⫾ 14 163 ⫾ 9.6
n.s. n.s. n.s. n.s.
Median Musculocutaneous Axillary Radial Ulnar Type of surgery Elbow and/or forearm Wrist Hand
Single response
First response
Second response
16 6 1 3 4
12 9 2 7 0
4 6 7 11 2
14 9 7
12 10 8
Data are presented as number of patients or means ⫾ SD where appropriate. n.s. ⫽ Not significant.
The type of surgery performed is shown in Table 1. One patient in Group 1 had a vascular puncture. One patient in Group 1 and two patients in Group 2 presented with hematoma just after the procedure. A Horner’s syndrome was identified in one patient in Group 2. No case of hoarseness or dyspnea was found. Significantly higher rates of sensory block (analgesia and anesthesia to pinprick) at 5 minutes were found on the distributions of axillary, musculocutaneous, and radial nerves in Group 2 when compared with Group 1. Significantly higher rates of sensory block (analgesia and anesthesia to pinprick) at 20 minutes were also found in the distribution of the axillary, musculocutaneous, radial, ulnar, and medial cutaneous of
the forearm nerves in Group 2 (Table 2). Significantly higher rates of motor block (paresis and paralysis) at the elbow, wrist, and fingers were found in Group 2 at 20 minutes, whereas differences at 5 minutes were found only for flexion and extension of the elbow and for extension of the wrist (Table 3). When just complete anesthesia and complete paralysis at 20 minutes were analyzed, differences between groups were kept for the same nerve distributions (Figure 1) and for the same joint movements (Figure 2). Global scores for sensory and motor block were significantly higher in Group 2 at 5 and at 20 minutes (Tables 2 and 3).
Discussion Incomplete anesthesia of the upper limb is a common finding after several approaches for brachial plexus anesthesia such as interscalene and axillary blocks.9 The infraclavicular block was initially described by the French surgeon Bazy in 1917.10 Raj, in 1973,11 described a modern approach guided by nerve stimulation with the aim of producing an extensive anesthesia of the upper limb without exposing patients to the risk of pneumothorax. However, a magnetic resonance imaging study showed that Raj’s approach still carried a significant risk of needle contact with the pleura.12 With the perpendicular coracoid infraclavicular block, the needle follows a more predictable course into the patient’s body toward the brachial plexus, giving less chance for the needle to contact with the pleura.13 Unfortunately, infraclavicular block does not consistently block the entire brachial plexus.1,8 However, some authors found that a lateral infraclavicular block, an approach similar to the approach described in this report, produced a more extensive block of the upper limb than an axillary block.14 Multiple injections of local anesthetic guided by nerve stimulation have been shown to enhance both the extent and the depth of anesthesia after axillary,2– 4 interscalene,5 and coracoid8 blocks. Triple injection of the local anes-
Table 2. Sensory Block at 5 and 20 Min 5 min
Axillary Radial Musculocutaneous Median Ulnar Medial cutaneous of the forearm Medial cutaneous of the arm Sensory block score (mean ⫾ SD)
20 min
Group 1 (n ⴝ 30)
Group 2 (n ⴝ 29)
p-value
Group 1 (n ⴝ 30)
Group 2 (n ⴝ 30)
p-value
18/10/2 8/15/7 17/10/3 5/16/9 8/16/6 12/4/14 15/9/6 5.76 ⫾ 3.91
5/8/16 0/11/18 6/9/14 3/16/10 4/18/7 4/10/15 11/8/10 8.89 ⫾ 3.28*
⬍0.001 0.001 0.002 n.s. n.s. n.s. n.s. 0.003
10/9/11 2/10/18 8/9/13 1/12/17 2/16/12 9/2/19 12/7/11 8.9 ⫾ 3.62*
3/3/24 0/2/28 0/1/29 1/6/23 1/7/22 0/2/28 5/7/18 12.4 ⫾ 1.73
0.003 0.009 ⬍0.001 n.s. 0.03 0.005 n.s. ⬍0.001
Data are shown as absolute frequencies of no analgesia/analgesia/anesthesia to pinprick. One patient in group 2 could not be evaluated at 5 min. *Difference between sensory block global score at 20 min in group 1 and sensory block global score at 5 min in group 2 was not significant. Group 1 ⫽ single stimulation; group 2 ⫽ dual stimulation; n.s. ⫽ not significant. J. Clin. Anesth., vol. 16, June 2004
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Original Contributions
Table 3. Motor Block at 5 and 20 min 5 min
Flexion of the arm Extension of the arm Flexion of the wrist Extension of the wrist Flexion of the fingers Extension of the fingers Adduction of the thumb Motor block score (mean ⫾ SD)
20 min
Group 1 (n ⴝ 30)
Group 2 (n ⴝ 29)
p value
Group 1 (n ⴝ 30)
Group 2 (n ⴝ 30)
p value
8/12/10 12/11/7 18/7/5 18/8/4 14/11/5 15/12/3 17/8/5 4.96 ⫾ 4.72
4/8/17 5/8/16 8/13/8 6/10/13 6/17/6 7/14/8 8/13/8 8.06 ⫾ 4.28*
n.s. 0.03 0.04 0.004 n.s. n.s. n.s. 0.014
3/10/17 5/11/14 9/8/13 9/10/11 9/11/10 10/9/11 10/8/12 8.03 ⫾ 5.24*
0/1/29 1/1/28 1/6/23 1/3/26 2/5/23 1/4/25 1/5/24 12.63 ⫾ 2.72
0.001 ⬍0.001 0.005 0.001 0.003 0.001 0.005 0.001
One patient in group 2 could not be evaluated at 5 min. Data are shown as absolute frequencies of no paresis/paresis/complete paralysis. *Difference between motor block score at 20 min in group 1 and motor block score at 5 min in group 2 was not significant. Group 1 ⫽ single stimulation; group 2 ⫽ dual stimulation; n.s. ⫽ not significant.
