https://www.vetnurse.co.uk/f/clinical-discussions/15440/flow-rates-with-lack-or-bainWhen you are using the lack or bains circuit do you work out your flow rate using the calculations taught when training e.g weight x resps x Tidal volume x circuit factor or do you use another faster method. I have heard of using 200ml per kg for Bainen-USTelligent Community 10https://www.vetnurse.co.uk/thread/121752?ContentTypeID=1Tue, 25 Oct 2011 13:23:09 GMT1a0763ec-3885-442c-853e-6cef656dfec5:9d457a48-8b2b-4051-a06e-1230306130c0emvn80<p>you should always calculate them for every patient, the calculation is based on the patients minute volume multiplied by the circuit factor (MV X CF).</p> <p>The minute volume (MV) = TV X RR.&nbsp; I normally use 10mL/kg for tidal volume. (Makes maths easy ;) )</p> <p>The circuit factor for a Bain is approx 2.5, the circuit factor for a lack is 0.8-1.0.</p> <p>The reason you shouldn&#39;t use general &#39;formulas&#39; is that this calculation shows that the fresh gas flow is dependant on the patients resp rate, therefore if the resp rate increases the fresh gas flow requirement will increase.</p> <p>You should use the resp rate prior to anaesthesia to calccultae it prior to induction (I do it in my head quickly when I&#39;m checking my equipment) then you can use the actual resp rate when the patient is anaesthetised to calculate a more accurate flow.</p> <p>If you have a capnograph this can tell you if your fresh gas flow is adequate- on a non-rebreathing circuit like these you will see rebreathing of CO2 (ie inspired CO2) if the fresh gas flow is inadequate.</p> <p>Hope that helps,</p><div style="clear:both;"></div>