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From the Department of Anesthesiology, Section on Regional Anesthesia and Acute Pain Management, Wake Forest University School of Medicine, Winston-Salem, North Carolina.
Address correspondence to James Crews, MD, Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1009. Address e-mail to jcrews{at}wfubmc.edu.
Abstract
Several variations on the technique for infraclavicular brachial plexus block have been described. The coracoid infraclavicular technique has become popular because of easily identified landmarks, reliable distribution of blockade, and low risk of respiratory complications such as pneumothorax. We report a case of pneumothorax in a patient after a coracoid infraclavicular brachial plexus block. Subtleties in landmark identification and measurement may affect the risk of pneumothorax.
Several variations on the technique for infraclavicular brachial plexus block have been described (1–14). The coracoid infraclavicular technique, originally described by Whiffler in 1981 (8), has become popular because of relatively easily identified anatomic landmarks, reliable distribution of neural blockade, and low risk of respiratory complications, such as phrenic nerve blockade and pneumothorax (9). At our institution, the coracoid infraclavicular brachial plexus block, based on the description of Wilson et al. in 1998 (9), has become our most frequently used brachial plexus block technique for upper extremity surgical procedures at or below the elbow. We report a case of pneumothorax in a patient after a coracoid infraclavicular brachial plexus block. The case illustrates subtleties in landmark identification and measurement that are pertinent to the risk of pneumothorax.
CASE REPORT
A 53-yr-old, male (height = 188 cm; weight = 87 kg) presented for left ulnar nerve transposition as an outpatient. He had previously undergone right ulnar nerve transposition with an upper extremity block at another hospital. The block procedure was performed by a PGY-4 resident, supervised by an attending anesthesiologist, after informed consent and standard monitoring and sedation. The supine patient was instructed to "reach toward his left knee with his left arm" to relax his shoulder musculature. The clavicle and the coracoid process were easily identified and a mark was made on the skin approximately 2 cm medial and 2 cm inferior to the coracoid process in the deltopectoral groove.
The skin was prepared, and after intradermal anesthesia was obtained with 1 mL of 1% lidocaine, a 90-mm 21-G insulated nerve block needle with a 20° cutting bevel (Polymedic® UPC 92090-21, Avid Medical, Inc. Toano, VA) was directed posteriorly from the previously marked skin site. The needle was advanced to approximately 5 cm depth without brachial plexus motor response. The needle was subsequently redirected caudally in the parasagittal plane, and bone, presumed to be rib, was contacted at approximately 5 cm depth. From this location the needle was redirected about 10° in the lateral direction and a motor response was obtained at approximately 7 cm depth in the distribution of the posterior cord of the brachial plexus (extension of the wrist). Twenty milliliter of 0.5% ropivacaine with epinephrine 1:200,000 and clonidine 0.00015% was injected in 5 mL increments after negative aspiration. The needle was withdrawn and repositioned and a lateral cord response (pronation of the forearm) was immediately obtained, and 20 mL of 0.5% ropivacaine with epinephrine 1:200,000 and clonidine 0.00015% was injected in 5 mL increments after negative aspiration. The needle was then redirected in a more caudad direction in the lateral parasagittal plane and a medial brachial plexus cord response (ulnar flexion of the wrist) was obtained and an additional 10 mL of 0.5% ropivacaine with epinephrine 1:200,000 and clonidine 0.00015% was injected in 5 mL increments after negative aspiration. The patient tolerated the procedure well and demonstrated adequate surgical anesthesia of the operative extremity within 15 min. The maximum depth of needle insertion was 7 cm in accordance with current clinical practice (9,15).