thetic produced a more extensive anesthesia of the upper limb than single-injection lateral infraclavicular block.8 No study to date has compared the effectiveness of dualinjection infraclavicular block with a single-injection technique. Sandhu et al.15 found by ultrasonography that the posterior cord was behind the axillary vessels and that the medial cord was just medial to them. However, these researchers did not use any method such as nerve stimulation to confirm whether the structures were actually the cords. Given this anatomical arrangement, we might have anticipated a high rate of arterial puncture in Group 2 when seeking posterior cord stimulation. However, this was not the case. A possible explanation for this might be the positioning of the patient’s arm when performing the block in our study, with the head of the humerus resulting in internal rotation. This position might have moved the posterior cord to a more anterior and lateral position with respect to the axillary artery. Evaluation of sensory and motor block after brachial plexus anesthesia has a very important subjective contribution from the patient, especially when concepts such as analgesia and paresis are considered. For this reason, we also decided to focus the study on differences concerning
complete anesthesia and complete paralysis with the aim of assessing the characteristics of the blockade more objectively. When complete anesthesia and complete paralysis at 20 minutes were considered (Figures 1 and 2), the same differences were found between groups. Additionally, we tried to provide some information about the global quality of sensory and motor block by means of two simple scores that included the categories of analgesia and paresis. We used the pinprick method instead of another more reproducible method such as electrical stimulation. Electrical stimulation is increasingly being used for assessment of sensory block after neuraxial anesthesia16 but not for brachial plexus anesthesia. Assessment of analgesia and anesthesia on the upper limb by electrical stimulation in our study would have required the use of seven couples of electrodes for the corresponding seven nerves studied. We might have had some problems in attaching two electrodes in the narrow distribution of ulnar nerve without overlapping the distributions of the median or radial nerves. There is a concern about the possibility of an increased risk of postoperative neurologic dysfunction with multipleinjection techniques in regional anesthesia. In the present
Figure 1. Complete anesthesia on the different nerve distributions of the upper limb. Data are shown as percentage. *p-value ⬍ 0.01.
Figure 2. Complete paralysis for joint movements of the upper limb. Data are shown as percentage. *p-value ⬍ 0.01.
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Is dual-injection enough?: Rodrı´guez et al.
