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I have no experience of Cryoalpha.
However, I've had my Cryopen for about 2 years and I wouln't be without it.
I use the beige nozzle mostly as it get a faster bigger freeze.
You need some practise to get the cap on and off when you want to freeze as there is no trigger action.
I also advise keeping a pair of pliers in your sugery for when you have put the cap on too tight and can't get it off!
The Cryopen is relatively cheap, easy to use and store.
I paid ~ £700 for mine when it was Canonbury's new thing they were promoting. You can get it cheaper elsewhere now, as you can the Nitrous Oxide Cylinders. That said my Cryopen paid for itself in 3 months, I use it a lot...
Robin -- you do not give info as to freeze times / rethaw times nor treatment frequency etc. Do you get patients to self treat with SA derivative in between visits? More info re your general treatment system please. I too, use CryoPen but in combination with self treatment using Occlusal -- seems to work reasonably well after 2/3 months
I've just bought a Cryoalpha S from www.kmed.co.uk for £150+vat, they're doing a special (or were) normal price is £200+vat. It seems a giant leap forward in value for money and without an apparent sacrifice of quality.
I've used the original Cryopen which was about 4 times the price. This cheaper device has the significant advantage of a valve to control the flow so you can just use how much you need. It can therefore use larger cartridges without wastage and avoids the need to change cartridges repeatedly during treatments. The cartridge can be removed at any time as there is an inbuilt valve. The cartridges also have an inbuilt filter so no more faffing around with them.
To get the new Cryopen with an on/off flow (CryoPen|x) would set you back a staggering £1,495.00+vat which Canonbury call "very affordable"
It uses the same gas so the temperature should be the same. Both are rated down to -89oC (the boiling point of the N2O).
Made in Switzerland and seems a high quality item.
The 16g cartridges are cheaper for the CryoPen|x at £12.50 compared to £29 for the Cryoalpha though with the initial outlay difference you would have to use it a lot for that to be a factor. You would only catch up after using around 80 cartridges but even with seriously heavy use expected it might be preferred to spread the cost.
The only other reason to go for the CryoPen|x would be changeable tips (which i never found a need for in the original version) and the "professional" plastic case.
I'm not sure how long the cartridges are going to last yet but it should be easily covered by the treatment costs. For anyone looking for a MUCH more affordable way to start doing Cryo privately I think this is the device we've been waiting for.
Both of these are ridiculously expensive when one considers that basically they are just the top section of a 1970's soda syphon using nitrous instead of CO2. I just don't get the grand plus price tag for the Canonbury product, on the surface the Cryoalpha seems more reasonable, but really? The manufacturing cost of this must be pence
If I purchased one, I'd empty the first cartridge of nitrous into my respiratory system to laugh off the cost. The suppliers wouldn't need it, they're laughing already (all the way to the bank). These should be about £20 + cartridge cost. How much was a box of soda syphon cartridges? Better, scale it up a bit and use a soda stream cartridge- how much was a refill on these?
__________________ Science is the antidote to the poison of enthusiasm and superstition
Apart from the fact that people who purchase this product must have more money than sense, this thread does highlight an interesting point. How does cryotherapy work in the treatment of VP's? That is to say, if freezing and thawing is key, why would it make any difference as to the freezing temperature so long as freezing and subsequent thawing were achieved? Is there any good quality evidence to suggest that the temperature achieved with nitrous is more efficacious than the temperature achieved with carbon dioxide, or ice?
BTW, I suspect there are far more parts to manufacture in a moped than in a sodastream
__________________ Science is the antidote to the poison of enthusiasm and superstition
Costs $933.00 - about half what it costs in the UK!
There are a few different models with changeable probes on some. The one i'm talking about is the "Cryoalpha S" model or "Cryoalpha Super" i don't see it listed on many website, i think partly because it's newer but partly perhaps because it's less profitable to sell?
