https://www.vetnurse.co.uk/f/clinical-discussions/31895/circle-system-soda-lime Hi all, we are having a debate at our practice regarding how often we should be changing our soda lime for our circle canister. We fall foul of waiting for it to just change colour however online states we should be changing after X amount of hoursen-USTelligent Community 10https://www.vetnurse.co.uk/thread/176082?ContentTypeID=1Wed, 03 Jun 2020 20:46:02 GMT1a0763ec-3885-442c-853e-6cef656dfec5:4757f1da-2909-419f-ba4c-f1a999f5d518Sarah Keane<p>Hi Vicki</p> <p></p> <p>Apologies for the late response to this post. There are a number of ways to tell if the soda has reached its limits. The first most reliable method is using a Capnograph. This will allow you to measure the CO2 inspiration levels. There are a few other methods but nothing as reliable as Capnography. The first is colour change in the soda lime canister most granules will change from white to pink/purple some are the opposite. An indicator to change is then approx 2/3 of the canister has changed colour&nbsp; but beware the granules can change back to white overnight so should only be analysed after anaesthesia and not left for prolonged periods. Beware of how the granules sit in the canister also. Air pockets or channels can develop in canisters that have not been filled correctly meaning that the patients inspired breaths can passed though the chamber via a air pocket and only exhaust granules in certain parts of the chamber reducing the soda lines ability to absorb carbon dioxide. Lack of heat in the canister is also an indicator that your soda lime may be exhausted. As the soda lime absorbs carbon dioxide it produces heat and moisture so a canister that does not feel warm to touch or have water droplets on the inner walls may not be functioning correctly. The presence of certain clinical signs without access to a capnograph may also be an indication of soda lime exhaustion. Increased heart rate, increased respiration, increase in BP, vasodilation and red mucus membranes can indicate respiratory acidosis due to soda lime exhaustion. The granules themselves should be easy to fragment and come apart easily when disposing of them and finally if no capnograph is available the hours of use may be a helpful indicator. A maximum of 14 hours of anaesthesia per canister is a helpful threshold though beware your canister may need changing prior to this and this number would be the maximum time frame that should be used.&nbsp;</p> <p></p> <p>I hope this was helpful. Let me know if you need anything more information.</p> <p>Thank you</p> <p>Sarah Keane&nbsp;</p><div style="clear:both;"></div>