Meloxicam surgical timing - an 'elephant in the room'?

RE: Meloxicam surgical timing - an 'elephant in the room'?

Carl Bradbrook — Wed, 22 Apr 2020 13:49:47 GMT

There is a wealth of evidence in human medicine for the development of chronic or maladaptive pain post surgery. Interestingly, the incidence depends on the type of surgery, as well as multiple other factors. What seems most important is the use of the concept of preventive analgesia, in this sense it is using appropriate analgesia for the entire peri-operative period as well as long as necessary in the recovery period (so dependent on procedure- maybe several weeks for certain procedures). They don't seem to use NSAIDs in the perioperative period in people- paracetamol is used extensively as well as application of local anaesthetic techniques.

Something else I also find interesting and relevant to this discussion are the other factors associated with the development of persistent post-op pain, such as mental well-being- just thinking about this in the context of one of our patients not being able to do what they enjoy (exercising, interacting with their owner, getting up to eat and drink) may also exert a negative impact on their recovery.

RE: Meloxicam surgical timing - an 'elephant in the room'?

Jennifer Whybrow — Tue, 21 Apr 2020 19:26:35 GMT

Has anyone personal experince of being given these drugs themselves in their own ops so they can speak from personal experince of the drawbacks of banging out pain vs having a little there (to make you rest) vs possibility of wind up, vs chronic pain syndrome developing.

RE: Meloxicam surgical timing - an 'elephant in the room'?

Anthony Todd — Sat, 18 Apr 2020 15:50:11 GMT

This thread is very valuable stuff and, although it isn't "in a paper", not published nor even peer reviewed, is obviously cutting edge and really relevant when you have a similar thing to do tomorrow [in normal times!!].

Don't knock "anecdotes"

RE: Meloxicam surgical timing - an 'elephant in the room'?

Carl Bradbrook — Sat, 18 Apr 2020 12:24:01 GMT

Thanks Rob for taking the time to ask some questions, some great points.

[quote userid="2235" url="~/001/veterinary-clinical/small-animal/anaesthesia/f/discussions/28453/meloxicam-surgical-timing---an-elephant-in-the-room/221831"]Without wishing to sound flippant, does it matter that we may miss some of these milder, reversible AKIs? Is there any evidence that it causes longer term problems?[/quote]

Good point about missing some of the AKIs, but we just don't know about long term renal or other organ damage and its extremely hard to quantify this. As I mentioned before we simply don't know how long you have to be hypotensive for and to what level to inflict organ damage, or what impact cumulative damage may have. We are fortunate to not see consequences in the majority of our patients, but definitely something to monitor for.

[quote userid="2235" url="~/001/veterinary-clinical/small-animal/anaesthesia/f/discussions/28453/meloxicam-surgical-timing---an-elephant-in-the-room/221831"]If the dog normally has NSAID in the morning, how do you achieve this along with fasting? Are you happy to give orally without food? Is the risk of adverse effects different between oral and injected NSAID?[/quote]

I normally approach oral NSAID dosing by giving them as soon as possible post anaesthesia. So if they were due in the morning we delay until the animal eats in recovery. This can then be timed the following day to move back to the morning, or if giving later in the day to the following evening. The risk of any adverse effect should not be related to the route of administration. What I find important is that if a patient is on long term NSAIDs that we should avoid them missing doses wherever possible (happy for a short delay).

[quote userid="2235" url="~/001/veterinary-clinical/small-animal/anaesthesia/f/discussions/28453/meloxicam-surgical-timing---an-elephant-in-the-room/221831"]Do you know what the speed of onset is for various NSAIDs? I don't have any figures, but my own observations would suggest that at least some of the time NSAIDs do appear to have a rapid onset, and surely within the likely time-frame from premed administration to start of surgery.[/quote]

Onset times vary, some examples for dogs of maximal plasma concentrations; meloxicam SC 2.5hr (cats 1.5hr); carprofen PO 0.8hr; robenacoxib SC 0.5hr. IV dosing will produce rapid maximal plasma concentrations and the route we use for meloxicam and carprofen in dogs to achieve a rapid onset time. It will therefore depend on route of administration, anaesthesia itself may affect onset and hydration status may affect absorption via SC injection and timing of injection. We must also consider the other analgesia we use in our premedication and intra-operatively, it may be difficult to determine which effect is from which drug when multiple analgesics are administered.

