Fluid therapy: matching ins and outs.

RE: Fluid therapy: matching ins and outs.

Anthony Todd — Mon, 01 Aug 2016 18:23:32 GMT

Love to know why the above attracted the usual one star.

Don't mind being shown I'm wrong, honest.

You know, just because a paper is published doesn't mean it's gospel....

RE: Fluid therapy: matching ins and outs.

Anthony Todd — Mon, 01 Aug 2016 16:49:10 GMT

I thought someone would pick up on this:

Ostroski C, Drobatz K, Reineke E. Fluid Overload in 17 Cats with Urethral Obstruction: 2002- 2012. IVECCS Abstract 2013: 821.

FLUID OVERLOAD IN 17 CATS WITH URETHRAL OBSTRUCTION: 2002-2012

Ostroski C, Drobatz K, Reineke E

but nobody has, but then if someone quotes a paper, even just the title, it's taken as gospel...

Remember this was given as evidence that fluid overload was fatal so, when you break down the summary you get this:

Results: 17 cats were included in the study.

Median body weight was 6.7kg (range: 5.6-8.8), with a median BCS of 6.9 (range: 5-8).

On presentation, 4/13 (31%) were hypotensive;

12/16 (75%) were azotemic,

and 10/17 (59%) were hyperkalemic.

Heart murmurs were heard in 2/17 cats,

7/15 (47%) and 14/17 (74%) developed a murmur or arrhythmia during hospitalization respectively.

Positive fluid overload scores were noted in 8/11 (73%) (range 4-12.6) cats.

Underlying heart disease was diagnosed in 7/9 (78%).

Sixteen cats survived to discharge;

And the final bit:

one cat was euthanized after urethral obstruction recurrence.

So none of them died, even though they had various serious[?] problems...!!

I'd say it is evidence that "excess fluid" saves blocked cats rather than the reverse!

[Bear in mind some of the reports in the literature quote quite high death rates, or at least some deaths.....]

PS I can't find the actual paper and it may pay to read it all.

RE: Fluid therapy: matching ins and outs.

Anthony Todd — Fri, 29 Jul 2016 20:19:48 GMT

[quote user="Glen McIntosh"]What do you think most good, professional pilots are going to pay attention to: - a couple of old pilots saying that they have never experienced engine loss from a bird strike in all their flying years, even when they flew the plane directly into a flock of geese, so therefore bird strike is a load of malarky;[/quote]

I doubt if they'd be that dogmatic but they might quote:

However, according to the FAA only 15% of strikes (ICAO 11%) actually result in damage to the aircraft.

and say "we were lucky".....

[quote user="Glen McIntosh"]Conclusion: Fluid overload is a possible complication of treatment of feline urethral obstruction.[/quote]

Or, better?

Fluid overload is a likely complication of treatment of feline urethral obstruction in cats with undiagnosed heart disease??

Perhaps feline heart disease is a new phenomenon which is why fluid overload wasn't seen back in the day together with the fact that I/V fluids were less used, if at all?

RE: Fluid therapy: matching ins and outs.

Anthony Todd — Fri, 29 Jul 2016 20:07:56 GMT

[quote user="Glen McIntosh"]I can see a couple of opinions that there is a complete lack of harm with even gross excess fluid.[/quote]

With the greatest respect I and others have cited evidence of gross fluid overload which appeared asymptomatic, obviously normal cats, whereas the disasters quoted were obviously not normal cats. I realise the conditions were not disclosed or known.

[quote user="Glen McIntosh"](almost all were on less than 5ml/kg/hr)[/quote]

This really bothers me as it is a very low infusion rate.

Two references refer to infusion rates:

Provide the maintenance rate plus any necessary replacement rate at , 10 mL/kg/hr · Adjust amount and type of fluids based on patient assessment and monitoring.

(J Am Anim Hosp Assoc 2013; 49:149–159. DOI 10.5326/JAAHA-MS-5868)

and

be 20 to 40 ml/kg IV (one-half this amount for cats) for 15 minutes, followed by 70 to 90 ml/ kg (dogs) or 30 to 50 ml/kg (cats) administered over one hour.

http://www.ivis.org/proceedings/wsava/2006/lecture1/Schaer1.pdf?LA=1

As these unfortunate cats quoted had preexisting heart disease this may account for the deaths but the death may not necessarily be related to fluid overdose.

As I think these cats were referred it is likely that they were much more compromised by the time they were treated as has been seen in the death rates in blocked cats from a University referral centre.

Alternatively the small volumes quoted may explain why I, and others, never gave any fluids to blocked cats, back in the time of the great dried food "epidemic", yet never lost any, at least in my experience.