study, no specific prospective search for postoperative nerve symptoms was done, because this was not a realistic objective as a result of the relatively small number of patients included in the study. Several hundred patients per group would be needed to detect a difference in the incidence of this type of complication. In a noncomparative, prospective, multicenter study of multiple nerve stimulation performed on nearly 4,000 patients, a 1.7% incidence of postoperative neurologic dysfunction was discovered,17 which is similar to that reported by other researchers using single-injection techniques,18 and an incidence of prolonged nerve damage of 1:4,000, which is similar to that reported by Auroy et al.19 in a multicenter prospective study from France. Interestingly, it was found that brachial plexus anesthesia and intravenous regional anesthesia had also a similar rate of severe nerve complications. Moreover, most postoperative nerve symptoms after brachial plexus anesthesia are attributable to surgical causes.20 In this study, we showed that the technique of dual injection of local anesthetic guided by nerve stimulation increased the efficacy of anesthesia after perpendicular coracoid infraclavicular block (Tables 2 and 3). The improvement in sensory block was observed on the distributions of axillary, radial, musculocutaneous, ulnar, and medial cutaneous of the forearm nerves. One limitation of the study is that motor function of the axillary nerve was not assessed. Although we had the clinical impression that many blocks still were increasing their extension at 30 minutes, we decided not to prolong the time needed for assessment more than 20 minutes because of time restrictions in a busy operating room. Another limitation of the study is that the time to perform the block was longer in Group 2, because time 0 was considered to be the moment when the second injection was finished. The time interval between the end of the first injection and the end of the second injection was 209 ⫾ 114 seconds (means ⫾ SD). This fact might have given the first dose of local anesthetic a chance to initiate its action before time 0 in Group 2; this action might have reduced the reliability of our results, especially at 5 minutes, although this small time interval should have less influence on anesthesia and paralysis at 20 minutes. Moreover, sensory and motor block global scores obtained at 5 minutes in Group 2 were nearly identical to the scores achieved at 20 minutes in Group 1 (Tables 2 and 3). This indicates that dual injection of the local anesthetic also shortens the onset time of motor and sensory block after coracoid block. Deleuze et al.21 compared single-hot lateral infraclavicular plexus block with triple-stimulation axillary block and found a similar effectiveness. However, they used 40 mL 0.75% ropivacaine, and their use of that high dose of local anesthetic might have biased their results. Gaertner et al.8 found that triple injection of the local anesthetic guided by nerve stimulation increased the quality of the motor and sensory block obtained by a coracoid block when compared with a single-injection technique. They obtained complete sensory and motor block in 72.5% patients in the triple-injection group. We demonstrated that dual injection of the local anesthetic
was also superior to single-injection coracoid block. We cannot compare our results with the results of Gaertner et al.8 point by point because of the differences in methodology between the two studies. In that study, 30 mL of a mixture of local anesthetics was injected, whereas 40 mL plain 1.5% mepivacaine was used in our study. In our dual-injection group, 60% patients had complete motor block whereas 47% patients had complete sensory block following our criteria, which included the distribution of the axillary nerve. Theoretically, the efficacy of tripleinjection coracoid block should be superior to that of dual-injection coracoid block, although this subject has not been investigated to date. Further studies that compare the efficacy of double-injection with triple-injection techniques are needed. With our approach, plexus location is achieved at a mean depth of 45 mm.1 In our experience with more than 350 infraclavicular blocks, we have not experienced a case of pneumothorax in spite of our use of an 80-mm-long needle. This is not the case with Kilka et al.’s approach,22,23 with a more proximal puncture site, just below the clavicle. In conclusion, dual injection of local anesthetic guided by nerve stimulator increases the efficacy of anesthesia after coracoid block and, most likely also shortens its onset time.
Acknowledgment We thank Dr. F Gude for his statistical help in the development of this study.
References ´ lvarez J: 1. Rodrı´guez J, Ba´ rcena M, Rodrı´guez V, Aneiros F, A Infraclavicular brachial plexus block. Effects on respiratory function and extent of the block. Reg Anesth Pain Med 1998;23:564 –8. 2. Koscielniak-Nielsen ZJ, Stens-Pedersen HL, Lippert FK: Readiness for surgery after axillary block: single or multiple injection techniques. Eur J Anaesthesiol 1997;14:164 –71. 3. Inberg P, Annila I, Annila P: Double-injection method using peripheral nerve stimulator is superior to single injection in axillary plexus block. Reg Anesth Pain Med 1999;24:509 –13. 4. Coventry DM, Barker KF, Thomson M: Comparison of two neurostimulation techniques for axillary brachial plexus blockade. Br J Anaesth 2001;86:80 –3. 5. Fanelli G, Casati A, Beccaria P, Cappelleri G, Albertin A, Torri G: Interscalene brachial plexus anaesthesia with small volumes of ropivacaine 0.75%: effects of the injection technique on the onset time of nerve blockade. Eur J Anaesthesiol 2001;18:54 –8. 6. Bailey SL, Parkinson SK, Little WL, Simmerman SR: Sciatic nerve block. A comparison of single versus dual injection technique. Reg Anesth 1995;20:81–2. 7. Casati A, Fanelli G, Beccaria P, et al: The effects of the single or multiple injection technique on the onset time of femoral nerve blocks with 0.75% ropivacaine. Anesth Analg 2000;91:181–4. 8. Gaertner E, Estebe JP, Zamfir A, Cuby C, Macaire P: Infraclavicular plexus block: multiple injection versus single injection. Reg Anesth Pain Med 2002;27:590 –4. 9. Lanz E, Theiss D, Jankovic D: The extent of blockade following various techniques of brachial plexus block. Anesth Analg 1983; 62:55–8. J. Clin. Anesth., vol. 16, June 2004
