Anaesthetic death of healthy cat with triple combi

Re: Anaesthetic death of healthy cat with triple combi

mariette asselbergs — Mon, 21 Oct 2013 13:28:57 GMT

Finally the [post mortem results. I am impressed what they do for £300!Extremely detailed report, macroscopic post mortem, swabs, tests for calici and herpes viruses, microbiology, faeces checked for parasites, histology off all organs. And a 2 page report. Absolutely NAD anywhere. All tests, cultures etc neg. No cause of death established. It said that peracute death often shows no symptoms on PM. The only suggestion they had was maybe death due to vagal inhibition.

I could imagine that in an abdominal operation but not in a castration?

In the olden days we always included atropine in the premeds, supposed to protect against vagal irritation, but then it turned out to cause more post op ileus so now nobody does that anymore.

Altogether I am glad there were no pre-existing conditions, otherwise I would worry forever about how to find them in all healthy looking youngsters for neutering.

Sending the report with sympathy card to the owners today, and the horrible thing is: both owners are elderly and facing surgery themselves...... Not easy to discuss unexpected anaesthetic death with them!

Mariette

Re: Anaesthetic death of healthy cat with triple combi

Mark Hedberg — Wed, 02 Oct 2013 20:29:16 GMT

[quote user="Alan Stevens"]

"The other thing to bear in mind, particularly with the smaller doses, is that when you draw up three drugs into one syringe you will draw up more of the first drug, as you have to fill the hub, you then draw up the correct amounts of the other two. As they mix in the syringe you will end up giving the cat slightly more than you intend of the first drug, and slightly less of the other two. Whether this makes any difference..."

[/quote]

Agree here - I think that's why people felt the 5mg/ml ACP dropped some patients like a rock. The 0.05ml you had in the hub was the equivalent of the dose you would give some small patients, and when you drew up the acp and then the bupe, you had far more acp than you intended.

Re: Anaesthetic death of healthy cat with triple combi

Alan Stevens — Wed, 02 Oct 2013 20:02:05 GMT

I agree with this sentiment. My standard triple for most cats, whatever the weight, is 0.15ml Medetomidine, 0.15 ml ketamine + 0.1ml Torbugesic drawn up and mixed in that order in 1ml syringe and given I/V only. But I am fully aware that the medetomidine dose is actually more than that stated as it also includes the volume in the needle hub. For fractious cats I double up the medetomidine and ketamine to 0.3ml each and give by i/m route.

Most cats can be spayed/castrated/sutured etc with this mix alone. O2 supplementation by mask or intubation. Isofluorane given at 1% if needed in some cases if required.

Never had any problems apart from the i/m dosed cat which kinked its airway during the process of induction.

I would suspect heart or respiratory obstruction/aspiration/vomiting as cause of sudden deaths.

Re: Anaesthetic death of healthy cat with triple combi

or3155 — Wed, 02 Oct 2013 12:43:31 GMT

Mariette - what a pain, anaesthetic deaths are pretty traumatic for everyone involved, but I totally agree, there are unknown risks with all anaesthetics and it looks like you were at the rubbish end of this bit of bad luck. I love DTK IM for healthy cat neuters, but I do tend to use even lower doses. I will normally use no more than 0.1ml (drawn up in an insulin needle) of each medetomidine (1mg/ml) Ketamine (100mg/ml) Butorphanol (10mg/ml) for any cat 3kg or above. Usually, this is sufficient to induce anaesthesia allowing intubation and spaying under low isoflourane concentrations and castration with or without intubation (although I usually intubate for piece of mind!). Occasionally, with the larger cats, I/V propofol will be needed as they will not anaesthetise with this dosage (although the profound sedation makes it pretty easy).

Off topic...capnography is brilliant. It gives information on breathing, circulation, correct intubation, circuit problems etc. What other single piece of equipment does all of that?!

www.capnography.com is a great website with loads of information and example traces and is a great learning resource for everyone thinking about getting, or already using capnography. It is aimed at doctors, but most of it is directly transferable to animals.

Just my 2 cents!

Re: Anaesthetic death of healthy cat with triple combi

Bob Russell — Tue, 01 Oct 2013 13:51:19 GMT

I will modify that statement to a 'good' respiration rate does not necessarily equate to good blood oxygenation.

Re: Anaesthetic death of healthy cat with triple combi

Anthony Todd — Tue, 01 Oct 2013 10:11:14 GMT

[quote user="Bob Russell"]Breathing does not equate to oxygenation[/quote]

Ok, I'll stop wasting energy then and just expire ;-)

Re: Anaesthetic death of healthy cat with triple combi

Bob Russell — Tue, 01 Oct 2013 09:43:12 GMT

I check the monitor regularly through a procedure. A glance at the trace is all that is needed when things are going well. We would generally expect to see changes before the alarms go off!