RE: Fluid therapy: matching ins and outs.

Glen McIntosh — Fri, 29 Jul 2016 16:43:34 GMT

[quote user="Anthony Todd"]there has been evidence of a complete lack of harm with even gross excess fluid[/quote]

I can see no such evidence anywhere in this thread (and that is probably because there is none in the literature).

I can see a couple of opinions that there is a complete lack of harm with even gross excess fluid.

But I can see several direct experiences of cats developing fluid overload.

I will add to those my own personal experience, which has included having to deal with at least 2 cats per year developing fluid overload that has been documented to have significant pulmonary oedema and/or pleural effusion on radiography. Around about 1/2 of these cases have occurred in post urethral obstruction cats. A fair few of them (but not all) went on to be diagnosed with heart disease by echo performed by a cardiologist, although none of them were identified as having heart disease prior to the fluid overload event. None of them were on excessively high fluid rates (almost all were on less than 5ml/kg/hr). Some of them died as a direct result of the fluid overload.

I have also seen several cases now where overzealous subcutaneous fluid administration has led to fluid overload and CHF.

All of these cases, though, have occurred since I have started working in Hong Kong in a large referral hospital. Prior to starting work here I don't think I can ever recall seeing a fluid overload cat case in the UK or Australia. I wonder if it is not something to do with inbreeding of cats in Hong Kong that predisposes them to heart disease, or whether being a large hospital we see more of those types of cases.

Whatever the reason, I am now much much more conservative in my approach to fluid therapy in cats.

I also would add the following evidence (although only an abstract):

Ostroski C, Drobatz K, Reineke E. Fluid Overload in 17 Cats with Urethral Obstruction: 2002- 2012. IVECCS Abstract 2013: 821.

FLUID OVERLOAD IN 17 CATS WITH URETHRAL OBSTRUCTION: 2002-2012

Ostroski C, Drobatz K, Reineke E

Department of Clinical Studies - PHL University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA, USA

Introduction: Feline urethral obstruction is a common reason for emergency hospitalizations and treatment with IV fluid diuresis. Fluid overload resulting in pulmonary edema and/or pleural effusion is a possible complication of aggressive IV fluid administration. The purpose of this study is to describe the development of fluid overload in a cohort of cats with urethral obstruction.

Methods: Medical records of cats (January 2002- December 2012) with urethral obstruction were reviewed for evidence of fluid overload. Fluid overload was defined as the development of pleural effusion and/or pulmonary edema while receiving IV fluids. Data recorded included: signalment, body weight (kg), body condition score, initial electrolytes, BUN and creatinine, initial hypotension, total IV fluid volume input and urine output, presence and development of a murmur or arrhythmia, underlying heart disease, treatment of fluid overload, and outcome. Fluid overload scores were calculated: (Total Fluids In - Total Fluids Out)/Admission Body Weight.

Results: 17 cats were included in the study. Median body weight was 6.7kg (range: 5.6-8.8), with a median BCS of 6.9 (range: 5-8). On presentation, 4/13 (31%) were hypotensive; 12/16 (75%) were azotemic, and 10/17 (59%) were hyperkalemic. Heart murmurs were heard in 2/17 cats, 7/15 (47%) and 14/17 (74%) developed a murmur or arrhythmia during hospitalization respectively. Positive fluid overload scores were noted in 8/11 (73%) (range 4-12.6) cats. Underlying heart disease was diagnosed in 7/9 (78%). Sixteen cats survived to discharge; one cat was euthanized after urethral obstruction recurrence.

Conclusion: Fluid overload is a possible complication of treatment of feline urethral obstruction.

[quote user="Anthony Todd"]Given that it is likely that cats can cope with vast excess [fluid] it seems that it is safe to give too much rather than too little, and the cat may benefit from this more.[/quote]

I disagree with this statement pretty strongly. There is weighty opinion and, I believe, evidence (especially in human medicine, but I do not have it to hand) that asserts that too excessive fluid administration has a detrimental overall effect and negatively affect outcomes (even for fluid rates that were previously considered beneficial - e.g. surgical fluid rates of 10ml/kg/hr).

Further, it is much easier to identify and correct hypovolaemia and dehydration (by turning up the fluid rate) than it is to try to identify and correct a fluid overload (simply turning down the fluid just won't cut it, and some of them will die, even with aggressive treatment).

But I think these statements have hit the nail on the head:

[quote user="Evelyn Barbour-Hill"]I remember being taught that it had been observed that domestic mammals could cope with 90ml/kg/hour – as long as – ay, there's the rub – its relevant homeostatic mechanisms were not already damaged......

