Tuesday, 27 August 2013

Gastroparesis (part 2)

Yellow rose
Groombridge Place, June 2013
In part 1, I described the symptoms of gastroparesis, what might be causing it in someone with diabetes, and the problems that arise - gastrointestinal symptoms, poor glycaemic control, malnutrition and weight loss, and depression. Now I'm going to write about possible treatments.

Nerve damage, if that's what is causing the problem, is irreversible. We can't (yet) mend nerves: once they're gone, they're gone. There doesn't seem to be an option to fix the faulty pacemaker cells either. But it is always useful to run through a list of things that will definitely not be helping. For example, opiate drugs are known for their constipating effects, and should be replaced with alternative painkillers if pain relief is necessary. Cigarette smoking has been shown to delay the gastric emptying of solids. Unfortunately, high blood sugar has also been shown to significantly delay gastric emptying, which is of no comfort to the person with diabetes who has been trying unsuccessfully to manage wild swings in blood sugar in the face of unyielding opposition from the gastroparesis itself. So I wouldn't bother opening that particular can of worms.

There are three methods used to help improve gastric emptying: pharmacotherapy (i.e. drugs), diet and surgical approaches. Two types of drugs can help with symptoms: prokinetics, which help to speed the intestinal contents on their way, and anti-emetics, which are used to prevent nausea and vomiting. These are routinely used, but changes to diet can be more effective than the medicines.

The Glycaemic Index (GI) is often used to assist with blood glucose control and weight management, and describes the speed at which carbohydrates are digested. High GI foods e.g. foods containing large proportions of monosaccharides and disaccharides (sugars) are digested quickly, and their glucose payload can reach the bloodstream before subcutaneous insulin has had time to get there, causing blood glucose to rise beyond the desired range. Low GI foods (complex starchy carbohydrates) such as oats and pulses are digested more slowly, and therefore deliver glucose to the blood slowly and more controllably, and keep you feeling fuller for longer. Unlike the majority of people with diabetes, high GI foods may help someone with diagnosed gastroparesis. These foods tend to contain simple sugars or processed carbohydrate and little fat and fibre - sweets, white bread, mashed potato.

Another good reason to avoid fibre, apart from its role in slowing gastric emptying, is that as it hangs around in the stomach it can contribute to the formation of unwanted fibrous masses called bezoars. The disadvantage of avoiding fat, however, is that someone with chronic gastroparesis is at risk of malnutrition, and could do with the calories supplied by energy-dense fatty food.

The diabetologist who referred the patient with gastroparesis to me suggested that a low carbohydrate diet might help reduce the volatility in blood glucose levels. The problem with this approach is that taking out the carbs leaves an energy deficit that can either be filled by protein or fat. Protein increases feelings of satiety, which is certainly not what we want, and fat slows gastric emptying. Blood glucose levels may be better managed with a greater proportion of high GI carbohydrate, which might actually be released from the stomach in a more predictable manner.

Research suggests other dietary recommendations, both to relieve symptoms and to maintain nutritional status. Small frequent meals are digested better than three large meals a day, and 'particle size' makes a difference - food should be chewed well, and liquids seem to leave the stomach more easily than solids. A patient might be prescribed three liquid supplements a day, adding a much needed 900 calories. Positioning during a meal, and sitting up and/or walking post-meal can promote gastric emptying; alcohol and carbonated drinks tend to exacerbate symptoms of bloating.

Placing a feeding tube below the stomach and pylorus in the jejunum (upper small intestine) allows nutrition to bypass the problem area, but brings with it the risk of infections and the inconvenience of having to be hooked up to a feed pump for hours at a time - jejunal feeding has to be much slower than feeding into the stomach. If nutritional status continues to decline, intravenous (parenteral) feeding is a possibility, but brings a whole new range of potential complications.

As well as addressing symptoms and nutrition, there are those pesky blood sugars to consider as well. Eating a meal containing carbohydrate requires a matching dose of insulin in order to maintain blood glucose within the desirable range, but we have seen that giving the insulin at the usual time (before, during or immediately after the meal) doesn't work if the glucose hits the bloodstream over a period greater than the lifetime of the insulin. So we could try splitting the insulin dose, perhaps giving 30% of the total dose just after eating, and the remaining 70% after an hour, or two, or whenever we think blood glucose is rising.

