Why it was difficult , wwe use this technique several times for many years without any problems

Dear Amal,

as i mentioned above, after I inserted the PBS into the lung it was difficult to retrieved it back as i tried to pull the syringe plunger but the liquid still remain in the lung. Do you mind sharing on how you perform to obtain the balf?

That happens to me on accasion.

Here is what I do in general:

We use 18G catheters from DB (green ones) to slide into the trachea (if the catheter is too small you need to use suture to tie off the trachea around the catheter). I cut the trachea of the mouse at the voice box as it is wider and has more structural integrity. I push downon the teeth of the mouse when it on its back to pop up the trachea so it is easier to insert the catheter. I slide the catheter so that the green plastic does not go past the tip of the nose of the mouse (this is for 30m length catheters when I use this as a reference.) This way I do not put the catheter too far into the lung. If you go to far you may pierce the lung inside, resulting in the thoracic cavity filling up as you push the PBS in. If that happens you will be unable to retrieve the fluid.

Other things that can cause blockage, are pushing it against the lung and dislodging debris. On accasion simply moving the catheter back a mm or two can help with this, sometimes moving it back a mm or two, expelling any air or liquid in the syring into the cavity and dislodge, then you can draw it back.

My guess though is that you put the catheter in too far (as I had a habbit of doing with the BD 48mm length by accident) and pierce the lung, releasing the fluid into the thoracic cavity.

BD catheters we prefer 381844 18G x 1.16 in. (1.3 mm x 30 mm) Green