A LARGE dose and volume of anesthetic are important determinants of successful brachial plexus block using a nerve stimulator.1Therefore, bilateral brachial plexus blocks are rarely performed because of fear of systemic local anesthetic toxicity. Ultrasound guidance helps to visualize the cords of the brachial plexus so that the anesthetic may be deposited precisely, making it possible to perform blocks with low doses of anesthetic agents.2,3We report a series of successful simultaneous bilateral infraclavicular brachial plexus blocks using low doses of lidocaine for surgery of both arms.
The patients were premedicated with 2 ± 1 mg midazolam and 50 ± 25 μg fentanyl. The arms were abducted to 90°. The deltopectoral areas on both sides were scanned for the optimal image with a 4- to 7-MHz C 11 curvilinear probe (Sonosite, Bothell, WA), and the outline of the probe was marked at each site. The entire upper chest was prepared with Betadine and draped in a single field. The technique used in this case has been described in detail, except that a smaller volume of anesthetic was used.2The medial, lateral, and posterior cords were imaged (fig. 1), and after placing a 17-gauge Tuohy needle close to each cord, 1 ml local anesthetic was injected to confirm its location, and then 3–5 ml more of the solution was injected as the anesthetic dose. The endpoint of injection was sufficient spread of local anesthetic on all sides of each cord as visualized by real-time sonography. The block was administered on each side using approximately 20 ml lidocaine, 2%, with sodium bicarbonate (0.9 mEq/10 ml) and epinephrine, 1:200,000 (LES). A 19-gauge Flextip catheter (Arrow, Reading, PA) was placed between the axillary artery and the posterior cord (fig. 2). The position of the catheter tip is not always apparent on the ultrasound monitor; it can be confirmed by injection of 1–2 ml air (fig. 3). The procedure was repeated on the opposite side using the same technique.
All blocks were performed by residents with an attending anesthesiologist holding the probe and were successful. The demographics and other details are shown in table 1. After completion of the procedure, the catheter was looped near its skin entry site and covered with a transparent dressing. The dressing should be placed cephalad on the site so that the spread of local anesthetic agent injected through the catheter can be observed by ultrasonography without removing the dressing, which may compromise the quality of the image.
Fear of toxicity prevents the simultaneous use of regional anesthesia at more than one site. A recent case report by Maurer et al. 4describes bilateral brachial blocks using an interscalene approach on one side and an infraclavicular approach on the contralateral side. The authors were concerned about the systemic toxicity of ropivacaine; therefore, they used 35 ml ropivacaine on each side instead of their usual 40 ml. They did not want to decrease the dose further for fear of block failure. Their concern about toxicity also made them delay for 20 min between doses to separate the peaks of absorption of the anesthetic. This is important for safety but may prolong the anesthesia preparation time and delay surgery. They also used a propofol infusion to increase the seizure threshold. Our experience of successfully using doses as low as 14 ml LES permitted us to perform bilateral brachial blocks safely.3Simultaneous administration in all but one patient decreased the time required and permitted us to use the same needles and sonography probe for both blocks.
This technique should ideally be used in relatively short procedures, because 20 ml can be expected to last only 1.5–2.5 h in our experience. In longer operations, anesthesia can be successfully extended by injecting the agent through the catheter, as in cases 6 and 8. The patient may become uncomfortable with prolonged immobilization during an extensive procedure; low-dose propofol (10–25 μg · kg−1· min−1) may be given for sedation. Propofol was used in only two patients despite successful sensorimotor block, after 4.5 and 5 h. To the best of our knowledge, there are no data on which to base the administration of additional doses of local anesthetic; we gave repeat injections relatively frequently (case 6). The block in this patient had partially dissipated by 2 h; 20 ml anesthetic through the catheter 3.5 h after the initial dose restored complete blockade. Further studies are needed to determine the optimal maintenance dose and its timing.
Catheters were placed with ultrasound guidance to supplement the anesthetic if the blocks were patchy or to prolong the duration of anesthesia if necessary. They may be used for prolonged periods as needed for pain relief, subsequent surgery, or sympathectomy for revascularized digits. In case 1, a larger volume (30 ml) of LES was used through the catheter for a second procedure, because the anesthetic had to spread to all of the cords from a single point, instead of the multiple injection sites used for the patient's first surgery.
Our patients were highly satisfied with their anesthetics. Patients 1, 5, and 7 had undergone infraclavicular blocks on previous occasions and subsequently requested another brachial plexus block. The use of ultrasound also significantly improves the quality of the nerve blocks,5making it possible to use regional anesthesia simultaneously in different areas of the body. Marhofer et al. 5approached the femoral nerve with the needle aligned parallel to its longitudinal axis. We approach both femoral and infraclavicular nerves at a right angle, with the nerve imaged in transverse section. This has several theoretical advantages: Nerves have more side-to-side mobility and may be displaced more with the block needle (because they are difficult to stretch lengthwise), and the needle, several nerves, blood vessels, and the spread of local anesthetic can all be viewed simultaneously in a single view, thus preventing nerve injuries and improving the quality of the block. Ultrasonography can also detect intravascular placement of the needle, and hence virtually eliminates the possibility of toxic reactions. The use of catheters adjacent to the nerves eliminates the need for analgesics in the recovery room and also provides excellent pain relief in the postoperative period. None of our patients requested any analgesics, and all had low pain and sedation scores in the recovery room. Patients can even be sent home using a bupivacaine infusion or given a bolus of the anesthetic before discharge, providing pain relief for 8–12 h. Pericatheter leaks are rare with the ultrasound-guided technique because the needle is redirected through the tissues several times during its advance; when it is withdrawn, the tissue planes resume their natural positions, and the resultant catheter path has multiple curves.
In conclusion, ultrasound-guided bilateral infraclavicular blocks provide safe and effective anesthesia with half of the conventionally used 40-ml doses, resulting in superior intraoperative and postoperative analgesia, and can be used as an alternative to general anesthesia.
The authors thank Sanford Miller, M.D. (Clinical Associate Professor of Anesthesiology, New York University School of Medicine, and Assistant Director, Department of Anesthesiology, Bellevue Hospital Center, New York, New York), for editing the manuscript.