If you don't want to end up as a pincushion, this type of insulin regimen can be managed much more comfortably and conveniently with an insulin pump, which can be programmed to deliver insulin at whatever rate you desire. Delivering 6 units of insulin at one-tenth of a unit every five minutes over five hours can't be done with conventional insulin injection devices, but is a piece of cake with a pump.

Unfortunately the NHS doesn't fund Continuous Glucose Monitoring (CGM) systems, which have a subcutaneous sensor that samples interstitial fluid every five minutes linked to a device that translates the reading into an estimated blood glucose level. We lend these systems to patients to wear for just seven days at a time when we can't work out what their blood glucose is doing. Otherwise, users have to buy the kit and consumables themselves, which works out rather expensive. Although not mentioned in the research papers I have read about this condition, I think that CGM in combination with an insulin pump would be a valuable and effective approach to managing blood glucose with gastroparesis.

Finally, there are more technical and innovative options to try.
  • Gastric electrical stimulation (GES) was approved in 2000 in the USA. Similar to a heart pacemaker, the GES device is implanted next to the stomach and mimics the role of the gastric pacemaker cells, stimulating and enhancing vagal function and muscle tone. 
  • Botox (Clostridium botulinum toxin) is a muscle relaxant used cosmetically to reduce facial wrinkles, but will relax muscles elsewhere to therapeutic effect. Injecting Botox into the pyloric sphincter may cause it to relax sufficiently to allow better gastric emptying, but trials have shown this effect to be short-lived. 
  • In future, that universally-cited panacea 'stem cell therapy' may be relevant, providing a way to replace or rejuvenate those faulty pacemaker cells of Cajal.

Friday, 23 August 2013

Gastroparesis (part 1)

Brandenburg gate with two people dressed as Star Wars characters in the foreground
Berlin, March 2013 - no idea about the Star Wars characters...
I saw a patient recently who is suffering with gastroparesis, and I say 'suffering' for a good reason. Gastroparesis is 'a chronic disorder of gastric motility that is characterized by delayed emptying of either solids or liquids from the stomach in the absence of any mechanical obstruction.'

Food is normally chewed and mixed with saliva to form the bolus that you swallow. The bolus passes down the oesophagus into the stomach, where it is mechanically, chemically and enzymatically digested to form chyme: an acidic slurry of food, fluid and enzymes. The pyloric sphincter at the bottom of the stomach is prompted to release chyme from the stomach into the small intestine in small bursts, where the acid is neutralized and further digestion takes place by enzymes released from the intestinal wall and the pancreas. [The release of digestive enzymes into the intestine is the exocrine function of the pancreas, and is usually unaffected by diabetes, which is a disorder of the endocrine system.]

Food normally starts to leave the stomach within minutes of ingestion. After one hour 10% or more will have passed through to the small bowel, after two hours at least 40% should have gone, and four hours post-meal more than 90% of the meal should have left the stomach heading for the intestines. The final products of digestion are nutrients - fatty acids, amino acids, sugars, vitamins and minerals - that are absorbed through the wall of the gut into the body, and the indigestible fraction passes on through to be excreted as faeces.

The symptoms of gastroparesis include nausea, reflux, bloating, early satiety and post-prandial fullness, abdominal discomfort and pain. Putting a camera down into and beyond the stomach, which is usually the first line of investigation in most disorders of the gastrointestinal tract, is done to see if there's mechanical obstruction (from a tumour, for example), and in the patient that I saw, showed the remains of a meal that had been eaten the day before.

So the symptoms of gastroparesis simply arise because the stomach is not emptying - the pyloric sphincter is not being prompted appropriately to allow the chyme through to the small bowel. The next diagnostic test might be to follow a radioactive meal through the GI tract. Using this technique, delayed gastric emptying has been found in 25-55% of people with Type 1 diabetes, and in 30% of people with Type 2 diabetes.

