Research your soda lime and its color

Soda lime typically needs to be changed every 12 hours' worth of anesthesia, unless your brand specifically states otherwise.

In theory, soda lime should be changed when two-thirds of the canister has changed color. It contains a dye (ethyl violet) that turns purple when the granules reach their CO2 absorbing capacity.

But don't go by the change of color alone. It can be very misleading. For the safety of your patients, research the exact requirement of the brand of soda lime you use.

There are low-flow and highflow types. Their change in color is not at all universal (Figure 1).

Also, most of the concentrated exhaust goes up through the middle of the canister. Therefore, the center of the granules may be changing colors while the outside remains white.

Bottom line: keep track of time to assess the safety of your soda lime. There are many options. Use a sticker with boxes. Each box crossed-off represents 15 minutes.

At the end of each procedure, the technician must remember to cross off the required number of boxes. When all boxes are full, based on your particular soda lime, change it.

(Note that the correct spelling is soda lime, and not soda Lyme or a variety of other creative vers