Approximately 5 min after completion of the block, the patient reported "muscle soreness" in the region of the left chest wall. He stated that the discomfort began around the time of the nerve block procedure. The patient’s vital signs were stable and he reported the discomfort as mild. The patient remained stable and after minimal sedation with propofol in the operating room, he reported complete resolution of the discomfort. With the history of encountering bone with one of the needle passes and the mild but suspicious chest discomfort, a pneumothorax was considered and a chest radiograph (CXR) was obtained in the operating room before the beginning of the surgical procedure. The patient remained asymptomatic throughout the surgical procedure with minimal to moderate sedation. At no time did he report dyspnea or sharp pain, and arterial oxygen saturation was 100% on 2 L of oxygen by nasal cannulae. During the surgical procedure, the supine CXR obtained preoperatively was reported as demonstrating a "small" pneumothorax. After completion of the surgical procedure, upright inspiratory and expiratory CXRs were obtained to more clearly define the extent of pneumothorax, and a 30% left pneumothorax was demonstrated. A thoracostomy tube was placed by the surgical team and the patient was admitted for postoperative observation and care. The chest tube was discontinued approximately 36 h later, and the patient was discharged home.
DISCUSSION
The coracoid infraclavicular approach to neural blockade of the upper extremity provides several advantages as compared to axillary, interscalene, and supraclavicular brachial plexus block. The anatomic surface landmarks are generally easy to identify, the head and arm may be in any position for the block, the technique is relatively easy to perform using either a nerve stimulator or ultrasound guidance, and the risk of pneumothorax is very low, particularly compared to supraclavicular approaches, which have a reported risk from 0.3% to 6% (16). A single report of pneumothorax with the coracoid approach appears in an observational series by Desroches (17), but none of the details of that particular complication are included. Pneumothorax (and phrenic nerve block) has been reported with the more medial "vertical infraclavicular block" originally described by Kilka et al. (5). Several variations of the coracoid infraclavicular brachial plexus block have been described with various surface landmarks and recommendations for needle direction.
In the description and study of the parasagittal anatomy important to the coracoid infraclavicular block by Wilson et al. (9), the specific point of needle insertion was described as being 2 cm medial and 2 cm caudad specifically to the lateral tip of the coracoid process. In general, the lateral tip of the coracoid process is prominent and is usually easy to identify. However, in some patients, due to anatomic variation and body habitus, the lateral, anterior, and medial aspects of the coracoid process may be palpated initially. After contact with bone (rib) in this patient, all subsequent needle passes were made with the needle directed more laterally. After thorough reassessment of the landmarks following completion of the procedure, it was determined that in this individual, the initial needle insertion site was located 2 cm medial to the medial tip of the coracoid (approximately 4 cm medial to the lateral tip) resulting in needle insertion approximately 2 cm more medial than originally described by Wilson et al. (9) (Fig. 1). Insertion of a 90-mm needle at a site 2 cm medial and 2 cm caudad to the medial aspect of the coracoid process placed the needle path sufficiently medial to result in the pneumothorax in this patient.
Variability in determining the point of needle insertion in peripheral nerve blocks, even among experienced anesthesiologists, has been reported (18). MacLeod et al. suggested a method for identification of the coracoid process for infraclavicular blocks (19).
We believe that the choice of needle insertion site based on palpation of the coracoid process for the coracoid infraclavicular block should be very particular. Our current practice is to mark the site for needle insertion 2 cm medial and 2 cm caudad to the lateral tip of the coracoid process or, alternatively, 2 cm caudad to the medial aspect of the coracoid process as the most medial extent of needle placement. If only one prominent part is encountered, needle insertion can be made 2 cm caudad to the medial aspect of the coracoid process as described in the study by Koscielniak-Nielsen et al. (20).
In conclusion, we present a complication of pneumothorax after a coracoid infraclavicular brachial plexus block where the correct measurements were made from the incorrect aspect of the coracoid process, resulting in an excessively medial needle insertion path. Anesthesiologists should be alert to the possibility of pneumothorax, particularly if rib is contacted during the procedure, or if the patient complains of chest pain after its completion.
Footnotes
Accepted for publication March 15, 2007.
Reprints will not be available from the authors.
REFERENCES
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