Breathing does not equate to oxygenation (rather CO2 build up for the capnograph!).

I would suggest anyone who has not used a capnograph gets one on loan to try (if you can). It was a real eye opener for us!

Re: Anaesthetic death of healthy cat with triple combi

Anthony Todd — Mon, 30 Sep 2013 23:24:13 GMT

[quote user="Andrew Kent"] Not sure this is quite true - I would expect to start seeing alteration in a capnograph well before apnoea so it should give you much earlier warning than an apnoea alarm.[/quote]

Back again, sorry, but I carefully made sure I said "apnoea or respiratory change" ie RR getting slower prior to apnoea.

The capnograph only alarms at a predetermined level and, let's face it, does someone stare at the screen all the time, I mean all the time?

Nah, they wait for the alarm, that's why it's there.

I'd love to see both instruments monitoring a gradual euthanasia together; the only way to compare.

Hope I'm not called back.

Re: Anaesthetic death of healthy cat with triple combi

Michael Woodhouse — Mon, 30 Sep 2013 23:14:38 GMT

[quote user="Bob Russell"]I don't like things that bleep if everything is OK![/quote]

www.youtube.com/watch

Invention number 2

(keep watching for the classic "women will like what I tell them to like" )

Re: Anaesthetic death of healthy cat with triple combi

Anonymous — Mon, 30 Sep 2013 22:53:25 GMT

Sorry for the messy reply - the quoting facility does not seem to worrk properly on my ipad....

Re: Anaesthetic death of healthy cat with triple combi

Anonymous — Mon, 30 Sep 2013 22:52:20 GMT

Surely you should have been able to tell the difference between irregular beeps from diaphragm or chest pressure and the regular beeps of normal respiration?

Mind you, and to be fair GDVs aren't the safest anaesthetics with a high mortality rate so perhaps it was an example, which we have been discussing, of a patient that suffered a cardiac arrest prior to respiratory failure?

I have never known Apalerts, or their clones, to beep when there is no air passing over the sensor. I've known the sensor to fail and ;beep when the sensor fails or the device is not charge.

We have had countless early warnings of possible complications when the beep stops or the frequency changes.It's a sensitive, reliable, foolproof indicator of anaesthetic or patient change which doesn't forget, ignore, or lose concentration when all sorts of distractions occur. Well, it is so long ago now, I cannot remember but I was concentrating hard, trying to figure out how to resect the necrotic areas of the stomach... I would still not use one again,although your comments make sense!

Re: Anaesthetic death of healthy cat with triple combi

Andrew Kent — Mon, 30 Sep 2013 22:42:49 GMT

[quote user="Anthony Todd"]

[quote user="Bob Russell"]Our capnograph lets you know in no uncertain way if the patient is apnoeic, CO2 goes too high or is too low.[/quote]

Don't want to flog a dying horse but, as the CO2 goes too high and the O2 goes too low well after apnoea or respiratory change, why not just endure those irritating bleeps.

You'll learn to love their reassurance, and get an early warning of trouble when all around you are distracted.

I'll get my coat....

[/quote] Not sure this is quite true - I would expect to start seeing alteration in a capnograph well before apnoea so it should give you much earlier warning than an apnoea alarm.

Re: Anaesthetic death of healthy cat with triple combi

Anthony Todd — Mon, 30 Sep 2013 22:24:41 GMT

[quote user="Bob Russell"]Our capnograph lets you know in no uncertain way if the patient is apnoeic, CO2 goes too high or is too low.[/quote]

Don't want to flog a dying horse but, as the CO2 goes too high and the O2 goes too low well after apnoea or respiratory change, why not just endure those irritating bleeps.

You'll learn to love their reassurance, and get an early warning of trouble when all around you are distracted.

I'll get my coat....

Re: Anaesthetic death of healthy cat with triple combi

Mark Holmes — Mon, 30 Sep 2013 21:51:56 GMT

Mariette and others - I see you wait 45 mins to give antisedan. Try this- use the im doses for Dom/torb ( or whatever opioid ) then the iv dose if Ketamine for the same body weight and give this iv. You don 't then need to wait 45 minutes. Very occasionally one will wait up chasing flies - but rarely.

Re: Anaesthetic death of healthy cat with triple combi

Yantha Smyth — Mon, 30 Sep 2013 19:36:03 GMT

Mariette, that is an awful thing to happen regardless of if an explanation is found or not- such an unexpected thing- although we all know the inherent risk of a GA, there are so many that do go right, and even really dodgy candidates, that it comes as a real shock for it to be an apparently fit healthy patient having a quick routine op.

