Felipe M.
Forum Replies Created
-
AuthorPosts
-
Hi Rachel
Great question. And it seems that in general the approach is quite diverse! I will give you my take on it:
I recommend giving omeprazole the night before anaesthesia (if possible) and the morning of. Evidence says omeprazole will increase gastric pH. This will decrease the chance of oesophagtis and stricture in case of regurgitation. In the case of aspiration, the pneumonitis due to acid will hopefully be less severe. On the other hand, another point of view is that the higher pH will make the stomach content less anti-bacterial and therefore in the case of regurgitation the chances of bacterial pneumonia will be higher. Due to the fact that good airway management and profilaxis makes aspiration pneumonia unlikely, I tend to favour the use of omeprazole as many animals will have silent or overt regurgitation during general anaesthesia.
This paper here gives evidence about a dose 3-4h before anaesthesia making a difference for the pH of the stomach and the incidence of reflux.
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1748-5827.2009.00818.x
In this paper, the use of a dose the night before plus another one 3h before anaesthesia made a difference on the gastric pH and the incidence of reflux. However only one dose the day before did not have an effect.
https://onlinelibrary.wiley.com/doi/10.1111/jsap.13328
So very often I will give omeprazole IV as soon as possible, when IV access is in place. I also administer maropitant to these patients at the same time. Granted, maropitant does not have any effect on gastro-oesophaegeal reflux, but in my head trying to reduce as much as possible any nausea (from drugs and so on) is very advisable in animals with already less-than-competent lower oesophageal sphincter and tendency to regurgitate anyway.
In animals suffering from frequent regurgitation needing a routine planned procedure (like airway surgery), omeprazole is usually prescribed for several days (as part of the treatment for the regurgitation), together with cisapride, to try to reduce incidence before anaesthetising.
Hope this helps!
Excellent!
Felipe
Replying to Jo C. 08/03/2024 - 10:59
Hi Jo
Hope you are well!
Great question, and it’s something I didn’t go into in the course but definitely interesting.
Pulseoximetry waveform has been used to assess cardiovascular status and even fluid responsiveness, many times as a surrogate for arterial line waveform. Just something to bear in mind, when doing a simple visual assessment (dicrotic notch, area under the curve…) it is important to ensure our plethysmogram has no auto-gain on. Many monitors do this as a default to always make it look as good as possible regardless of the changes, but turning this feature off (in some monitors it is not possible!) allows us to appreciate these changes.
This is a human study where they looked at it in big numbers:
https://doi.org/10.1186%2Fcc1219Another one from human anaesthesia with its use in hypovolaemia:
https://doi.org/10.1097/ALN.0b013e3181da839fA very nice review of its uses for haemodynamic monitoring:
https://doi.org/10.1016/S1036-7314(00)70611-4A veterinary one this time, on the use of PVI (derived from plethysmography) and its similarities to PPV in monitoring outcomes:
https://doi.org/10.1016/j.vaa.2017.07.007Another veterinary one, on the use of PI (also derived from plethysmography) in haemodynamic monitoring:
https://doi.org/10.1111/vec.12985Hope this helps, happy reading!
Felipe
Hi there all!
Right, as promised, here you have some examples.
– Free: patient handover sheets; pre-anaesthesia, time-out and pre-recovery patient checklists; anaesthesia machine checklists; emergency drug sheets for every patient; meetings to discuss difficult cases beforehand; debriefs after incidents or mistakes; having an open, no blame culture; ensuring everyone has proper rest; promoting a culture where people can say if they feel out of depth or not at their best; handover sheets; M&M rounds; monthly (or more frequently even!) training;
– Under 300 pounds: PVC tubes, laryngoscope, overpressure valves for circle breathing systems, airway manometers, cuff inflating devices, oxygen tubing and masks, portable oxygen cylinder, T-pieces with paediatric APL valve, ambu bag, airway box (with tubes, ambu bag, induction agent, disposable laryngoscope), bougies for difficult airways, tuohy needles for epidurals.
– Under 1000 pounds: portable pulseoximeter, portable suction unit, crash trolley/backpack, syringe driver for infusions
I am sure there are many more, but these are the ones I can think of at the moment!
Felipe
Replying to Christina L. 04/03/2024 - 08:41
Hi Christina!
Great question actually, and I have to disclose I am not a rabbit specialist at all!
