Cleaning Breathing Circuits & Reservoir Bags
Unfortunately, there are no standard of care guidelines available for cleaning breathing circuits in veterinary medicine, so it is going to be strictly the decision of the individual hospital to do what they feel is best. In human anesthesia a new circuit is used on every patient so the risk of cross contamination is zero.....however, in veterinary medicine this option is simply not an option due to economics.
Here is what I have done in the past.......
I have worked in two university settings that had different protocols. The first one we kept the rebreathing circuits on the machines for one week. We had a limited number of non-rebreathing circuits so those were only set up when needed. We had a high case load but as long as there was no gross contamination (e.g. blood, other bodily fluid, etc.) on the breathing tubes or they were used on a contagious patient we would only change them out once a week. We had enough circuits in use that we had one set up on every anesthesia machine while the other set was cleaned and then allowed to air dry for the week. We also had a small supply of brand-new circuits so if one was damaged it could be replaced without coming up short on enough sets. Every week the dual wye hose rebreathing circuits were collected and soaked in a dilute chlorhexidine for about 15-20 minutes, then each one was thoroughly rinsed with water and allowed to air dry for the week.
The second university I worked at had a policy in place when I started to wash the breathing hoses out with water after every use. We did not keep enough circuits in use at any one time, so circuits were hung to dry and then potentially used again right away. I had a few issues with this policy. First, just running water through the hoses does not constitute cleaning them. If you are going to take the time to clean them then a soap solution or disinfectant agent such as chlorhexidine should be used along with a thorough rinsing of water. Second, since the hoses potentially did not have enough time to dry out in between being rinsed and hung to dry they usually had water that collected in the corrugated tubing. You can swing the tubes (dual wye hose only) to try and get as much water out as possible but there is still going to be some water accumulation. If excessive water is present in the tubing during use, then this can potentially create an increase in the resistance to breathing.
After bringing my concerns to the table for discussion, we started hanging the breathing circuits back up after use without cleaning as long as there was no gross contamination on the inside or outside of the hoses. We kept the circuits in use for about 4-6 months and then completely replaced them with new circuits. Gross contamination was immediately washed off after use and if the tubes were cleaned with dilute chlorhexidine, then I pulled them from circulation until they were completely dry. If the patient was contagious, we threw the circuit away immediately after use.
Not cleaning breathing circuits can be justified by a 2007 study that showed cross contamination of pathogens between breathing circuits was very low to almost non-existent. https://pubmed.ncbi.nlm.nih.gov/17444932/
To my knowledge, no study exists to counter the conclusions made in this older study. Currently, I do not disinfect the dual wye breathing hoses in any way. After use they are simply hung back up and the condensation evaporates on its own. Gross contamination on the outside of the breathing hoses is immediately cleaned with a dilute ProVet solution. If gross contamination (e.g. blood) got inside the breathing hoses, they are discarded after the case.
The Jackson Rees non-rebreathing circuit can be handled in the same manner as the dual wye hose configuration. Care should be taken to not get water and cleaning solution down the fresh gas inlet hose because it will be more difficult to get that hose dry.
Coaxial Circuits
The universal F rebreathing circuit is a coaxial design so there are some special precautions to consider. These circuits should NOT be submerged in liquid because of the concern that the inner hose will not dry out. The inner hose of these circuits is large enough that some believe the inner hose will dry out appropriately. There is now a Bair hugger attachment that allows you to hook the breathing circuits up to help with the drying process. My issue is that I am still unable to confirm complete drying on the inner hose because I cannot physically inspect the inside of the inner hose.
DO NOT swing coaxial circuits to get the excess water out of the tubing! Swinging these tubes can cause the inner hose to become disconnected from its attachments. If this happens then the entire length of the tubing will be contributing to mechanical dead space. This will clinically manifest as significant rebreathing of CO2 and could easily go unnoticed if you are not monitoring ETCO2 or inspired CO2.
Bain Coaxial non-rebreathing circuits should NOT be submerged in water or dilute disinfectant. The inner hose of this circuit is very narrow. If water gets into the inner hose, it will take forever to dry out. We actually had a Bain Coaxial circuit accidentally submerged in water so we hung it up to dry to see how long it would take.....3 months later you could still see water droplets on the inner hose. We decided to disassemble the circuit and when we cut into the inner hose it was lined with mold. I have heard people recommend hooking it up to a forced air spout or oxygen flow meter to help the inner hose dry out. These options are acceptable but will add an extra cost for supplies and time for personnel to handle these circuits more during the cleaning process. A Bain Coaxial should NEVER be swung as that inner hose can easily become disconnected from its attachments leading to significant rebreathing of CO2.
Remember that breathing circuits are intended for single use only!
Therefore, they should be replaced on a regular basis. If you have a high case load, I recommend replacing them every 4-6 months. For lower caseloads you can consider replacing them every 6 months to 1 year.
Reservoir Bags
Reservoir bags can be cleaned with a soapy solution or dilute chorhexidine solution and then thoroughly rinsed with water. The important thing is that you hang them upside down to dry out. Do NOT just lay them on the counter after you have rinsed them with water....they will not dry out that way! You can use binder clips to hang the reservoir bags upside down.
I do not clean reservoir bags anymore unless there is gross contamination on the bag. There are some brands that have a surfactant layer on the inside that helps the bag move freely. If you wash the bag, then it is more likely to stick together even after it is dry. This may ultimately lead to a decreased lifespan of the bag because it has to be stretched to get it apart before use.
In the end, the decision to clean breathing circuits needs to be one that is decided by the individual clinic. Factors that should be considered include how many anesthesia machines you have, the case load that uses the machines, types of cases that you see, types of breathing circuits that you use, time and supplies spent cleaning the circuits and how much the clinic is open to having 'extra' inventory on hand. I do think it is a good idea to have a few back up circuits in case one is damaged and no longer pressure checks... but how many 'extras' you have on hand will depend on the above factors.