Apart from the fact that people who purchase this product must have more money than sense, this thread does highlight an interesting point. How does cryotherapy work in the treatment of VP's? That is to say, if freezing and thawing is key, why would it make any difference as to the freezing temperature so long as freezing and subsequent thawing were achieved? Is there any good quality evidence to suggest that the temperature achieved with nitrous is more efficacious than the temperature achieved with carbon dioxide, or ice?
BTW, I suspect there are far more parts to manufacture in a moped than in a sodastream
I think it's more to do with having no other option for effective small scale cryo use than no sense. The old cryopen did work well enough and was profitable fairly easily. But that was "only" £600 odd pounds. Someones trying to pay off their Range Rover with the new version.
I think the point about effectiveness rests a lot on speed of effect. Equilibrium is our enemy here. The trouble is the cold we apply gets evened out through the surrounding tissue as rapidly as the blood flows relative to the amount of heat it can carry to the area. At one extreme we could effectively kill vps by putting the whole foot in a bucket of ice water for a day or two (guessing, never tried it) it would cause necrosis of the VP tissue but the peripheral damage will be up to the ankle at least, possible the whole body will have shut down due to hypothermia before sufficient necrosis has occurred. This is probably unacceptable for most patients. The ideal on the other hand would be something that creates the biggest temperature difference on the surface tissue and can keep that temperature long enough for the cold to pass to deeper tissues before the blood flow has a chance to equalize the temperature. The colder the better i would say. I don't see how it could be too cold.
Any liquid with a subzero boiling point is a candidate as it's the expansion when boiling off that creates the cold. The lower the boiling point the more aggressive the boiling off and therefore the colder the resulting gas.
If you're going to experiment you'll need a factor in a few things -
You should be mindful of not having a "BLEVE"
Quote:
BLEVE (pronounced /ˈblɛvi/ BLEV-ee), is an acronym for boiling liquid expanding vapor explosion. This is a type of explosion that can occur when a vessel containing a pressurized liquid is ruptured. Such explosions can be extremely hazardous.
A BLEVE results from the rupture of a vessel containing a liquid substantially above its atmospheric boiling point. The substance is stored partly in liquid form, with a gaseous vapour above the liquid filling the remainder of the container.
If the vessel is ruptured — for example, due to corrosion, or failure under pressure — the vapour portion may rapidly leak, lowering the pressure inside the container. This sudden drop in pressure inside the container causes violent boiling of the liquid, which rapidly liberates large amounts of vapour. The pressure of this vapour can be extremely high, causing a significant wave of overpressure (an explosion) which may completely destroy the storage vessel and project fragments over the surrounding area.http://en.wikipedia.org/wiki/Boiling...apor_explosion
Again this could be unacceptable to many patients.
I think it's more to do with having no other option for effective small scale cryo use than no sense. The old cryopen did work well enough and was profitable fairly easily. But that was "only" £600 odd pounds. Someones trying to pay off their Range Rover with the new version.
I think the point about effectiveness rests a lot on speed of effect. Equilibrium is our enemy here. The trouble is the cold we apply gets evened out through the surrounding tissue as rapidly as the blood flows relative to the amount of heat it can carry to the area. At one extreme we could effectively kill vps by putting the whole foot in a bucket of ice water for a day or two (guessing, never tried it) it would cause necrosis of the VP tissue but the peripheral damage will be up to the ankle at least, possible the whole body will have shut down due to hypothermia before sufficient necrosis has occurred. This is probably unacceptable for most patients. The ideal on the other hand would be something that creates the biggest temperature difference on the surface tissue and can keep that temperature long enough for the cold to pass to deeper tissues before the blood flow has a chance to equalize the temperature. The colder the better i would say. I don't see how it could be too cold.
Any liquid with a subzero boiling point is a candidate as it's the expansion when boiling off that creates the cold. The lower the boiling point the more aggressive the boiling off and therefore the colder the resulting gas.
If you're going to experiment you'll need a factor in a few things -
You should be mindful of not having a "BLEVE"
Again this could be unacceptable to many patients.