Rabbits seem to have a similar blood pressure to dogs and cats, with systolic around 90-130 and diastolic of 70-90 (while conscious). So I always apply same rule as for dogs/cats, young and healthy minimum MAP 65mmHg, and in. geriatrics or there is any disease that makes me worry about organ perfusion, then minimum MAP is 70mmHg. This is only a general guide, as sometimes I will even increase this minimum MAP to even 75mmHg, and this is anyway always tailored to every animal. As an example, a patient with hypertension may require even higher (for example 80mmHg), if their normal MAP while conscious is 130-140mmHg.
Hope this makes sense!
Excellent!
Felipe
Replying to Rachel C. 01/03/2024 - 16:40
Hi Rachel
Great to hear you’ll be pushing for PVC tubes. I know they’re supposed to be “single use” and the rubber tubes virtually indestructible. However they can be used for a very long time, and if one breaks, it’s only 3-5 pounds to replace. By all means let me know if you need further information on the benefits of PVC tubes.
Regarding the pressures, yes sure, let me clarify! I think I may have not been very clear and given both parts are pressure doesn’t help.
When we inflate the cuff, we want to ensure the airway is leak-free, both for gas getting out and polluting the workplace, and for fluid getting in. The “accepted” (mind, there are also controversies in this) has been to give a breath and get our ear -not our nose- close to the mouth of the patient to hear for a leak. If we hear one, we will start inflating the cuff -while holding that breath- until it disappears. If this is all we do, this has been shown to potentially induce us to inflate the cuff beyond safe levels. But we still want the airway leak free! So here’s where we refine the system by doing the procedures to a known safe pressure value.
First, the breath. It’s easy to give a very large breath, at high pressure, which requires more cuff pressure to stop a leak. If we can measure, we inflate that chest to only 20cmH2O, as that is enough. Now we know how much we need to, and are inflating the chest rather than just seeing the chest excursion. However this visual inspection is sometimes all we can do if the breathing system does not allow connecting a pressure gauge easily (such as a modified T-piece).
So now we know how much to inflate that chest when we sustain a breath and listen for the leak. We want to inflate the cuff to stop an airway leak happening at 20cmH2O of airway pressure.
Next we refine the second part, how much air do we put in the cuff to stop said leak? Whatever stops the audible leak is the answer, but TO A MAXIMUM of 20-30cmH2O of cuff pressure (here is where we use our cuffill) in a dog, or up to a cuff pressure of 20cmH2O in cats.
However in some cases it may happen that no leak was ever audible, in that case I do still inflate the cuff slightly, just to give it a bit of tension, to far less than the max pressure (a random amount, admittedly, just to feel the pilot balloon having something in, but let’s say around or below 10cmH2O).
In other cases, we may still be hearing that leak (occurring at a breath sustained at 20cmH2O of airway pressure measured in that airway manometer) despite having already reached our max cuff pressure we allow. In this case, I give a couple of breaths to the patient, ensure good depth, and re-intubate with half or one size up (as per clinical judgment). And re-start the above procedure for inflating the cuff.
So the airway pressure we measure in an airway manometer is just to ensure we don’t overinflate that chest, and the cuff pressure ensures we are not putting too much pressure on the trachea.
As a disclaimer, all I he above applies to most animals, but we need to keep in mind in some cases applying positive pressure to the airway may be contraindicated (closed pneumothorax, bullae…). In these cases I just inflate the cuff to the maximum safe pressure without inflating the chest or listening for leaks. This is faster, and avoids the IPPV, however in my opinion the complete procedure, if adequate, is safer.Hope this helps but do let me know if you need further info as I may not be nailing this explanation in the head!
Excellent!
Felipe
Replying to Rachel C. 28/02/2024 - 15:42
Hi Rachel
Great question, and definitely a controversial topic. In past training, years ago I was even told to favour non cuffed et tubes in cats and go for the biggest size to create a seal (sort of really), so clearly opinions are very varied.
After years of practice and hundreds and hundreds of cats anaesthetised, I have my own opinion too.
