Medetomidine / ketamine anaesthesia in cats

Re: Medetomidine / ketamine anaesthesia in cats

Ella Massy-Greene — Mon, 08 Jun 2009 19:45:44 GMT

Further to this discussion, I have just read an interesting article on pain relief for OVH in cats in this month's JFMS (Vol 11, No6, June 2009, p420-429). One of the most useful parts of the article is the composite pain score on p.422-423. Maybe this is something we should be using more in general practice? The authors' conclusion is that analgesia is required for 3 days after routine OVH.... food for thought.

Re: Medetomidine / ketamine anaesthesia in cats

Evelyn Barbour-Hill — Sat, 06 Jun 2009 16:08:28 GMT

[quote user="james hunt"]

^{Risk factors for anaesthetic-related death in cats: results
from the confidential enquiry into perioperative small
animal fatalities (CEPSAF)†
D. C. Brodbelt1*, D. U. Pfeiffer2, L. E. Young1 3 and J. L. N. Wood1 4}British Journal of Anaesthesia 99 (5): 617– 23 (2007)

"Factors associated with increased odds of anaesthetic-related death
were poor health status (ASA physical status classification), increasing age, extremes of weight,
increasing procedural urgency and complexity, endotracheal intubation, and fluid therapy. Pulse
monitoring and pulse oximetry were associated with reduced odds. "

The authors' recommendation is that greater care is exercised with endotracheal intubation and fluid administration, and that pulse and pulse oximetry monitoring should be routinely implemented in cats.

They also noted that the increased odds associated with fluid administration may reflect residual confounding factors (ie. older, sicker, more likely to die animals received fluids) but that, given the small blood volumes of these patients, fluid overload was possible.

Perhaps pertinent to the discussion on neutering of very young animals - in this study cats weighing less than 2Kg were sixteen times more likely to die than those between 2 and 6Kg, and those over 6Kg were nearly three times more likely to die.

[/quote]

Another study that, while valuable, useful and interesting, could mean all sorts of different things.

Pulse monitoring is not the same as pulse oximetry. Why did they lump them together I wonder?

One might well hypothesise, for instance, that practices which take the trouble to monitor the pulse or use pulse oximetry are likely to be more careful anyway.

[quote user="james hunt"]The authors' recommendation is that greater care is exercised with endotracheal intubation and fluid administration[/quote]

Well, who could argue with that?

Re: Medetomidine / ketamine anaesthesia in cats

james hunt — Sat, 06 Jun 2009 14:33:03 GMT

Re: Medetomidine / ketamine anaesthesia in cats

Arlo Guthrie — Sat, 06 Jun 2009 08:21:04 GMT

[quote user="Ella Massy-Greene"]I have had major spinal surgery and felt severe pain for about a month after surgery from all the muscles that they cut through- it was an abdominal approach (and I was on so much morphine, I had withdrawal symptoms when it was removed).[/quote]

I've had the same (1 failed fusion requiring approach from front and back, followed 5 years later by addition of some titanium scaffolding). They tried to fob me off with the push button morphine, which lasted all of five minutes before I was screaming for the proper horse-sized dose.

Re: Medetomidine / ketamine anaesthesia in cats

Ella Massy-Greene — Fri, 05 Jun 2009 23:18:28 GMT

I have come to this discussion rather late..... and have spent some time reading everyone's points of view on whether animals feel post operative pain and how much we should pre-emptively treat it. Obviously there is some disagreement

There is so much we don't know in veterinary medicine because the studies just haven't been done (or they're just too difficult to do, given our lack of communication with our patients). I think we should practice using evidence where available.

This is the evidence I have heard/ read .... Two of the biggest risk factors for peri-operative mortality are:

1) using perioperative fluids (I can't remember, this may be cats only) - maybe it's not such a good idea to have a blanket philosophy on this. Most of us don't have the sort of anaesthetic monitoring that would allow us to pick up on problems associated with pulmonary oedema. There is definitely a case for any animal with renal insufficiency, but what's the use of using fluids to keep the kidneys working in 5 years time if it dies under or immediately after the anaesthetic? However, maybe once you are measuring blood pressure, ETCO2, pulse ox, arterial blood gases etc!

2) not using premedication (!) The reason for this could be argued, but it makes sense that it would result in lower doses of both induction and maintenance agents, and also a reduction in anaesthetic related arrhythmias. There is a definite case for using premeds as a standard for every anaesthetic.

So there are other reasons for using premeds (which include pain medication) other than just post-op pain relief. Having said that, I don't feel I need evidence to believe that animals suffer pain after surgery. I have had major spinal surgery and felt severe pain for about a month after surgery from all the muscles that they cut through- it was an abdominal approach (and I was on so much morphine, I had withdrawal symptoms when it was removed). Very recently, I had a small skin lump removed- 1 inch scar under local. The pain started about 2-3 hours after the procedure and the next day it was very unpleasant, and I actually lost weight due to reduced appetite! There is no evidence that animals feel pain any less than we do, and I would rather give them the benefit of the doubt.

- Ella.

Re: Medetomidine / ketamine anaesthesia in cats

Brad O'Hagan — Wed, 03 Jun 2009 00:24:56 GMT

[quote user="roland stevens"]Currently there is a debate within our practice with regard to the safety of this combination, in particular the affect on core tissue perfusion eg renal perfusion. The manufacturers tell us that core blood flows are maintained, only peripheral perfusion is significantly altered. Any facts or thoughts on this would be appreciated.[/quote]

One of the problems with forum discussions, especially based around standard of care in the anaesthesia suite, is that anecdote can take over and the point ofthe initial question can be lost.

Here is an abstract that addresses the initial question

1: Vet Res Commun. 2008 Feb;32(2):175-86. Epub 2007 Sep 25. Links

Effects of medetomidine on Doppler variables of major abdominal arteries in normal dogs.

Miño N, Espino L, Barreiro A.

Departamento de Ciencias Clínicas Veterinarias, Facultad de Veterinaria, Campus Universitario s/n, 27002 Lugo, Spain. natmin@lugo.usc.es

The purpose of this study was to evaluate the effects of medetomidine administration on the Doppler variables of abdominal arteries. The study population consisted of 20 healthy dogs. The haemodynamic effects of the medetomidine were defined using Doppler variables of the abdominal aorta, renal arteries, cranial mesenteric artery and celiac artery. The dogs were monitored continuously and different measurements were performed before medetomidine injection, at 10, 40 and 80 minutes after medetomidine medication and after atipamezole administration. Changes in the characteristic Doppler spectra of different vessels were more marked in the abdominal aorta, in which a greater reverse flow was found. There was a significant decrease in peak systolic velocity (PSV), end diastolic velocity (EDV), and mean velocity (MV) at ten minutes in every vessel studied and this effect persisted until atipamezole administration. Pulsatility index (PI) increased significantly in the abdominal aorta at ten minutes and persisted during the study until atipamezole administration. Resistive index (RI) did not vary significantly in any vessel. A significant decrease was found in flow volume of the abdominal aorta, the cranial mesenteric artery and the celiac artery at ten minutes, persisting until atipamezole administration. We conclude that medetomidine can be a good sedative in aiding sonographic evaluation of RI in all the abdominal vessels studied. On the other hand, the changes in other Doppler variables suggest that medetomidine administration causes significant hemodynamic differences between sedated and non-sedated dogs.

Anaesthesia is a very emotive issue, analgesia makes it more so. I think of anaesthesia as inducing a pathological state (albeit a hopefully reversible one). It is after all not normal (ie therefore pathological) for a cat to lay on its back and have its ovaries and uterus removed. For this reason, standard of care is very diverse based on opinions and experience - veterinary anaesthesia seems to be one of the area where we are weakest on using evidence based medicine. There is plenty of science available to make informed decisions on the techniques and procedures that you perform, it is just a matter of finding time to look, and in busy practice this is not always easy, but I am sure that it will become increasingly important into the future as we will have to be able to justify our decisions to give or not to give a medication, perform a procedure etc etc. We are all scientists and should attempt to use evidence as the back bone of our decision making processes.

Re: Medetomidine / ketamine anaesthesia in cats

james hunt — Tue, 12 May 2009 22:42:58 GMT

Yes, haemoglobin saturation measured by puse oximetry.

In an anaesthetised patient with normal haemoglobin concentrations then I think values less than 97% are reason to check oxygen delivery, ventilation and any factors which may be compromising these (surgeon leaning on the chest).

Values less than 95% I think are reason to check all these things again more carefully, give a few ventilations to see if this improves matters.

Values less than 90% I think you need to have identified cause(s) and be instituting measures to rectify - ie. some hypoventilation whilst breathing room air - increase inspired conc O2 and potentially intubate/ventilate to overcome hypoventilation.

Anaemic patients - less tolerance of desaturation so then yes I think taking action earlier is very wise.

You're quite right - patients with normal lung function breathing an oxygen enriched gas should have Hb sat close to 100%.

Re: Medetomidine / ketamine anaesthesia in cats

listhestar — Tue, 12 May 2009 20:38:55 GMT

[quote user="wishworthy"]respiratory depression as judged by haemaglobin saturation [/quote]

Is that pulse oximetry you are refering too? If so I was under the impression that any less than 97% already meant significant problems?

Re: Medetomidine / ketamine anaesthesia in cats

Arlo Guthrie — Tue, 12 May 2009 07:52:08 GMT

[quote user="beldather"]As an aside Arlo if your reading this, any chance of setting up the boards so you can quote from multiple people at once. [/quote]

Yes, I agree this would be very helpful. I'll ask our technical guru.

Re: Medetomidine / ketamine anaesthesia in cats

beldather — Tue, 12 May 2009 07:41:26 GMT

Funny, I was kind of thinking the exact same thing, so to allow Evelyn to have that graciousness of years,

Re: Medetomidine / ketamine anaesthesia in cats

Evelyn Barbour-Hill — Mon, 11 May 2009 23:36:05 GMT

I sometimes think that in fora such as this and threads such as this, a sort of natural end point is reached but nobody wants to let go in case they are thought to have "lost".

So in the graciousness of years, I shall allow beldather to be the last poster.. Oops, curse it, it's me again

Re: Medetomidine / ketamine anaesthesia in cats

beldather — Mon, 11 May 2009 22:06:02 GMT

[quote user="Evelyn Barbour-Hill"]I'm sorry your dog had such a poor anaesthetic the first time. I can't comment as to why, I wasn't there at the time. [/quote]

Unfortunetely I'm well aware of why. complete and utter lack of pain relief. The only chance was the local blocks and most of those teeth were out before it ever had a chance of kicking in.
It does go someway towards explaining my slight obsession with pain relief.

[quote user="Evelyn Barbour-Hill"]Your question about the young cat versus the cat with chronic renal failure certainly made me think (though not yet completely change my mind)[/quote] Come to the dark side, young barbour-hill.

As an aside Arlo if your reading this, any chance of setting up the boards so you can quote from multiple people at once (in other words not just being able to view the message where you hit the reply button). Makes it kind of tricky if your dealing with people like Evelyn and myself who have this habit of hitting that post button too often

Re: Medetomidine / ketamine anaesthesia in cats

Stephen Ashman — Mon, 11 May 2009 22:04:39 GMT

Aside from whether you would give analgesia or not; I would consider anti inflammatories to be analgesic too. Are you referring to opioids only?

Re: Medetomidine / ketamine anaesthesia in cats

beldather — Mon, 11 May 2009 21:56:56 GMT

[quote user="Evelyn Barbour-Hill"]You wouldn't give analgesic to the cat with flea dermatosis? The dog with "kennel cough"? How do you know they are not in pain?[/quote]

Because I've never met someone sobbing in agony from a skin infection or a cold. These cases would be treated with common sense in regards to their presentation. Topical steroids, antiinflammatory and antitussives. The only data we have is human response to nociception as a guide to pain, hysterectomies are rated higher then a cough, and there would have to require some seriously strong evidence to show a profound difference in neural pathways before I stop using that common sense approach.

Re: Medetomidine / ketamine anaesthesia in cats

Evelyn Barbour-Hill — Mon, 11 May 2009 21:08:15 GMT

Hell, wrong button again

[quote user="beldather"]My first epithany came with my own dog who just had one of those wierd problems which we tentavely diagnosed as some type of enamel dysplasia. By the age of 3 my wonderful, bouncy, crazy, bone chewing, border collie needed to go to the veterinary dentist for multiple extractions. It was an acp/atropine premed, local blocks and extractions started within a min. It was a horrible anaesthetic. They were running her on 5% iso at times to keep her still (And being only a few months out I wasnt goign to argue with the specialist), the teeth were out quickly and effiently, and I got to attend one of the worse recoveries I've ever dealt with(excluding the fact it was my own dog). However she recovered herself within a few days and she rapidly turned into this wonderful, bouncy, crazy, bone chewing, border collie, but 100% times better then she had been (she was happier, cant describe it any other way) and everyone noticed, not just those who knew about the teeth.
This year (when visiting back at aus) I noticed she had open pulp in one of her remaining molars, so made the decision to extract all the remainders cause they were heading that direction anyway. acp/methadone premed, CRI morphine, local blocks and a less efficient me doing the extractions. Wonderful anaesthesia, fantastic recovery (and I had been shaking when I induced from memories from last time, that was my second epiphany) She has since done another step up in terms of personality. At no time did I ever have any notion about discomfort (and trust me after the first time I was looking) until I removed that source of pain. [/quote]

I'm sorry your dog had such a poor anaesthetic the first time. I can't comment as to why, I wasn't there at the time. It doesn't happen with my patients. Then your discovery that she was so much better straight after the extractions and you hadn't realised the pain she was having...... as with Raj's head nurse, it's a common experience, Which still gives me a thrill when clients report it. I've spent twenty-five years pointing out to people that an open pulp means toothache (and some still don't get it).[quote user="beldather"]

[quote user="Evelyn Barbour-Hill"]The experience exemplified by your head nurse's cat is a very common one.[/quote] This is where I struggle a bit Evelyn, it is dental extractions of fractures and resorptive lesions that convinced me of the amazing ability of my patients to hide these things, and the benefit that is seen when these things are addressed yet you obviously deal with this on a far more regular occasion then me, and yet we have both reached different conclusions.[/quote]

Have we? Apart from some details of GA regimes we seem to be in complete agreement.

I like to question things, it makes people think sometimes, and post interesting and thoughtful replies sometimes. Your question about the young cat versus the cat with chronic renal failure certainly made me think (though not yet completely change my mind)

Re: Medetomidine / ketamine anaesthesia in cats

Evelyn Barbour-Hill — Mon, 11 May 2009 20:47:58 GMT

[quote user="beldather"][quote user="Evelyn Barbour-Hill"]OK, fair answer, but think a little deeper. Logically you would then give analgesics to every single patient that came into your consulting room, regardless of the complaint, because you don't know if it might be in pain?[/quote]
No, logically I would give analgesics to every patient that walked into my room with a laceration deep enough to penetrate either scrotal skin or through the linea alba. [/quote]

You wouldn't give analgesic to the cat with flea dermatosis? The dog with "kennel cough"? How do you know they are not in pain?

[quote user="beldather"]Pain is variable, nociception isn't.[/quote]

Quite so. Now we are beginning to get into greater philosophical depth.

[quote user="beldather"][quote user="Evelyn Barbour-Hill"]After the biggest surgery, there was pain which gradually faded over weeks. I was given various oral medications, which didn't bring a lot of benefit, although of course I can't say what I would have been like without.[/quote]
So you had a big procedure with fairly chronic pain, with ok response to post op analgesics. Have you ever wandered what would have happened if premptive analgesics had been used? This has proven to be an extremely important part of managing that long term pain, so is there a possibility you yourself are a good example of the limitations of post operative pain management?[/quote]

Well I don't want to bang on and on about me, but as I did say I imagine I got at least one if not several pre-emptive analgesics. I was asleep at the time. I was going to ask later, but I forgot. I don't know about the limitations of post-op drug analgesia, but I did try to point out that there were considerably more factors involved than the drugs (and, in passing, that the hospital nursing manifestly failed to consider those factors).

[quote user="beldather"]Ever seen an effective brachial plexus block, or epidural on fracture before.[/quote]

Yep. But I wouldn't be sending the dog home until it had worn off.

[quote user="beldather"]Because in my opion, the probability of an unstable pelvis causing pain and the cat not showing it, is far higher then the probability that she isnt experiencing it. And since I have no way of actually knowing what she's feeling, the worst that will happen if she isn't feeling it is a bit of a drug trip (reversable).[/quote]

Good, OK.

Re: Medetomidine / ketamine anaesthesia in cats

beldather — Mon, 11 May 2009 16:54:53 GMT

[quote user="Evelyn Barbour-Hill"]OK, fair answer, but think a little deeper. Logically you would then give analgesics to every single patient that came into your consulting room, regardless of the complaint, because you don't know if it might be in pain?[/quote]
No, logically I would give analgesics to every patient that walked into my room with a laceration deep enough to penetrate either scrotal skin or through the linea alba. Logically if I didn't think that I'd just tie em down for the surgery

Pain is variable, nociception isn't.

[quote user="Evelyn Barbour-Hill"]Assuming the GA for the 9year old is important: not really, just be (even more) careful. Probably have an iv fluid line for a procedure that I might not have had a fluid line for in the young cat.[/quote] Ok, so why are we concerned over the need for fluids for an elderly cat but not the young one. I will assume that part of that reason is that you do not want to push those last functional nephrons over the edge, yet why are we happy to accept that same risk because the younger cat has a lot more of them. The difference appears to be that in the older cat you will see an immediate effect of that nephron damage, yet the younger one will not present for many years to come. I don't 'think' I'm being illogical here.

[quote user="Vincent Wager"]I came on here to get some ideas and inspiration. After the 40 oddd emails and the arguing I think I may look elsewhere. [/quote] Vincent, as previously stated, one of the biggest risks with this style of communication is the lack ability to put context to the words. Emoticons are good (but kind fiddly to use) :) :)- work not too bad :)
Also, this style of discussion cant help but lead to some feelings of attack no matter how carefull we are, because we are discussing the way we each do things. We obviously wouldnt be doing them if we all didnt feel that we were doing the right things. For instance, I'm generally regarded as one of the most relaxed, easy going individuals around, but even knowing myself and reading my posts that definitely doesnt come across. Doesnt help that i'm a much better talker then I am a writer. Hang in there though, its from these type of discussions that the little vet pearls are often gained. (did you know that dogs have plateau's on their predominantly carnivore teeth )

[quote user="Evelyn Barbour-Hill"]After the biggest surgery, there was pain which gradually faded over weeks. I was given various oral medications, which didn't bring a lot of benefit, although of course I can't say what I would have been like without.[/quote]
So you had a big procedure with fairly chronic pain, with ok response to post op analgesics. Have you ever wandered what would have happened if premptive analgesics had been used? This has proven to be an extremely important part of managing that long term pain, so is there a possibility you yourself are a good example of the limitations of post operative pain management?

[quote user="Evelyn Barbour-Hill"]In fact it is quite obvious that we do not abolish all such pain, otherwise all orthopaedic patients would go home on four sound legs.[/quote] Ever seen an effective brachial plexus block, or epidural on fracture before. However that is not always ideal (unless youre happy with your plate or pin), and just because we can't remove all pain, doesnt mean we shouldnt strive to reduce it as much as possible.
It is true I will never know what level of pain my patients are in, but if I cut a hole in them, its going to hurt, and probably quite a bit. Analgesics are rarely scary or dangerous (NSAID's probably being were I am most wary) so the risk of overtreating to me is les then undertreating.

[quote user="Evelyn Barbour-Hill"]If the pain didn't bother her, why should it bother us? Or, if the pain didn't bother her, was it pain?[/quote]
Because in my opion, the probability of an unstable pelvis causing pain and the cat not showing it, is far higher then the probability that she isnt experiencing it. And since I have no way of actually knowing what she's feeling, the worst that will happen if she isn't feeling it is a bit of a drug trip (reversable).

My first epithany came with my own dog who just had one of those wierd problems which we tentavely diagnosed as some type of enamel dysplasia. By the age of 3 my wonderful, bouncy, crazy, bone chewing, border collie needed to go to the veterinary dentist for multiple extractions. It was an acp/atropine premed, local blocks and extractions started within a min. It was a horrible anaesthetic. They were running her on 5% iso at times to keep her still (And being only a few months out I wasnt goign to argue with the specialist), the teeth were out quickly and effiently, and I got to attend one of the worse recoveries I've ever dealt with(excluding the fact it was my own dog). However she recovered herself within a few days and she rapidly turned into this wonderful, bouncy, crazy, bone chewing, border collie, but 100% times better then she had been (she was happier, cant describe it any other way) and everyone noticed, not just those who knew about the teeth.
This year (when visiting back at aus) I noticed she had open pulp in one of her remaining molars, so made the decision to extract all the remainders cause they were heading that direction anyway. acp/methadone premed, CRI morphine, local blocks and a less efficient me doing the extractions. Wonderful anaesthesia, fantastic recovery (and I had been shaking when I induced from memories from last time, that was my second epiphany) She has since done another step up in terms of personality. At no time did I ever have any notion about discomfort (and trust me after the first time I was looking) until I removed that source of pain.

[quote user="Evelyn Barbour-Hill"]The experience exemplified by your head nurse's cat is a very common one.[/quote] This is where I struggle a bit Evelyn, it is dental extractions of fractures and resorptive lesions that convinced me of the amazing ability of my patients to hide these things, and the benefit that is seen when these things are addressed yet you obviously deal with this on a far more regular occasion then me, and yet we have both reached different conclusions.

[quote user="Evelyn Barbour-Hill"]Of course, what we do with FORLs is extract the teeth, not give a course of analgesia.[/quote] And we extract them because........

Phew, I talk too much.

I think most of it comes down to, some of us are confident that we can assess pain in our patients, others of us are so sure. the question then that i ask sincerely, is what is the worse case scenario if we are wrong.

Regards

Blair

Re: Medetomidine / ketamine anaesthesia in cats

Evelyn Barbour-Hill — Mon, 11 May 2009 13:57:17 GMT

[quote user="Tim Newton"]I hesitate to arue with you in your area of specialty Evelyn, but I am not sure abourt FROL's not being painful unless touched. Our head nurse recently brought her cat in for routine dentsitry, and we found 3 FORL's, the teeth of which we extracted. Afterwards she showed a very noticeable chnage in activity and behaviour, such that my nurse felt guilty for not having noticed the pain. But that is the point, surely. A cat may suffer a fair amount of pain and show no sign.[/quote]

Its OK, but I think you've missed my point. Probably I put it very badly; it was late at night. I didn't mean that FORLs are only ever painful if touched. FORLS are jolly variable anyway. I was just pointing out, because it's interesting, that FORLS are painful because of exposed dentinal tubules. The same mechanism as gives you a "sensitive tooth" . So, if nothing touches it except saliva and neighbouring mucosa, without pressure, it probably doesn't hurt. Some cats learn well how to avoid it hurting, others may not. The experience exemplified by your head nurse's cat is a very common one.

Of course, what we do with FORLs is extract the teeth, not give a course of analgesia.

I would defend owners' apparent inability to observe that there is something wrong with their pet, to some extent anyway, if the painful condition has come on gradually. Many car owners may not notice a slight tracking problem,perhaps, although the mechanic detects it instantly, because it came on gradually.

[quote user="Tim Newton"]The upshot of all this is that if you think there might be pain, treat it in case, as you cannot know for certain.[/quote]

I agree entirely. I don't think anyone is suggesting otherwise.

