Failure to establish Analgesia?

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Hi All

I am pondering the mechanism of Mepivacaine HCl 3% (Scandonest Plain) and recent failure to establish analgesia in a patient.

I initially saw him last week and attempted a hallux digital block with 4.4Mls injected. After 20mins, no analgesia established. Pt then informed me he had come to Clinic straight from the gym after an intensive leg-press session.

I abandoned the session and re-booked him for the LANS a week hence.

I used the same LA, 2.2 Mls today... and established analgesia in 10mins. (He hadn't been to the gym!)

There seems a clear correlation between the gym/leg heavy workout last week and LA failure. My question is... what was the likely biochemistry underpinning this failure? Lactic acid changing the pH?

The Pt is otherwise, fit, well, no remarkable medical history or clinical presentations... a 25yr old Marathon runner!

I also appreciate there could be other reasons underpinning the LA failure on the first attempt (ie, improper injection technique) but this is first time this has happened to me in over 12years... and I had notable success today on the same 'rinse and repeat' approach!

Many thanks
K

 

From what you were saying is it possible that a notable increase in Blood pressure through the area could have altered the effectiveness of the LA?
Possibly increasing the re-uptake time of the LA back into larger blood vessels and out of the toe?

Jaimee

 

I have had 2 experiences in 30 years of LA not "taking".

In the first case the area was inflamed and I can only presume that the increased blood supply to the area was responsible for "sweeping away" the drug. In this case I injected again slightly more proximal to the inflamed area and all was well.

In the second case there was no obvious reason for the failure to achieve anaesthesia, so the patient was requested to return the next day, when I used a different batch of the LA. As there were no problems on the second attempt, I put this down to a fault with the manufacturer and threw away the rest of the original batch.

Regards

Poddess

 

Podess

It was my understanding that if a toe was 'inflamed' because of (usually) infection - then the pH (acid/alkaline levels) in that area is drastically changed and therefore prevents the usual channels from working properly with LA to block pain? Therefore that is why the LA doesnt work - not because it is flushed away - although I don't as a rule inject near the infection for fear of spreading sepsis into deeper tissues.

Regards
Linda

 

Kaleidoscope,
You may well be correct.

I am actually attending the LA Update by Jean Mooney at Northampton in March so hopefully the reasons for LA not working will be discussed.

I also dislike injecting into an infected area but in the case of a very painful IGTN it can sometimes be the lesser of two evils.

regards

Podess

 

Podess

Why would you ever inject into an infected area ? What were you taught and who ever suggested that you should ?

There are proximal alternatives ! The lawyers would have an open and shut case if there were consequences.

Regards

 

In my experience, it is very very unlikely that a patient will not respond properly to LA, regardless of what the underlying pathology, age, patient health, marathon runners, couch potatoes, hyperemic, sexual orientation....etc......

As I have most likely mentioned before on this site, in the tens of thousands of local injections I have given over the years, I have had just ONE documented case where xylocaine did not render anesthesia. This patient did not respond to even a Sub-Q raised wheel. The interesting part of this is that this patient stated that several relatives of hers also had similar "immunity" (for lack of a better word" to LA.

I would suggest some genetic "blocking" of the mechanism of LA rather than an acquired "immunity"

Steve

 

All,
I have now attended to LA update by Dr Jean Mooney and can respond better to previous posters about this topic.

The more vascular the tissue, the more rapid the absobtion into the local circulation. Also the greater the vasodilatory effect of the LA drug the shorter it's action as an anaesthetic. As inflamed areas are highly vascular the LA is therefore not as effective.

A question was raised about IGTN and infection.
If a nail sliver is present then the condition will not resolve without its removal. If there is pus being discharged then obviously the toe is infected and a short course of antibiotics is required before LA is considered. In this case I would certainly not use LA.

However, if there is no pus being discharged but the toe is inflammed then it is possible that the toe may still be infected. How is the practitioner to know if this is the case? How many courses of antibiotics should the patient have to take before surgery is considered ?
I have had patients come to me after 4 courses of antibiotics where the hypergranulation tissue is 3/4" above the nail plate and the big toe is bright red. In addition they are in severe discomfort.
Perhaps other pods on this forum could suggest how they would manage this situation?

I am not trained to do ankle blocks but an injection into the base of the first metatarsal can be useful.

Also, when I use LA I am using very small amounts ie. 0.5 mil each side of a toe.

 

Podess

I have had patients come to me after 4 courses of antibiotics

Yes, because if there is a pocket of pus the antibiotic surrounds it but does not eradicate it, the surrounding tissue may be clear but once antibiotic effect is removed the infection reappears.

