surgical fluid rate

Re: surgical fluid rate

Siobhan Steven — Thu, 08 Aug 2013 09:55:30 GMT

Yes, so for example if you have a 25kg dog you put 4 x its Sx rate (1000ml) as the 'rate' and 250 ml as the 'volume'. We have Baxter Colleague CX pumps and its the easiest way to do it (and explain to students!), to do the fluid 'challenge' we input 1200mls as the rate and the Sx rate (250ml for example) and start it.

Again, the fluid therapy plan for a cat is a complex issue, as you have to understand why you are delivering the fluids, what type of fluids should be delivered for the 'why', at what rate, what underlying issues there are with the patient etc. So I wouldn't say 'yes thats the rate I deliver to cats' because I would hate to say that and then a cat with HCM gets fluid overload, or pulmonary problems etc. In general you can give a bolus to cats but I am more conservative and monitor them closely.

If anyone is interested in Fluid Therapy I would recommend you look at 'vetmedteam.com' click into the 'CE Catalog' then 'Medical/Scientific CE Race Approved For Veterinary Technicians', you will see the courses on offer, 'Basic Principles Of Fluid Therapy & Transfusion Medicine' is available on demand. I haven't done this course but I have taken many of their courses and they are very good, you could then move on to the advanced course.

Also, I can recommend 'vet education.com.au' Phillip does have a Fluid Therapy, I did it years ago, you could email him and ask when it will be offered next, he is great! Hope that helps. :)

Re: surgical fluid rate

Laura Moss — Wed, 07 Aug 2013 15:00:08 GMT

Hi Siobhan the second way of giving a fluid bolus was 10ml/kg/hr over 15mins. I don't seem to understand this did you mean 10mls/kg over 15mins ? Also would you give the same (10ml/kg) for cats? Thanks Laura

Re: surgical fluid rate

Siobhan Steven — Wed, 07 Aug 2013 12:12:55 GMT

There are various interpretations of a fluid 'bolus' or fluid 'challenge', to be honest with you where I work we deliver a bolus in a couple of ways. We have fluid pumps, so we normally deliver surgical rates at 10ml/kg/hr (assuming its not contraindicated). Our pumps max out at 1200 mls, so if we want a fluid challenge we will input the rate at 1200 for the patients Sx rate fluids. So a 20kg dog would get 1200mls for 200mls if that makes sense. The other way we deliver a bolus is the rate at 10 ml/kg/hr over 15 minutes and assess the patient.

The 'shock rate' administration' of fluids has been readdressed but is quite a long winded discussion, however it is admirable that hypotension is monitored and addressed to any extent so good for you guys!

Re: surgical fluid rate

Craig McDonald — Wed, 07 Aug 2013 00:15:44 GMT

I had a patient go down to a worryingly 46mmHg on Monday, we don't have dopamine/dobutamine being in charity practice so we just lighten anaesthetic and go for shock rate fluids (Hartmanns) cats 60ml/kg/hr and dogs 90ml/kg/hr. Our patient was a cat so we did this for 10/15mins and it went back up to 60mmHg so we then reduced the drip. Is this the same shock rate fluids that anyone else does? I worry about keeping them on that high rate for too long as don't want to over infuse them.

Re: surgical fluid rate

Laura Moss — Mon, 05 Aug 2013 16:14:09 GMT

Hi could I please ask when you give a bolus of fluids due to hypotension (after assessing the situation) how much do you give and over what length of time?

Re: surgical fluid rate

Siobhan Steven — Mon, 22 Jul 2013 12:40:11 GMT

Hmmm, I tend to think it is quite a god 'gross' indicator of fluid overload, or it would be there from induction, it may be harder to perceive in smaller patients due to the anatomy (cats) or relative smaller size of patient therefore less obvious, I don't see it in, say, the elective desexing, but as I said, if indiscriminate fluid administration allowed during prolonged surgeries it is quite apparent, whichever ever way we look at it we are trying to optimise MAP to maintain organ function throughout and after surgery, without compromise to the patient, it is a 'fluid' situation, and therefore in the 'science' of anaesthesia we have to analyse on a case by case and patient by patient basis to some extent, as we know, our patients don't read the rule book! :)

Re: surgical fluid rate

Susanna Taylor — Mon, 22 Jul 2013 11:57:03 GMT

Good points Siobhan!