Hyperglycaemia, or high blood glucose, is pretty toxic to the smallest blood vessels in the body, found in the retina and the kidneys, and also damages nerves. Often the nerves that are damaged are the smallest ones furthest from the brain, which is why foot care is so important. For some very unlucky people, the nerve that is affected is the vagus nerve, which transmits the signals that manage the extremely complex processes going on in the intestinal tract. But it turns out that hyperglycaemia affecting the vagus nerve is not usually the culprit in diabetes, but more often it is due to destruction of the pacemaker cells ('cells of Cajal') that link the vagus nerve with the smooth muscle of the stomach, and the result is the absence of peristalsis and atrophy of gastric smooth muscle.

Let's look next at what happens to the food once it has been digested, and glucose from carbohydrate in food has been transferred from the gut to the bloodstream. Insulin is secreted from the pancreas in order to allow the glucose to enter cells of the body where it is used for energy. In someone without diabetes, the pancreas simply responds to the level of glucose in the blood: lots of glucose leads to lots of insulin, little glucose means little insulin. It's automatic, and maintains tight control of blood glucose levels very effectively, to prevent those toxic effects of hyperglycaemia (or the unpleasant and potentially dangerous effects of hypoglycaemia, low blood sugar).

Now, we'll throw Type 1 Diabetes into the mix. Insulin secretion by the pancreas is non-existent, so the diabetic patient has to supply the insulin by injection. Usually it takes about the same time for glucose to reach the bloodstream from digested food as it takes for rapid-acting insulin to reach the bloodstream from the injection site. This type of insulin is effective over about 4 to 6 hours, which is about the time it usually takes for the whole meal to leave the stomach, be digested, and all the glucose to be delivered to the bloodstream.

With gastroparesis, there is a delay. Some glucose may turn up in the bloodstream straight away, but there is no way of knowing how much, or how long it will take for the whole lot to come through, and at what rate. So you can calculate the insulin that is needed to match the carbohydrate in the meal, but if you inject it all at once, it will arrive in the bloodstream before the glucose, and your blood glucose level will drop. The way to deal with low blood glucose from too much insulin is to consume some sugary carbohydrate that should be quickly digested, but - will it reach the bloodstream in time, given that the pyloric sphincter is mostly stuck shut? Later, when the rest of the carbohydrate from the meal finally gets through to the bloodstream, the insulin will no longer be there to deal with it, and your blood glucose level will rise. And there is no reliable way to predict how long this will take. The insulin and blood glucose graphs look like roller coasters.

Meanwhile, you feel uncomfortably full all the time and find it difficult to eat even a small amount of food. Eating is no longer pleasurable, you're losing weight, your family are initially sympathetic but you keep vomiting after a trivial amount of food, your breath smells terrible and with the constipation alternating with diarrhoea, the bathroom is never free. The diabetes team give the impression that your terrible glycaemic control is because of something you're doing wrong with the carb counting or insulin dosage, but you're doing everything you can think of to try and avoid high or low blood sugar, it's just that nothing's working. The high and low blood sugars make you feel awful too. Depression is a well-documented side effect of diabetes, and if you have gastroparesis too, well, there aren't many happy days.

Although part 1 ends on a low note, part 2 should provide some reassurance that treatments are available and can help.

Thursday, 15 August 2013

Presents and a prize

Toy bee on bicycle handlebars
Rented bicycle in Berlin, March 2013
It's been present-tastic at Lola Towers, partly due to my birthday and Mr A's birthday being less than a week apart, and partly because I've won another blog prize - this time, a box full of gluten-free snacks from Veronica's Snacks via The Happy Coeliac blog, and a tote bag to carry my snacks in. All I had to do was to suggest a new flavour for their crisps.