......Nobody suggested that it was a good thing to do. If I'm making a point at all, it's just that the healthy body can cope with far more excess fluid than you might imagine.[/quote]

and:

[quote user="Kate Richardson"]Regarding fluid therapy in cats, the reason for caution is that subclinical cardiac disease is common and being sub clinical, you can't tell which cats have it; they may not even have a murmur. The prevalence of HCM appears to be around 15% in the general cat population. So whilst may cats will cope with large volumes of IV fluids, it is important to remember that some cats can't. If high volumes are indicated then fine, but remember to monitor closely and act accordingly if you start seeing signs of volume overload[/quote]

I think the reason behind your observation:

[quote user="Anthony Todd"]

Trouble is, on vetsurgeon.org, is there is often negative reasons given for most suggestions and hardly ever positive ones so that, in this present thread, even so there has been evidence of a complete lack of harm with even gross excess fluid, the negative comments may prevent cats' getting adequate fluid.

Usually the negative or cautionary posts get more stars than the positive ones.... [see aboves]

[/quote]

is that as veterinary professionals they pay us the big (ok, fairly average sized) bucks not for the safe recovery of the 99 cases that go well no matter how much fluid you give them, but for the safe recovery of the 1 in 100 (or whatever) cases that will go pear shaped. And, of course, for doing no harm.

*****Laboured metaphor warning*****

I know you are a fan of aviation, so I will try make a comparison with the aviation industry. I think pilots are also in a similar situation in that they really earn their money, not for the 99 flights that are so incredibly routine that the main issue for them is staying awake, but for the 1 in 100 (or whatever) flights where it is not so routine (e.g. having to land in a storm). During those flights they earn their money and keep the plane in the air usually (and preferably) NOT by heroic flying but by avoiding by knowing how to avoid situations that will lead them to have to undertake heroic measures (e.g. diverting to another airport rather than flying directly into a storm to land).

Most of the time (999 times out of 1000 or whatever), an average pilot will be able to land their plane in a storm without any problems. But for a good, professional pilot (the vast majority of pilots I hope), "most of the time" is unacceptable, and not what we pay them for, and they will divert to another airport rather than fly into a storm to land.

What do you think most good, professional pilots are going to pay attention to: - a couple of old pilots saying that they have never experienced engine loss from a bird strike in all their flying years, even when they flew the plane directly into a flock of geese, so therefore bird strike is a load of malarky; - or pilots who have actually experienced engine failure from a bird strike (let alone Sully Sullenberger and his experiences over New York city), along with references to prevailing current opinion regarding the incidence of bird strike?

RE: Fluid therapy: matching ins and outs.

Anthony Todd — Thu, 28 Jul 2016 23:25:27 GMT

Usually the negative or cautionary posts get more stars than the positive ones.... [see aboves]

Given that it is likely that cats can cope with vast excess [fluid] it seems that it is safe to give too much rather than too little, and the cat may benefit from this more.

PS Although blocked cats were never given fluid after of before unblocking, back in the day, and I'm not suggesting that this was, in any way, good practice, I do not know of a single cat that died after unblocking, which was always done ASAP, which, we thought, was key.

RE: Fluid therapy: matching ins and outs.

Kate Richardson — Thu, 28 Jul 2016 21:16:55 GMT

Regarding fluid therapy in cats, the reason for caution is that subclinical cardiac disease is common and being sub clinical, you can't tell which cats have it; they may not even have a murmur. The prevalence of HCM appears to be around 15% in the general cat population. So whilst may cats will cope with large volumes of IV fluids, it is important to remember that some cats can't. If high volumes are indicated then fine, but remember to monitor closely and act accordingly if you start seeing signs of volume overload

RE: Fluid therapy: matching ins and outs.

Rob Loxley — Thu, 28 Jul 2016 19:31:24 GMT

[quote user="Anthony Todd"]As has been shown here "massive" apparent overdose in cats doesn't seem to cause problems[/quote]

A lot of the time you will get away with it as the renal and cardiovascular systems are good at coping; when they aren't you will get bitten. Likewise many drugs you can give overdoses without ill effect but that's no reason not to work out and aim to give the right dose?

As for the OP who asks [quote user="Elizabeth Billimore"]how do you know that the volume replaced isn't going to cause diuresis in itself[/quote], I'm not sure why giving fluid should promote excessive 'diuresis' - unless for very extended periods e.g. the psychogenic polydipsia dogs where you get renal medullary washout over time?

We estimate the animal's current fluid deficit and think how long to restore that over and estimate ongoing needs/losses and add these together. Then adjustments based on clinical status. I tend less and less to leave indwelling catheters in post-obstruction, and even when I did found closed collection systems more trouble than benefit.

