Never had to do it but have helped Radiologist place many chest drains and it makes sense that if the empyema is particularly thick/purulent, you'd want it thinned out and also to keep the tubing/drain from becoming blocked w/crud (nursing term!
). The chest drain is not in the lung itself, probably just in the fluid collection, so if you irrigate, you don't push fluid into the lung - just into the space that the fluid collection has created by its presence.
BTW, placement of chest drains is usually done guided by CT scan, so the Radiologist "sees" exactly where he's placing the tube = no guesswork! You do know you're in position, too, when the fluid (pus) starts rolling out
! We'd also confirm placement, too, by doing a few CT scan "cuts" throught the affected area, and also by post-placement CXR.
There's always something more to learn, eh?
Take care -- D