Need some help with a bit of capnography equipment!!

RE: Need some help with a bit of capnography equipment!!

Ivan Crotaz — Tue, 24 Oct 2017 20:06:34 GMT

Hi Gill

Hopefully I can help a little - I teach capnography and anaesthesia in rabbits as well as being involved with v-gel R&D!

The inspiration/expiration monitors are available from JAK and AnimalCare; there also used to be a tiny one that fitted in line with the circuit, but I can't find one on sale now. I used to use them about 10 years ago. My concern with these is that it's not the frequency of breathing that is the issue, it's the efficacy of breathing.

Rabbits have a pretty poor respiratory design at the best of times which is further compromised by surgical positioning and drugs. It's quite possible for them to be ventilating apparently well, but have massively high CO2 levels and consequently very high risks of respiratory related anaesthetic deaths.

When the beep slows significantly on these alert monitors, it is likely that it is already too late for you to diagnose and sort out the problem.

I would recommend the following, using the equipment that you already own:

1) you should have a low dead space sidestream connector in the kit with the capnograph - if you can't find it you should be able to track one down easily - let me know if you have issues with this. If the fitting has a luer connector then this will attach directly to the v-gel, so minimising dead space.

2) add an average of 150ml/min to your calculated flow rates to allow for the sidestream capnograph sampling rate (ideally check what sampling rate it is in the documentation). I'll often add a bit extra to try to dilute any CO2 if I'm dealing with larger than ideal deadspace. (Incidentally, it's very important with sidestream monitors to get the adapter that takes the sampled gas out through the bottom of the sensor and dumps it into your scavenging line. This stops anaesthetic contamination into theatre. Let me know if you need help tracking it down and I'll find where we got ours).

3) Don't worry about the few seconds delay, it is annoying but very rarely significant. I prefer mainstream but I'll use either.

4) Don't worry about complex patterns. I use the trace to tell me firstly that my patient is breathing, and the number to tell me how well it's breathing. 35-45mmHg Co2 is normal range. Above 50 I start to ventilate/IPPV to bring the CO2 back to normal range. Most rabbits will have high CO2 and benefit from ventilation.

The last step alone is very likely to reduce your anaesthetic risk significantly. My opinion is that many 'unexpected' deaths are due to respiratory compromise. Capnograph patterns are certainly useful but I'd just use the fact that you have a decent trace and the number itself first, then go into more detail later when you're happy.

If you look at the machine like that then you should find it much more use and you don't have to spend more on monitors that aren't telling you as much.

Please let me know if I can be of any help

Ivan

RE: Need some help with a bit of capnography equipment!!

Chris Geddes — Tue, 24 Oct 2017 11:18:13 GMT

Hi Gill, others,

I work for Docsinnovent, who manufacture the v-gel devices. The device you’re talking about is an Apalert I believe.

http://www.jakmarketing.co.uk/apalert-rm5-respiration-monitor

Capnographs can either be connected directly to the v-gel or via a side port. I believe the Apalert can connect either way also. If you have a capnograph already, I would advise using that as you get a lot more useful information – and it saves you investing in another device. You will get a bit of extra dead space, but it is nothing to worry about.

If you want to have a chat, please call our Product Specialist (Dawn) on 07807274595

As a side note – we recommend the use of capnography for all veterinary anaesthesia, but especially in rabbits, who don’t ventilate at the best of times! It will alert you to problems before you can see them. HOWEVER, remember the v-gel is just an airway device and can be checked in the same way as other devices when no capnograph is available. The key to the correct and secure v-gel placement is choosing the right size device for the patient. Videos for size selection and securing in can be found on our website (www.docsinnovent.com/videos).

Chris

RE: Need some help with a bit of capnography equipment!!

James Colver Cert. Ed, RVN — Mon, 23 Oct 2017 17:10:36 GMT

(also have a look at the 'securing the rabbit Vgel' video demonstration on the gallery of this site - they have used a sidestream capno)

RE: Need some help with a bit of capnography equipment!!

James Colver Cert. Ed, RVN — Mon, 23 Oct 2017 16:49:00 GMT

Hi! It sounds like a respiratory monitor rather than a capnograph. They are right not to use the Vgel without capno but I am not sure about resolving the deadspace issue. Perhaps there is some sort of adaptor that you can get? Maybe a call to the Vgel folks would be helpful :)