It's been a while since I gave you a social update, so in brief:
  • Mr A and I have done a lot of 'gardening', which consists of pruning, hacking, bagging and dumping vast amounts of shrubbery, and in Mr A's case, sawing down and then digging out the roots of our sadly deceased ceanothus.
  • We have had another posh dinner at Queans to celebrate our birthdays.
  • I have had ongoing car trouble involving the brakes, ever since the service in March. The car has done over 180,000 miles and (apart from the brakes) is still in perfect working order, but will unfortunately need further attention from the garage. They are being very reasonable about it, acknowledging the fault and trying to remedy it without charge, but so far without success.
  • I have a new Nexus 7 tablet, which I am still getting used to. Unfortunately, it is not quite as good as a laptop for Facebook and blogging (which is mostly what I do), and complains that it isn't compatible with BBC iPlayer or the Carbs & Cals app. It does run Skype, which my laptop has stopped doing, so that's one benefit I suppose, but I'm hoping to mend my laptop as soon as I find the MS Office CD.
  • I have been out for pizza twice with work colleagues - once with the new lot and once with the ones from my previous job. I like the old lot better, and there may be a Diabetes job advertised there soon, but it is likely to be part time and temporary, and therefore not as good as the job I have now.
  • I tried to do some homework on my case study, but my housemates came home and turned on the TV. My room is too small to work effectively, and at work they won't allow wireless access for personal laptops. I have put in a request for an update to the browser on the office PC, because at the moment the technology they're using is so rubbish that I can't use it properly for academic research.
  • I have been cycling to work a bit, which has been a great deal easier since Dr Bike adjusted my saddle. The Trust is very supportive of cycling, and will fund half an hour for free basic servicing with Dr Bike up to once a month for staff. I also have a locker in a changing room with showers and free use of towels.
There will probably be more cycling news soon, because I have taken some photos of my route to work on a sunny day this week. I can also announce that, for the first time, I managed to cycle all the way up the steep hill to my weekday lodging. My legs subsequently turned to jelly and I felt sick, but I'm hoping it will get easier!

Bags of baked crisps and tote bag from Veronica's snacks

Sunday, 11 August 2013

What I've been reading

Image of the book cover

Regency Buck
by Georgette Heyer

narrated by June Barrie
"It is in regrettable circumstances that beautiful Judith Taverner and her brother Peregrine first meet Julian St John Audley. The man, they both agree, is an insufferably arrogant dandy. But unfortunately for them, he's also the Fifth Earl of Worth, a friend of the Regent, and their legal guardian."
I thought (until I looked it up) that the narrator was the actress who plays Peggy Woolley in The Archers, but it turns out she isn't. She was very good, anyway, and the story was fine, but somehow it didn't meet my expectations. Of course there was the obligatory happy ending, but it didn't have the usual spark; I didn't find the characters completely believable, except for the gormless Peregrine, who was nicely done.

Image of the book cover

The Lady Most Likely
by Julia Quinn, Eloisa James and Connie Brockway
"Hugh Dunne, the Earl of Briarly, needs a wife, so his sister hands him a list of delectable damsels and promises to invite them — and a few other gentlemen — to her country house for what is sure to be the event of the season."
Number nine of my twelve books of Christmas. It looks as though it will take me nearly the whole year to read them all, because after each one I need a few books of quality in order recover my composure. This one is among the better ones, and interesting when read in such close proximity to Georgette Heyer; they have a lot in common, set in the Regency period and including a modicum of laugh-out-loud humour. But in this one the characters are two-dimensional, the story is predictable, and the innovation of having three interconnected stories is not enough to counteract the overall inevitability of the plot. [And there's too much sex in it.]

Image of the book cover

Through the Looking Glass (and What Alice Found There)
by Lewis Carroll

narrated by B. J. Harrison
"In this sequel to Alice's Adventures in Wonderland, Alice once again finds herself in a bizarre and nonsensical place when she passes through a mirror and enters a looking-glass world where nothing is quite as it seems."
A long time since I last read this, and I can still remember some of the poems. When I was young I never saw the point of learning poems by heart, but it is a comfortable feeling to recite well-remembered rhythms, a bit like being able to remember the words of a song. It is a short book, and makes for quite a different experience when read with an adult's perspective. When I read it as a child it seemed longer and more confusing.

Image of the book cover

by David Eagleman
"Why is a person whose name begins with J more likely to marry another person whose name begins with J? Why is it so difficult to keep a secret? And how is it possible to get angry at yourself: who, exactly, is mad at whom? A thrilling subsurface exploration of the mind and all its contradictions."
I like books about the brain, and this one is pretty good. It particularly highlights the issue of free will - do we really choose our own path? If someone who has suffered a brain injury experiences a personality change and commits a crime that is incompatible with their former personality, what should be taken into account when sentencing? It really is a grey area, and chimes with a lot of the work I do in weight management. Is an obese person responsible for their condition any more than someone suffering from depression? The physiological state of the brain seems to dictate behaviour a great deal more than our puny efforts to control it.