The AAHA guidelines are worth reading here https://www.aaha.org/public_documents/professional/guidelines/fluidtherapy_guidlines_toolkit.pdf for what is currently recommended

RE: Fluid therapy: matching ins and outs.

Anthony Todd — Thu, 28 Jul 2016 18:02:54 GMT

[quote user="Joyce Whitehead"] I know it is n=1 but it could have been a dead one! [/quote]

As has been shown here "massive" apparent overdose in cats doesn't seem to cause problems, in the few cases quoted, and it may well be that what is said to be an overdose actually isn't and, in the cases quoted, where there were apparent problems there may have been compromising conditions.

I can't find my very old textbook but I seem to recall the recommendation for "fluid therapy" was 2cc/lb[?]/hr sub cut slowly, so times and recommendations can change!!

Does anyone measure CVP in cats, 'cos that is, I understand, the best way to measure fluid overdose.

RE: Fluid therapy: matching ins and outs.

Joyce Whitehead — Thu, 28 Jul 2016 17:30:44 GMT

I would agree Martin that normally this would cause no issues, but on this occasion it did, and the figures were correct. He recovered fully once fluids were withdrawn, no evidence of underlying disease (he was anorexic and mildly dehydrated off the top of my memory). It's just made me a touch more cautious. I know it is n=1 but it could have been a dead one!

RE: Fluid therapy: matching ins and outs.

Robin Grimmer — Thu, 28 Jul 2016 13:46:56 GMT

[quote user="Martin Atkinson"]

[quote user="Joyce Whitehead"]

I've had two cats in recent years with over perfusion issues. Both adults, approx 4kg. Can't remember all the details off the top of my head, but one was only on 40ml/hour for 2 hours before getting signs of pulmonary oedema. No obvious underlying cause. But it's made me more cautious.

[/quote]I frequently give cats fluids at that rate, even with total renal failure, with no issues, in fact if it wasn't going in that fast in a dehydrated cat I would not expect it to benefit. Either your figures are wrong or the cat was already severely compromised.

[/quote]

Actually for treating dehydration you want to give fluids more slowly so it has got time to get in to the interstitial fluid and cells.

RE: Fluid therapy: matching ins and outs.

Rob Davis — Thu, 28 Jul 2016 13:10:37 GMT

[quote user="Anthony Todd"]

Can you give us the details, weights, rates, times and the condition of the cat's circulation too, if known etc because this is actual evidence and there has been very little so far....

Approximate values are fine.

[/quote]

Approximate from memory: can't remember weight of cat but had approx 180ml normal saline given in one hour (24xmaintenance rate). Cat was in for thyroidectomy having been stabilised medically. As it was a (controlled) hyperthyroid cat there was likely to be some degree of HCM, although the cat had certainly not shown any signs of CHF prior to this.

RE: Fluid therapy: matching ins and outs.

Martin Atkinson — Thu, 28 Jul 2016 13:00:03 GMT

[quote user="Joyce Whitehead"]

RE: Fluid therapy: matching ins and outs.

Anthony Todd — Wed, 27 Jul 2016 20:27:41 GMT

[quote user="Joyce Whitehead"]40ml/hour for 2 hours [/quote]

Is that 80mls over 2 hours or 320ml over 2 hours? [ie per Kg or total fluid]

Why were the cats on fluids?

What were the outcomes?

RE: Fluid therapy: matching ins and outs.

Joyce Whitehead — Wed, 27 Jul 2016 20:11:52 GMT

RE: Fluid therapy: matching ins and outs.

Anthony Todd — Wed, 27 Jul 2016 20:09:08 GMT

[quote user="Rob Davis"]I would never be blasé about over-infusing cats.[/quote]

Can you give us the details, weights, rates, times and the condition of the cat's circulation too, if known etc because this is actual evidence and there has been very little so far....

Approximate values are fine.

RE: Fluid therapy: matching ins and outs.

Rob Davis — Wed, 27 Jul 2016 18:29:33 GMT

I have seen a cat drowned following a fluid rate miscalculation. The cat was on a pump but the wrong rate was entered and it was given 24 hours maintenance dose in one hour. I appreciate N=1 and this was a serious overload, but it was a very bad day and I would never be blasé about over-infusing cats.

RE: Fluid therapy: matching ins and outs.