I always feel inflate the cuff in ALL my patients, dogs and cats, to avoid a leak while sustaining a breath at 20cmH2O of airway pressure, and inflating the cuff to no more than 20-30cmH20 (dogs) or 20cmH2O (cats) of pressure. If higher pressures are required to not have airway leak while sustaining that breath, this tells me a bigger tube should be fitted. These pressure cutoffs for the cuff inflation are based on research showing the maximum pressure that does not cause ischaemia of the tracheal mucosa. The more conservative value for cats is a personal adjustment I do based on a less sturdy trachea in the felines, but more compliant neck, which I hypothesise might make things like tracheal rupture more likely when moving the neck with an inflated cuff. Leaving an non inflated cuff or a non cuffed tube implies a risk of aspiration or microaspiration of saliva, blood, gastrointestinal contents or lavage fluids. This can happen in any type of procedure.
As I said in my previous post, the issue with those rubber tubes is that whatever pressure you have in the cuff, this is only applied on a small surface due to the low volume, and may therefore insufficient to stop that leak at equipotent pressures when compared to high volume/low pressure (which stop the leak by having less pressure over a large surface). Also, being less compliant tubes, they will tend to push towards their original shape, potentially causing uneven pressures in the cuff, or pressure points on the trachea. So I would really encourage everyone to make the change to PVC or silicone.
In terms of measuring pressure in the airway, there are very cheap in-line airway pressure gauges for circle breathing systems (around 30 pounds I think), in a T-piece, often a breath is of sustained to a normal chest excursion by visual confirmation (unless you have spirometry or any other means of measuring airway pressure in a T-piece, which have no easy place for a pressure gauge although it’s doable!).
In terms of measuring cuff pressure, there are devices like the Cuffill, which easily give a reading while inflating the cuff. They are great because of being basically a syringe, which allows for easy and controlled inflation in dogs and cats.Hope this helps!
Excellent!
Such a great topic Scott!
I have to say that I am most often happy with blood tests from IVCs, as this obviously spares a phlebotomy and some stress. But I could definitely see how for accuracy and monitoring treatment (i.e. internal medicine -wink,wink-), this may not as suitable.
I have to say that another source of repeated measurements that do require accuracy for anaesthesia is blood gas and acid base status analysis from arterial cannulae. These are always through a cannula (we would not get too many samples off a needle from arteries!), but I wonder if the same applies, and we just live with it. I guess gases and acid-base may not be as variable. However we do care about potassium!!
So interesting, thanks a lot!
Felipe
Hi there Emylia!
This is a very interesting topic indeed:
– Rubber tubes are much harder (hence their durability) than PVC tubes. This means that they will accommodate far less the shape and angle of the patient’s trachea, which can cause pressure points or predispose to lesions, especially when moving the neck. For the same outer diameter, they have a smaller inner diameter, meaning they impose higher resistance for the same size tube, than PVC tubes. Additionally, their cuffs are low volume-high pressure. This means that rather than sealing the airway by volume, they do it by putting a lot of pressure on a small area. This has been shown to cause tracheal mucosa ischaemia and predispose to rupture.Lastly, they are completely opaque, which means complete cleanliness or good condition of the material can never be fully guaranteed. Although long-lasting, they are actually fairly expensive!
– PVC tubes are all the contrary. They are fairly compliant and get even more when warmed up, conforming very well to the patient’s trachea. Their cuffs are quite often (and definitely readily available as a choice) low pressure/high volume. They are very well tolerated as material, and totally transparent, which allows easy inspection. As opposed to rubber tubes, their inner diameter is bigger for the same size tube. Lastly, they are very cheap!
– Silicone tubes are also great, however some of them come with low volume/high pressure cuffs which I do not recommend. They are very soft and floppy, great for accommodating tracheas. However they seem to kink a bit more for this reason, and they are a bit more difficult to intubate with. Lastly they are quite a bit more expensive than PVC.
– Storing them in a rack seems a great idea for easy access, but I personally do not like it as the pilot balloons get all intertwined and they become difficult to retrieve. They are also more likely to gather dust or fall on the floor. I personally really like a dedicated drawer separated in sections for each size. This is clean, dust free and neat!. Alternatively, clear boxes separated in sections for sizes as well works great, and there are plenty of options in DIY shops.
– Cleaning ET tubes has been a subject of study for some time, especially as, as you well say, some cleaning products have caused problems. After doing some research, we use F10 disinfectant, following the instructions included. We found this product was airway-safe, and have used for months now without any problems at all. We do rinse and brush the tubes first. I know other practices (in particular this was an equine one) have in the past used Milton solution for ET tubes, but cannot give first-person feedback about this one I am afraid.Hope all this helps, but please do fire away any other questions.
Excellent!
Felipe
Hello everyone!