Thursday, 1 August 2013

Behaviour change

Close up of pink thistle flower
National Botanic Garden of Wales, May 2013
I was definitely going to do some homework this evening. I brought home the folder of notes which I had been accumulating during the taught sessions of my Masters module, and brought the computer down to the dining table to make it easier to type (my bedroom doesn't have space for a chair as well as a bed, table and chest of drawers). I did the washing up, some laundry, had supper, spoke to Mr A, and then prepared to do some work.

The only thing missing was the actual case study - up to now I've been working on it at the hospital, and hadn't emailed myself a copy. Taking it back and forth on a memory stick is complicated due to NHS file security policies - they make it very difficult to take data out, so that we can't easily compromise patient confidentiality. So, no homework, and I'm blogging instead.

I didn't have a clinic today, so I went back to those carbohydrate reference tables again. It feels as though I have been working on this project forever, and in fact it has been an enormous amount of work. My colleagues came up with some suggestions and comments after I presented the first draft, and true to the adage, the last 20% has taken as much time and effort as the first 80%. It's nearly done now, and the time will soon come to compromise on perfection and go ahead with some flaws still present. For example, I would have to hold back for a few more months to get any decent carbohydrate figures for Christmas pudding.

I continue to have too few patients. I am starting to worry that unless I can fill my clinics, any extension to my contract will be at risk. Part of the problem seems to be that I keep discharging patients rather than offering them follow-up appointments. Having discussed a patient's lack of motivation to lose weight, for example, it serves no purpose to keep making them come to the hospital to have another discussion about how they haven't lost weight again. I may be repeating myself by saying that losing weight is one of the most difficult things in the world for most people to achieve, and you've got to want to do it to have any hope of succeeding.

There are a number of techniques that can be used in the complex world of behaviour change. Obviously active listening and open questioning are important to establish the topic to focus on - never assume that what's in the notes or the referrer's letter or even what you talked about last time will be what needs to be discussed this time. Circumstances change, things happen, and people move on. Last time the patient was 100% in favour of increasing the amount of exercise they wanted to do, this time they are worried about gallstones. Also important at this stage are empathy and taking care to withhold judgement.

Having established the topic, what does the patient want to do? What is the actual aim we are working towards? If it's a change towards 'healthy eating', how will we know when we have succeeded? What amount of weight loss in what period of time will bring about significant health benefit? It helps to describe the objective as fully as possible.

Then it's always worth exploring how realistic the aim is, often by questioning the importance it has to the patient, and their confidence in achieving it. At the most basic, you can use the Lickert scale, which is just a scale of 1 to 10. Anything less than 7 suggests ambivalence and is worth exploring further, and the whole thing can come apart when you really examine some of the practicalities of changing diet or lifestyle. Eating is really fundamental to who we are and how we fit into our families and wider society, and change isn't usually easy.

When it comes down to it, behaviour change is about breaking habits that aren't helpful, and developing and embedding more useful habits. Giving up smoking provides some obvious parallels - if someone always smokes with their afternoon cup of tea, then it will be important to discuss how to manage the feelings that will inevitably arise when having a cup of tea but denying oneself the cigarette. Replace 'cigarette' with 'biscuit' and there really is no difference. Setting a goal of cutting out biscuits while ignoring a lifetime of food-based habits is a recipe for failure.

We can ask questions about how a patient would feel if they achieved their objective, and what the first step will be towards that goal. What are the barriers that will interfere with success? How can they be anticipated, and overcome? Some of the barriers can be brought to light using an 'ambivalence grid', on which we record the positive and negative aspects of making a change, but also the positive and negative aspects of not making the change. It can be illuminating to examine how life would be worse if the patient lost weight (those of us who dislike shopping for clothes are well aware of one of the pitfalls). If the patient thinks that cutting out biscuits will lead to them taking up smoking again, then perhaps they should set a different goal.

These skills and techniques are among those used in Motivational Interviewing, Cognitive Behavioural Therapy, and addressing the Cycle of Change. The trouble is that I can't remember the theory or evidence base for any of these high-falutin' psychological theories, and I feel that for best practice I should know why I'm doing something as well as how best to do it. But for the moment I'm doing my best, and reflecting afterwards on whether I could have done things better, or differently, and that's how I hope to improve my practice. As well as doing my homework. Tomorrow.

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