Good luck
Interesting, but your clinical evidence for the above contention?
__________________ Science is the antidote to the poison of enthusiasm and superstition
I have the Cryoalfa. Dont know about comparing performance but I notice the cryopen cartridges are much cheaper, although slightly smaller. However they are asking to take it back to modify it for a bigger cartridge,(their idea, not mine!) and I am about to do that. Maybe cryoalpha is cheaper in other countries than here in Ireland? The Cryopen cartridge price is from Canonbury in England. By the way there was very little backup information when I bought it first, but after persevering with the supplier i got more comprehensive info.
While we are on the subject maybe somebody could give feedback on what they think of them for treating verrucae, e.g. suggestions on time etc.
The contention that speed of freezing achieved by lower cooling temp should be more efficacious in the treatment of VP's. I always thought it was the freeze-thaw cycle that was key? My example of ice was somewhat taking the piss, but what of the difference between carbon dioxide and nitrous oxide, does it make any difference in terms of the treatment outcomes after x number of treatments?
The answer you are probably looking for is: no, Simon- it doesn't. Unless you have a reference to an RCT up your sleeve that I'm not aware of. Quite possible you have as VP's are the most boring subject in the world and I only dip into these topics when I'm really, really bored.
BTW, I think I've got a reasonable grasp of physics and how the lower limb functions within its laws. But since you consider yourself to have physics on your side, you must understand thermo-dynamics better than me. So, lets take the following example, which I'm sure you can enlighten me upon: lets say we have a VP measuring 1cm x 1cm and we freeze it in its centre with a cryo instrument with a tip measuring 2mm x 2mm. If we freeze it with nitrous oxide how much of the surrounding "healthy" tissue would we inadvertently have to freeze in order to achieve freezing of all the cells within the pathologic tissue? How does this compare to the same situation using carbon dioxide as the cryogen? Which one would result in the "removal" of the VP with the least number of treatments?
"I don't know, Simon" is the answer you are looking for.
__________________ Science is the antidote to the poison of enthusiasm and superstition
Which cryoalpha do you have? The canonbury cartridges won't work as they are not the screw in type and don't have a filter in the cartridge so might clog your pen. A fair amount of swarf gets caught in the filters of the cryopen so i wouldn't risk using an unfiltered cartridge.
I haven't had a lot of use from this yet but keep us posted on how it goes with your Cryoalpha. It's about time there was a cheaper contender in the market.
Cryoalfa 'perfect'. Sorry I think I confused you. I have not used the Cryopen cartridge on the Cryoalfa. I was just comparing the gas prices (that constitutes a pun in Ireland !) . by the way there was a charge of €50.00 to adapt the unit but free if you bought min. 4 cartridges at €29 a pop.
The contention that speed of freezing achieved by lower cooling temp should be more efficacious in the treatment of VP's. I always thought it was the freeze-thaw cycle that was key? My example of ice was somewhat taking the piss, but what of the difference between carbon dioxide and nitrous oxide, does it make any difference in terms of the treatment outcomes after x number of treatments?
The answer you are probably looking for is: no, Simon- it doesn't. Unless you have a reference to an RCT up your sleeve that I'm not aware of. Quite possible you have as VP's are the most boring subject in the world and I only dip into these topics when I'm really, really bored.
BTW, I think I've got a reasonable grasp of physics and how the lower limb functions within its laws. Yourself?
Yes thank you
The reason you don't need clinical evidence is that this physical destruction of tissue is predictable and has been modelled. "The process of freezing in a capillary porous medium is numerically simulated with regard to temperature and stress fields with consideration of phase change in the context of cryosurgery applications. The temperature-dependent mechanical equilibrium equation is then solved in a quasi-static manner to analyze the resulting thermal stresses and deformations." http://www.sciencedirect.com/science...9536d1d1101ee2
But really you would have to be seriously bored to get into it that much
However it is logically clear that if you apply something only slightly cooler than the skin it won't take much capillary blood flow to equalize the temperature to ambient body temperature, i.e. it wouldn't take much time, whereas if you apply something much cooler it would take more capillary blood flow to equalize it. The importance of this equalizing speed is in the transfer of the cold to deeper tissues. It also takes time. All the while it is loosing it's effect so the greater the starting temperature difference the greater the depth of penetration where the all important freeze-thaw cycle can occur.
