Current TCCC guidelines advocate the use of 14g, 3.25" (80mm) needle. This recommendation evolved after studies looking at chest wall length demonstrated that the average size angiocath (1.77") would fail in as many as 50% of patients on the battlefield (1).
A newer study by the UK military revisited not just chest wall thickness, but also distance to vital structures from the 2 recommended needle thoracostomy sites- 2nd intercostal space MCL and 5th intercostal space mid axillary line. Several interesting points were made. First, was that chest wall thickness averaged about 37mm at 2ICS MCL and 34.5mm at 5ICS MAL. Second, that if the standard 3.25 in (80mm) needle decompression device was placed in the chest wall to the hub, injury to underlying vital structures (diaphragm, heart, aorta, pulmonary arteries) would occur in 21% of patients. (3)
It should be noted that there are several limitations to this paper. It was retrospective, involved only 63 patients, of which all were young healthy males. The UK averages for chest wall thickness were smaller than US studies for chest wall thickness. US chest wall averages published were 48.6-53.6 mm depending on angle of needle through chest wall. (2) The Harke paper noted that chest wall thickness increased with age and in females, but the majority of those studied can still be treated with the 3.25" needle.
1) Current needle decompression needle length of 3.25" (80 mm) should be long enough for 99% of the studied population.
2) DO NOT HUB the needle. Going too far can be just as bad as not going far enough.
3) Parallel to chest wall has shorter distance than parallel to floor/litter.
1. Stevens RL, Rochester AA, Busko J, et al. Needle thoracostomy for tension pneumothorax: failure predicted by chest computed tomography. Prehospital Emergency Care 2009;13:14-17.
2. Harke HT, Pearse LA, Levy AD, et al. Chest wall thickness in military personnnel: implications for needle thoracentesis in tension pneumothorax. Military Medicine. 2007; 172:1260-1263.
3. J Chen, R Nadler, D Schwartz, H Tein, A Cap, E Glassberg. What is the optimal device length and insertion site for needle thoracostomy in UK military casualties? Can J Surg. 2015 Jun;58(3 Suppl 3):S118-24. PMID: