Tension pneumothorax is a killer. It needs immediate intervention. Unless we do a thoracotomy we are to perform a needle decompression. Classically this is done in the 2nd intercostal space in the midclavicular line. Some clinicians opt to use the 5th intercostal in the anterior axillary line. Two similar studies in the recent issue of Injury aim to measure the thickness of the chest wall at these two sites.
Decompressing a pneumothorax is quick and easy to learn. Still, reported success rates vary wildly. Success rates range from 19-96%. One of the reasons for failed decompressions is how we we underestimate the thickness of the chest walls. If the needles is not long enough to penetrate the chest and enter the pleura then decompression will fail. With obesity rates doubling in 20 years the current recommendation from the ATLS of using a 4,5 cm needle may be insufficient. The military and PHTLS have adapted and their standard practice is to use 8,25 cm long catheters.
The two studies in Injury ar similar. Both set out to measure the thickness of the chest wall at the common decompressions sites. Both studies are retrospective CT- studies of trauma scans. The first study, by Schroeder et al, includes 201 patients while the second, Akoglu et al, includes 160. The thickness of the chest wall is measured at the 2nd intercostal space mid clavicular lane (2ICS/MCL) and at the 5th intercostal space anterior axillary line (5thICS/AAL)
The Schroeder study reports average chest wall thickness of
4.08 cm in the 2ndICS/MCL
4.55 cm in the5thICS/AAL
In the 2ndICS/MCL the average thickness in females was significantly thicker than in males. (4,28 cm vs 3,93 cm). Interestingly, at least 30% of all patients had chest wall thickness > 4,5 cm.
The other study, by Akoglu et al, reports similar dimensions. They measure in the 5th intercostal space in the mid-axillary line. As far as I can this is identical to the anterior axillary line measurement in the Schroeder study.
2ndICS/MCL was 3,8 cm for men compared to 5,2 cm for women.
5thICS/MAL was 3,3 cm for men and 3,8 cm for women.
Again a significant proportion of pneumothoraxes would be inaccessible using a 4,5 cm cateheter. In the 2nd ICS 15% of men and 48% of women measured more than 5 cm. In the 5th intercostal those numbers are 13% of the men and 48% of the women.
These studies suggest the chest wall is a lot thicker than we think. A significant many pneumothoraces are not accessible even with a 4-5 cm long needle. If we are to decompress we have to go for a needle long enough to do the job. The PHTLS recommends using a 8,25 cm long catheter. The ATLS recommendation of 4,5 cm is not good enough.
Studies live here:
Injury. 2013 Sep;44(9):1183-5. doi: 10.1016/j.injury.2013.03.027. Epub 2013 Apr 23. Average chest wall thickness at two anatomic locations in trauma patients. Schroeder E, Valdez C, Krauthamer A, Khati N, Rasmus J, Amdur R, Brindle K, Sarani B.
Determination of the appropriate catheter length and place for needle thoracostomy by using computed tomography scans of pneumothorax patients. Akoglu H, Akoglu EU, Evman S, Akoglu T, Altinok AD, Guneysel O, Onur OE, Eroglu SE. Injury. 2013 Sep;44(9):1177-82. doi: 10.1016/j.injury.2012.10.005. Epub 2012 Oct 30.