Is that proof enough that greater temperature difference, i.e. colder = greater depth of penetration = better potential to be an effective treatment = all else being equal less number of treatments needed?
I don't know why CO2 isn't used instead of N2O, they both have a similar (but lower) boiling point. It is likely to be logistical/economical factors. I would guess that as CO2 doesn't have a natural liquid state it would require more effort than N2O in getting it there. Bare in mind that the CO2 in your soda stream container is not likely to be liquid CO2 but compressed gas, so if you're thinking it would be much cheaper you might have to think again. If it has already boiled, ie it's already a gas you've lost a lot of the potential cooling effect but with any compressed or propelled gas you could still freeze using the Venturi effect. To be honest i don't know why we can't have a small electric compressor that takes air from the room and forces it through a tiny hole at great speed into an expansion chamber which has a side to be pressed to the VP. Anyone know why that's not possible?
Cryoalfa 'perfect'. Sorry I think I confused you. I have not used the Cryopen cartridge on the Cryoalfa. I was just comparing the gas prices (that constitutes a pun in Ireland !) . by the way there was a charge of €50.00 to adapt the unit but free if you bought min. 4 cartridges at €29 a pop.
Ah i thought you might have been thinking of trying the cheaper cartridges. Never mind
What size were you using and any idea how many 15 second freezes you were getting out of it?
BTW, I think I've got a reasonable grasp of physics and how the lower limb functions within its laws. But since you consider yourself to have physics on your side, you must understand thermo-dynamics better than me. So, lets take the following example, which I'm sure you can enlighten me upon: lets say we have a VP measuring 1cm x 1cm and we freeze it in its centre with a cryo instrument with a tip measuring 2mm x 2mm. If we freeze it with nitrous oxide how much of the surrounding "healthy" tissue would we inadvertently have to freeze in order to achieve freezing of all the cells within the pathologic tissue? How does this compare to the same situation using carbon dioxide as the cryogen? Which one would result in the "removal" of the VP with the least number of treatments?
"I don't know, Simon" is the answer you are looking for.
I nearly missed this update, now i don't know if you saw my last reply to your original question or if you are now only interested in this clearly impossible to answer exactly question. If all you want is your ego tickled then here you are "I don't know, Simon"
However if you actually want the answer to the relevant and more interesting question of does colder equal more effective treatment i'll paste it again for you -
It is logically clear that if you apply something only slightly cooler than the skin it won't take much capillary blood flow to equalize the temperature to ambient body temperature, i.e. it wouldn't take much time, whereas if you apply something much cooler it would take more capillary blood flow to equalize it. The importance of this equalizing speed is in the transfer of the cold to deeper tissues. It also takes time. All the while it is loosing it's effect so the greater the starting temperature difference the greater the depth of penetration where the all important freeze-thaw cycle can occur.
Colder = greater depth of penetration = better potential to be an effective treatment = all else being equal less number of treatments needed?
Even if it was possible to use CO2 in the same way as N2O it has a higher boiling point so would be less cold = less effective.
What i mean by physics being on my side is just that clinical podiatry evidence of some kind is not needed to know the above, it is already known in physics. It would be possible to draw an equation if you could find someone who was bothered to.
