Paediatric Circle Circuit

RE: Paediatric Circle Circuit

Susanna Taylor — Mon, 01 Jul 2019 13:53:28 GMT

I also learnt the 10kg circle limit in the UK, and I still teach it as an 'easy to remember rule'.

However... resistance in circles is caused by a few things. 1) amount of CO2 absorber/canister size, 2)weight of 1 way valves, and 3)diameter and corrugation of tubes. The sum of these things in, for example, a burtons circle system, makes it high resistance for <10kg.

But - if you consider a 'hamster wheel' system, with a smaller canister, light weigh valves (actually burtons are lightweight too), and adjusted with smaller and smooth-bore tubing (from ACE consumables), it is much less resistance and ok for many patients under 10kg.

IF - you are providing continuous IPPV (manual or mechanical) then resistance it pretty much obsolete as YOU are doing the work and not the patient.

How do we know if a patient is coping with a circle? Subjectively - look at respiratory effort and chest movement. minimal movement, increased effort and increased RR means its not coping. Objectively - shark fin capnogram and low ETCO2 with spontaneous breaths but high ETCO2 on a ventilated breath or blood gas, means its not coping.

It is worth noting however, lots of places in the world (including the US) use circles much more commonly than the UK. Here in Hong Kong many practices only have circles (1 type for everything) and there are a lot of small patients. From my experience patients are not dying left right and centre because of it. Does that mean its ok? or ideal? probably not. IN reality there are not a ton of studies on breathing systems, I guess its never been seen as cool enough for researchers. So a lot of what we (think we)know is based on theory and anecdotes.

RE: Paediatric Circle Circuit

Alice Weaver — Tue, 25 Jun 2019 16:50:59 GMT

[quote user="Nick Shackleton "]

However, I was always taught that patients less than this body weight have difficulties maintaining themselves on this kind of circuit due to the resistance incurred with the different valves within the circuit.

[/quote]

Thanks Nick. I thought this too. Apparently the paediatric tubing is low dead space but I thought it was the resistance of having to breathe through soda lime that would cause issues too. I’ll stick with the Ayres T-Piece for now!

RE: Paediatric Circle Circuit

molladog — Tue, 25 Jun 2019 15:36:03 GMT

Nick Shackleton wrote the following post at Tue, Jun 25 2019 2:05 PM:

I’ve received a lot of back lash from USA nurses who routinely use circle circuits on patients <10kg, which goes against everything i was taught, even at diploma level

Really ?? Perhaps they need to do some urgent research on their anaesthesia.....

RE: Paediatric Circle Circuit

Nick Shackleton — Tue, 25 Jun 2019 15:05:28 GMT

I’ve received a lot of back lash from USA nurses who routinely use circle circuits on patients <10kg, which goes against everything i was taught, even at diploma level

RE: Paediatric Circle Circuit

molladog — Tue, 25 Jun 2019 14:25:09 GMT

I would always use a Ayres T-Piece (paediatric version) as perfect for animals under 7kg as very little resistance/dead space.

RE: Paediatric Circle Circuit

Nick Shackleton — Tue, 25 Jun 2019 14:13:25 GMT

The only low flow circuit available for paediatric patients ie <10kg would be the Humphrey ADE. You would you use it without the soda lime canister. I have heard of them using a circle system in the US in patients less than 10kg. As far as I am aware this type of circuit is unavailable in the UK. However, I was always taught that patients less than this body weight have difficulties maintaining themselves on this kind of circuit due to the resistance incurred with the different valves within the circuit. They may have different circuits in available in the USA. In my option I would stick to a non rebreathing circuit. Whether that be T-Piece, mini lack or mini Bain. If you are likely to have to perform IPPV go for a Mini Bain or T-Piece