We are trained to use an iv cannula for emergency decompression of pneumothoraces.  The problem is how these cannulas often are too short to reach the pleural cavity. The solution to that is using longer specialized cannulae or doing thoracotomies. But here’s a trick in case an IV cannula is all you’ve got.

Take the needle out of the plastic catheter. 

By doing that you will gain around 2 cm. Increasing your chance of reaching the plaural cavity. Especially if you have one of the larger iv cannulas.

I’ve added a few pictures comparing the lengths of the Venflon® iv catheters 14G (orange) and 18G (green) and the G14 Venflon with and without the plastic catheter attached. As well as a larger bore needle, you gain a lot of lenght with increasing Venflon sizes. And the bare needle gives you another 2 cm.

The orange G14 cannula is about 2cm longer
than the green G18 cannula.

The reach of the bare needle is about 2cm longer
than the needle in the plastic cannula.

If you use the bare needle, you will have to hold on to the needle while decompressing, and remove when done. Some advocate using the needle with the catheter and leave the catheter in as a drain, but we all know how easily an iv catheter kinks. You can’t trust them. Rather, just keep an eye on your patient, and re-decompress if the need arises.


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  1. Christopher says:

    We’ve switched to using 3.25″ (8.2 cm) straight angiocaths at our service, and at least with this brand (BD) we’re lucky enough to get the catheter itself for almost its entire length. You can also get 5.25″ (13.3 cm) angios from BD.

    • Christopher says:

      I hit enter too fast, our safety caths we use don’t allow us to leave the needle in unfortunately! So our only option is to use an older non-safety angiocath.

      • Thomas D says:

        True, those safety iv. cannulas would ruin this trick. Unless you can rip off the safety plastic thing? I haven’t got one available to give it a try.


  3. Pingback: RESPIRATORIO – Neumotórax a tensión: largo de la aguja (y un truco) |

  4. Javier says:

    “If you use the bare needle, you will have to hold on to the needle while decompressing, and remove when done”……. but if you remove the bare neddle, tension neumothorax will reappear!!.

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