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Original Contributions 10. Bazy L. L’anesthe´ sie du plexus brachial. In: Pauchet V, Sourdat P, Laboure´ I (eds.). L’Ane´ sthesie re´ gionale. Paris: G Doin et Cie, 1917, 222–5. 11. Raj PP, Montgomery SJ, Nettles D, Jenkins MT: Infraclavicular brachial plexus block—a new approach. Anesth Analg 1973;52: 897–904. 12. Klaastad O, Lilleas FG, Rotnes JS, Breivik H, Fosse E: Magnetic resonance imaging demonstrates lack of precision in needle placement by the infraclavicular brachial plexus block described by Raj et al. Anesth Analg 1999;88:593–8. 13. Wilson JL, Brown DL, Wong GY, Ehman RL, Cahill DR: Infraclavicular brachial plexus block: parasagittal anatomy important to the coracoid technique. Anesth Analg 1998;87:870 –3. 14. Kapral S, Jandrasits O, Schabernig R, et al: Lateral infraclavicular plexus block vs. axillary block for hand and forearm surgery. Acta Anaesthesiol Scand 1999;43:1047–52. 15. Sandhu NS, Capan LM: Ultrasound-guided infraclavicular brachial plexus block. Br J Anaesth 2002;89:254 –9. 16. Curatolo M, Petersen-Felix S, Arendt-Nielsen L: Sensory assessment of regional analgesia in humans: a review of methods and applications. Anesthesiology 2000;93:1517–30. 17. Fanelli G, Casati A, Garancini P, Torri G: Nerve stimulator and multiple injection technique for upper and lower limb blockade: failure rate, patient acceptance, and neurologic compli-
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cations. Study Group on Regional Anesthesia. Anesth Analg 1999;88:847–52. Selander D, Edshage S, Wolff T: Paresthesiae or no paresthesiae? Nerve lesions after axillary blocks. Acta Anaesthesiol Scand 1979; 23:27–33. Auroy Y, Narchi P, Messiah A, Litt L, Rouvier B, Samii K: Serious complications related to regional anesthesia. Anesthesiology 1997; 87:479 –86. Horlocker TT, Kufner RP, Bishop AT, Maxson PM, Schroeder DR: The risk of persistent paresthesia is not increased with repeated axillary block. Anesth Analg 1999;88:382–7. Deleuze A, Gentili ME, Marrett E, Lamonerie L, Bonnet F: A comparison of a single-stimulation lateral infraclavicular plexus block with a triple-stimulation axillary block. Reg Anesth Pain Med 2003;28:89 –94. Kilka HG, Geiger P, Mehrkens HH: Die vertikale infraclavicula¨ re blockade des plexus brachialis. [Infraclavicular vertical brachial plexus blockade. A new method for anesthesia of the upper extremity. An anatomical and clinical study.] Anesthesist 1995;44: 339 –44. Mehrkens HH, Geiger PK: Continuous brachial plexus blockade via the vertical infraclavicular approach. Anaesthesia 1998;53 (Supp 2):19 –20.
*Staff Anesthesiologist †Assistant Professor of Anesthesiology; Head of Department of Anesthesiology Address correspondence to Dr. Rodrı´guez at the Servicio de Anestesiologı´a y Reanimacio´n. Hospital Clı´nico Universitario de Santiago, Travesı´a da Choupana, s.n. 15706, Santiago de Compostela, Spain. E-mail: [email protected] Received for publication April 22, 2003; revised manuscript accepted for publication August 7, 2003. Journal of Clinical Anesthesia 16:251–256, 2004 © 2004 Elsevier Inc. All rights reserved. 360 Park Avenue, South, New York, NY 10010
Study Objective: To test the hypothesis that dual injection of the local anesthetic in coracoid infraclavicular brachial plexus block might enhance both sensory and motor block for anesthesia of the upper limb when compared with a single-injection technique. Design: Comparative, prospective, randomized, investigator-blinded study. Setting: University-affiliated hospital. Patients: 60 patients scheduled for surgery of the hand, forearm, or elbow. Interventions: Patients were randomly assigned to receive either a coracoid infraclavicular block guided by nerve stimulator with a single injection technique (Group 1) or a dual-injection technique (Group 2). Injection of 40 mL 1.5% mepivacaine was made after eliciting one evoked motor response in the upper limb with a nerve stimulator for coracoid infraclavicular block in Group 1 and injection of two separate doses of 20 mL 1.5% mepivacaine after elicitation of two motor responses in Group 2. Measurements: Assessment of sensory and motor block in the upper limb 5 and 20 minutes after the end of the injection of the local anesthetic. The time needed to elicit the second response and to inject the second dose of local anesthetic was also recorded. Main Results: Significantly higher rates of sensory block to pinprick on the distributions of axillary, musculocutaneous, radial, ulnar, and medial cutaneous of the forearm nerves were found in Group 2 at 20 minutes. Significantly higher rates of motor block for arm, wrist, and hand movements were found in Group 2 at 20 minutes. Conclusions: Dual injection of local anesthetic guided by nerve stimulator increases the efficacy of coracoid block when compared with a single injection of the same dose of local anesthetic. © 2004 by Elsevier Inc. Keywords: Anesthesia, techniques; nerve stimulation; brachial plexus; infraclavicular.
