Anaesthesia of CRF cats

Re: Anaesthesia of CRF cats

Julian Earl — Thu, 10 Mar 2011 23:13:39 GMT

[quote user="Kate Richardson"]

Induction is with alfaxan to effect, interestingly needed significantly less alfaxan when we used domitor in the premed.

... but tapered the dose of domitor down further to 0.01-0.005ml/kg and it was still really effective as a premed. And significantly reduced the amount of alfaxan needed to induce them by about a 1/4 of the usual dose needed. The only thing I would say is that they seem to be slower to recover, but if necessary i will give them anti-sedan.

[/quote]

I have some original SKB recommendations for anaesthesietic agents following Domitor pre-medication: propofol for dogs is 1ml per 10kg instead of 1 per 4kg, and the Saffan dose (remember Saffan?) is similar. The dose reduction is therefore much greater than ACP/Vetergesic, plus as someone has said, they wake up extremely rapidly when Antisedan is given simply because there is so little anaesthetic agent in the system.

Anyway, I have a cat with CRF and did a dental and a toe amputation in the summer and he is still going strong(-ish). Vetergesic, Alfaxan, and lots of fluids = no apparent problems.

Re: Anaesthesia of CRF cats

Fiona French — Thu, 10 Mar 2011 21:36:31 GMT

If there is significant renal disease, ideally I like to admit them the night before the dental and have them on twice maintenance fluids overnight.

I tend to give buprenorphine only premed, and propofol for induction, maintain on isoflo. I am happy to give an NSAID when they have had a decent length of time on fluids, but normally give it during recovery.

I have had no problems with this protocol, even for some fairly long dentals, though of course every effort should be made to minimise the length of the anaesthetic.

Re: Anaesthesia of CRF cats

Evelyn Barbour-Hill — Thu, 10 Mar 2011 20:31:58 GMT

[quote user="Mark Holmes"]For example what is the point in leaving a single premolar?[/quote]

None at all.

On the other hand, I think we are all agreed on the principle of getting done promptly whatever is necessary to restore cat's health and keep it good enough for the rest of its little life. So it might well be that by insisting on extracting that premolar you add significantly to the surgical time: if it isn't as straightforward as you thought it would be, you might add 20 minutes easily. So the decision about each tooth would depend entirely upon its exact state and the overall situation at the time. Use your common sense and treat each cat as seems best at the time.

Sorry I didn't mean to "suggest an answer". I hit the wrong button and I can't see how to undo it.

Re: Anaesthesia of CRF cats

Michael Woodhouse — Thu, 10 Mar 2011 17:52:21 GMT

[quote user="Louise Alexander"]And you've never had any post-op complications with this techinique?! I would avoid alpha-2 agonists at all costs in anything that isn't young, fit and healthy![/quote]

I dread saying it but no never had a problem with medetomidine. What I have had are many problems with IVFT in cats. They get tangled up, a lot of grumpy cats not keen on you placing a catheter conscious so need pre-med before they will tolerate it. We have no drip pumps so have to be very careful as there is a fine line between stopped and clotted and over-perfusion.

Sub cut fluids are effective, so much cheaper, so much less messing about and effective.

I really don't see the fear with alpha 2's. The absolute beauty is you can 'turn them off' if there is a problem with the Atipamazole [IV if you need to]. Everybody seems to forget that there is little change in blood pressure with Domitor, but a large reduction with the vasodillating ACP. I really don't see why you'd give these cats ACP and not an alpha 2. The ACP is vasodillatory for up to 4 hours, the alpha 2 effects all go very quickly when reversed.

I even use them [at low doses] in animals with bad hearts for the same reason!

As a student I was in a practice that had bought a new blood pressure monitor. ABP was maintained with Domitor pre-med and fell lower with ACP. You are worrying about nothing! I am not a fan of masking anything down - inhalational anaesthetics all depress BP, you WILL need a higher vaporiser setting with no pre-med. You are much better giving a little bit of a lot of drugs than a lot of one.