If you don`t have the skill to block proximally (and the patient can`t stand the pain) don`t take the case on. We can`t do everything !

Regards

 

Not entirely true - its actually got to do with the pH level of the tissue (inf lammed or infected) and this can be countered with sodium bi-carb as necessary

Again not entirely true - pus does not always mean infection. Clinical infection is a more complicated animal than that. Redness, pain, inflammation, sloughing, possible exudate, tissue breakdown could all be signs of clinical infection.

There are only two logical reasons not to use LA in an infected digit. 1) It may not be as effective or work as quickly as clinically required. 2) Introduction of a sharp object through soft tissue may increase the chances of "spreading" the infection.

The first issue as described above can be bypassed by using antibiotics or sodium bi carb as a buffer. The second issue can be bypassed bu injecting away from the clinical site of localized infection

Correct - and this is the more important thing to remember.....

Good clinical diagnosis, examination and history taking. When in doubt - take the safest route possible for the patient to achieve the desired outcomes.

How long is a piece of string? This really depends on your clinical decision making. If you believe a clinical soft tissue infection is present and believe you have to do an invasive procedure to rectify the presenting complaint, then the safest route possible for the patient would be to place them on a course of broad spectrum antibiotics (or preferably the more specific the antibiotics the better for the infection if you have pathology) then wait at least 48-72hrs before considering any tissue invasion.

On review of the case over the following days, decide whether a repeat is necessary after good care and hygienic redressing.

As stated above - that doesnt mean its infected, it means they have hypergranulation tissue due to a piece of nail embedded in their soft tissue and it is inflamed - which would be the normal course for response. After four courses of appropriate antibiotics (complete overkill in most instances where a simple course of broad spectrum antibiotics is all that is required)

The more tools on your tool belt...the better you are! Not difficult to learn and will improve your clinical anatomy as well. You sound eager to learn which is an awesome thing - so my advice, learn as much as you can and enjoy the rewards it will bring your patients!

You should always use the least amount possible to achieve the desired clinical result. Remembering your maximum safe dose with most amide based local anaesthetics is considerable I doubt you could get enough into a toe to cause any symptoms of clinical systemic toxicity.....

 

Umm no. Pus is a buildup of dead leukocytes (white blood cells) from the body's immune system in response to infection. Pus is not the infection itself.

By definition it is:

"A fluid product of inflammation, consisting of a liquid containing leukocytes and the debris of dead cells and tissue elements liquefied by the proteolytic and histolytic enzymes (leukoprotease) that are elaborated by polymorphonuclear leukocytes"

Read my post above - just because there is PUS does not mean there is infection....

Also can we change the TITLE of this thread as it is misleading - it should be ANAESTHESIA not ANALGESIA.

 

Paul Bowles

just because there is PUS does not mean there is infection....

Yes, but you would be wise to assume there may be. Their are many surgical conditions, away from the feet, where this also applies and normal practice is to assume some infection is present !

Regards

 

Not really - this is sort of why the whole "antibiotic resistance" thing got a bit out of hand. Pus does not always mean infection. I don't treat any surgical conditions "away from the feet" because I am a Podiatrist so won't comment on those areas specifically.

The typical presenting features of all skin infections include soft tissue redness, warmth and swelling, but other features are variable - pus is a variable feature. A good example of this is cellulitis - it may present with or without pus/exudate/crusting. Regardless whatever makes you feel better in your clinical practice. Here is a link to a nice overview on antibiotics in soft tissue infections:

http://jac.oxfordjournals.org/content/65/suppl_3/iii35.full

 

Paul

All very text bookish, can I take it that you make a practise of injecting in to resolving infectious areas when pus (an indicator) is or is not present ?

I don't treat any surgical conditions "away from the feet" because I am a Podiatrist so won't comment on those areas specifically.

But it is useful to know what goes on elsewhere !

 

Take what you want from what I have said.....its a clinical decision and the textbooks, research and clinicians alike will say that exudate is an additional "variable" in describing a possible infection - it is not the sole variable.

It is not always present - and when it is it does not categorically mean there is an infection present.

The example I gave before "cellulitis" I think covers it pretty well.

Ask yourself another question - if you see pus without Calor, dolor, rubor, and tumor: (Heat, pain, redness, and swelling. The four classical signs of inflammation, originally recorded by the Roman encyclopedist Celsus in the 1st century A.D.) would you automatically assume infection? If this did occur would you prescribe antibiotics?

What about joint infection? Heat, pain, redness, and swelling - no visible pus - would you prescribe antibiotics for this?

