Many surgical procedures of upper and lower limb may be undertaken under regional anaesthesia in the emergency setting . The axillary approach is the most familiar technique of brachial plexus anaesthesia. However, advantages of the infraclavicular block (ICB) include the ability to perform the block with the patient's arm in any position, and ease of securing a continuous brachial plexus catheter to the chest wall at the site . Thus ICB offers an interesting alternative to the axillary approach particularly in emergency conditions , with a similar success rate and extent of block . Recent data suggest a multistimulation technique may improve the success rate of the ICB . A dual injection seems to present the best balance between efficacy and comfort for patients . However, all these studies were performed with a high volume of local anaesthetic (≥40 mL). Our hypothesis was that using a double-injection approach, a lower volume of local anaesthetic may be sufficient. Thus, the aim of this prospective, randomized study was to compare the success rate of a double-injection, low-volume ICB and a single-injection, high-volume ICB performed in an emergency department.
Over a 6-month period, after written and informed consent and with institutional approval, 50 patients undergoing emergency surgery (within 24 h after admission) for elbow, forearm, wrist or hand trauma, under ICB, were included in this prospective and randomized study. Patients with local infection, coagulopathy, nerve damage to the upper limb or refusal were excluded. After an intravenous cannula was placed and standard non-invasive monitors were applied, oxygen (3 L min−1) was administered via a facemask. All the ICBs were performed by the same anaesthesiologist in a special room of the emergency department reserved for pre-anaesthesia care using a nerve stimulator (HNS 11; B/Braun, France) and a 22-G, short bevel, 50-mm insulated needle (Stimuplex; B/Braun, France). The patients were allocated into two groups according to a computed randomization list: Group 1 = single-injection technique with ropivacaine 0.75% 40 mL (n = 25) and Group 2 = double-injection technique with 30 mL of the same local anaesthetic (n = 25). Ropivacaine 0.75% (Astra Zeneca; France) was chosen because of the unpredictable time and duration of surgery in emergency conditions. The patient was supine with the head turned to the contralateral side. The upper limb was kept in the least painful position for the patients. We used a Sim's derived technique recently evaluated in 300 patients . The puncture site was the same in both groups: 1 cm medial to the coracoid process, below the clavicle (infraclavicular fossa). After subcutaneous infiltration with lidocaine 1% 1 mL, the needle was directed vertically at an 80° angle from the fossa to the apex of the axillary crease. In Group 1, the location of the needle was judged adequate when current <0.6 mA with an impulse duration 100 μs still elicited a distal motor response (median, radial or ulnar nerves). After the injection of 1 mL of local anaesthetic stopped the twitch, the intensity of the current was increased until the motor response re-appeared at which point 39 mL of local anaesthetic was injected through the needle, with intermittent aspiration every 5 mL. In Group 2, the first response was the musculocutaneous nerve, and 7 mL of local anaesthetic was injected. Then the needle was withdrawn 1 cm and redirected medially until a distal and clear motor response on median, radial or ulnar nerve appeared. The remaining 23 mL of local anaesthetic was injected in the same manner as described in Group 1. The observational assessments were age, gender, height, weight, ASA physical status, time from needle insertion into the skin to needle removal (performance time), distal motor response obtained (median, radial or ulnar nerves), minimal intensity of stimulation eliciting a motor response initially and after 1 mL of local anaesthetic was injected, time from end of injection to readiness to surgery (onset time), success rate and incidence of complications. Sensory block was assessed every 5 min after the injection of the drug using the abolition of cold and pinprick response in all seven nerve territories of the upper limb (median, radial, ulnar, musculocutaneous, medial cutaneous of forearm, medial cutaneous of arm and axillary), for 30 min after the injection of the local anaesthetic. Motor block for opening and closing the hand, extending and flexing the wrist, and flexing the elbow was assessed at 30 min after the end of injection using the following scale: 0 = can move; + = cannot move at all. A complete block was defined as the abolition of cold and pinprick responses in all five nerve distributions distal to the elbow (median, radial, ulnar, musculocutaneous and medial cutaneous of forearm nerves) within 30 min of the injection of local anaesthetic. In case of incomplete block a supplemental regional technique or general anaesthesia was used. Continuous variables are presented as mean ± SD and categorical variables as percentage. Continuous variables were compared between groups by U-test and categorical variables by χ2 analysis or Fisher's exact test. A P-value ≤ 0.05 was considered statistically significant.
There were no statistically significant differences between the two groups in patients characteristics data (Table 1) or the nature of injuries. Performance time of the block was similar in both groups (3.5 ± 1.7 min in Group 1 vs. 4.5 ± 2.0 min in Group 2). There was no statistically significant difference between both groups in mean intensity of stimulation eliciting a distal motor response (0.45 ± 0.08 mA in Group 1 vs. 0.44 ± 0.08 mA in Group 2) and after injection of 1 mL of local anaesthetic (2.27 ± 0.87 mA in Group 1 vs. 2.11 ± 0.92 mA in Group 2). The distal motor responses obtained among the three main nerves are presented in Table 2.
In Group 1, five patients had no sensory block after 30 min in all cutaneous territories even though nerve stimulation was obtained as described above (technical failure).
Of those patients with any block, the rate of complete block was higher in the double-injection group, but the difference was not statistically significant (92% vs. 80%; P = 0.23). Eighty percent of patients in the single-injection group and 96% of patients in the double-injection group were eligible for surgery without any supplemental anaesthesia (n.s.).