I nearly missed this update, now i don't know if you saw my last reply to your original question or if you are now only interested in this clearly impossible to answer exactly question. If all you want is your ego tickled then here you are "I don't know, Simon"
However if you actually want the answer to the relevant and more interesting question of does colder equal more effective treatment i'll paste it again for you -
It is logically clear that if you apply something only slightly cooler than the skin it won't take much capillary blood flow to equalize the temperature to ambient body temperature, i.e. it wouldn't take much time, whereas if you apply something much cooler it would take more capillary blood flow to equalize it. The importance of this equalizing speed is in the transfer of the cold to deeper tissues. It also takes time. All the while it is loosing it's effect so the greater the starting temperature difference the greater the depth of penetration where the all important freeze-thaw cycle can occur.
Colder = greater depth of penetration = better potential to be an effective treatment = all else being equal less number of treatments needed?
Even if it was possible to use CO2 in the same way as N2O it has a higher boiling point so would be less cold = less effective.
What i mean by physics being on my side is just that clinical podiatry evidence of some kind is not needed to know the above, it is already known in physics. It would be possible to draw an equation if you could find someone who was bothered to.
I really just wanted my ego massaged by you, oooh it feels sooo good. I understand your point re: temperature gradients, I just think you'd need to pump an awful lot of hot blood to a small area for it to prevent freezing to the depth required when you are using cryogens with temps as low as they are. What is the vascular reaction to cooling in the skin in terms of the superficial plexus and deep plexus?
The reality is that either gases might result in eradication of the VP in one treatment, or may be unsuccessful in 100 treatments. I lost count of the number of times I treated my own VP with nitrous, it never worked. And I can assure you that I really did freeze it! Yet I've also treated people once with a much warmer cryogen and their VP has gone. So if it was all about freezing and temperatures and "physics" we wouldn't see such variation in outcomes.
__________________ Science is the antidote to the poison of enthusiasm and superstition
About 5-6, 15 second aplications from a cartridge. Cartridge 16g. Thats the current, let you know when they adapt mine shortly, what the difference is. Like Simon said the results (i.e. number of applications ) vary alot - but i have found that with all treatments and all verrucae. I gather from the thread that like myself, verrucae are not your favourite topic. Now, Friday, 22.30 ,I'm off for a couple of Guinness, though with a few worries about my oesophagus after following your physics discussion on the application of cold liquid to tissues.
At least VPs are a sociable thing. In fact i know one podiatrist who got to know her patient so well she ended up marrying him. I can't say if free continuation of treatments was a part of the prenuptial agreement or not. Maybe she felt she owed him by then
I've developed a favourite approach by now that usually works and just accept that like simon's there will be a few stubborn ones determined to try and make us look incompetent. Such is life.
I think your oesophagus will be ok, i reckon the body has a very effective system for removing local extremes of temperature before damage occurs. Just a shame about the liver and brain though
In case anybody else is using the old style cryopen like myself and has noticed the sudden increase in price with most suppliers charging around £14.95 per box of 10 cartridges . I have managed to secure 30 boxes today for £8.9 from http://www.vet-direct.com/ tel 0800 068 3300.
Mathew Vaughan
Last edited by Admin : 13th November 2009 at 01:45 PM.
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The reality is that either gases might result in eradication of the VP in one treatment, or may be unsuccessful in 100 treatments. I lost count of the number of times I treated my own VP with nitrous, it never worked. And I can assure you that I really did freeze it! Yet I've also treated people once with a much warmer cryogen and their VP has gone. So if it was all about freezing and temperatures and "physics" we wouldn't see such variation in outcomes.
The idea that there is no reasonably definitive amount of treatment for cryotherapy and its effect on VP is worrying.
I have witnessed plenty of new patients attend the clinic who have had cryotherapy on one verruca elsewhere, only to then have clusters form around the original site.
Perhaps the purchase of such an expensive piece of kit clouds the mind, and thus modifies the idea of causality.
If I was to put baked beans on a verruca 1-100 times, and watched it finally disappear, did the baked beans cause the verruca to vanish?
I think as humans we want to be seen as actively helping a situation, and whilst the motive may be good, can sometimes lead to overplaying of ones hand.
Cryopen v cryoalpha pen
and have change left over for a helmet 
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