Don't get me wrong - I am the most medically minded Podiatrist you could ever meet - I am not against antibiotics use, when done so correctly, I just see too many people taking antibiotics for the most inane reasons! For some superficial wounds, especially in a fit, healthy, active, non medically complicated patient nothing a good warm saline flush on a regular basis with sterile dressings and good aseptic technique won't usually handle.....

Lets get back on topic here - anaesthesia.....thanks for the discussion

 

Paul

If you check you'll see that I`ve never advocated antibiotics (although they have a place).

From experience, in a case such as described, the most important job is to remove the offending piece of nail.

And from experience, most will heal without antibiotics !

Regards

 

http://www.frca.co.uk/article.aspx?articleid=220

The above will explain to you why Local anaesthetics are rendered ineffective in acid environments, eg infection.

Throw away any ideas of increased blood pressure having any effect on anaesthesia and recognise that although the level of vascularisation will reduce the period of anaesthesia it will not prevent it.

Bill

 

I agree with Bill .......... in addition.......when dealing with infected nails one gives a ring block, not an injection into the infected area.

Treating ingrown toe nails is Podiatry 101.

The point of this thread was that "k" 's patient did not respond to local anesthesia. This has absolutely nothing to do with whether or not the toe was infected.

Steve

 

Thank you wdd & dsarbes

Confirms my original advice to inject proximal to the compromised area !

Regards

 

OOPS I have posted what is essentially the same post twice in error!

Confirms my original advice to inject proximal to the compromised area !

I think it might be more complicated than that.

My own feeling is that if there is no anaesthesia it is almost always results from technique and I think that the technique that was taught in Britainand may still be taught might be responsible for increasing the probability anaesthetic failure.

In the UK, at least the name, 'ring block' and possibly the technique, was in the 1980s and possibly still is contraindicated because the digital arteries are end arteries and the fear is that mechanical compression of the end arteries, associated with the introduction into the tissues of a volume of local anaesthetic agent might compromise the artial flow and result in digital ischaemis and possibly gangrene.

Although a study published in JAPA in the 1970 looking at temperature changes in the digits following LA injections found no evidence of reduced temperature and therefore of reduced bloodflow and only increased temperature, ie increased bloodflow, this evidence did not find its way into the British literature.

Because at the time the profession was hypervigilant and fearful that negative outcomes might result in the right to use local anaesthesia being withdrawn the technique taught required the discret deposition of local anaesthetic around a dorsal and a plantar branch of the digial nerve on each side of the toe. The succes of this technique is largely dependant upon the ability to place the local anaesthetic close to a dorsal and plantar branch of the digital nerve. The success of this technique is directly related to the presence of discret dorsal and plantar nerves and the distance between the anaesthetic and the specific nerve.

A study by Louis Schmidt back in the 1970s looked at the distribution of the digital nerves in a small number (6?) of dissected big toes. He was unable to a discret dorsal or plantar nerve. He found that in all cases, by the time the digial nerves reached the toes they had branched to form a network.

Kahuna when you do a digital block do you attempt to deposit local anaesthetic around distinct dorsal and plantar nerves or do you do a ring block, ie form a continuous chain of anaesthetic agent around the toe?

Another remnant of this hypervigilance of the 1980s is contained in the title of this thread and in one of the responses - Also can we change the TITLE of this thread as it is misleading - it should be ANAESTHESIA not ANALGESIA.. In the early days of LA podiatrists assumed that it w

 

Kahuna what type of njection technique do you use?

Do you direct your needle towards at dorsal digital nerve and then inject a bolus of anaesthetic around it and then retract the needle and redirect it towards a larger plantar nerve and then inject a larger bolus of anaesthetic around the plantar digital nerve and then repeat on the other side of the toe, ie two discret boluses of local anaesthetic on each side of the toe?

or

Do you use a digital block where a chain of anaesthetic agent is formed around the toe?


Depending upon your reply Peter Bowles request might be relevant.

Also can we change the TITLE of this thread as it is misleading - it should be ANAESTHESIA not ANALGESIA.

When podiatrist first started using LA in the UK they were hypervigilant. There was a fear that access to the Local anaesthetic agent could be withdrawn if there were any adverse outcomes. There was also fear that podiatrists were not legally allowed to use LA to produce anaesthesia (without sensation) but could use it to produce analgesia (without pain). Irrational? Definitely but it show the level of fear and anxiety, insecurity and powerlessness with in the profession.

Bill

 

Thank you Paul Bowles for a most comprehensive and informative post - #10.