I, like some others, am not a fan of the triple combi in general, but can see how convenient it can be. The majority of places I have worked have routinely used premed acp/opioid followed by propofol/mask. But as a locum I try to follow the protocol the practice uses, so have used the triple at times. The last place I was at used triple IV always followed immediately by intubation and O2 for castrates. The advantage of the IV admin I was told was a) they are on the table for induction under direct supervision, and b) the reversal can be given IM at the end of the procedure- ie not having to wait 45min post-IM; those things plus the intubation, O2 and nurse monitoring did make me feel more confident with it.

Will be interesting to know the PM result- bound to have been an underlying cardiac issue if anything.

Of course, as sods law would have it- so far (touch wood!) all the hundreds of greek cats I have done with ketamine-xylazine, unreliable fasting, no pre-op exams, unsavoury health status' have sailed through!!

Re: Anaesthetic death of healthy cat with triple combi

Bob Russell — Mon, 30 Sep 2013 17:50:40 GMT

I don't like things that bleep if everything is OK!

Our capnograph lets you know in no uncertain way if the patient is apnoeic, CO2 goes too high or is too low. Silence is golden IMO. We have an apnoea alert monitor but that now lives in a cupboard.

I would hate to be without a capnograph. Even the shape of the trace can hint when things are not right! Higher risk cases we will connect up the ecg leads!

Should add that we don't use any monitoring for cat castrates so we would have been in precisely the same situation as the OP. I am pretty certain that the nurse would have picked up the problem in the same way and we would have had the same panic stations, probably with the same sad outcome.

Re: Anaesthetic death of healthy cat with triple combi

mariette asselbergs — Mon, 30 Sep 2013 16:09:45 GMT

No PM result yet ..... But I'll post it as soon as it is in!

"my personal experience is that apnoea is an end product of other problems and some of the indicators of those problems are alterations in CO2 and blood pressure (grossly measured by peripheral perfusion - digital pulses). if you are actively monitoring the patient and charting values every five minutes you will see changes early and therefore take action to prevent the situation escalating." (Hanna Bennett)

Yes this is what we do with all other, intubated longer anaesthetics, but a cat castrate is normally injecting, 10 mins later on the table, nurse plucks and desinfects testicles while vet scrubs up, castration lasting 2 minutes and back in the box to recover. Antisedan 45 mins after the ketamine.

In my former life cat castrates always got a lighter anaesthetic, usually xylazine and acp (and atropine a LONG time ago). Since in UK every practice I worked in uses the triple cocktail and I have never had any problems with it, neither in cat spays.

This cat was never out of out sight from injection, and while I was cutting testicles the nurse noted no breathing and tongue getting blue. Then all out alarms and in full ressucitation mode.

What we also know now is that it came from a breeder who had had a lot of problems with sneezing and runny eyes in the kittens. But this one had none of that at time of castration or vaccinatios, and was a normal weight (3 kgs at 5 months), normal heart and lung sounds before anaesthetics.

Mariette

Re: Anaesthetic death of healthy cat with triple combi

Anthony Todd — Mon, 30 Sep 2013 00:11:01 GMT

[quote user="vetmeddeni"]In my old surgery, we had one of those resp monitors that bleeped with every breath - I have forgotten its proper name now because it is a most UNuseful piece of equipment! Operated on a GDV dog and my nurse ( and me) never noticed that he stopped breathing because we were relying too much on the alarm - it continued to "bleep" as I applied presure onto the abdomen....needless to say that the dog died ..., What is the result of the PM? Please post ASAP , Mariette! Very curious...

[/quote]

Surely you should have been able to tell the difference between irregular beeps from diaphragm or chest pressure and the regular beeps of normal respiration?

I have never known Apalerts, or their clones, to beep when there is no air passing over the sensor. I've known the sensor to fail and not beep when the sensor fails or the device is not charged.

Re: Anaesthetic death of healthy cat with triple combi

Anonymous — Sun, 29 Sep 2013 22:43:43 GMT

In my old surgery, we had one of those resp monitors that bleeped with every breath - I have forgotten its proper name now because it is a most UNuseful piece of equipment! Operated on a GDV dog and my nurse ( and me) never noticed that he stopped breathing because we were relying too much on the alarm - it continued to "bleep" as I applied presure onto the abdomen....needless to say that the dog died ..., What is the result of the PM? Please post ASAP , Mariette! Very curious...

Re: Anaesthetic death of healthy cat with triple combi

Stephen Courtney — Sun, 29 Sep 2013 22:38:58 GMT

[quote user="Anthony Todd"]

[quote user="Stephen Courtney"]Basic principles have the answer to almost everything...at a superficial level. At a deeper level, insh' allah.[/quote]

Sorry to respond, but we start off with a normal cat, totally asymptomatic as far as anyone knows, has an anaesthetic and dies.

