Identifying a safe site for intercostal catheter insertion using the mid-arm point (MAP)

Background: Over 85% of chest injuries requiring surgical intervention can be managed with tube thoracostomy/intercostal catheter (ICC) insertion alone. However, complication rates of ICC insertion have been reported in the literature to be as high as 37%. Insertional complications, including the incorrect identification of the safe zone chest wall location for ICC placement, are common issues, with up to 41% of insertions occurring outside of this safe area. A new biometric approach using the patient's proportional skeletal upper limb anatomy to allow correct identification of the chest wall skin site for ICC insertion may reduce complications. Aim: The aim of this study was to examine the performance of the mid-arm point (MAP) method in identifying the safe zone for ICC insertion. Methods: Thirty healthy volunteers were recruited from The Alfred Hospital, a Level I Adult Trauma Centre in Melbourne, Australia. Blinded investigators used the MAP to measure the mid-point of the adducted arm of each volunteer bilaterally. A skin marking was placed on the anterior axillary line of the adjacent chest wall, and with the arm then abducted to 90 degrees, the underlying intercostal space was identified. Results: Using the MAP method, all of the 120 measurements fell within the 'safe zone' of the fourth to sixth intercostal spaces bilaterally. The median intercostal space identified was the fifth space, with investigators finding this in 86% of measurements independent of age, sex, height, weight or side. Conclusion: A simple technique using the MAP is a reliable marker for the identification of the safe zone for ICC insertion in healthy volunteers. The clinical utility for patients undergoing pleural decompression and drainage needs prospective evaluation.