Numerous techniques are now available to block the brachial plexus and several studies have been performed in recent years to improve the success rate, which had steadily increased since the study by Goldberg et al. (1) (70%) to nearly 100%. (2) The major way to improve the success rate has been to locate and separately block each nerve distribution. Other factors should now be assessed to compare various techniques to choose the optimal one. Because of economic constraints, the turnover of operating rooms (ORs) should be optimized. (3) Among factors that play a role in OR turnover, anesthetic time (time to perform the block + onset time, i.e., latency of the block) is of utmost importance, especially when patients receive a regional block for which the time between block performance and readiness for surgery may be long. Infraclavicular brachial plexus block (ICB) has been shown to be frequently successful while using a two-stimulation technique, (4) whereas most other techniques (i.e., axillary or humeral blocks (HB)) require 3 or 4 stimulations to obtain a success rate >90%. As the anesthetic time is likely proportional to the time to perform the block (and probably to the number of nerves that should be blocked), we hypothesized that ICB would be associated with a shorter anesthetic time when compared with a more complex technique such as the HB. Moreover, the humeral route has never been compared with the ICB even though both techniques seem to provide more frequent success than the axillary plexus block. (5–7)
The aim of this study was thus to compare ICB using a double stimulation to the four-stimulation HB using the anesthetic time as a primary outcome measure.
This prospective study was conducted from January 2003 through May 2003 in 120 patients who underwent surgery from the inferior third of the humerus to the hand (emergency and scheduled) in a single University Hospital. After approval by the local Ethical Committee, all patients provided informed consent. Patients were randomized to receive ICB (group I, n = 60) or HB (group H, n = 60). Pregnant women and patients with any contraindication to regional anesthesia (patient’s refusal, major hemostasis anomalies, or local infection), bilateral surgery, pneumonectomy, dementia, and allergic reaction to local anesthetics were excluded from the study. After insertion of an IV catheter in the contralateral arm, standard monitoring was applied. Sufentanil (0.1 μg/kg) was given IV 5 min before the procedure. All blocks were performed by an experienced senior anesthesiologist with a nerve stimulator (BRAUN® Stimuplex® HNS 11; B Braun, Bethlehem, PA) and an insulated needle (BRAUN® Stimuplex®, 50 mm and 22-gauge). Lidocaine 1.5% with 1/400,000 epinephrine was used at all cases. The nerve stimulator was set at 100 μs and 2 Hz. We considered a distal and clear motor response in the hand or the wrist at a current output ranging between 0.3 and 0.5 mA.
For ICB, as previously described, (4) patients were placed supine, with the head turned away from the arm to be anesthetized. The forearm was gently placed on the abdomen. Landmarks, i.e., the clavicle and the coracoid process, were easily palpated in all patients. The puncture site was located 1 cm under the clavicle, and 1 cm medially to the coracoid process. After antiseptic preparation of the area, the insulated needle was inserted in the direction of the top of the axillary fossa (in relation to the axillary artery) with an angle of 45° to locate the musculocutaneous nerve. Ten mL of lidocaine was injected with repeated aspiration tests to minimize the risk of unrecognized intravascular injection. Then, the needle was withdrawn 1 or 2 cm and redirected medially and posteriorly. A satisfactory response was defined as a distal and clear motor response in the hand or the wrist (lateral, medial or posterior cord) for a stimulating intensity ranging between 0.3 and 0.5 mA. (8) Thirty milliliters of the same local anesthetic solution was then slowly injected.
The HB was performed in a supine position with the upper arm abducted not more than 90° and the elbow flexed at 110°. After antiseptic preparation of the area, the axillary artery was palpated at the junction of the proximal and the middle third of the arm. The four nerves (median, ulnar, radial, and musculocutaneous) originating from the brachial plexus were located in the humeral canal with a nerve stimulator and blocked using the same local anesthetic solution (10 mL on the radial, ulnar, and median nerves, 8 mL on the musculocutaneous nerve, and 2 mL for the brachial and antebrachial cutaneous nerves).
The duration of the procedure was measured from needle insertion to withdrawal. The onset of sensory block (from the end of block performance to the time when all four branches of the brachial plexus block distally achieved analgesia) was evaluated every 5 min on the radial (posterior part of the wrist and of the three first fingers), median (anterior part of the wrist and of the three first fingers), ulnar (medial part of the wrist and of the hand), musculocutaneous (lateral part of the forearm), axillary (shoulder), medial brachial and antebrachial cutaneous (medial part of the arm and of the forearm) nerve territories using cold and pinprick test and then compared to the same stimulation on the contralateral arm. Rating was undertaken by using the following scale: 0 = no sensation, 1 = hypoesthesia, and 2 = normal sensation. Motor block was assessed every 5 min on the radial (thumb abduction), median (third finger flexion), ulnar (fifth finger flexion), musculocutaneous (elbow flexion), and axillary (arm abduction) nerves and then compared to the contralateral arm. Rating was performed by using the following scale: 5 = normal muscle strength, 4 = slightly reduced muscle strength, 3 = significant muscle strength reduction, 2 = only minimal muscle contraction possible (inability to move against gravity), 1 = complete paralysis. A successful block (efficacy) was defined as the absence of cold and pinprick response (score = 0) in all 4 major nerves distributions of the brachial plexus (radial, median, ulnar, and musculocutaneous), within 30 min after injection of the local anesthetic solution. In the ICB group, if one or two nerves were not blocked, selective supplementation was performed using a nerve stimulator using the humeral puncture site. In the HB group, if one or two nerves were not blocked, supplementation at the elbow was performed using a nerve stimulator. If more than two nerves remained unblocked, general anesthesia was performed in either group. Immediate and late complications were noted after the procedure. Patient satisfaction was assessed immediately after surgery in the postanesthesia care unit with a 5-point scale (from 0 = dissatisfied to 5 = very satisfied). Patients were questioned as to which anesthetic method (same regional anesthesia technique or general anesthesia) they would choose for future surgery. Each patient was followed-up by the attendant surgeon postoperatively for several weeks to identify complications or complaints.
