Circle Circuit Queries

RE: Circle Circuit Queries

ruths — Fri, 05 Feb 2016 08:02:56 GMT

[quote user="Gillian Mostyn"]

[quote user="ruths"]You can run the ADE as a circle with the switch in one position (semi closed if you use oxygen above the metabolic rste) and if you use a very low oxygen rate, you can get down to a closed circuit without touching the valve.[/quote]

There isn't a 'switch' on the ADE, so I'm not sure what you mean. The only lever is one that you use if connecting to a ventilator - we've never used it.

The manufacturer doesn't recommend using it as a closed circuit, so although it is theoretically possible to put the O2 level very low, I think (off the top of my head) they don't suggest going below about 600ml - although I guess if you're using a capnograph then you could.

[quote user="ruths"]flip the switch and it becomes a totally non- rebreathing circuit (Semi-closed) with the valve open[/quote]

The only thing that dictates whether it is rebreathing vs non-rebreathing is the use/removal of the soda lime canister. You shouldn't be changing anything else.

[/quote]

Oh yes, sorry, it's been a while since I used it. You need to flip the lever down when ventilating.

RE: Circle Circuit Queries

Gillian Mostyn — Thu, 04 Feb 2016 21:08:17 GMT

There isn't a 'switch' on the ADE, so I'm not sure what you mean. The only lever is one that you use if connecting to a ventilator - we've never used it.

[quote user="ruths"]flip the switch and it becomes a totally non- rebreathing circuit (Semi-closed) with the valve open[/quote]

The only thing that dictates whether it is rebreathing vs non-rebreathing is the use/removal of the soda lime canister. You shouldn't be changing anything else.

RE: Circle Circuit Queries

Gillian Mostyn — Thu, 04 Feb 2016 21:03:29 GMT

[quote user="ruths"]

re the ADE- it's a lovely system and I think it works really well in a practice if you are only anaesthetising one thing at a time. It will do the tiniedt kitten and the biggest dog.

but if you are anaesthetising 4 or 5 things at a time in the hopsital, then having a range of circuits is probably much more economical tbh.

[/quote]

We have 2 of them - one for prep, one for theatre, and we are only a small practice (2 vets working at any one time). Don't see why you'd need to only own one...???

RE: Circle Circuit Queries

Anthony Todd — Thu, 04 Feb 2016 19:55:24 GMT

[quote user="Evelyn Barbour-Hill"]And the Komesaroff is better[/quote]

Don't know it [heard of it] but how and why? [genuine interest, not adversarial]

If it's better than the Stephens it's gotta be brill!

RE: Circle Circuit Queries

Evelyn Barbour-Hill — Thu, 04 Feb 2016 19:49:54 GMT

[quote user="Anthony Todd"]Economical, Eco friendly and really easy to manage, at least the Stephens was! [/quote]

And the Komesaroff is better.

[quote user="Anthony Todd"]Totally fool-proof, even in vets' hands.....[/quote]

Indeed.

RE: Circle Circuit Queries

Anthony Todd — Thu, 04 Feb 2016 19:44:57 GMT

[quote user="ruths"]The VIC circuits are certsinly very economical and Eco friendly but really hard to manage if you are used to the more common vapourisor out of the circuit.[/quote]

Economical, Eco friendly and really easy to manage, at least the Stephens was! Totally fool-proof, even in vets' hands.....

I'm very wary of a system which can become "non-rebreathing" with the flick of a switch. Recipe for a disaster sooner or later...

There was an American system which had a lever which enabled you to bypass the sodalime, thereby increase the pCO2 and stimulate respiration.... "who moved that lever?"

You want to read the pilots' forum "pprune" before you have systems which change with "a flick of a switch"....

But,at the end of the day, the golden rule is to use an agent and/or a system you are familiar and confident with.

Just imagine my old boss trying to drop a horse using today's systems and drugs......!!

RE: Circle Circuit Queries

ruths — Thu, 04 Feb 2016 19:36:48 GMT

[quote user="Evelyn Barbour-Hill"]

[quote user="ruths"]The VIC circuits are certsinly very economical and Eco friendly but really hard to manage if you are used to the more common vapourisor out of the circuit. And really freaky if you are doing positive ventilation. You have to realy be on top of the case [/quote]

Yee...ess..... but it's really not that hard. Obviously you have to learn how to use it, if all you have known is the out-of-circuit vapouriser.