Introduction Single-injection coracoid infraclavicular brachial plexus block produces an inconsistent anesthesia of the upper limb, with a low success rate in the distributions of axillary, radial, musculocutaneous and medial cutaneous of the arm nerves.1 The technique of multiple injections of local anesthetic guided by nerve stimulation has been shown to increase the number of blocked nerve 0952-8180/04/$–see front matter doi:10.1016/j.jclinane.2003.08.006
Original Contributions
distributions of the upper limb when compared with the corresponding similar approach with single-injection techniques in axillary2– 4 and interscalene5 approaches for brachial plexus anesthesia. In a similar fashion, a shorter onset time was observed with both sciatic6 and femoral7 nerve blocks when multistimulation was used. Recently, Gaertner et al.8 found that triple injection of the local anesthetic guided by nerve stimulation increased the quality of the motor and sensory block obtained by a coracoid brachial plexus block. To our knowledge, the efficacy of double injection in nerve stimulator-guided coracoid block has not been compared with a singleinjection technique to date. The aim of this study was to investigate whether the technique of dual injection of local anesthetic guided by nerve stimulation could enhance the efficacy of sensory and motor block after a coracoid infraclavicular brachial plexus block.
Material and Methods After approval of the Ethics Committee (Comite´ E´ tico de Ensayos Clı´nicos de Galicia) and obtaining written informed consent from each patient, 60 patients undergoing surgery on the upper limb were randomly assigned to receive an infraclavicular block guided by a nerve stimulator (Multistim; Pajunk, Geisingen, Germany) with a single-injection technique (Group 1) or with a dualinjection technique (Group 2). Randomization was performed by means of a computer-generated randomization list. For the infraclavicular block, a perpendicular coracoid approach was used.1 To perform the block, patients were requested to flex their arm with their forearm and hand lying over the torso. The puncture site was located 1 cm below and 1 cm medial to the coracoid process and the needle was inserted perpendicularly to the table with the patient in the supine position. All blocks were performed with 40 mL plain 1.5% mepivacaine. The current output of the nerve stimulator was initially set at an output of 2 mA with a frequency of stimulation of 2 Hz and a duration of pulse of 0.1 msec. A 22-gauge, 800-mm long stimulating needle (Pajunk) was introduced perpendicularly to the patient’s body and advanced until the elicitation of a motor response of the upper limb. A satisfactory response to nerve stimulation was considered when the motor response could be elicited with a current intensity equal to or below 0.5 mA. In Group 1, 40 mL of local anesthetic was injected in a single bolus after the first location of the brachial plexus. In Group 2, 20 mL of local anesthetic was injected after the first location of the brachial plexus, and the remaining 20 mL was injected after the second location. To achieve this second location, the needle was withdrawn to the subcutaneous tissue, the nerve stimulator was reset at an output of 2 mA, and the needle was advanced again perpendicularly toward the brachial plexus until a new nerve location was achieved with further reduction of the intensity of stimulation below 0.5 mA. If the first stimulation had produced a response corresponding to the lateral or medial cord (musculocutaneous, median, or ulnar 252
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nerves) the needle was withdrawn and reintroduced. The needle was again directed perpendicularly at a point 0.5 cm cranial to the first puncture site to locate the posterior cord. Conversely, if the first stimulation had produced a response corresponding to the posterior cord (radial or axillary nerves), the needle was withdrawn and reintroduced perpendicularly at a point located 0.5 cm caudal to the first puncture site. The procedure for location of the medial or lateral cord was reinitiated. No specific search to stimulate a certain nerve element was made in any group. The time needed to elicit the second response and to inject the second dose of local anesthetic was also recorded. Brachial plexus block was assessed 5 and 20 minutes after the end of the injection of the total dose of local anesthetic (time zero) by a study-blinded investigator. Sensory block was assessed in the following nerve distributions: axillary, musculocutaneous, radial, median, ulnar, medial cutaneous of forearm, and medial cutaneous of the arm. Sensory block was assessed by the pinprick method with an 18-gauge long bevel needle, using the following scale: 0 points ⫽ pinprick perceived as painful, 1 point ⫽ analgesia to pinprick (tactile sensation), and 2 points ⫽ anesthesia to pinprick (no perception). Motor block was assessed for flexion and extension of the elbow, flexion and extension of the wrist, flexion and extension of the fingers, and adduction of the thumb, using the following scale: 0 points ⫽ no paresis, 1 point ⫽ paresis, and 2 points ⫽ complete paralysis. Additionally, global scores for both sensory block (minimum, 0 points; maximum, 14 points) and motor block (minimum, 0 points; maximum, 14 points) were calculated basing on the sum of the individual scores obtained (see scales above). Specific search was addressed to side effects and complications such as hoarseness, Horner’s syndrome, dyspnea, vascular puncture, and hematoma formation. For the sample size calculation, we postulated that using dual stimulation would provide an increase from 50% to 85% in the rate of sensory block (analgesia and anesthesia) on any nerve distribution compared with single stimulation. Based on this, we calculated a sample size of 27 patients per group to achieve a statistical power of 0.8 with an ␣ of 0.05. Statistical analysis consisted of 2 test for gender, sensory block, and motor block; Student’s t-test for demographic quantitative variables, and Wilcoxon rank sum test for sensory and motor block global scores. A p-value ⱕ 0.05 was considered significant.