RE: Meloxicam surgical timing - an 'elephant in the room'?

Bob Russell — Sat, 18 Apr 2020 11:23:34 GMT

Can we ever say any bout of aki does not matter? Is it causing damage that may become important over time?

Edited because of predictive spelling!

RE: Meloxicam surgical timing - an 'elephant in the room'?

Rob Davis — Fri, 17 Apr 2020 17:13:15 GMT

Thanks for your contribution, Carl, very interesting. A few questions:

[quote userid="6032" url="~/001/veterinary-clinical/small-animal/anaesthesia/f/discussions/28453/meloxicam-surgical-timing---an-elephant-in-the-room/221823"] What I have noticed over recent years is that AKI is more common than I had previously thought (for any anaesthesia protocol) especially in complicated cases as we monitor urine output in recovery and notice this may be abnormal initially but does recover. I think it likely we used to miss these cases when not monitoring urine output and blood pressure.[/quote]

Without wishing to sound flippant, does it matter that we may miss some of these milder, reversible AKIs? Is there any evidence that it causes longer term problems?

[quote userid="6032" url="~/001/veterinary-clinical/small-animal/anaesthesia/f/discussions/28453/meloxicam-surgical-timing---an-elephant-in-the-room/221823"]In dogs on long term NSAIDs presenting for surgery then I would continue to give their oral meds when normally given and not use any injectable NSAIDs[/quote]

If the dog normally has NSAID in the morning, how do you achieve this along with fasting? Are you happy to give orally without food? Is the risk of adverse effects different between oral and injected NSAID?

[quote userid="6032" url="~/001/veterinary-clinical/small-animal/anaesthesia/f/discussions/28453/meloxicam-surgical-timing---an-elephant-in-the-room/221823"]For example, for a short procedure a SC NSAID at either premed or induction is unlikely to be effective during the procedure, and therefore not necessarily part of the provision of intra-operative analgesia[/quote]

Do you know what the speed of onset is for various NSAIDs? I don't have any figures, but my own observations would suggest that at least some of the time NSAIDs do appear to have a rapid onset, and surely within the likely time-frame from premed administration to start of surgery.

RE: Meloxicam surgical timing - an 'elephant in the room'?

Carl Bradbrook — Fri, 17 Apr 2020 13:58:01 GMT

This is a really interesting discussion and am only coming into it rather late! I don't feel there is an answer that fits all scenarios.

First thing which I think is important here, and has been touched on are the concepts of pre-emptive or preventive analgesia, and multi-modal analgesia. We have so many ways to provide analgesia that it is not always essential to give a NSAID prior to surgery. I always give an NSAID, at an appropriate time when there is no contraindication to using one. We have very good evidence for their effect, and despite everyones concerns for using them their safety margin is good.

With regard to evidence due to use during e.g. hypotension and concern over renal injury this is a difficult one. There are lots of factors here, for example current patient health status, degree of hypotension, duration of hypotension and patient volume status which will all impact on the extent of any renal injury. What I have noticed over recent years is that AKI is more common than I had previously thought (for any anaesthesia protocol) especially in complicated cases as we monitor urine output in recovery and notice this may be abnormal initially but does recover. I think it likely we used to miss these cases when not monitoring urine output and blood pressure.

In dogs on long term NSAIDs presenting for surgery then I would continue to give their oral meds when normally given and not use any injectable NSAIDs. If an otherwise healthy dog, and low risk of hypotension so no anticipated haemorrhage, short procedure I would give an NSAID once happy with BP during anaesthesia. If not a simple procedure, anticipated blood loss or other complications I would hold off until into recovery and the patient is stable, so this may be some time post procedure.

In cats I am more cautious and reserve NSAIDs for recovery.

With regard to the important consideration of pre-emptive analgesia the other great options we have, ensure we can still fulfil this without a pre-surgery NSAID. Thinking about premedication is important- use of a full mu opioid e.g. methadone and if safe to do so an alpha-2 agonist will be an effective option, and use of intra-operative analgesic infusions. Local anaesthetic techniques have transformed clinical practice, and when it is possible to use one this has a very positive patient benefit and something we now use on almost all cases. All of these options make me happy to delay NSAID use until the recovery period.

