Placement of an Axillary Catheter in the Subpectoral Space

Abstract

To the Editor: The axillary approach for continuous brachial plexus anesthesia allows the clinican to provide prolonged neural blockade. However, the appropriate catheter length that should be threaded into the sheath has not been determined. We present a case that may advise against the practice of inserting catheters far along the axillary sheath. A 30-yr-old man suffering from reflex sympathetic dystrophy of the left hand was admitted to the hospital for intermittent axillary blockade to facilitate physical therapy. After locating the pulse just distal to the axillary crease, an 18-gauge Tuohy needle was advanced over the course of the artery. The penetration of the sheath was felt as a sudden loss of resistance, 10 mL of mepivacaine 1% was injected through the needle, and a multi-orifice epidural catheter was threaded 10 cm. Paresthesias and motor weakness of the extremity developed within a few minutes. The following day, when the catheter was injected for the first time, the patient reported shooting pain over the upper chest. A neurologic examination revealed dense sensory block in the musculocutaneous and median nerve dermatomes. A computed tomographic scan with contrast at the level of the coracoid process showed the catheter entering the subpectoral space (Figure 1). Another at the level of the second rib showed the contrast between the pectoralis major and minor muscles (Figure 2). The catheter was removed without further complication.Figure 1: Computed tomography of the thorax, which illustrates the catheter entering the subpectoral space. The long arrows are pointing to the catheter (big arrowhead) and the neurovascular bundle (small arrowhead). The short arrows outline the pectoralis major (big arrows) and the serratus anterior (small arrows). * = iodine contrast, R = second rib, C = coracoid process, A = acromion.Figure 2: This image shows how the iodine contrast (*) diffuses between both pectoral muscles. The short arrows outline the pectoralis major (big arrows) and the pectoralis minor (small arrows). The long arrow is pointing to the neurovascular bundle.The subpectoral space is separated from the axilla by the clavipectoral fascia, which extends from the clavicle to the inferior axilla. This fascia is pierced solely at its superior portion, the costocoracoid membrane, by the thoracoacromial vessels and the lateral pectoral nerve. We propose that the catheter followed that route to reach the subpectoral space, consistent with the paresthesia the patient felt (stimulation of the lateral pectoral nerve) and the close proximity of the musculocutaneous and median nerves to the thoracoacromial trunk. Furthermore, Figure 1 shows the area just above the subscapularis and pectoralis minor insertions, which is consistent with the costocoracoid foramen. We emphasize that this complication could be prevented by avoiding the insertion of extreme lengths of catheters. Jose Luis de Cordoba, MD* Josep Balsells, MD* Jose Angel de Marcos, MD** Jose Bernal, MD* Departments of *Anesthesiology and **Radiology; Hospital Mutua de Terrassa; University of Barcelona; Barcelona, Spain 08030