Re: Anaesthesia of CRF cats

Mark Holmes — Thu, 10 Mar 2011 17:38:23 GMT

[quote user="Martin Atkinson"]Interesting thought I had never considered increased haemorrhage as a potential problem [/quote]

Peripheral vasoconstriction, bleeders are not apparant under ga and then once dom reversed, hey ho off we go! One or two lovely clean and tidy wounds have turned into a bloodbath. Peripheral vasodilation (acp) on the otherhand and the opposite happens, anything that might beed is encouraged to at an appropriate time.

Re: Anaesthesia of CRF cats

Martin Atkinson — Thu, 10 Mar 2011 16:46:44 GMT

[quote user="Mark Holmes"]

I have used dom and torb for a long time as a premed and am very happy with it. The only complication I have had using it is that reactionary heamorrhage is a greater problem and so I avoid it for lumpectomies where the blood supply isn't predictable.

Anecodotal report alert * I worked at two different clinics, one used DTK routinely and did shed loads of cat neutering (tens of cats a week) the other used ACP/Vet and did a handful a week. Both clinics used pre op nsaids. The second clinic used to see ARF a couple of times a year from a much smaller number (a fraction) of cats than the first which saw none. Anecdotal for sure but it made me wonder!

Once you get over the membrane colour its great. (They are more prone to hypertension though so be careful with fluids)

[/quote]

Interesting thought I had never considered increased haemorrhage as a potential problem - what is the reason for that? Basically I would use Dom/Torb or substitute Xylazine for the Dom, GA with minimal amount of propofol and maintain on Iso. Ketamine for increased analgesia as well as sedation properties is a consideration but I hate the hangover they seem to suffer & I suspect they do as well. Most importantly do pre surgical blood profile for BUN, Crea, Phosphate and electolytes and urine SG for current status. All will get I/V fluids and correct potassium if low and stay on them until they go home. I would reverse the alpha agonist as soon as I've finished with atipamazole. I wouldn't mind giving a tiny dose of carprofen or meloxicam if I done painful extractions so long as the fluids are going in.

Re: Anaesthesia of CRF cats

Mark Holmes — Thu, 10 Mar 2011 16:13:07 GMT

I also work under the maxim "if in doubt take it out" you don't eant to be repeating the proceedure in 6 months because you tried to save a tooth.

For example what is the point in leaving a single premolar?

Re: Anaesthesia of CRF cats

Peter Ding — Thu, 10 Mar 2011 15:44:50 GMT

Sevo gas induction and i/v fluids seems to work best of all in maintaining normal BPs for quick dentals in old cats in my hands.

Miniscule amounts ketamine and low dose buprenorphine/vetergesic premed.

Incredibly well tolerated and very quick recoveries to standing and eating. No PAE. Don't knock Sevo gas induction until you have tried it ; 3 finger restraint in most cats just holding the mask on for about 10 breaths, then intubate.

Use capnography and pulse oximetry to help monitor tissue perfusion/aneasthesia. BP as well if someone is spare. I would agree GET ON WITH IT should be everyone's maxim.

Re: Anaesthesia of CRF cats

Mark Holmes — Thu, 10 Mar 2011 15:30:46 GMT

Once you get over the membrane colour its great. (They are more prone to hypertension though so be careful with fluids)

Re: Anaesthesia of CRF cats

Rob Loxley — Thu, 10 Mar 2011 14:50:11 GMT

[quote user="Louise Alexander"]I would avoid alpha-2 agonists at all costs in anything that isn't young, fit and healthy![/quote]

Hmm, I would certainly avoid 'datasheet' doses in anything not young, fit and healthy (and in fact most of them only need lower doses). Went to an interesting CPD on anaesthesia where the speaker seemed more keen on using alpha 2s in older animals for the beneficial effects on blood pressure (peripheral vasoconstriction helping reduce hypotension directly, and dose sparing so less depressing effects of propofol and inhalant gas) and in cats with HCM amongst other cases, but going very easy on the doses.

Re: Anaesthesia of CRF cats

Kate Richardson — Thu, 10 Mar 2011 14:00:15 GMT

I use ACP/buprenorphine as my premed; for routine ops in healthy patients we use 0.05mg/kg ACP, but for elderly cats I halve this dose to 0.025mg/kg and use 0.01-0.02mg/kg buprenorphine, both given IM. When ACP was unavailable last month, I used domitor at ultra low doses with buprenorphine. Gave great sedation, using 0.005mls/kg domitor with no adverse effects, BP and HR remained within normal ranges.

