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32 MARCH 2015 | EMSWORLD.com NEEDLE DECOMPRESSION static image cannot account, such as chest wall compliance and recoil, changes in body positioning and other complications (kinking, occlusion, etc.). This underscores the importance of using animal models or cadaver trials. One weakness in these studies is that when patients are needle-decompressed, they are lying supine with their arms at their sides and breast tissue falling to depen- dent positions, usually laterally. However, in the CT scanner, the arms are positioned above the head, which stretches and thins the muscles of the chest wall and redistrib- utes breast tissue across the chest. Thus it is unclear how this may affect CWT at the 2ICS-MCL and 4ICS-AAL and the success rates of radiologic decompression versus true needle decompression (ND). 15 A study done by a Canadian military group compared differences in complica- tion rate, mainly occlusion risk, between the anterior and lateral approaches in a simulated model. Those authors strapped porcine chest walls to the chest wall of a volunteer soldier and performed ND, then prepped the patient on a military stretcher with arms adducted for a simulated two- minute transport. They visually observed bending/kinking of the catheters at the midaxillary line, especially when straps were placed to secure the arms in the adducted position. This was better quan - tified by indirectly measuring the thresh- old pressures to initiate flow through the catheter. The pressure required to establish flow through the catheter at the MCL was 7.9±1.8 mm Hg. The pressure required to establish flow through the catheter at the MAL was higher, at 13.1±3.6 mm Hg. Thus it was concluded that the lateral approach did not work as well as the anterior approach because the catheters were more likely to be kinked and occlude. 1 A 2011 study led by Inaba used 20 ran- domly selected human cadavers to assess differences in CWT (distance) and ND suc- cess (entry intro pleural space) between the 2ICS-MCL and the 5ICS-MAL. NDs were performed on both the right and left sides using a 5-cm catheter. The CWT was sta- tistically less at the 5ICS-MAL when com- pared to the 2ICS-MCL on both the right and left by 1 cm on average. Furthermore, the NT was successful 100% of the time in the 5ICS-MAL bilaterally versus 60% on the right and 55% on the left in the 2ICS-MCL, both of which were statistically significant. The study concludes that although their EMS1503S For More Information Circle 29 on Reader Service Card BASED ON THE CURRENT EVIDENCE, ADVOCATING FOR A CHANGE IN PRIMARY SITE SELECTION IS PREMATURE.