Evelyn Barbour-Hill — Wed, 27 Jul 2016 16:45:30 GMT

[quote user="Anthony Todd"]Sorry, and in the spirit of EBM, this sounds like the usual "teaching" information which probably is based on another opinion in a textbook and not on any evidence.[/quote]

It was actually presented in a Congress lecture, it was Jerry Lucke who presented it and experts of the day in the audience agreed, and it was simply the information that the observations had been made. It wasn't based on any textbook because there was only one textbook about fluid therapy at that time, which did not mention this point. Nobody suggested that it was a good thing to do. If I'm making a point at all, it's just that the healthy body can cope with far more excess fluid than you might imagine.

RE: Fluid therapy: matching ins and outs.

Anthony Todd — Wed, 27 Jul 2016 16:08:00 GMT

Sorry, and in the spirit of EBM, this sounds like the usual "teaching" information which probably is based on another opinion in a textbook and not on any evidence.

For students, who never challenge anything because, by definition, they have no Experience or Evidence it is obvious that they must be given some idea but I wonder how dangerous 100ml/Kg/hour would be.

RE: Fluid therapy: matching ins and outs.

Anthony Todd — Wed, 27 Jul 2016 15:43:32 GMT

[quote user="mariette asselbergs"]thrombus had been either dislodged or pushed aside or bypassed or what, it recovered![/quote]

It seems to me that increasing the blood pressure or perhaps dilating the aorta may well dislodge an obstruction??

RE: Fluid therapy: matching ins and outs.

Anthony Todd — Wed, 27 Jul 2016 15:41:16 GMT

[quote user="mariette asselbergs"] Two experienced vet surgeons with usually opposite opinions,[/quote]

Apart from the fact that we are always both right.

But, and as usual, it depends on where and if the "authorities" have based their dogmatic view; on "evidence" or because it makes sense to assume that a "gross overdose" actually is harmful.

I don't think the other poster [no names in the new peace and harmony era] made his view up and the third poster agrees too, and the the opinions are EBM.....

I don't think any of we three were irresponsible or suggesting that cats should get unlimited fluid I/V.

I wonder, as they seem to tolerate apparent gross overdose well and not badly, whether the results, when a lots of fluid are needed, eg to lower parameters after a blocked cat is relieved, will actually be better.

As I said before, I hope others here will add to the Evidence Base, not opinion or quotation, but evidence of harm.

RE: Fluid therapy: matching ins and outs.

Evelyn Barbour-Hill — Wed, 27 Jul 2016 15:40:37 GMT

I remember being taught that it had been observed that domestic mammals could cope with 90ml/kg/hour – as long as – ay, there's the rub – its relevant homeostatic mechanisms were not already damaged.

RE: Fluid therapy: matching ins and outs.

mariette asselbergs — Wed, 27 Jul 2016 11:27:12 GMT

Ha, that is REALLY interesting! Two experienced vet surgeons with usually opposite opinions, agree on something that is against the modern "evidence based" teachings. How heavy must that count as evidence? I can add to it another of my n=1 experiences, which was a cat with a thromboembolus on fluids, and at some point in order to flush the catheter we put it on 80ml/hr (a 3 kg cat), meant for only a minute, and then distracted and forgot and realised two hours later! Cat was fine, and thrombus had been either dislodged or pushed aside or bypassed or what, it recovered!

Mariette

RE: Fluid therapy: matching ins and outs.

Martin Atkinson — Wed, 27 Jul 2016 10:07:27 GMT

For once I (partly) agree with Anthony. I've found its almost impossible to over-infuse cats unless they are anuric/in total renal failure. I'm very unscientific about it I'm afraid, it becomes the art of veterinary science and by various parameters: clinical signs of dehydration, weight, urine output based on fullness of bladder/frequency of urination have a guesstimate. Seems to work for me, frustrates my nurses who are filling in charts and not much help for the OP.

RE: Fluid therapy: matching ins and outs.

Anthony Todd — Mon, 25 Jul 2016 17:03:58 GMT

[quote user="mariette asselbergs"]Strange that you mention that cats are good dealing with overloads, whereas I think the general opinion based on evidence is now that cats are really bad with dealing with too much fluids and at risk of getting pulmonary oedema easily. In all my CDs and courses of the last years lecturers stress this risk.[/quote]

[see addressing a post to the poster instead of the thread could upset some but not me..]

I'd be interested to hear other's experience on "gross fluid overdose in cats" because my experience of a few animals where those slidey roller regulators failed was that the cat seemed unaffected, although we used to panic.

I'm not suggesting a litre flat out to a small cat but they seem very tolerant IMHO; I'll wait to get slammed again.

We did try not to leave indwelling catheters in blocked cats, and I never did because they always gave one disaster or another; the critical thing is to get the cat emptying its bladder itself ASAP.