Hyperbaric oxygen therapy


First some background science and history. (If you know all this or can’t bear to read it all, skip to the image and read from there) You can also read my blog entry here

Hyperbaric oxygen therapy, or HBOT for short, is the delivery of 100%oxygen under increased atmospheric pressure. This enables the body to absorb oxygen in higher concentrations.

Atmospheric pressure is the ‘weight’ of the air bearing down on the earth. At sea level it is said to be I atmosphere (1ATA) or 1bar. Up a mountain, with less of the atmosphere above us, the pressure is less, and under the sea it is increased due to the added weight of the water overhead.

Air contains a mixture of gases and Oxygen comprises 21% of the total, so the percentage of the pressure in the atmosphere exerted by the oxygen is 21% of an atmosphere (or 0.21 ‘bar’…think of the weather forecasts talking about “isobars” those lines that you see on the maps that join spots with the same pressure.) The oxygen from the air enters our lungs and diffuses into the blood where it is transferred to red blood cells which are specially designed to bind the oxygen in higher concentration (19 mls of oxygen per 100mls blood contained in red blood cells) than is possible if merely dissolved in the plasma (0.3 mls/100mls in plasma). The circulation then carries it to all the cells of the body where it is released to enter the cells in various tissues, to be used in the vital energy making pathways. Without oxygen the tissues die rapidly. The brain in particular is very sensitive to lack of oxygen and requires 20% of the total body blood flow to supply enough oxygen to the tissues which is very ‘energy greedy.’

Study of the brain at high altitudes has shown that at low pressure (and thus low oxygen pressures) the brain swells and the blood vessels leak (altitude sickness). When divers breathe  air from a tank under water, the increased pressure causes more gas to dissolve in the blood and if they come up quickly it bursts out of solution rapidly and forms bubbles in the tissues (like the muscles and the brain). This gives symptoms known as ‘the bends’. The culprit gas is not actually oxygen but nitrogen (nitrogen is the main component of air at 78%) and it can give painful muscle cramps and even fits.

It has been known for centuries that Oxygen is important to life. In the emergency room it is standard practice to give 100% oxygen in all cases of serious illness and injury although we rarely consider giving it under pressure. Despite growing evidence that oxygen under increased pressure is beneficial for many conditions it is still not be used routinely. The oxygenation of tissues under hyperbaric pressures in cases of gas gangrene of wounds and carbon monoxide poisoning is well known to be life saving. However there are few hyperbaric chambers available in the NHS and even in these cases it tends to be a treatment of last resort in many cases.

In recent years private clinics and charities have been offering this therapy and evidence is mounting of its wide reaching benefits. A number of MS centres, and charities supporting this or other diseases, have invested in the technology because of reports of benefit to their sufferers. Some of them will offer treatments to non-MS patients for a fee. (At the one I attend, I have shared the chamber with sufferers of ME, stroke, other cancers and  injuries including footballers keen to shorten the time they spend recovering from injury.) There are also “private” chambers that also charge a fee. It is really hard to get a comprehensive list of chambers but this website allows you search your location https://www.hyperbaricoxygentherapy.org.uk/find-chamber

Hyperbaric  Chamber similar to the one I had access to at Chiltern MS centre. it is a multi – person chamber (up to 5 people)

It was to one of these centres I found myself drawn. I had heard of the reported benefits of HBOT for cancer patients way back when I had my diagnosis, but had felt that getting to a centre regularly would be too difficult and expensive for me. Besides, after surgery, Bob was gone and I was well. For nearly two years I put HBOT on my list of ‘possible treatments’ to keep in the bag for use if things changed. Then a good friend stumbled upon this centre which is a couple of miles from my home! We went for a look round and I resolved to have a trial ‘whiff’ of gas out of curiosity. I didn’t do much about it for a couple of months, then after Christmas I started to feel my memory was getting worse. On my scan in December, whilst reported as ‘no evidence of recurrence’,  I noted that the area around the scar where Bob had been removed had a sort of ‘haze’ around it. It was always a bit ‘messy’ in that area but to my amateur eye this looked worse than the last scan. I was told it was nothing to worry about – a bit of fluid – but I did not like it. I was aware that, mentally, a bit of ‘brain fog’ was quite common after radiotherapy, and though I am not ungrateful, after all I am alive and tumour free, I did not like it. Though nobody else took my forgetfulness seriously (I am after all ‘of an age’ when these things happen) I didn’t like it. I took some memory tests on line and fell ‘just below the average score for my age’. See, people would say, we all get a bit dippy with age and just below average shows you are not abnormally impaired. But I DID NOT LIKE IT!