Prob worth mentioning as well that paediatric patients rely more heavily on heart rate to determine blood pressure then adult animals, so anticholinergics should be used sooner rather then later in bradycardic puppies (and kittens)

Also, interesting to hear you mention about fluid leaking from nose as a sign of fluid overload... Ive heard many differing opinions about this over the years, and I stress opinions, as I have never come across any evidence for it.. have you? My query with it being a reliable indicator is that you only every really see it in large (maybe medium) dogs... surely we would see it more in cats and small dogs if the same fluid rates were causing overload in them? I tend to think it is more likely just normal nasal secretions that are more volumus in large dogs and therefore drip out... Interested to hear others thoughts!

Re: surgical fluid rate

Siobhan Steven — Mon, 22 Jul 2013 10:54:12 GMT

It's worth keeping in mind that hypotension may be due to one of, or a combination of a few factors. For example, you may have hypotension in response to a lack of cardiac output due to bradycardia, you would treat this completely differently to how you would treat hypotension due to hypovoleamia.

So if you had a medium breed dog who had a heart rate of 34BPM and a MAP of 55mmHg there is a fairly strong indication that bradycardia is causing a decrease in CO, so an antycholenergic could be administered (atropine or glycopyrolate at 0.01 mg/kg IV).

If you had just suctioned 3 1/5 L of blood (as happened in a haemabdomen of mine the other day) you obviously wouldn't be administering an antycholenergic...it is a volume issue so at the least bolus fluids, but preferably Whole Blood/Plasma, colloids etc...lots and lots...and phenylephrine/ephedrine/dopamine to assist in contractility.

Also, vaso-dilation can lead to hypotension, all the blood floating around in bigger 'hoses'! Thats how I explain it to the vet students, garden hoses (normal vessels) vs 'fire hoses' (vaso dilation) so if you think of the amount of water you have to force down a fire hose to get a high pressure vs a garden hose you get the picture :) (ACP the guilty drug as is isoflurane, I shy away from ACP as much as possible, I love medetomidine...)

As far as surgical rate fluids are concerned, we aim to maintain MAP above 60mmHg, and generally run our IVF at 10mls/kg/hr for most elective procedures, however for say a 4-6 hour hip replacement assuming BP is good I will titrate my IVF as I don't want to fluid overload my patient, so I squeeze the patients nostrils as I monitor, to feel for fluid 'leaking' out the nostrils, also look for increased lacrimation, bulging eyes, edeama (puffy face under the drapes!) I will drop the rate to 5ml/kg/hr or sometimes maintenance rates, assuming there is no contraindication.

Usually the course of action to assist in correcting hypotension is, check the depth of your patient and lower the % of volatile agent being delivered, give fluid bolus (not ad nauseum though = fluid overload...). Administer dopamine at 5-10ug/kg/min CRI, give an anticholinergic if bradycardic...and onwards from there depending on the cause of hypotension.

I hope this makes sense? Just had a big day at work...

Re: surgical fluid rate

Susanna Taylor — Fri, 19 Jul 2013 22:06:23 GMT

Found it- http://www.jaaha.org/content/49/3/149.abstract

You have to subscribe or pay to view, but it is worth it as its a good paper.

in summery, the authors suggest initially starting at 3 mL/kg/hr in cats and 5 mL/kg/hr in dogs.

Re: surgical fluid rate

Susanna Taylor — Fri, 19 Jul 2013 21:33:49 GMT

HI Nick - Good find but unfortunately this is a USA licensed product. I doubt you would be able to get it in the UK even under cascade. Would be interested to know if anyone does tho.

Laura - bear with me, digging through trying to find a useful paper or 2. And regarding your original question, as I understand it, critical hypotension is defined as mean below 60mmHg as below this the organs (particualarly of concern the kidneys) can not auto-regulate their BP so damage occurs. My general treatment plan would be (after discussion with VS...) reduce iso/sevo (incr analgesia if required), increase/bolus crystalloids, bolus colloids (if available, which they arnt...), start pressor therapy (dobutamine/dopamine). In very sick cases vasoconstrictors can be used such as noradrenaline...

Generally hypotension under anaesthesia is caused by relative hypotension, caused by vasodilation from iso/acp ect. So a reduction of this will usually work with appropriate fluid support. Always consider that an additional analgesia need is the reason iso/sevo too high and causing hypotension...

