PFO test anyone

[Helen (AKA Hellvet)]

We have had 3 PFO's diagnosed in our club after 3 bends in the last 12 months, mine being the first of these. Several of our club members have since been considering having a screening test for a PFO "in case" after seeing one of them lifted off the boat by helicopter, and 2 of them hospitalised for recompression for a week (seperately!), but these are difficult to justify to the NHS, and expensive if funded privately.

Most people have heard of Dr Peter Wilmshurst in relation to these tests, but he is very busy and it can be difficult to get referred to him. One of our club members has recently had his PFO fixed on the NHS by Dr Mark Turner at Bristol Royal Infirmary. This is lifted from an email from him offering these PFO tests to our club members, and may be of interest to some clubs/members.


"We discussed PFO tests for your diving colleagues. If any wish for this to be done I can arrange a session for your club. If there are 5 or more we can do £ 160 each. If individually £200 each. Most people charge > £ 350 and some up to £480. If a smaller group than 5 we can discuss.

This is for test only. If positive and discussion needed I will see patients at end of session or will make arrangements to see them another time.

I am one of two doctors in the South West trained to close PFOs and was trained in diving medicine in the Royal Navy. I was a Ship’s Diving Officer and Submarine Escape Instructor (and have escaped from a submarine!). Thus I think I am qualified to do the test! I use Peter Wilmshurst protocol and it is extremely important that this test is done well in order to be sure that diving is safe.

Please feel free to distribute this to your colleagues. I am happy to discuss over the phone.

Mark Turner

Tel. 07968 724075"

[JimW]

Hi Helen

Dr Peter Wilmshust presented to DOC two years ago on his latest research into PFO and the correlation he had discovered with Migraine.

His findings were pretty much that there was a clear correlation between people who suffered migraine with aura and the presence of a large PFO. Such large PFO's are likely to represent a risk of DCI in divers who have such a condition.
On the other hand people with small often asymptomatic PFO may well remain asymptomatic throughout a diving career and there is no medical indication that they should be tested.

So to paraphrase Dr Wilmshurst
If you have a history of migraine with aura then there may be a risk of DCI and a PFO test (and closure if necessary) can be advised.
In the abscence of a history of migraine with aura or an unexplained DCI there is no medical indication that a PFO test would be beneficial.

My interpretation and so always better to check with the source but the advice on PFO testing has, to the best of my knowledge, always been not to routinely test as the testing itself may force open an asymptomatic PFO that may not otherwise have occured and the first rule of medicine is do no further harm?

Jim

[Helen (AKA Hellvet)]

So to paraphrase Dr Wilmshurst
If you have a history of migraine with aura then there may be a risk of DCI and a PFO test (and closure if necessary) can be advised.
In the abscence of a history of migraine with aura or an unexplained DCI there is no medical indication that a PFO test would be beneficial.

My interpretation and so always better to check with the source but the advice on PFO testing has, to the best of my knowledge, always been not to routinely test as the testing itself may force open an asymptomatic PFO that may not otherwise have occured and the first rule of medicine is do no further harm?

I would completely agree with you...but i had a history of teenage migraine which i "grew out of" and the other 2 club members have no history of migraine, or even headache, certainly no aura - so none of us would have been sent for a test, but all of us got bent, and 2 of us ended up with severe neurological bends, which could not only have left us with permanent diving bans but with severe long term problems.

It is also not easy to get referred on the NHS even after a bend - i struggled to get referred even after a cerebral, muscle and skin bend on a perfect profile (according to the chamber i did NOTHING to deserve my bend), and ended up going private after a 3 month fight with my local NHS PCT. Those i know of trying to get referred on the NHS for migraine (and therefore a check for diving) have been looking at 12-18months, and then a further 12-18m before repair.

I have NO wish to scaremonger, but there was a genuine interest in our club in getting tested, so as this guy says he's happy to do tests i thought i'd open it up to other BSAC clubs, cos i'm sure we can't be the only one getting a little paranoid, and with people wanting to get tested!

This is a genuine attempt to pass on useful information if people are trying to get tested, but if you feel it is inappropriate then please feel free to remove it!

[Adrian Kelland]

This is a genuine attempt to pass on useful information if people are trying to get tested, but if you feel it is inappropriate then please feel free to remove it!
As long as the doctors make sure any patients going for such a test without prior incident under stand the risk of opening up a PFO, then I think that the information posted is useful.

Adrian

[John Bantin]

A cautionary tale:

I am told by someone who was involved, Dr P. Wilmshurst tested a lot of members of No1 branch and found a high proportion had PFO. This was about 15 years ago. Two of them went on to run a very successful diving liveaboard, one habitually runs across the Sahara, and another was in a film sequence that involved so many re-takes of an emergency ascent that I thought it might get ME bent. (I did not know about her PFO at the time.)

I am by no means a doctor of medicine but it does seem that a the proved existence of a PFO might not be the end of your diving.

On the other hand, another friend who had surgery for a PFO got severley bent on a non-eventful 20m dive almost immediately after getting the all-clear to go diving.

[Nigel Hewitt]

On the other hand,So...
What you're saying is that we don't need a PFO.
We can get quite adequately bent without one....

I have a suspicion that most PFOs are benign as far as diving goes. If it's one in three now then it was one in three when they were testing the tables we use and it's already factored in. There are aggravating factors but we don't see very many 'undeserved' bends and, although it would be nice to pin a reason on a bend and cure it, bends happen.

