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EMSWORLD.com | MARCH 2015 33 evidence suggests a lateral approach, trials with living humans are necessary before a change in practice should be advocated. 9 It is often overlooked that the instruments used to decompress a patient with a tension pneumothorax are not primarily designed for this purpose. Consequently the catheters have an unacceptable and variable rate of fail- ure despite being in the pleural space. This was demonstrated in a two-arm study that created tension pneumothoraces in porcine models until they reached hemodynamic compromise or pulseless electrical activ- ity arrest. In the first arm, of the 19 created tension pneumothorax events, five catheters (26%) failed due to kinking, obstruction or dislodgment within five minutes of insertion, all associated with hemodynamic decline. Of the 14 that remained patent at five minutes, six failed to relieve tension physiology, for an overall failure rate of 58%. In the second arm, there were 14 tension pneumothoraces with PEA events treated initially with ND. The ND failed to restore perfusion in nine events (64%). A tube thoracostomy was per- formed as a rescue intervention and restored perfusion in eight of the nine NT failures. 11 Bottom Line Based on the current evidence, advocating for a change in primary site selection is pre- mature. However, there are some valuable conclusions that can be drawn from this pool of data. The fourth/fifth intercostal space at the anterior axillary line should be considered in trauma protocols as an alter- native site. The British Thoracic Society has included the axillary approach as an alterna- tive since 1993. 12 Furthermore, after com- pleting a study of their own that showed the viability of this alternative site, authors of the Tactical Combat Casualty Care Guidelines revised their guidelines to include the lateral approach as an acceptable alternative. 7 There are circumstances in which the 2ICS-MCL may be difficult to access or contraindicat- ed, including a gunshot wound, indwelling Port-A-Cath, AICD, overlying infection or protective body armor. An alternative site may be needed. The data are unclear whether chest wall thickness is greater at the 2ICS-MCL or the 4/5ICS-MCL. In the series of studies focusing on ND, a trend of increasing needle length has been seen. With the increase in needle length, success of radiographic decompression increased. Based on the pat- terns seen in these studies, one can conclude that the 8-cm needles will maximize success rates independent of approach. However, note that with such long needles, the lat- eral approach may increase risk of injury to proximal vital structures. From the limited number of studies that have looked at differ- ences in site safety, it appears the anterior approach is farther from vital structures and has less of a chance of injury with incorrect needle insertion. 5 However, when needle angle is corrected to perpendicular, the For More Information Circle 30 on Reader Service Card