Results Groups were similar in terms of age, height, weight, and gender (Table 1). One of the patients in Group 2 could not be evaluated at 5 minutes. The elicited motor responses are shown in Table 1. The time interval between the end of the first injection and the end of the second injection was 209 ⫾ 114 seconds (means ⫾ SD). In Group 1, the brachial plexus was located with an intensity of 0.46 ⫾ 0.07 mA (means ⫾ SD). In Group 2, the first location was achieved with an intensity of 0.5 ⫾ 0 mA and the second location was achieved with 0.5 ⫾ 0.1 mA.
Is dual-injection enough?: Rodrı´guez et al.
Table 1. Demographic Characteristics of Both Groups, Motor Responses Elicited by Nerve Stimulation, and Type of Surgery
Gender (M/F) Age (yr) Weight (kg) Height (cm)
Single Stimulation (n ⴝ 30)
Dual Stimulation (n ⴝ 30)
p-Value
12/18 52 ⫾ 14 69 ⫾ 12 161 ⫾ 7.8
17/13 53 ⫾ 19 71 ⫾ 14 163 ⫾ 9.6
n.s. n.s. n.s. n.s.
Median Musculocutaneous Axillary Radial Ulnar Type of surgery Elbow and/or forearm Wrist Hand
Single response
First response
Second response
16 6 1 3 4
12 9 2 7 0
4 6 7 11 2
14 9 7
12 10 8
Data are presented as number of patients or means ⫾ SD where appropriate. n.s. ⫽ Not significant.
The type of surgery performed is shown in Table 1. One patient in Group 1 had a vascular puncture. One patient in Group 1 and two patients in Group 2 presented with hematoma just after the procedure. A Horner’s syndrome was identified in one patient in Group 2. No case of hoarseness or dyspnea was found. Significantly higher rates of sensory block (analgesia and anesthesia to pinprick) at 5 minutes were found on the distributions of axillary, musculocutaneous, and radial nerves in Group 2 when compared with Group 1. Significantly higher rates of sensory block (analgesia and anesthesia to pinprick) at 20 minutes were also found in the distribution of the axillary, musculocutaneous, radial, ulnar, and medial cutaneous of
the forearm nerves in Group 2 (Table 2). Significantly higher rates of motor block (paresis and paralysis) at the elbow, wrist, and fingers were found in Group 2 at 20 minutes, whereas differences at 5 minutes were found only for flexion and extension of the elbow and for extension of the wrist (Table 3). When just complete anesthesia and complete paralysis at 20 minutes were analyzed, differences between groups were kept for the same nerve distributions (Figure 1) and for the same joint movements (Figure 2). Global scores for sensory and motor block were significantly higher in Group 2 at 5 and at 20 minutes (Tables 2 and 3).