[John Bantin]

What I am saying is that eg. I might have a PFO. If I get tested, do I resign my job? Or do I carry on now worried about something I did not have to worry about before? It does seem that some of those people I cited that disregarded medical advice some years ago might have been right to do so and someone who took medical advice and acted on it might have been wrong. Diving seems less cut and dried than we would like. I remember a friend of mine who is/was a well-known lung surgeon and had the chair at a well-known University might have been wrong when he diagnosed me as having a pneumonia and said I would never make a scuba-diver! (I also thought it strange that he was a heavy smoker - but what do I know?)
I would think that a regular test for prostate cancer might be more useful for both you and me!

[Helen (AKA Hellvet)]

well i'd be worried if a test for prostate cancer came up positive for me!

I'm not trying to advocate anyone goes and gets tested randomly, i'm just trying to be helpful to those who are fighting desperately to get the test and or waiting for ever, and give them another option. I know i was desperate for the test after my bend, and i had to really fight for it - i'm not sure if it hadn't been for all my reading of the research and access to the medical journals that i would have got tested at all.

[Lou]

Helen,

I think it's good of you to bring this to everyones attention. It's always good to get information on this kind of thing and may bring relief to some worried people out there who are frustrated with the wait for the NHS. Giving people this info certainly isn't scaremongering, after all we're all adults capable of making informed decisions! (I think!!)

[Tristan Cope]

the testing itself may force open an asymptomatic PFO that may not otherwise have occured

Jim

Jim,

Whats your source for this information? I don't believe it is correct.

Tristan

[AndyDavis]

Does BSAC, and/or other organisations, have a policy regarding diving with PFO?

Would there be depth/deco limits? Increased conservatism? No more diving?

[Tristan Cope]

As yet, there is no advice in the UK Sports Diving Medical Council medical standards regarding PFO. As far as I am aware there is nothing in the medical standards of any of the organizations about PFO.

Arguably the evidence on exactly what difference PFO makes to your overall DCI risk is equivocal. DAN are undetaking a large prospective study in which volunteers are screened for PFO and followed up over subsequent years. The volunteers (quite rightly) are not informed of the test result. The point of this study is that we don't really know whether having a PFO makes a big difference to DCI risk or not.

Dr Peter Wilmshurst gives quite specific advice to divers he finds to have a PFO. From memory, that advice is something along the lines of: max depth 15m, avoid repetitive ascents, avoid repetitive dives (i.e max 1/day).

[Josepherely]

I would be surprised if an ultrasound would make an existing PFO larger, the stress used is nothing that you would not subject to yourself lifting a tank and putting it on a boat.

The issue is not just a PFO, the issue is a shunt, which can come from more than just a PFO (although a PFO is the most common source).

Testing for this is a lot easier and less complicated than for a PFO, and a lot more reliable (more difficult to get wrong)

What is the correlation between a PFO and a higher risk of DCS? I have not seen any studies that clearly make it a causal factor. Would be interested if any references exist that show it.

Remeber the problem isn't the PFO, the problem is the bubbles that Nitrogen create after the dive, no bubbles (or few) less risk.

Joe

[Helen (AKA Hellvet)]

What is the correlation between a PFO and a higher risk of DCS? I have not seen any studies that clearly make it a causal factor. Would be interested if any references exist that show it.

If you go to PUBMED (a journal listing site used for searching for references by doctors) and search for decompression illness and shunts or PFO or Patent foramen ovale, there are a number of references which show a definite association between PFO, intracardiac shunts, and an increased incidence of decompression illness but here are a few of my favourites to be going on with...!
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=15343047&query_hl=3&itool=pubmed_docsum
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=11294694&query_hl=3&itool=pubmed_docsum
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=10887059&query_hl=3&itool=pubmed_docsum
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=12544998&query_hl=24&itool=pubmed_docsum
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=11294694&query_hl=24&itool=pubmed_docsum

[Tristan Cope]

Ultrasound certainly won't do anything to a PFO. I think the implication was that perhaps bubbles going through a PFO might "enlarge" it. I don't think there's any reasonable physical basis for this concern, let alone evidence.

There are other causes of shunt, but contrast echocardiography will detect all forms of shunt, not just PFO. In experienced hands, contrast echo is the most sensitive way of detecting shunt. There are other "easier" ways to detect shunt - i.e. requiring less user expertise, but I don't think they're as sensitive as echo.

Peter Wilmshurt claims a 100% relationship between cutaneous DCI and shunt - in other words that everyone who gets cutaneous DCI has a PFO, or some other form of shunt. The converse is not true. PFO is quite common. The statistical relative risk of PFO has not been established. Hence the DAN prospective study.

It isn't necessarily that easy to ensure bubble-free dives. Look at the DCIEM tables. They are very conservative, but they are "low bubble" not "no bubble" tables. There is a great deal of individual variation. Some people just seem more prone to producing bubbles than others. There is also a great deal of intra-individual variation from dive to dive.

[Tristan Cope]

These are retrospective studies that show PFO is more common in divers that have had DCI than in the general population. This demonstrates a statistical relationship between PFO and DCI, although it does not demonstrate causality.

What it does not tell you is what is the risk of DCI if you have a PFO. We suspect that the risk of DCI is increased if you have a PFO, but we don't know by how much. For most sensible dive profiles within tables, the risk of DCI is very low. Think how many dives are done each year in the UK and how many of those result in DCI. It is a very small proportion. Statistically, a significant proportion of divers must have PFO, but most of those do not get DCI. Why not? Perhaps it is the size of the shunt that is important. Perhaps there are other factors involved.

[Josepherely]

Thanks Helen, interesting articles
Joe