For the estimation of the sample size, we assumed that a 20% difference in the total anesthetic time would be considered clinically important. To compare the two groups with a β error of 20% at a significance level α of 5%, the sample size required was 45 patients in each group. We enrolled 60 patients to allow for dropouts. Statistical analyses were performed using the StatView® software (version 5.0; SAS, Cary, NC). Data are presented as mean ± sd or percentage. A χ2 test, analysis of variance, or a Student’s t-test was performed when appropriate. P < 0.05 was considered statistically significant.
All 120 patients completed the investigation. Demographic and surgical data are shown in Table 1. The success rate was 92% for ICB and 95% for HB (not significant). Four patients in the ICB group and two patients in the HB group needed supplementation (not significant). General anesthesia was performed in one patient in each group. Axillary nerve block success rate was 73% in the ICB group and 0% in the HB group. Anesthetic time was similar between the 2 groups (ICB, 19.5 min; 95% confidence interval [CI], 17.4–21.6 min versus HB, 20.8 min; 95% CI, 18.7-22.9 min), although time to perform the block was significantly shorter in the ICB group (4.5 min (95% CI, 4-5 min) versus 9.8 min (95% CI, 8.9-10.7 min) in the HB group (Figure 1). The onset time was 15 min (95% CI, 13-17 min) for ICB and 11 min (95% CI, 9-13 min) for HB (P < 0.05). In the HB group, a tourniquet was applied in 51 patients, of whom 9 needed IV analgesics because of tourniquet discomfort. A tourniquet was applied in 55 patients in the ICB group and 6 of these patients felt a small degree of tourniquet pain although no patient needed supplementary opioids.
A high degree of satisfaction (grade 4 or 5) was recorded in 95% (HB) versus 100% (ICB) of cases. Most patients (HB 97% versus ICB 100%) stated they would ask for the same regional anesthesia technique for a similar surgical intervention.
Venous puncture was observed in one patient in each group but neither had clinical consequence. No other clinical complications, including vascular absorption of the local anesthetic, overdose, recurrent laryngeal or phrenic nerve block, residual paresthesia, Horner’s syndrome, or pneumothorax, were observed.
This is the first prospective randomized study to compare ICB and HB. Efficacy and anesthetic time were not significantly different, as time to perform the block was shorter with ICB but onset time was shorter with HB.
Whatever the definition, decreasing anesthesia controlled time may improve the global OR turnover time, (9) which is an important challenge for the OR manager. In addition, performing blocks in the preanesthetic area (before OR entry) should also save valuable OR time. In our study, total anesthetic time was not statistically different between groups. However, the time to perform the block was shorter in the ICB group than in the HB group. The 5-minute difference is likely to be clinically important for both patients and busy anesthesiologists. A simpler technique using a reduced number of arm movements might be desirable, especially in trauma patients, and probably explains the significant satisfaction rate with ICB (100%). Withdrawal and redirection of the stimulating needle to elicit four different muscular twitches indeed increases patient discomfort as well as the duration of block performance with HB (10) and increases pain at the fracture site induced by muscle contractions. It is also likely that the shorter the time to perform a highly efficient block, the greater the patient’s confidence in regional anesthesia, explaining why all patients who had ICB would prefer to receive the same technique in the future. Moreover, after the block has been performed (and during block onset), the anesthesiologist is available to perform another procedure in a nearby area.
A difference in onset time was found between groups. A comparison with times recorded by other authors is difficult because different local anesthetics solutions were used in the various studies. The longer onset time in the ICB group could be attributed to the more proximal approach of the nerves (cords), whereas HB is associated with a more peripheral approach to the four nerves. The shorter onset time in the HB group might also have been attributable to the fact that each nerve is individually identified and blocked. Shortening the ICB onset time would be useful, as this would decrease anesthetic time.
The success rate was frequent and not different between the 2 groups (92% versus 95%). Comparison of techniques should thus now be made on other criteria. Anesthetic time is a particularly useful criterion for a busy unit, but several other factors could influence the technique chosen. Ease of training is an important consideration and it is expected that a 2-stimulation technique (i.e., ICB) would be associated with a steeper learning curve than a 4-stimulation technique. However, this remains to be demonstrated. Specific clinical conditions might also influence the technique chosen. In HB, the four nerves are anatomically separated, allowing for a selective administration of different local anesthetic solutions on the various nerves. It is therefore possible to extend the sensory block duration in one or several nerves of the brachial plexus to provide postoperative analgesia targeted to the specific nerve distribution involved in the surgical area while obtaining a complete block of the whole upper limb during surgery. (11) A selective duration of the postoperative block is a major advantage with the HB approach.
In conclusion, both ICB and HB provide frequent success and are associated with a similar anesthetic time and few differences can be demonstrated between the two techniques. As the ICB performance time is shorter, the anesthesiologist’s availability is increased.
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8. Borene SC, Edwards JN, Boezaart AP. At the cords, the pinkie towards: interpreting infraclavicular motor responses to neurostimulation. Reg Anesth Pain Med
9. Williams B, Kentor M, Williams J, et al. Process analysis in outpatient knee surgery. Anesthesiology
10. 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 complications. Anesth Analg
© 2005 International Anesthesia Research Society
11. Bouaziz H, Narchi P, Mercier FJ, et al. The use of a selective axillary nerve block for outpatient hand surgery. Anesth Analg