Re: Medetomidine / ketamine anaesthesia in cats

Tim Newton — Mon, 11 May 2009 08:20:05 GMT

I hesitate to arue with you in your area of specialty Evelyn, but I am not sure abourt FROL's not being painful unless touched. Our head nurse recently brought her cat in for routine dentsitry, and we found 3 FORL's, the teeth of which we extracted. Afterwards she showed a very noticeable chnage in activity and behaviour, such that my nurse felt guilty for not having noticed the pain. But that is the point, surely. A cat may suffer a fair amount of pain and show no sign.

On eof the Pfizer vet advisors I spoke to a few years ago had developed an considerable interest in pain management. She told me about her own dog that had an enucleation. I forget the details and why the eye was taken out, but there was no suspicion that the dog was in pain, yet after the eye was removed the dog was a much happier animal and the change was ascribed to relief of undetected pain. She also said that Pfizer got a tema of 12 "papin specialists" together at Gotingen uni some years ago now and they were asked to paijn score a dog that had just had cruciate surgery. Their scores varied form 2 to 11 and there was no statistical agreement. There also, was, she told me, a trial at Bristol, where a team of 6 behaviourists and 6 medical boffins tried to find reliable pain indicators in cats, and could come up with none.

The upshot of all this is that if you think there might be pain, treat it in case, as you cannot know for certain. Speak to any bloke who has had a vasectomy, and I reckon he will advise pain management after neutering. I am told it is very painful.

Regards

Re: Medetomidine / ketamine anaesthesia in cats

Evelyn Barbour-Hill — Mon, 11 May 2009 03:25:38 GMT

[quote user="RAJAT MUKHERJEE"]BTW, do you use gaseous anaesthesia for feline spays?[/quote]

Yes.

[quote user="RAJAT MUKHERJEE"]I can't argue dentistry with you Evelyn.. so will defer humbly to your opinion here - but I reckon FORLs are painful but hardly any cats show any signs or oral pain or a reduced appetite with them and usually owners are totally oblivious.If one uses a dental probe it exerts a high pressure over a small surface area of likely exposed pulp/nerve and this will provoke a reflex reaction due to the high intensity stimulus which is hardly surprising. When I probe the affected teeth in these cats through the buccal mucosa or directly with my thumb they usually show mild discomfort/resentment, but I don't know that this isn't just behavioural. Under GA, before placing nerve blocks, their jaws usually 'chatter' when I probe them with a dental probe. I reckon, in a conscious cat acute pain usually results in acute pain to any surrounding living creatures too (dogs/cats/humans etc)!![/quote]

Quite so. FORLS are painful mainly because of exposed dentinal tubules (or exposed pulp in the extreme case). The probe (whatever it is) just has to touch to cause pain.

If you don't touch the dentin directly or very nearly so, the pain will be less or none.

When the pulp dies, there's no pain. Well, there may be some depending on what's left of the tooth. If there's a rotten stump still poking through the gum, there's inflammation and inflamed tissue is sensitive. If there's a sharp bit of crown still hinged on a bit of gum, that will hurt the tissue around it.

Anyway, if they don't get probed and the cat slides its food straight past, I think the cat can avoid them hurting. Other cats do show signs of discomfort, quite subtle sometimes of course.

[quote user="RAJAT MUKHERJEE"]The point is most of the time it wasn't there, or a sensation. That sounds like decent analgesia post major surgery. Sucks for the time you were in pain though :([/quote]

Yea.... the point I was revolving, and it's not easy to put in words, was that the pain sensation was definitely there, impulses definitely zipping up to the medulla or whatever, but it wasn't pain if my mind wasn't on it; also that the pain was worse in hospital.

Re: Medetomidine / ketamine anaesthesia in cats

Rajat — Mon, 11 May 2009 02:05:03 GMT

[quote user="Evelyn Barbour-Hill"]I don't know, I just do it. It might be because I came relatively late to propofol, having previously used Saffan for many years and before that thiopentone.[/quote]

[quote user="Evelyn Barbour-Hill"]Yes of course. I do know all about capillary refill in a recently deceased animal. I am aware of the uses and the limitations of blood pressure measurement, exhaled CO2 assay, electrocardiography, pulse oximetry. But just read again what I actually wrote.[/quote]

I think that objective measures of cardiorespiratory function show at least a temporary worsening on induction with propofol, the dose of which will be higher in unpremidcated patients who have not received opioids and are about to undergo painful surgery. If one maintains with gaseous anaesthesia, a higher percentage is needed which again increases CV compromise, hypotension and respiratory depression. It seems simpler to prevent these problems by using an appropriate premed including an opioid and nsaid along with a sedative of ones choice. If 0.2mg/kg midazolam or diazepam is given IV just before induction it may further reduce the dose of propofol needed for intubation to 1-2mg/kg

In addition to all the literature, in my experience propofol has always led to a reduction in BP and HR and increase in ETCO2 immediately post induction. Sometimes SPO2 also drops depending on degree of hypoventilation. This tends to happen less when I used the above or other co induction and also is dose and speed of administration dependent as I am sure you know...