Induction is with alfaxan to effect, interestingly needed significantly less alfaxan when we used domitor in the premed. Then maintainence with iso, occasionally sevo.

I start them on iv fluids as soon as they are admitted, so as to maintain renal perfusion, and they stay on fluids until they are discharged; they won't have eaten for at least 12hours and certainly won't drink for the day they are in hospital, so fluids is of paramount importance in these cases. Fluid rates will depend on the degree of renal insufficiency.

Pain relief will depend on what gets done, generally repeated doses of buprenorphine either IM or PO, and home with oral bup if necessary. I will usually give them metacam as well, despite the renal disease, as I firmly belive it is safe as long as renal perfusion is good, and I think they need some anti-inflammatory. They are more likely to be slower to resume normal feeding/drinking if they are painful, and it is imperative to get them eating and drinking asap. I also use nerve blocks (when I remember!) especially if mutiple extractions

I probably do at least one geriatric dental a week, and touch wood, have had no problems with my protocol, and much happier kitties once their mouths are treated.

As an aside, I used to be petrified of going anywhere near a GA with domitor, but 6months ago I started using it in my premeds for'naughty kitties'- mainly the young spays and castrates, as ACP wasn't sedating some of them enough and getting an IV catheter in was occasionally a bit fraught and stressful for the cats and for us. A colleague suggested her 'naughty kitty' premed of 0.02mls/kg domitor with 0.07mls/kg vetergesic, so I tried it a few times and it was great. Heart rate and BP remained normal, and the whole process was so much less stressful for all involved, but especially for the cats. When ACP became in short supply, I used it more widely, but tapered the dose of domitor down further to 0.01-0.005ml/kg and it was still really effective as a premed. And significantly reduced the amount of alfaxan needed to induce them by about a 1/4 of the usual dose needed. The only thing I would say is that they seem to be slower to recover, but if necessary i will give them anti-sedan.

Re: Anaesthesia of CRF cats

James Allsop — Thu, 10 Mar 2011 13:52:44 GMT

My understanding of the principals for anaesthesia in these cats is to avoid hypotension, maintain adequate renal perfusion (IV fluids and drug choices) and be quick. I was told that duration of GA seems to affect outcomes significantly so plan well, have all the tools readily available and use experienced staff to minimise delays. The general consensus seems to be that its better to treat the dental disease efficiently under anaesthetic than leave the cat in pain and with low grade dental infection as this will have more effect on kidney health and appetite.

Re: Anaesthesia of CRF cats

Louise6732 — Thu, 10 Mar 2011 13:44:45 GMT

[quote user="Michael Woodhouse"]I don't do anything different with the anaesthesia - triple combination. Reverse the alpha 2 after half an hour assuming procedure done. Just make sure they get fluids of some sort - if it's a quick dental then I'll give 150ml warmed Hartmans sub cut - it's gone by they wake up. [/quote]

And you've never had any post-op complications with this techinique?! I would avoid alpha-2 agonists at all costs in anything that isn't young, fit and healthy!

Why not put a bolus of fluids IV if they're under GA? Would work much quicker than sub-cut with the vasoconstriction effect of alpha-2s?

Louise

Re: Anaesthesia of CRF cats

Michael Woodhouse — Thu, 10 Mar 2011 13:07:45 GMT

I don't do anything different with the anaesthesia - triple combination. Reverse the alpha 2 after half an hour assuming procedure done. Just make sure they get fluids of some sort - if it's a quick dental then I'll give 150ml warmed Hartmans sub cut - it's gone by they wake up.

Re: Anaesthesia of CRF cats

Laurence Webb — Thu, 10 Mar 2011 10:46:11 GMT

Ideally 20mins although I have given them all IM at the same time occasionally.

Re: Anaesthesia of CRF cats

Hannah Wynne Richards — Thu, 10 Mar 2011 10:35:28 GMT

Sounds good to me-how long do you wait between bupre/benzo and ketamine?

Wynne