[/quote]

agree- it's hard to move from one system to another

I used to be a Locum and found it hard to go from one system to another as well as having to know which nurses I could trust- and which were less on top of their game. I would tend to feel stressed with the VIC places. There weren't many!

RE: Circle Circuit Queries

Anthony Todd — Thu, 04 Feb 2016 19:34:46 GMT

[quote user="ruths"]positive ventilation.[/quote]

Too true, you need to know minute volumes for sure, fortunately we don't have to do it too often.

But it's the same as any drug. It's the rate you drink alcohol, with an alcohol percentage to 5 decimal places, that gets you #p***sed not the percentage per se.

RE: Circle Circuit Queries

Evelyn Barbour-Hill — Thu, 04 Feb 2016 19:33:07 GMT

Yee...ess..... but it's really not that hard. Obviously you have to learn how to use it, if all you have known is the out-of-circuit vapouriser.

RE: Circle Circuit Queries

ruths — Thu, 04 Feb 2016 19:27:13 GMT

You can run the ADE as a circle with the switch in one position (semi closed if you use oxygen above the metabolic rste) and if you use a very low oxygen rate, you can get down to a closed circuit without touching the valve.

flip the switch and it becomes a totally non- rebreathing circuit (Semi-closed) with the valve open.

The VIC circuits are certsinly very economical and Eco friendly but really hard to manage if you are used to the more common vapourisor out of the circuit. And really freaky if you are doing positive ventilation. You have to realy be on top of the case

RE: Circle Circuit Queries

Anthony Todd — Thu, 04 Feb 2016 18:55:54 GMT

[quote user="Gillian Mostyn"]these are all semi-closed systems[/quote]

So more O2 and more anaesthetic? And you've got to collect the excess anaesthetic.

[they're sort of advertised as closed systems aren't they; Stephens was.]

RE: Circle Circuit Queries

ruths — Thu, 04 Feb 2016 18:54:55 GMT

The issue about closed, semi -closed and open systems is nothing to do with the position of the valve. It's all about wether or not the animal is rebreathing.

When you use a circle at a flow that is equal to metabolic oxygen requirements, you are running it as a closed system whether or not you have the valve closed.

re the ADE- it's a lovely system and I think it works really well in a practice if you are only anaesthetising one thing at a time. It will do the tiniedt kitten and the biggest dog.

but if you are anaesthetising 4 or 5 things at a time in the hopsital, then having a range of circuits is probably much more economical tbh.

I think the ADE works if you are an anaesthetist and you just take your cicuit with you.

RE: Circle Circuit Queries

Gillian Mostyn — Thu, 04 Feb 2016 18:21:28 GMT

You only need to use a max of 1l with an ADE (after the initial 3l for a couple of minutes to get rid of nitrogen). There is no need to go any higher.

Anthony - these are all semi-closed systems, so the scavenge valve is open. The ADE, however, has a clever valve which does fancy stuff - all info available online if you're interested.

RE: Circle Circuit Queries

Anthony Todd — Thu, 04 Feb 2016 17:00:19 GMT

[quote user="Bob Russell"]We run it higher[/quote]

Crikey, I'll say, you'd have to run a spill, or release excess O2 every so often?

We ran the Stephens at metabolic just by filling the bag up as necessary so it was a fully closed circle system.

As I was new, and a colonial I didn't like to challenge a new boss regarding anything. let alone anaesthesia of horses, lung disease or not.

RE: Circle Circuit Queries

Bob Russell — Thu, 04 Feb 2016 16:44:57 GMT

Fresh gas flow recommendations (after induction) – MINIMUM 300 ml/min
Cats – all weights	70-100 ml/kg/min – semi-closed – without absorber
Dogs under 7kg	70-100 ml/kg/min – semi-closed – without absorber
Dogs over 7 kg	30 ml/kg/min induction – re-cycling with soda lime canister 10 ml/kg/min maintenance

We run it higher because we have a capnograph attached to the system and I am a bit of a coward! More if I am worried about the patient eg pyometra etc.

Probably don't need to be such a coward as the monitor checks O2 and iso levels in addition to the CO2.

Chloroform might have been safe for the procedure but what did it do to the lungs?