My name is Felipe, and I am very excited to be sharing this opportunity with you to take a deep dive in all the foundational aspects of anaesthesia.
Although in itself anaesthesia is a multi-faceted and includes several different sets of skills, to this day I stay convinced that the core of patient care and safety is defined by our approach, culture and attention to the basic aspects of the peri-anaesthetic care (which is in itself quite complex). So you may find me making a lot of emphasis on this!
However, you are very welcome to ask anything and everything anaesthesia related in the forum! As well as delivering this course to you I will be keeping an eye on all your questions, answering them and also asking some others to hopefully bring some interesting topics to the table.
I sincerely hope you enjoy this course as much as I have enjoyed preparing it, I am very excited to start this journey with all of you!
Thank you ever so much for choosing us, and thank you Scott for getting me involved!
Kind regards
Felipe
Hi Loren
Anaesthesia management of caesarean sections is fascinating and indeed multifaceted.
Indeed opioids are a source of debate here. I tend to go opioid free until puppies are out, and then potentially use fentanyl sparingly if needed, 1mcg/kg at a time IV. I have to say that generally a good line block covers everything very nicely but if I need a bit of extra analgesia for the last parts of the procedure I like giving a short acting.
However an alternative approach that is some times what I recommend in advice requests, is giving a 0.1mg/kg methadone IV as a preanaesthetic medication. I also use this if the mum is looking painful, stressed, or needs a bit of sedation before induction. The main study looking at effect of different anaesthetic drugs on APGAR (vitality) newborn scores (https://doi.org/10.1016/j.vaa.2018.10.005) did not find a deleterious effect from methadone, however the vastly differences in foetal stress and urgency of the procedure makes comparing APGAR scores/mortality very difficult. Still, some authors are now recommending using methadone in the pre-anaesthetic medication (https://doi.org/10.1136/inp.i3201 ; https://doi.org/10.12968/coan.2019.24.2.84) . We must not forget that we can always administer naloxone IM or sublingual to the newborns if we perceive them as sedated or taking long to recover, so withholding opioids is only justified if we are happy we have the analgesia requirements of the mother covered.
Buprenorphine is an controversial drug for a couple of reasons: first, legally buprenorphine is contraindicated for pre-operative use in caesarean sections. This unfortunately makes it a literal contraindication for pre-anaesthetic medication. The use post-operatively is only authorised under caution due to the potential respiratory depression of the puppies (which I guess is the same for any opioid). Second, the high affinity of buprenorphine makes it difficult to antagonise with naloxone. For this reason, should the puppies become sedated or have respiratory depression due to the crossing on to the milk, reversing this may be prove challenging.
So personally, I do believe I see higher vitality in puppies when I do opioid free until they have been taken out, but I will generally give that fentanyl or a 0.1mg/kg methadone IV to the mother to finish the procedure and recover comfortable. Then I am happier that whatever crosses in the milk will have a more subtle effect on the puppies. But just to emphasise, I would give the opioids judiciously even before pups are out if I think the mother is in pain, and just administer naloxone if necessary once out.
Personally, I do rely heavily post-operatively on paracetamol (without codeine) and a single dose of non-steroidal after recovery. This is generally sufficient to have mum and pups discharged happy and comfortable. If pain seems to be a problem, I would consider strategies like low dose methadone if hospitalised or repeating the non-steroidal on the day after (depending when the mother has become painful).
Hope this all makes sense, but please let me know if you’d like me to elaborate on any points.
Excellent!
Felipe
Hi Loren
Excellent question. Maropitant is indeed a drug quickly becoming more and more used in the peri-operative period, due to it’s lack of side effects and various properties.
As an antiemetic, it plays a big role in anaesthesia. Perioperative Nausea and Vomiting (PONV) is a well known complication in humans leading to delayed recovery and discharge. It is very easy to justify administering antiemetics to animals undergoing abdominal surgery (visceral manipulation can cause PONV) or with a pre-disposition to nausea, vomiting or regurgitation (e.g. brachycephalics). So definitely a sound use of maropitant.
Studies have failed to demonstrate clinically relevant effects of maropitant as literal analgesic in acute pain models. This, although perhaps disappointing, makes perfect sense. NK-1 receptors are heavily involved in the wind-up part of sensitisation, which doesn’t necessarily happen in acute pain but in more prolonged states of it. So as a NK-1 receptor antagonist, it makes sense that maropitant may play a role in chronic pain/sensitisation scenarios. However to my knowledge this is still a theoretical fact.
