Fluid rate under anaesthesia

Re: Fluid rate under anaesthesia

Siobhan Steven — Mon, 28 Jan 2013 07:48:07 GMT

This may be a bit late, but hope it helps...we need to understand why we are providing fluid therapy, assuming we are not replacing blood or amending a truly hypovoleamic or a coagulopathy we are usually helping to optimise perfusion of the vital organs under anaesthesia using Lactated Ringers Solution or Hartmann's (crystalloids).

Prior to Sx the dehydration status of the patient should be determined, this can be done by physical exam (tacky MM's, tenting skin etc) and a PCV/TP.

The easiest way to assess the efficacy of IVF therapy during Sx is by monitoring blood pressure, a mean blood pressure above 60mmHg (prefer 75-90mmHg) indicates adequate perfusion, so, your fluids should be administered at 10ml/kg/hr, if overperfussion becomes apparent during the procedure the fluids may be titrated down, I still only go down to 5ml/kg/min.

Volume overload may occur in a prolonged 'non invasive' surgery, so say a TPLO by a surgeon who is atraumatic (don't we wish they all were?!), therefore the patient isn't haemorrhaging, if for some reason the Sx went for say 3 hours due to some complication but BP wasn't compromised there may be overperfussion. How can you tell? Fluid dripping from the patients nostrils, I squeeze the nostrils together at the being of the GA to get a baseline feel of the 'wetness' of the patients nose, and if fluid is trickling out some time later I titrate the fluids down, increased lacrimation, subcutaneous edema, chemosis ('bulging' eyes), increased lung sounds and increased respiration are indicators of excess IVF delivery. You also run the risk of diluting the RBC's and plasma proteins (hemodilution) with excessive IVF.

We monitor all our patients BP and all our patients get IVF, you would be surprised how many of them suffer from hypotension, this can be due to the drugs administered ACP and Isoflurane for example, or physiological compromise, we never really know how many of these patients end up with organ compromise due to a badly managed GA, whether its 'just a desexing' or 'just a dental'.

This is a VERY simplistic breakdown on fluid therapy for non compromise elective surgery, there so much more to it...

Re: Fluid rate under anaesthesia

Celine — Tue, 11 Dec 2012 13:26:18 GMT

We use 10ml/kg/hr also, although most of our animals are not actually being opened up. We tend to be doing a GA if an animal is unwell or injured, so we can get our hands on it to get bloods, rads etc - guess you could argue that they benefit from this level of IVFT as they are compromised / dehydrated already though...?

Re: Fluid rate under anaesthesia

Emma Wills, Cert AVN (Anaesthesia) RVN — Mon, 10 Dec 2012 22:45:46 GMT

Hi there,

We don't routinely put our spays and castrates on IVFT but any animal that has been starved overnight, presents as 2% deH2o before the off. If we did however, surgical rates are 10ml/kg/hour. Monitored throughout with Capnograph and oesophageal steths and obs.

This is something I would like to change in practice but cost wise, I don't see it happening. We offer food and water straight after surgery when the patient is holding their own head and a good level of consciousness.

Great topic though, good to know what others are doing. (I know I'm a bit late in replying lol)

Re: Fluid rate under anaesthesia

Claire Bloor — Tue, 23 Oct 2012 23:58:32 GMT

Generally use 10ml/kg/hour...monitor BP/pulses etc...titrate fluids accordingly.

We definitely have to think about loss of fluids / evaporation from body cavities etc, but also remember that whether they are healthy patients or not, and despite the length of their surgery, if they are being given various GA meds there will be negative physiological changes caused no matter what, e.g. hypotension amongst other things, so IVFT should be used to maintain adequate circulating volume, GFR and tissue perfusion.

Re: Fluid rate under anaesthesia

Susan Jackson — Sun, 14 Oct 2012 23:17:52 GMT

I've always been taught 10mls/kg/hr on healthy animals 5mls/kg/hr with ones with heart disease. It's not about just maintaining the fluid but keeping perfusion and maintaining blood pressure. The rate of course goes back down once they are recovering.

Also if you think about it, animals are usually withdrawn from fluids and don't usually eat or drink for a few hours post op. Maintainance won't be enough to replace those losses.

Re: Fluid rate under anaesthesia

Jenny Cook RVN — Sun, 14 Oct 2012 13:35:31 GMT

My practice use 4xm for surgical procedures and BP is monitored throughout ans the fluid rate adjusted where necessary.

Re: Fluid rate under anaesthesia

xhappysvn21x — Sat, 13 Oct 2012 16:47:52 GMT

[quote user="Sparky"]

We put all our patients on fluids, just protocol....just not cat castrates.....

[/quote]

curious, how much does the client pay out for a routine procedure with fluids? noticing more companies are now doing discounted memberships making cheaper bills. for example a cat spay - £30.00.

Re: Fluid rate under anaesthesia

Juliet Drummond DAVN (med) RVN D32/33 — Fri, 12 Oct 2012 22:28:32 GMT

i use 5ml /kg/hr for gaseous anaesthesia. i work in medical referral. our medics use 5x maint or 10ml/kg/hr. i monitor bp throughout, and adjust rates accordingly.

Re: Fluid rate under anaesthesia

Phrin Vernon RVN — Fri, 12 Oct 2012 21:36:25 GMT

[quote user="Steph Worsley"]

[quote user="Phrin Vernon RVN"]

I have always been taught to use 10mls/kg - it kinda makes sense - they are loosing loads of fluid thru open op site etc, whereas maintenance only to my mind is for a healthy animal not undergoing surgery... don't want to disagree with Steph tho... lol

[/quote]

technically in my mind though in a nice routine op they shouldn't be losing too much fluid, especially not 10ml/kg/hr worth of fluids,

I have just looked in my anaesthesia book in that they go between us both and say 5-10ml/kg/hr for routine surgery

[/quote]

7.5ml/kg/hr then :D

Re: Fluid rate under anaesthesia

Sparky — Fri, 12 Oct 2012 21:32:59 GMT

We put all our patients on fluids, just protocol....just not cat castrates.....

Re: Fluid rate under anaesthesia

FINNIGAN — Fri, 12 Oct 2012 20:53:46 GMT

sorry, dont know why that went on twice!!

Re: Fluid rate under anaesthesia

FINNIGAN — Fri, 12 Oct 2012 20:53:11 GMT

we dont put our castrates and spays on fluids, never have done unless there are any problems, which ther arent

Re: Fluid rate under anaesthesia

FINNIGAN — Fri, 12 Oct 2012 20:51:39 GMT

as a rule we dont put our spays and castrates on fluids

Re: Fluid rate under anaesthesia

Steph Worsley — Fri, 12 Oct 2012 20:51:20 GMT

[quote user="Phrin Vernon RVN"]

[/quote]

technically in my mind though in a nice routine op they shouldn't be losing too much fluid, especially not 10ml/kg/hr worth of fluids,

I have just looked in my anaesthesia book in that they go between us both and say 5-10ml/kg/hr for routine surgery

Re: Fluid rate under anaesthesia

Phrin Vernon RVN — Fri, 12 Oct 2012 20:40:19 GMT

Re: Fluid rate under anaesthesia

Steph Worsley — Fri, 12 Oct 2012 19:41:50 GMT

We don't see any truely "healthy" patients, however for the ones who aren't dehydrated/needing fluids for any other reason we would just provide maintenance fluids,