RE: Circle Circuit Queries

Anthony Todd — Thu, 04 Feb 2016 16:25:05 GMT

[quote user="Bob Russell"]Not sure what the life expectancy of these circuits are but the ADE allows very low flow rates and covers pretty much every weight of patient.[/quote]

What sort of flow rates of O2 are you using?

BTW I remember at my second job the boss, at interview, said he was going to cut a colt and said he used chloroform [scoff from yours truly].

He said he was used to it, which is just as important with anaesthetics and systems today.

We had eventually 8 Stephens machines, starting in 1970, derided by those who'd never used them, but absolutely foolproof and totally safe, if used correctly.

Most, if not all, of the in-circle vapouriser systems in use today are variations on the Stephens theme.

RE: Circle Circuit Queries

Anthony Todd — Thu, 04 Feb 2016 16:15:17 GMT

Just wondering what you do with anaesthetic vapour when you want to clear the system.

I assume there is a port to an absorber??

RE: Circle Circuit Queries

Bob Russell — Wed, 03 Feb 2016 16:59:52 GMT

Not sure what the life expectancy of these circuits are but the ADE allows very low flow rates and covers pretty much every weight of patient.

I would tend to agree that in an either/or situation, I would go for a capnograph. Overall I would prefer to go for an ADE which will last a lifetime. It does require a service annually (should!) so does have some running costs.

My advice would be to get both, leasing if necessary!

RE: Circle Circuit Queries

Gillian Mostyn — Tue, 02 Feb 2016 22:06:10 GMT

[quote user="John Flynn"]To comment on the aside - if you have an extra £1000 do NOT spend it swapping this perfectly fine circle system for a Humphrey's equivalent[/quote]

We'll agree to disagree then!

RE: Circle Circuit Queries

John Flynn — Tue, 02 Feb 2016 19:57:20 GMT

That looks a fine circle circuit to me. Looking at the other ones they have, I'd have paid the extra for the push down IPPV button http://www.jakmarketing.co.uk/purfect-ppv-lightweight-circle-circuit but that's a personal preference.

To comment on the aside - if you have an extra £1000 do NOT spend it swapping this perfectly fine circle system for a Humphrey's equivalent ... get a capnograph instead!

RE: Circle Circuit Queries

Bob Russell — Tue, 02 Feb 2016 17:37:01 GMT

ADE is the most fantastic bit of kit. Ours cost an arm and a leg 15 years ago but is as good as new!

We do have a t piece somewhere but hardly ever use it!

OK going off on a tangent but the ADE was just about the best veterinary purchase I have ever made!

Meanwhile back to the thread!

RE: Circle Circuit Queries

Gillian Mostyn — Tue, 02 Feb 2016 17:08:02 GMT

Just an aside: if ever you get another system or need to replace this one, I don't think there is anything to beat the ADE. Worth the investment IMO.

RE: Circle Circuit Queries

Seadna — Tue, 02 Feb 2016 16:48:59 GMT

Thanks for the replies all.

Here is a link to a picture of the circuit: http://www.jakmarketing.co.uk/purfect-lightweight-circle-circuit

The absorbent is Spherasorb. It turned briefly white-to-violet during surgery and had changed back to white the following morning at which point I asked the nurse to replace it. I must admit that the canister isn't full to the brim with Spherasorb but I hadn't thought that this was necessary. I will fill it myself now and see how it copes with the surgical load tomorrow.

RE: Circle Circuit Queries

Anthony Todd — Tue, 02 Feb 2016 14:10:30 GMT

Any thoughts, anyone, on the best sodalime and the most sensible colour changes?

And does it still get sort of waterlogged?

If staff are going from theatre to theatre there is a chance of error. [we had someone changing sodalime " ' cos it was exhausted" which is wasn't....

RE: Circle Circuit Queries

Rob Loxley — Tue, 02 Feb 2016 13:40:30 GMT

Remember that "after being used if the soda lime remains in the absorber for 10–48 hrs, some of the NaOH regenerates and the pH increases, changing the colour of the soda lime back to its “fresh” appearing colour. This is often mistaken for a regeneration of CO2 absorbing potential... ...upon reuse, the indicator color will rapidly return to it’s exhausted state"
i.e. you need to assess the colour change at the end of the op; it may have gone back to it's 'fresh' colour by the next day