For other anaesthetic techniques it is important to also think about onset times for drugs used. For example, for a short procedure a SC NSAID at either premed or induction is unlikely to be effective during the procedure, and therefore not necessarily part of the provision of intra-operative analgesia. If using IM protocols then the other components- opioid, ketamine, alpha-2 will provide excellent intra-operative analgesia and the NSAID will be fantastic for post-operative analgesia.

What I think is most important is to consider each case or scenario/procedure, taking into account the combinations used and therefore when to administer your NSAID.

Carl

RE: Meloxicam surgical timing - an 'elephant in the room'?

Lindsey Edwards — Tue, 27 Aug 2019 12:30:48 GMT

[quote user="Rob Davis"]evidence to back up the concerns over renal perfusion in healthy patients.[/quote]

my concerns have never been "the healthy patient", or even "the known unhealthy" but the asymptomatic/subclinical/odd ball patient that decides to crash under anaesthetic for no obvious reason, sudden hypotensive/poor perfusion crisis or unknown bleeding tendency/surgical accident...any and all of which are thankfully rare but not predictable!

RE: Meloxicam surgical timing - an 'elephant in the room'?

Rob Davis — Fri, 23 Aug 2019 14:55:06 GMT

I have used pre-op (usually given with pre-med, but occasionally just after induction) for over 20 years and do not recall ever having reason to regret it. I too would be interested to know if there is any evidence to back up the concerns over renal perfusion in healthy patients.

RE: Meloxicam surgical timing - an 'elephant in the room'?

Lindsey Edwards — Fri, 23 Aug 2019 13:24:36 GMT

I prefer post-op - there is some analgesia present from the pre-med and if there is a post-op crisis which may affect blood pressure/perfusion etc I don't have to panic because I have already put in the nsaid - in the vast majority of uneventful cases I can then give when they come of the table (less than a couple of hours from pre-med). If there are concerns I can delay and top up with alternative analgesia until I am happier to give nsaid.

I did give pre-op for a while to prevent wind-up etc but can't say that recoveries were any better or smoother, didn't have any major crisis either but don't recall having any nightmare anaesthesia/surgery at the time either

RE: Meloxicam surgical timing - an 'elephant in the room'?

Neil Wheadon — Fri, 23 Aug 2019 09:18:46 GMT

I do feel sometimes that the power of a forum such as this would be a real help. Some pre-op, others post op. Having a case with a post op issue is reasonably obvious, so if we quantify these cases that would go a long way.

So if you pre-op, do you see any issues? This need to be balanced against stats from post op as well, as this will smoothe it statistically?

Much like vet compass I guess

Neil

RE: Meloxicam surgical timing - an 'elephant in the room'?

Julie Innes — Fri, 23 Aug 2019 08:57:31 GMT

I do dogs pre-op or immediately after induction, but in cats where I use triple combo I give the loxicom with the reversal agent. Rightly or wrongly (and I know this idea has been shot down on here before!) I worry about renal perfusion in cats, and ever since I had a 6 mth old cat castrate develop ARF 24 h post surgery, I have changed to this regime.

I don't worry too much about wind up, as in dogs they have methadone on board pre-op, and in cats there will be some pain relief until butorphanol wears off. I wouldn't argue that my regime is better/ right, just the way we do it, with hopefully a little bit of logic behind it!

RE: Meloxicam surgical timing - an 'elephant in the room'?

Thomas Johnson — Fri, 23 Aug 2019 08:39:09 GMT

[quote user="Beats"]I used to get to give the morning before orally and then just inject a maintenance dose (0.1mg/kg) SC at time of surgery - typing this I wonder if that did not make more sense...[/quote]

A very well thought through post, thank you! The above is what I do with patients coming in for surgery that are already on oral Metacam.

RE: Meloxicam surgical timing - an 'elephant in the room'?

Beats — Thu, 22 Aug 2019 20:19:38 GMT

Pre-op: logic is that get COX-inhibition of inflammation prior to causing inflammation which one could imagine to be more effective from an analgesia stand-point, presumably also the potential to reduce other agents' requirements such as being MAC-sparing on the amount of (hypotension-inducing) isoflurane used [not sure I think makes much difference though personally...]; it is hypothesized, and seemingly borne out by experience, that preventing nociception during anesthesia leads to less pain after anesthesia (the "wind-up" theory).