With cardiac cases, depending on level of disease, I would start fluid levels very low 2-4ml/kg/hr (for more sever cases) and carefully titrate upwards if needed. For surgical cases, a fentanyl infusion is really handy as it allows you to bring the iso/sevo very low.

Re: surgical fluid rate

Nick Shackleton — Fri, 19 Jul 2013 17:34:29 GMT

Cheers Suzanne. Only work in a branch surgery doing nurse clinics as weekends these days. Have just googled and come across this...... http://www.abbottanimalhealth.com/veterinary-professionals/products/fluid-therapy/solutions/colloids.html

Re: surgical fluid rate

Laura Moss — Fri, 19 Jul 2013 01:56:25 GMT

Hi Susanna I would be interested in the references. Also which colloid do you guys use now? Thanks Lauraemoss9@hotmail.com

Re: surgical fluid rate

Susanna Taylor — Thu, 18 Jul 2013 21:59:57 GMT

Just to mention that Voluven (hetastarch colloid) has recently been recalled and removed from the human market, meaning it is also now unavailable top the vet market as it could only be used under the cascade. More info here: http://www.ava.eu.com/news/uk-commission-on-human-medicines-suspends-use-of-hes/ and a statement from the AVA with other suggested treatments, such as they are...

Also, although 10ml/kg/hr has historically be used for surgical fluid rates, there is no evidence to support this figure and in fact some evidence is now appearing showing that this is probably too much. Most vet anaesthetists are now using 5ml/kg/hr and titrating up if hypotenison as others have mentioned above.

Can dig out some references if anyone interested...

Re: surgical fluid rate

Nick Shackleton — Thu, 18 Jul 2013 17:55:07 GMT

Used to use Hetastarch. I'm sure there are a number of other starch based colloids available. Have used Voluvens but as posted in other places on the forum this has been recalled. Mean Blood Pressure: 70 – 100 (dog) 60 – 90 (cat). Look for trends in hypotension rather than one off lows. Bolus of crystalloid (10mls/kg), then assess response. If no improvement after 15mins give bolus of colloid (5mls/kg up to max of 20ml/kg/24hr)

Re: surgical fluid rate

Laura Moss — Tue, 16 Jul 2013 03:11:53 GMT

which colloids do you tend to use and what rate?

Re: surgical fluid rate

Nick Shackleton — Thu, 11 Jul 2013 18:32:30 GMT

We had vet anaesthesia specialist where I used to work so generally ran things passed him first especially where increasing fluids, boluses and colloids were concerned. Surgeons were usually up to their necks in the surgery

Re: surgical fluid rate

Lyndsay Kennedy — Thu, 11 Jul 2013 10:50:50 GMT

I tend to use 10ml/kg/hr as well, and when monitoring blood pressure, as Nick says, look for a trend rather than low readings. If I see my patients BP starting to drop (even if it isn't going below 90) I gradually lighten my anaesthesia at that point. We use Sevo, and I find even dropping it by 0.25% at a time can be enough to get them to a point where the BP remains relatively stable.

As with all my monitoring, I inform the vet as soon as I have any concerns about my patient and let them make a decision about how to deal with any situations arising.

Re: surgical fluid rate

Nick Shackleton — Sat, 06 Jul 2013 19:50:25 GMT

5-10mls/kg/hr. all depends on what procedure is being performed. With regards to hypotension. Ensure your blood pressure cuff is positioned correctly ie in line with the base of the heart. Non-invasive blood pressure is least reliable. Doppler is far more reliable. And then CVP and arterial blood pressure are gold standard monitoring. Look for trends rather than one of high/low readings. You can either give a bolus of crystalloid or give a bolus of colloid.

Re: surgical fluid rate

Lisa Goodship — Sat, 06 Jul 2013 06:48:26 GMT

Yes I also use 10 ml / kg / hr for surgical rates in both cats and dogs. If you had a cardiac patient I would steer clear of 0.9 % saline as your fluid of choice, we tend to use hartmanns for all our surgical procedures. Normal blood pressure systolic 90 - 160 mm hg, if it drops below this I would ccertainly increase my ivft rate and lighten my anaesthesia and just be aware is it bleeding related? It's really up to the vet when to intervine eg with dobutamine. Hope some of this helps, will be interested what others do.