Though I suspect this is old news by now, I’ve just read a couple of papers on it and thought I’d share my thoughts. They’re both by the very smart and talented Kenji Inaba.
- where should we put a cannula if we want to decompress a tension pneumothorax?
Inaba, Kenji, Bernardino C Branco, Marc Eckstein, David V Shatz, Matthew J Martin, Donald J Green, Thomas T Noguchi, and Demetrios Demetriades. “Optimal Positioning for Emergent Needle Thoracostomy: a Cadaver-Based Study.” The Journal of Trauma: Injury, Infection, and Critical Care 71, no. 5: 1099–1103. PMID 22071914
- 20 fresh frozen cadavers
- 14G 5cm cannulae placed in 2nd ICS and 5th ICS
- throacotomy to assess pleural puncture (considered a +ve outcome)
- chest wall thickness measured in each cadaver at each puncture position
- total of 80 punctures
- all succeeded in the 5th ICS; 57% succeeded in the 2nd ICS
- stick it in the 5th ICS [if at all]
Inaba, Kenji, Crystal Ives, Kelsey McClure, Bernardino C Branco, Marc Eckstein, David Shatz, Matthew J Martin, Sravanthi Reddy, and Demetrios Demetriades. “Radiologic Evaluation of Alternative Sites for Needle Decompression of Tension Pneumothorax..” Archives of Surgery (Chicago, Ill. : 1960) 147, no. 9: 813–818. PMID 22987168
- chart and image review of all their trauma pts over a year who got a chest CT
- split them into BMI quintiles
- measured the chest wall thickness on CT at the 2nd ICS and 5th ICS
- 680 pts
- 46mm in the 2nd ICS; 33mm in the 5th ICS
- half of the pts had a chest thicker than 50mm at the 2nd ICS
- if a standard 14 G cannula is 50 mm then we’re going to fail to drain a whole bunch in the 2nd ICS
I’ve drained a number of tension PTX in the past – it’s usually fun to get the hiss – all have been in the ED and quickly followed by a chest drain. I’ve received a number from the pre-hospital environment that probably worked initially but now the cannula has kinked and a second cannula shows a second release of air.
All this is a little bit silly I think – as I’m now convinced that we just need to get on and do the bloody drain (or at least make a cut and stick a finger in). If the patient is crashing in front of you and the quickest option is to place a cannula then great – just don’t get lulled into thinking you’ve fixed the problem.
Haldun Akoglu left a comment about a paper that he just published (PMID 23116647). It was a review of 150 CT scans of people with PTX, mainly traumatic. They found that a 5cm cannula would also fail a lot of the time but failed to find a thinner chest wall at the 5th ICS when compared with the 2nd. I’m not sure why they they didn’t find a difference when Inaba did but either way 5cm cannulas are not the way to go.