Also - an opoid such as buprenorphine has a high safety profile vs propofol and is licensed. So why not use it pre-op? Surely its 'potency' is less?

[quote user="Evelyn Barbour-Hill"] My point is, when I was busy either physically or mentally but not harassed ("stressed") either I didn't feel it at all or it was just strong sensation, not pain. It hurt worst while I was still in the hospital and not one of those conditions I listed for comfort (read 'em) was provided. Well, no, they didn't make me wear an Elizabethan collar, but apart from that.[/quote]

Its interesting you should say that, and you're right pain is difficult to pin down because it's different between people. For some, emotional and mental processing can make a huge difference. How do some people tolerate extreme pain without wincing? How do people have major surgery under hypnosis? Cetainly fMRI will tell us much more about pain in the coming years. In human post op pain, improvements in pain scores often reflect what you said - that interventions often don't abolish the awareness of the pain altogether- it just makes it tolerable or something which is in the background and not an active concern. A complete absence of pain is rare but for the majority provided appropriate pre peri and post op analgesia, it is certainly minimised to the best of a clinicians ability.

[quote user="Evelyn Barbour-Hill"]It would be very nice to abolish all post-op pain, but my feeling is that whatever you do there will be some pain at the actual op site especially on stimulation (such as being prodded) and my doctor and surgeon and physiotherapist would definitely agree. In fact it is quite obvious that we do not abolish all such pain, otherwise all orthopaedic patients would go home on four sound legs.

What is pain? Never mind the dictionary definition of the word "pain", what is it actually? I'm not sure that I know, but I am sure that it is not at all simple[/quote]

Yes we don't abolish all post op pain, but why not try to minimise it in the first place?Surely that's the right way to approach this problem for our patients, to minimise suffering?

As for the definition of pain - well if you speak of the human species for me it would include mental, emotional and sensory experiences .. in animals it's up for debate but I would not rule out mental/emotional influences in certain species and individuals..

So pain for me is something which is either physically or mentally debilitating, something which hurts physically or mentally. Emotionally it could be the loss of a family member, a divorce, physically - trauma of your choice, and mentally - stress of your choice . Since we have higher centres which modify and influence these signals, I believe we would all experience pain differently to a certain degree. However, I also believe, we all hurt!

As for your experiences- like you say you can't know what you would have been like without the meds. Sounds like you got some pain relief from the meds, I'm sure you would have received peri op meds... maybe I am being optimistic, but hasn't this been routine in human surgery for some time? How long ago are we talking? .

The point is most of the time it wasn't there, or a sensation. That sounds like decent analgesia post major surgery. Sucks for the time you were in pain though

[quote user="Evelyn Barbour-Hill"]I expect you gave her loads of analgesia anyway, and I would have done the same. But here's a thought. If the pain didn't bother her, why should it bother us? Or, if the pain didn't bother her, was it pain?[/quote]

I know what you're saying Evelyn, but the problem is that I dont know for sure there was no pain. In human ER, often acute gunshots or RTA cases report no pain initially often for 10-15 minutes, sometimes longer. The adrenaline kicks in and acts as a painkiller. I thought of this as a possibility for her but it had been a few hours at least. I'm glad you'd have done the same, and I think maybe the reason it bothers us is because there is the underlying very real possibility that pain could be present and masked, and none of us would like that to happen to us or our patients. I know I didn't do any harm by providing pain medication and most likely helped, although I can't prove that conclusively!

I don't think that our indicators of what bothers a cat neccessarily correlates with pain in cats. Often subtle behavioural signs are depressed and these are most obvious in the home environment to the clued up owner...I don't profess to be very clued up as I don't spend the whole day watching my cat!!

If a human had been injured and didn't feel the need for analgesia, then that's fine because if it starts hurting later, he can always ask. Our patients don't have that luxury.

[quote user="Evelyn Barbour-Hill"]No, it's a lot more subtle than that.

The NSAID goes in subcutaneously. That's the correct mode of administration and it is effective quite rapidly.

A vet monitoring and assessing every patient in the recovery kennels? Yes, there should be. Or rather, to be realistic, an experienced nurse. That's another bee in my bonnet but it's for another thread another time.

Final point, before I get on with what I'm supposed to be doing. (Not like you lucky people off to bed). With regard to a feline resorptive lesion: if you touch it with a probe, you'll be left in no doubt that it hurts [/quote]

I don't know what the time of onset for SQ nsaid is whether rimadyl or meloxicam will have to look it up. If it reaches peak plasma concentrations within 10minutes? of injection one has one analgesic agent on board for the surgery.

BTW, do you use gaseous anaesthesia for feline spays?