Rosherville, when I trained in nail surgery (many years ago) I cannot remember what I was told regarding contraindications. In the course of that training I undertook 6 procedures and not one of them involved a toe that was the slightest bit inflamed. That is why I have attended subsequent updates.

In subsequent courses I have been told not to inject into an infected area. However, it has never been made clear to me how I determine whether or not infection is present.

I have never knowing injected into an infected area. However I have injected once into an area that was slightly inflammed. Was it infected? I don't know. The anaesthetic didn't take. I injected again in a slightly different area (that was also slightly inflamed) and achieved minimal anaesthesia. However, this was good enough to remove a nail sliver that took about 30 seconds. The toe healed without issues.

I did point out to the patient before the procedure that a) the anaeathetic might not take and
b) there was the danger of spreading infection (if in fact any was present) and the patient was OK with this. They were taking a course of antibiotics at the time.

The alternative was to send the patient to the GP for referral to the NHS for a procedure using partial ankle block which could have taken another week at least. The patient was self-employed and taking time off work because of the IGTN.

Kaleidoscope you have mentioned "spreading infection" but with digital injections in a toe that is already infected where would it spread to and how? And how would you know if the toe was infected or not?

It seems some of the eminent practitioners on this site can't agree about this.

Interestingly, infection/inflammation is not listed as a contraindication here,

http://www.medicines.org.uk/emc/medicine/26502/spc

Incidentally this -

was contained within the lecture notes I was given.


I look forward to hearing more opinions about this interesting topic.

regards

Podess

 

Sorry, I inadvertantly posted twice and had to delete one of them !

 

Podess

Consent or no, had the patient had complications and decided to litigate and it was proved that you had injected in to a potentially infected area you'd have had no defence ! Had you injected proximally and had problems you could have presented a defence.

Simply do not attempt to do what you don't have confidence in, refer on, regardless.

Regards

 

Rosherville, thanks for your reply.

However, it doesn't answer my query about how to determine whether the toe is infected or not?

Or where the infection would be spread to, via the injection, if it was present?

regards

Podess

 

Podess

You can' t determine without lab tests but always err on the side of caution, especially if all the cardinal signs are present !

Where will it spread to ? Anybody's guess but certainly it has the potential to radiate in one direction or another.

Find a potentially infected toe inject a few mls and sit back and wait, then you'll see where it could spread to ! NO don't, just joking.

Regards

 

Rosherville,
Thank you for your post.

As I understand it, inflammation can be caused by other factors than infection. Therefore, it is possible that a foreign body such as a nail sliver could cause inflammation without infection. It has already been stated on this forum that the presence of pus does not necessarily indicate infection.

That's why I asked the question.

That sounds a bit unscientific but I take your point about erring on the side of caution.

regards

Podess

 

I'll second that.

When a patient arrives in the clinic having had one or more courses of antibiotics for their 'infected' toe I take it as an indicator of the GP doing the things that a GP does, ie 'here's an infection, most likely bacterial. What do I do for bacterial infections? Oh yes, I give a course of approproiate antibiotics. Job done'. No.

The cause of the infection/inflammation is the piece of nail embedded in and irritating the tissues. The only way to get rid of the infection/inflammation is to remove the irritation. If the source of irritation is left in place and antibiotics are given , it's the wrong treatment and arguments as to whether or not it is infected become academic.

Following removal of the offending piece of nail, even in the most badly infected/inflamed toes and even without antibiotic cover, I have never seen a case where the infection progressed. They have almost invariably resolved without incident. In a small percentage the inflammation has taken a considerable time to resolve. Sometimes this was because there was a piece of nail remaining. In the residual cases of prolonged inflammation where there still seemed to be visual evidence of infection and where there was no evidence of mechanical irritation a single course of appropriate antibiotic always resolved the problem.

I have never known a case, no matter how badly inflamed/infected and whether or not they had antibiotic cover before the surgery, where following removal of the irritation under LA, injected into the toe as proximal as possible to the inflammation, the infection/inflammation got worse.

I think that the use of antibiotics in the management of so called ingrown toe nail is one of those areas where the over use and inappropriate use of antibiotics is rife and needs to be rationalised.

Bill

 

As inflamed areas are highly vascular

I know that it is probably a detail but vascularity is a measure of the number/density of blood vessels in the area not of inflammation.

An area may have a large or small number of blood vessels and still become inflamed.

Possibly the sentence would be more accurate if it read 'As in inflamed areas the vessels are highly dilated'.

Bill

 

Thanks to all who contributed to this thread, I have found it very useful.

Regards

Podess