Below average? Who aims for below average!? If I had aimed for average , never mind below average, on this journey I would have been dead by now!! I have never been below average in my life*! I am not going to start now!

[* for honesty’s sake I have to add that this is not entirely true… eg i am certainly below average height and have somewhat less than average musical ability; I can’t hit a ball to save my life and my below average leg length makes running comical and definitely below average when tested on school sports days… and the list goes on but these are not things that matter to me.  – Since Bob, I have learned not to sweat the small stuff, something that I used to do in above than average amounts. ]

So I signed up for a course of HBOT. My reasons were:

Firstly, there was good evidence that is was beneficial not only for its anti cancer effects but its beneficial effects on radiation scars.

Secondly, I reasoned that though I was not suffering severe symptoms, and my scan did not report severe radiation necrosis, prevention was better than cure.

Thirdly, and even more significantly, it had providentially entered my life just when I had been questioning the need for a remedy for a new annoying symptom. Not only that, my objections that it would be too far away, too expensive and too much of a hassle, had been completely negated. (The MS centre is a charity and offers the treatments at a fraction of the cost of the private centres and would cost next to nothing to get there since it was more or less round the the corner from my home .)

So off I trotted and having got permission from my GP. There are few contraindications such as trouble with the eardrums and lung disease that might predispose to pneumothorax (burst lung) and a few drugs cannot be taken at the same time as HBOT. The table referenced here (http://emedicine.medscape.com/article/1464149-overview#a1) gives a comprehensive list.

I was offered the standard 15 session initial course – 1 hour every weekday for 3 weeks. For the first week we were ‘sunk’ to 1.5 ATA or the equivalent of 16.5ft under the sea. The second week takes us down to 1.75 ATA (24ft) and finally, on week 3, the big dive, 2 ATA or 32ft. Thereafter we could ‘top up’ our therapy periodically if we found it helpful.

The 64 million dollar question would be, after the course was finished, – ‘has this been beneficial?

I realised, for my own satisfaction, I needed to do this scientifically!

First I made a list of the symptoms that could be monitored and that I would like to improve or at least halt the decline.

speaking (reading aloud)
short term/working memory
cognitive function

It would be interesting to compare before and after MRI scans.

I needed tests to measure my progress and they had to be easy to administer and repeatable at regular intervals. In order to be sure this was true effect of the treatments, it was no good picking a test designed to train my brain that would allow me to constantly learn and steadily improve.  Though there was always going to be some improvement, especially in the early tests due to familiarity and technique, this needed to be differentiated from true improvement due to the therapy.

I did not expect my reading and spellings to improve at all as they had been static since my surgery and were no doubt due to the missing bit of brain, but I hoped for improvement in memory and cognition.

A search of the internet  soon identified some suitable on-line assessments that seemed to fulfil these criteria.

Two tests were used. The first (www.spellingtraining.com) was a random word test (designed for older children). The advantage was that is tested me on simple as well as moderately hard words and there was a huge number of lists. I administered three lists each time, each time a different list and without prior sight of it.
The second test was similar but harder. (www.merriam-webster.com). This stretched me more but I was aware that there was a component in this test related to my naturally poor spelling skills, nothing to do with Bob’s journey through my brain. Again, three lists were administered. The scores were always lower on this test.

The average score over the 6 tests was then calculated each time.

Average score at the start was 58% and it steadily rose to over 70%.

This I could not do on line. I chose a paperback book and read aloud three full pages (no diagrams or other breaks in the text). Every stumble was marked and the average count per page calculated.

At the start I made around 12.7 stumbles per page. It improved  to around 8 by the end of therapy.