Post-op: logic is that if COX-inhibition in the presence of hypotension is potentially deleterious to patients' kidneys (even if only in rare cases, and again being a theory), then wait until it is clear that hypotension is not occurring and if there has been no intra-operative hypotension, and one is now turning off the hypotension-inducing isoflurane unlikely to be post-operatively, that if one gives the drug iv you get pharmacological effects quickly - the observable benefits of which may look to the untrained eye to be identical to those when it is given pre-operatively. Other potential COX-inhibition intra-operative "wish-I-hadn't" scenarios can of course also be dreamed up such as seemingly poor platelet function in a bleeding patient perhaps or the (minority) of orthopods who get twitchy about effects on fracture-clot formation, or the I'm now giving a shot of dexamethasone due to unexpected reason and don't like the idea of a sequential blockade of both steroid and NSAID etc.

Personally, practically-speaking, I doubt that a decision on whether you give Meloxicam pre- or post-operatively to a dog is likely to be a large feature in ensuring you maximise either anesthetic safety or peri-operative comfort and well-being of the patient, so I would stick with the status quo (whatever you currently do) unless you have a strong inclination to change. Indeed the act of changing what you do could potentially be more deleterious than the "worse" of the two options (whatever you consider it to be) given that it could lead to accidental double-dosing or no-dosing of a patient if you or colleagues get confused by the change in habit. I generally give it SC at time of pre-med, or SC at time of induction; I went through a phase of giving SC at time of admission but rarely do that now.

The cases I'm less sure of dosing and timing are the ones already on NSAIDs long-term... if we take the typical cruciate, I usually give one or two clear days (rarely more if I reckon the patient doesn't really need it in the pre-op period - but then why would I be doing surgery...- and surgery not until the following week etc) off Metacam pre-op and then give half (0.1mg/kg) of a loading dose[0.2mg/kg] injected SC at time of premed and other half (0.1mg/kg) of loading dose later after anesthetic recovery prior to discharge with instructions to restart orally the following morning. As the drug potentially takes up to 72hours to clear from the system IIRC, i'm not sure this is wholly logical and would be interested in what others do and their reasons. I used to get to give the morning before orally and then just inject a maintenance dose (0.1mg/kg) SC at time of surgery - typing this I wonder if that did not make more sense...

RE: Meloxicam surgical timing - an 'elephant in the room'?

Bob Russell — Thu, 22 Aug 2019 14:17:35 GMT

I can assure you there really is a debate! I am just not sure what evidence there is for pre- v's post-!

The problem is that this is a decision possibly based on hearsay.

Formulary just says should be used with caution during perioperative periods.

Assuming pain relief during and immediately after surgery is by opioids then a NSAI should kick in as these leave the system.

(I don't have the answer to my question hence my asking!)

RE: Meloxicam surgical timing - an 'elephant in the room'?

Michael Woodhouse — Thu, 22 Aug 2019 13:33:52 GMT

The data sheet says:

"Single intravenous or subcutaneous injection at a dosage of 0.2 mg meloxicam/kg body weight (i.e. 0.4 ml/10 kg body weight) before surgery, for example at the time of induction of anaesthesia."

So post op is technically off licence.

I agree that it's imperative that NSAID is given pre-op and before painful stimulation with any planned surgery. I don't see any debate.

RE: Meloxicam surgical timing - an 'elephant in the room'?

Nicola Cole — Thu, 22 Aug 2019 13:31:08 GMT

I‘m not sure there’s a huge amount of proper evidence (!) on it:

-better pre-op to prevent wind up (I’m guessing there’s evidence for this)

-concern with pre-op is blood pressure and maintaining renal perfusion in the face of nsaids therefore post-op better (I’m guessing also evidence for this).

-but as far as blood pressure is concerned doesn’t it potentially stay lower d/t GA for a couple of hours post-op. So giving nsaids on recovery you’re still risking the lower blood pressure. Therefore give pre-op as blood pressure issue isn’t circumnavigated by giving on recovery so cancels itself out, and pain relief better if given pre-op.

Not sure my answer is very evidence-based....

RE: Meloxicam surgical timing - an 'elephant in the room'?

Bob Russell — Thu, 22 Aug 2019 13:19:59 GMT

That would be a logical assumption!!

(This is a genuine question as I would prefer to make a decision based on facts)

RE: Meloxicam surgical timing - an 'elephant in the room'?

niall morton — Thu, 22 Aug 2019 13:18:33 GMT

Surly pre-op is simply to give pain killers prior to pain stimulus