Yet you say that this is caused by:

[quote user="Stephen Courtney"]Poor circulation, plus structural myocardial changes that degrade the ability for blood to flow through the myocardium itself, like fibrosis. And damage to the purkinje system, resulting in electrical abnormalities, QED.[/quote]

Hardly QED to me?

I don't understand how an anaesthetic, or sedative for that matter, can do this, bearing in mind that cardiac demand in a well oxygenated anaesthetised animal or human, because of accompanying low oxygen and circulatory demand, must be minimal and much lower than when conscious and leaping about.

People die in the street, and athletes collapse in marathons which I can understand, 'cos the heart is under maximum stress and probably starved of oxygen.

But totally relaxed, under a GA; I just don't get your explanation, or do they all have asymptomatic pre-existing pathology.

Paradoxically animals that have compromised circulations seem to cope with anaesthesia very well, it's usually the boisterous six month old lab. that's the one that dies suddenly without expectation.

[/quote]

The reason you get sudden death is because something was wrong that you did not know about. Cats can hide severe myocardial disease, that sometimes would not be picked up without at the very least an echo. when you add an anaesthesia onto a compromised cardiovascular system, then things are more likely to go wrong. Eating yourself about the exact physiological mechanism of death is pointless - but sudden death under GA is either a consequence of respiratory failure or a myocardial problem. Sedative and anaesthetic drugs cause profound alterations to all sorts of things, if you want to understand the details...there are places to look for this information. my explanation is a simplification, but suits my outlook on these things.

Yes, I believe that the unexplained GA death probably does have pre existing pathology, failing that an idiosyncratic drug reaction eg allergic reaction, or an iatrogenic issue eg mistake in technique, which seems unlikely in this case.

Should we echo every neuter as part of a gold standard pre GA assessment? Personally i don't think so. when the state of the art advances to hand held medical 'tricorders' that can be waved vaguely at animals/ people and instantly tell us everything...perhaps then there won't be any unexpected events.

Re: Anaesthetic death of healthy cat with triple combi

Anthony Todd — Sun, 29 Sep 2013 22:28:26 GMT

[quote user="Hanna Bennett"]

my personal experience is that apnoea is an end product of other problems and some of the indicators of those problems are alterations in CO2 and blood pressure (grossly measured by peripheral perfusion - digital pulses). if you are actively monitoring the patient and charting values every five minutes you will see changes early and therefore take action to prevent the situation escalating.

[/quote]

Sure totally agree; in a perfect world.

Try suggesting that pilots do away with audible alarms then.

And surely apnoea will be the early warning of a change in peripheral perfusion to come, as the pO2 falls and the pCO2 rises rather than the other way round?

Once the peripheral blood pressure starts to fall things are getting very critical, I mean way beyond apnoea, aren't they?

Re: Anaesthetic death of healthy cat with triple combi

Hanna Bennett — Sun, 29 Sep 2013 19:55:54 GMT

Re: Anaesthetic death of healthy cat with triple combi

Anthony Todd — Sun, 29 Sep 2013 19:48:31 GMT

[quote user="Hanna Bennett"]fingers on a digital pulse[/quote]

Aren't we back to asystole versus apnoea?

One notes changes in respiratory rate very quickly when the beep rate changes but, when the nurse or vet is distracted, a screen may not be studied for sometime.

When the beep rate changes with an audible signal the whole prep-room and theatre looked up back in the day....

As I've said before, why do you think pilots, with nothing to do but look at instruments and stay awake, have more audible alerts and alarms than the latest computer game?

Re: Anaesthetic death of healthy cat with triple combi

Hanna Bennett — Sun, 29 Sep 2013 17:17:03 GMT

I'm with Michael on the capnograph - early warning system if ever I saw one - you will see subtle changes on this well before anything else, including evidence that your tube is kinked which an Apalert isn't to give you til the animal has stopped breathing. Other than that my favourite piece of monitoring is a nurse with her fingers on a digital pulse. I'm not a fan of triples but think that is due to the lack of decent monitoring a lot of these get - jabbed and recovered in another room without anyone around to watch them in my experience in previous practices.

Re: Anaesthetic death of healthy cat with triple combi

Michael Woodhouse — Sun, 29 Sep 2013 15:00:13 GMT

[quote user="Anthony Todd"]Has it got an audible exhalation signal and an audible apnoea alarm?[/quote]

No bleep, but does have an apnoea alert. Never looked in the settings - I may be able to get it to bleep each breath.

We had one of the simple breathing monitors but I found the bleep loud and distracting - especially if you had a panting bitch spay.

An alarm if apnoea is fine by me.