On inspiration we expand the thorax by rib and diaphragm movement. This as you know creates a slight negative pressure. The water seal prevents air from moving in through the chest tube. This is noted by a rise in water in the column of the water seal bottle. On exhalation, thorax and diaphragm relaxes down to it resting position creating a slight positive pressure which allows air to be passively exhaled. Also this positive pressure squeezes down on the pneumo which allows some of the air to escape down the column of the water seal bottle. This is seen as the bubbling on exhalation. When bubbling stops either the pneumo has resolved or the chest tube is plugged.

Very well explain I'm an aspiring RT myself and this is a really huge help

Hey, I just wanted to thank you for the eureka moment while you described the suction bottle.

You have Nailed this sir!!!! Thank you!

Thank you SO much for this video!

Very nice explanation of three bottle system

thanks a lot it really helps

very helpful. thank you

wow this made all the sense!

well - explained! that you sir!

Thank you for the amazing illustration, i was wondering if you can make a demo on how to measure water level against vaccum pressure in suction bottle?.

Very helpful. You need to understand the three bottle system to fully understand a chest drain. Good stuff

Thank you for this sir

thank you sir

The only thing I don't understand at this point is that you mention that on expiration bubbling should occur through the water seal bottle, but often we wait until there is no bubbling through the water seal bottle for multiple days before removing a chest tube.

thank u Sir