Among the four incomplete blocks of the single-injection group, there were two males and two females, and the distal motor response obtained was the median nerve in all cases. One patient was anaesthetized and regional anaesthesia was performed in three patients (one mid-humeral block and two blocks performed at the elbow). The first incomplete block of the double-injection group concerned a woman with only four cutaneous territories distal to the elbow anaesthetized (except radial nerve). She was eligible for surgery without any other supplemental anaesthesia. The second incomplete block in the double-injection group concerned a young man with complex digital injuries. An axillary block was performed for surgery.
The onset time of the block (loss of cold and pinprick sensation) was shorter in Group 2 (15.4 ± 5.6 min vs. 18.4 ± 5.4 min, respectively; P < 0.05). Extension of anaesthesia (percentage) of the loss of cold and pinprick sensation (minutes) in all seven nerves' territories of the upper limb are reported in Figure 1. All the patients with a complete sensory block had a grade+motor block after 30 min (cannot move fingers, wrist, forearm and elbow). The only observed complication or side-effect was venous blood aspiration during performance of the block in one patient of the double-injection group. No patient reported pain during the procedure.
In emergency conditions, certain advantages make the ICB very appealing. An infraclavicular approach allows the block to be performed with the patient's arm in any position, avoids of the neurovascular structures of the neck, has few effects on respiratory function and simplifies securing a continuous brachial plexus catheter to the chest wall at this site, even at home [2,8,9]. In fact, except for our recent case report , we have found only one case in the literature describing the use, in the emergency setting, of an ICB combined with an interscalene block for bilateral distal radius fracture . The axillary approach remains the most familiar technique of brachial plexus anaesthesia in such conditions. However, Kapral and colleagues has reported a greater extent of blockade with a lateral infraclavicular approach as compared to an axillary approach, thus allowing most anaesthesiologists to reconsider the ICB technique as an alternative to the axial approach . On the other hand, Deleuze and colleagues concluded these two approaches were equally effective .
ICBs have been described using single- or multiple-nerve stimulations. A single stimulation is particularly interesting in emergency conditions, to decrease pain related to stimulation of the traumatized limb. However, Gaertner and colleagues reported an improvement of the ICB using a triple-injection technique . More recently, Rodriguez and colleagues have studied the number of injections needed with an infraclavicular coracoid block to provide as complete an anaesthesia as possible . They concluded that dual injection of local anaesthetic presents a higher success rate than a single injection and a lower side-effect incidence than a triple injection. However, the musculocutaneous nerve was the nerve stimulated in five patients in the single-injection group. This might have lead to an underestimation of the success rate. It is well known in ICB that a single injection must be avoided to the musculocutaneous nerve because of frequent localization outside the sheath at this point . Minville and colleagues have shown in a descriptive study of 300 patients, the effectiveness of a double-injection ICB technique on the musculocutaneous nerve and one of the main three others . The success rate was 92% with a lidocaine 1.5% 40 mL injection.
We decided to compare a lower-volume, double-injection ICB with a single-injection technique. Using the same definition found in the literature (i.e. analgesia in the five nerves distal to the elbow) [4,11,13–16], our success rate (92%) in the double-injection group was the same as the Minville and colleagues study. However, from a practical point of view, operability is the main objective when performing regional anaesthesia. In this case, our success rate was 96% in the double-injection group. Results of our study confirm those of Rodriguez and colleagues : a multiple injection with more than two stimulations does not seem to be necessary, even though we did not investigate this technique in a prospective and randomized manner. Our double-injection results seem similar to those of Gaertner and colleagues with a triple-injection multistimulation technique .
Our success rate in the single-injection group is particularly low as compared to those published in the literature varying from 40%  to more than 90% [4,13,16]. The overall success rate in Group 1 was 64% and the difference was statistically significant when compared to Group 2. However, in five cases, sensory block did not appear in any cutaneous territories after 30 min, even though a low current intensity elicited a clear and distal motor response before injecting the local anaesthetic. In this condition, we decided to exclude from the analysis these five technical failures to avoid such a bias (probably wrong position of the tip of the needle). Even excluding these five cases, our success rate is low (but with no statistically significant difference with Group 2). In the 20 remaining patients in Group 1, nerves were localized in all cases with a low current intensity during stimulation and a similar time to perform the block and local anaesthetic was injected according to methods defined previously. Inhomogeneous diffusion of local anaesthetic in the brachial sheath could explain these results.
One of the most important points of our study we wish to highlight is the success rate obtained with only 30 mL in the double-injection group. The volume of local anaesthetic used for ICB in the literature is commonly 40–50 mL. In our study, a double-injection technique was effective even with a 25% reduction in local anaesthetic volume, thus reducing the risk of toxicity.
Onset time to sensory block was also better in the double-injection group as compared to the single-injection group or to data published elsewhere , even though the 3-min difference is not clinically relevant. A complete block was obtained on average 15 min after the end of the second injection, allowing rapid anaesthesia and pain relief for patients who often suffer after trauma (emergency conditions). Moreover, the onset time to sensory block was comparable in our study with Minville's study , where they used a short-acting local anaesthetic (lidocaine). Thus it appears that using such a double-injection technique, the onset time of sensory block does not seem to be influenced by the choice of the local anaesthetic.
In summary, the ICB appears to be a useful alternative to the axillary block following trauma, avoiding arm mobilization and thus reducing pain. In such conditions, the double-injection technique of the ICB with only 30 mL of local anaesthetic seems to be an alternative technique to a single-injection technique, allowing a high success rate with a smaller volume of local anaesthetic, reducing the onset time to sensory block in all territories with no increase in performance time, while decreasing risk of toxicity.
The authors thank Prof. François Singelyn, MD, PhD (Department of Anaesthesiology – Cliniques Univeristaires St-Luc – Brussels) and Dr Jane Torrie (Department of Anaesthesiology – Auckland) for their invaluable advice and support.
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