Discussion Incomplete anesthesia of the upper limb is a common finding after several approaches for brachial plexus anesthesia such as interscalene and axillary blocks.9 The infraclavicular block was initially described by the French surgeon Bazy in 1917.10 Raj, in 1973,11 described a modern approach guided by nerve stimulation with the aim of producing an extensive anesthesia of the upper limb without exposing patients to the risk of pneumothorax. However, a magnetic resonance imaging study showed that Raj’s approach still carried a significant risk of needle contact with the pleura.12 With the perpendicular coracoid infraclavicular block, the needle follows a more predictable course into the patient’s body toward the brachial plexus, giving less chance for the needle to contact with the pleura.13 Unfortunately, infraclavicular block does not consistently block the entire brachial plexus.1,8 However, some authors found that a lateral infraclavicular block, an approach similar to the approach described in this report, produced a more extensive block of the upper limb than an axillary block.14 Multiple injections of local anesthetic guided by nerve stimulation have been shown to enhance both the extent and the depth of anesthesia after axillary,2– 4 interscalene,5 and coracoid8 blocks. Triple injection of the local anes-
Table 2. Sensory Block at 5 and 20 Min 5 min
Axillary Radial Musculocutaneous Median Ulnar Medial cutaneous of the forearm Medial cutaneous of the arm Sensory block score (mean ⫾ SD)
20 min
Group 1 (n ⴝ 30)
Group 2 (n ⴝ 29)
p-value
Group 1 (n ⴝ 30)
Group 2 (n ⴝ 30)
p-value
18/10/2 8/15/7 17/10/3 5/16/9 8/16/6 12/4/14 15/9/6 5.76 ⫾ 3.91
5/8/16 0/11/18 6/9/14 3/16/10 4/18/7 4/10/15 11/8/10 8.89 ⫾ 3.28*
⬍0.001 0.001 0.002 n.s. n.s. n.s. n.s. 0.003
10/9/11 2/10/18 8/9/13 1/12/17 2/16/12 9/2/19 12/7/11 8.9 ⫾ 3.62*
3/3/24 0/2/28 0/1/29 1/6/23 1/7/22 0/2/28 5/7/18 12.4 ⫾ 1.73
0.003 0.009 ⬍0.001 n.s. 0.03 0.005 n.s. ⬍0.001
Data are shown as absolute frequencies of no analgesia/analgesia/anesthesia to pinprick. One patient in group 2 could not be evaluated at 5 min. *Difference between sensory block global score at 20 min in group 1 and sensory block global score at 5 min in group 2 was not significant. Group 1 ⫽ single stimulation; group 2 ⫽ dual stimulation; n.s. ⫽ not significant. J. Clin. Anesth., vol. 16, June 2004
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Original Contributions
Table 3. Motor Block at 5 and 20 min 5 min
Flexion of the arm Extension of the arm Flexion of the wrist Extension of the wrist Flexion of the fingers Extension of the fingers Adduction of the thumb Motor block score (mean ⫾ SD)
20 min
Group 1 (n ⴝ 30)
Group 2 (n ⴝ 29)
p value
Group 1 (n ⴝ 30)
Group 2 (n ⴝ 30)
p value
8/12/10 12/11/7 18/7/5 18/8/4 14/11/5 15/12/3 17/8/5 4.96 ⫾ 4.72
4/8/17 5/8/16 8/13/8 6/10/13 6/17/6 7/14/8 8/13/8 8.06 ⫾ 4.28*
n.s. 0.03 0.04 0.004 n.s. n.s. n.s. 0.014
3/10/17 5/11/14 9/8/13 9/10/11 9/11/10 10/9/11 10/8/12 8.03 ⫾ 5.24*
0/1/29 1/1/28 1/6/23 1/3/26 2/5/23 1/4/25 1/5/24 12.63 ⫾ 2.72
0.001 ⬍0.001 0.005 0.001 0.003 0.001 0.005 0.001
One patient in group 2 could not be evaluated at 5 min. Data are shown as absolute frequencies of no paresis/paresis/complete paralysis. *Difference between motor block score at 20 min in group 1 and motor block score at 5 min in group 2 was not significant. Group 1 ⫽ single stimulation; group 2 ⫽ dual stimulation; n.s. ⫽ not significant.
thetic produced a more extensive anesthesia of the upper limb than single-injection lateral infraclavicular block.8 No study to date has compared the effectiveness of dualinjection infraclavicular block with a single-injection technique. Sandhu et al.15 found by ultrasonography that the posterior cord was behind the axillary vessels and that the medial cord was just medial to them. However, these researchers did not use any method such as nerve stimulation to confirm whether the structures were actually the cords. Given this anatomical arrangement, we might have anticipated a high rate of arterial puncture in Group 2 when seeking posterior cord stimulation. However, this was not the case. A possible explanation for this might be the positioning of the patient’s arm when performing the block in our study, with the head of the humerus resulting in internal rotation. This position might have moved the posterior cord to a more anterior and lateral position with respect to the axillary artery. Evaluation of sensory and motor block after brachial plexus anesthesia has a very important subjective contribution from the patient, especially when concepts such as analgesia and paresis are considered. For this reason, we also decided to focus the study on differences concerning
complete anesthesia and complete paralysis with the aim of assessing the characteristics of the blockade more objectively. When complete anesthesia and complete paralysis at 20 minutes were considered (Figures 1 and 2), the same differences were found between groups. Additionally, we tried to provide some information about the global quality of sensory and motor block by means of two simple scores that included the categories of analgesia and paresis. We used the pinprick method instead of another more reproducible method such as electrical stimulation. Electrical stimulation is increasingly being used for assessment of sensory block after neuraxial anesthesia16 but not for brachial plexus anesthesia. Assessment of analgesia and anesthesia on the upper limb by electrical stimulation in our study would have required the use of seven couples of electrodes for the corresponding seven nerves studied. We might have had some problems in attaching two electrodes in the narrow distribution of ulnar nerve without overlapping the distributions of the median or radial nerves. There is a concern about the possibility of an increased risk of postoperative neurologic dysfunction with multipleinjection techniques in regional anesthesia. In the present
Figure 1. Complete anesthesia on the different nerve distributions of the upper limb. Data are shown as percentage. *p-value ⬍ 0.01.