I agree re the experienced nurses, we are lucky to have a great nursing team and great post op monitoring. It's sooo important.

I can't argue dentistry with you Evelyn.. so will defer humbly to your opinion here - but I reckon FORLs are painful but hardly any cats show any signs or oral pain or a reduced appetite with them and usually owners are totally oblivious.If one uses a dental probe it exerts a high pressure over a small surface area of likely exposed pulp/nerve and this will provoke a reflex reaction due to the high intensity stimulus which is hardly surprising. When I probe the affected teeth in these cats through the buccal mucosa or directly with my thumb they usually show mild discomfort/resentment, but I don't know that this isn't just behavioural. Under GA, before placing nerve blocks, their jaws usually 'chatter' when I probe them with a dental probe. I reckon, in a conscious cat acute pain usually results in acute pain to any surrounding living creatures too (dogs/cats/humans etc)!!

Re: Medetomidine / ketamine anaesthesia in cats

Evelyn Barbour-Hill — Mon, 11 May 2009 00:31:14 GMT

[quote user="RAJAT MUKHERJEE"]So what tells you a cat is painful? If it does the obvious, right? Screams when you prod the site, hisses when you approach whereas it was a sweetheart before.[/quote]

No, it's a lot more subtle than that.

The NSAID goes in subcutaneously. That's the correct mode of administration and it is effective quite rapidly.

Re: Medetomidine / ketamine anaesthesia in cats

Evelyn Barbour-Hill — Mon, 11 May 2009 00:12:10 GMT

[quote user="RAJAT MUKHERJEE"] found curled up in a garden. sweet, in good health, purring and head rubbing but non ambulatory. I thought it may be neurological but she had fractured her pelvis in 2 places - it crunched pretty nasty on palpation! She continued to be sweet and affectionate all the way through her 2 surgeries 2 weeks in hospital with neuro incontinence and ataxia...3 months and some metal work from an orthopedically minded colleague later I ended up adopting her![/quote]

I expect you gave her loads of analgesia anyway, and I would have done the same. But here's a thought. If the pain didn't bother her, why should it bother us? Or, if the pain didn't bother her, was it pain?

Re: Medetomidine / ketamine anaesthesia in cats

Evelyn Barbour-Hill — Mon, 11 May 2009 00:04:20 GMT

[quote user="RAJAT MUKHERJEE"] find it difficult to see how you can use propofol without premeds (assuming so as you didnt describe earlier) to effect intubate, maintain on inhalant and give nsaids and do surgery and not have significant CV depression in some patients. Even when you use propofol 'properly' - not sure what you mean but if you found a way to not make it cardio-resp depressing please do tell all![/quote]

I don't know, I just do it. It might be because I came relatively late to propofol, having previously used Saffan for many years and before that thiopentone.

[quote user="RAJAT MUKHERJEE"]Rather than rely on subjective measures, how bout using BP and ETCO2? And I am sure you have heard people talk about testing a dead animals CRT...it works.. again good measures all put together but still a bit subjective..? [/quote]

Yes of course. I do know all about capillary refill in a recently deceased animal. I am aware of the uses and the limitations of blood pressure measurement, exhaled CO2 assay, electrocardiography, pulse oximetry. But just read again what I actually wrote.

I can't just now find your other points I wanted to quote for reply. So anyway. When I had surgery, I did not have premed opiates. I would guess I had perioperative opiates but I don't know...... I was asleep at the time. Yes there was pain afterwards. The self-injection opiate made a bit of difference but not much, and I do have a strong feeling that people get relief from it by a placebo effect at least as much as direct effect....... nothing wrong with that, I just mentioned it for interest. After the biggest surgery, there was pain which gradually faded over weeks. I was given various oral medications, which didn't bring a lot of benefit, although of course I can't say what I would have been like without. My point is, when I was busy either physically or mentally but not harassed ("stressed") either I didn't feel it at all or it was just strong sensation, not pain. It hurt worst while I was still in the hospital and not one of those conditions I listed for comfort (read 'em) was provided. Well, no, they didn't make me wear an Elizabethan collar, but apart from that.

It would be very nice to abolish all post-op pain, but my feeling is that whatever you do there will be some pain at the actual op site especially on stimulation (such as being prodded) and my doctor and surgeon and physiotherapist would definitely agree. In fact it is quite obvious that we do not abolish all such pain, otherwise all orthopaedic patients would go home on four sound legs.

What is pain? Never mind the dictionary definition of the word "pain", what is it actually? I'm not sure that I know, but I am sure that it is not at all simple.

Re: Medetomidine / ketamine anaesthesia in cats

james hunt — Sun, 10 May 2009 23:35:21 GMT

9 year old cat with renal insufficiency - I might be more inclined to use midazolam rather than ACP in premed, reserve NSAID administration until end of surgery if possible, judicious use of iv fluids, preferably monitoring blood pressure.