Working memory/short term memory.
Working memory is assessed by on line test tests of digit span(recalling a string of numbers) and visual span (recalling a string of meaningless shapes). The test administers progressively longer strings of numbers/shapes as you succeed in remembering them and calculates your memory level in terms of the average number in your span. I was always better at number recollection than shapes.
Memory is also assessed as part of the cognitive performance tests below. (It is a significant component of spacial planning and contributes a small part to odd one out and double trouble challenges. It also is a major part of the episodic memory challenge)

At the start I was devastated to find I could only remember about 4 numbers at a time. This steadily improved to around 7 numbers

Shape recall was even worse, I struggled to remember 2 or 3 at the start but improved to around 5 at the end.


Cognitive performance
This is calculated by a combination of measurements.

Cambridge brain sciences tests.(www.cambridgebrainsciences.com)
Spatial planning: requires re-ordering of numbered balls on a tree using logic to move. This tests reasoning (working out a strategy) and short term memory (remembering the order of your strategy) (50/50)
Odd one out: tests mainly reasoning but requires some sort term memory.
Double trouble: mainly tests verbal score but requires some input from short term memory and reasoning. It involves selecting the colour of a word (as opposed to what it says, eg the word blue written in red requires you to click the word ‘red’ even though they may have written the response ‘red’ in blue and the wrong response in red. )
Grammatical reasoning: this involves reading a complex description of a figure eg “the square does not encapsulate the circle.” True or false responses, for example in this case requires you to understand that it is describing a square inside a circle as well as the double negative. This tests your verbal skills mainly but also requires some reasoning.

From these 4 challenges a composite overall cognitive score is obtained and can be expressed in terms of the % of people who score lower than this on average. The individual contribution to the % made up by memory, reasoning and verbal skills can be calculated.

The composite score improved from a devastating 20% to around 80% Whooo hooo! Above average! It was interesting that on individual tests the contribution of memory and recall often went the opposite  way from the verbal score. I suspect this is a fluke of the scoring system on this particular test, and it emphasises the need to not rely too heavily on one type of test.

Online cognitive function test. (www.foodforthebrain.org)
This further assessment, designed to detect early cognitive decline, is geared mainly to detecting early Alzheimer’s disease but is useful for monitoring cognitive function in general. It measures the following modalities:
Episodic memory: this is tested by presenting information and testing it after a period of unassociated activity. It uses a grid of common objects to be identified, then those objects are later recalled along with their position on the grid.
Executive function is tested by several symbol and letter matching exercises performed against the clock, which require attention and processing speed as well as judgement.
Processing speed, is a measure of mental efficiency and is calculated from the timed exercises above.
The results are expressed as a composite score. Average for the age group 50-70yrs is 54. A score of 43 is one standard deviation below norm, (only 16% of people fall below this). A score below 38 (1.5 SD below norm) is cause for concern as only 6.7% of the population fall into this zone.

On my first attempt I scored 39! After a bit of practice I pulled myself up to 41. Definitely not happy! By the end of therapy I had improved my score of 39 (in the bottom 16%) to a wonderful 58 – echoing the other cognitive test, I was now firmly above average! Happy at last!

Below are the graphs of the results of my ‘study’. I am encouraged – all trends seem point to improvement, even the reading and spelling. They are not smooth curves but that’s because they are values for one subject, and we all have good and bad days and extraneous factors play a part. For example, the sharp dip on value 5 for memory spans was due to my mouse playing up on that test. On another occasion, the phone went and put me off in the middle of a timed test. little spikes and dips abound. Excitement? Expectation? Hunger? Tiredness? Time of day?  Regardless of the spiky graphs, the general trends are clear.

You can make your own conclusions. Would I have improved as much by just practicing  the same tests without the HBOT? It it placebo? Is it true improvement? Is it sustainable? Will I slip back if I stop it now?

I am continuing the therapy at a reduced frequency (twice a week at present) and will continue to monitor myself to see what effect that will have. There will be one other important test to bring to bear on the results – my next scan on 24th March (results 5th April). That will make the scanxiety interesting to observe this time.

I shall be updating this page so… Watch this space.


Effects of HBOT on language and cognitive function

Image 13-03-2017 at 00.03


hyperbaric Oxygen and cancer

Hyperbaric Oxygen as an adjunct to treatment

hyperbaric oxygen and gamma knife for brain tumour

HBOT in radiation induced damage in children with brain tumor.

Cochrane review of benefit of HBOT for radiotherapy damage. While there is encouraging evidence in some cases this is beneficial, and clinicians are using HBOT in this context, there is urgent need for further research because there are limited studies and data is of poor quality.