Maropitant has actually been found to be MAC sparing during visceral stimulation in ovariohysterectomies (probably where the visceral analgesia claim comes from). So it seems that maropitant may actually help spare inhalant agents.
It is worth noting that maropitant does not decrease regurgitation, however in my head it makes sense to try to alleviate any additional nausea in animals prone to regurgitation, so as to not make it worse.
I am amazed by Scott’s comment on the novel use of maropitant in respiratory disease, I was not aware and it is very interesting indeed!
Another amazing drug with many uses.
Excellent!
Felipe
Hello everyone!
My name is Felipe and I will be the anaesthesia and analgesia specialist joining you in this course. I am a EBVS and RCVS recognised specialist currently working in private practice in the North East of England.
I have a special interest in everything pertaining to perianaesthetic patient safety and critical patient anaesthesia, but anything anaesthesia related I find fascinating!
I will be very happy indeed to answer any questions you have.
Just want to take the chance to thank you for having chosen us for your CPD, and to wish you enjoy this course!
Felipe
Hi all!
Hope you are well
Elaborating a bit on the topic, and as very rightly pointed out by Scott, one of the first concerns that come to mind when considering using this molecule is the lack of pharmaceutical standards.
As happens with other pharmaceuticals that are sold unregulated by the medicines standards, we find ourselves at risk of prescribing a molecule but administering a whole array of unwanted and undeclared others.
Given the popularity of CBD products, the Food Standards Agency carried out an analysis of different formulation published last year. Please find it here!
https://www.food.gov.uk/research/research-projects/analysis-of-cbd-products
So as you see, the results are consistent with our concerns.
What do everyone think about these? Is it enough to put you off of prescribing CBD or would you still be happy to do so?
Felipe
Hi everyone!
First of all, I would like to thank each one of you for having chosen this course to dive a bit deeper in everything anaesthesia. I sincerely hope you have enjoyed it and found it helpful. It’s been a pleasure for me to put this course together and to have followed its progress through the forum.
I would also like to thank Scott, Liz and Andy at Vtx for having me as their resident specialist, couldn’t hope for a better team!
Just a very quick last thought. Anaesthesia (like any other discipline I guess!) is composed by a myriad of processes, many of them happening simultaneously. This makes it sometimes daunting, and causes the main difficulty in introducing change after doing further training. Any and every little change can introduce variability and decrease situation control or confidence, which is why changing anaesthesia practices can be very stressful.
So please allow me to give a tiny bit of advice: if you have found several things you want or need to change in your everyday practice, go for it! But do it introducing change slowly, one thing at a time and after discussing and making the whole team aware of what will happen. Choose the right day and patient to introduce new procedures or approaches, to ensure you remain comfortable and in control of the situation at all times. Don’t leave it for “at some time”, but don’t rush it either. Keep in mind that any change, implemented based on evidence or best practice, will always have a positive effect on patient safety and/or comfort.So with this in hand, I wish you all the very best and hope you enjoy anaesthesia a bit more every day.
Kindest regards
Felipe
Replying to Tascha B. 03/07/2023 - 13:11
Hi there Tasha
Hope you are well!
This is a great point that has a direct effect on patient safety.
Whilst cuff manometers can vary in accuracy, we also know that inflating “to stop the leak” can without doubt result very frequently in overinflation. We also know that subjective feeling of the cuff is highly inaccurate.
In my opinion, a combined approach gives further safety:
I inflate the cuff to stop a leak of a sustained breath at 20cmH2O of airway pressure (unless there is a contraindication for IPPV -airway originating pneumothorax, lung contusions etc) whilst measuring pressure with a cuff manometer. If the pressure in the cuff to stop the leak needs to be more than 30cmH2O in dogs, or 20cmH2O in cats, I will deflate the cuff and re-intubate the trachea with half a size or one size bigger tube. Then I will repeat the procedure. If on the other hand the leak stops with a cuff pressure lower than 30cmH2O in dogs or 20cmH2O in cats, then even better, I do not inflate further as it is not necessary to protect the airway.
I feel this approach takes the best of both techniques by ensuring the airway is leak free and protected, while keeping the cuff pressure to the minimum possible and definitely within safety levels.
I hope this helps!
Excellent!
Felipe
-
AuthorPosts