Figure 2. Complete paralysis for joint movements of the upper limb. Data are shown as percentage. *p-value ⬍ 0.01.
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Is dual-injection enough?: Rodrı´guez et al.
study, no specific prospective search for postoperative nerve symptoms was done, because this was not a realistic objective as a result of the relatively small number of patients included in the study. Several hundred patients per group would be needed to detect a difference in the incidence of this type of complication. In a noncomparative, prospective, multicenter study of multiple nerve stimulation performed on nearly 4,000 patients, a 1.7% incidence of postoperative neurologic dysfunction was discovered,17 which is similar to that reported by other researchers using single-injection techniques,18 and an incidence of prolonged nerve damage of 1:4,000, which is similar to that reported by Auroy et al.19 in a multicenter prospective study from France. Interestingly, it was found that brachial plexus anesthesia and intravenous regional anesthesia had also a similar rate of severe nerve complications. Moreover, most postoperative nerve symptoms after brachial plexus anesthesia are attributable to surgical causes.20 In this study, we showed that the technique of dual injection of local anesthetic guided by nerve stimulation increased the efficacy of anesthesia after perpendicular coracoid infraclavicular block (Tables 2 and 3). The improvement in sensory block was observed on the distributions of axillary, radial, musculocutaneous, ulnar, and medial cutaneous of the forearm nerves. One limitation of the study is that motor function of the axillary nerve was not assessed. Although we had the clinical impression that many blocks still were increasing their extension at 30 minutes, we decided not to prolong the time needed for assessment more than 20 minutes because of time restrictions in a busy operating room. Another limitation of the study is that the time to perform the block was longer in Group 2, because time 0 was considered to be the moment when the second injection was finished. The time interval between the end of the first injection and the end of the second injection was 209 ⫾ 114 seconds (means ⫾ SD). This fact might have given the first dose of local anesthetic a chance to initiate its action before time 0 in Group 2; this action might have reduced the reliability of our results, especially at 5 minutes, although this small time interval should have less influence on anesthesia and paralysis at 20 minutes. Moreover, sensory and motor block global scores obtained at 5 minutes in Group 2 were nearly identical to the scores achieved at 20 minutes in Group 1 (Tables 2 and 3). This indicates that dual injection of the local anesthetic also shortens the onset time of motor and sensory block after coracoid block. Deleuze et al.21 compared single-hot lateral infraclavicular plexus block with triple-stimulation axillary block and found a similar effectiveness. However, they used 40 mL 0.75% ropivacaine, and their use of that high dose of local anesthetic might have biased their results. Gaertner et al.8 found that triple injection of the local anesthetic guided by nerve stimulation increased the quality of the motor and sensory block obtained by a coracoid block when compared with a single-injection technique. They obtained complete sensory and motor block in 72.5% patients in the triple-injection group. We demonstrated that dual injection of the local anesthetic
was also superior to single-injection coracoid block. We cannot compare our results with the results of Gaertner et al.8 point by point because of the differences in methodology between the two studies. In that study, 30 mL of a mixture of local anesthetics was injected, whereas 40 mL plain 1.5% mepivacaine was used in our study. In our dual-injection group, 60% patients had complete motor block whereas 47% patients had complete sensory block following our criteria, which included the distribution of the axillary nerve. Theoretically, the efficacy of tripleinjection coracoid block should be superior to that of dual-injection coracoid block, although this subject has not been investigated to date. Further studies that compare the efficacy of double-injection with triple-injection techniques are needed. With our approach, plexus location is achieved at a mean depth of 45 mm.1 In our experience with more than 350 infraclavicular blocks, we have not experienced a case of pneumothorax in spite of our use of an 80-mm-long needle. This is not the case with Kilka et al.’s approach,22,23 with a more proximal puncture site, just below the clavicle. In conclusion, dual injection of local anesthetic guided by nerve stimulator increases the efficacy of anesthesia after coracoid block and, most likely also shortens its onset time.
Acknowledgment We thank Dr. F Gude for his statistical help in the development of this study.
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