Friday, 18 May 2012

Texture and consistency - the theory

Swathes of wildflowers
Norfolk, July 2011
The hospital job that I do involves quite a lot of consideration of texture modification, of both food and drink. This is due to many reasons - poor dentition and dysfunctional swallow being the main ones. Hospital food is obviously not a gourmet delight, and you would be crazy to expect a rare steak (we can't even offer runny egg yolk), but without proper teeth it can be tricky to get through even the softest cut of meat. So there are a lot of soft and wet options on the menu, using minced meat, fish in sauce and stews as well as baked potatoes and sandwiches.

Sometimes the process of swallowing is damaged, either by a stroke or a neurological condition like Parkinsons Disease, Motor Neurone Disease or Multiple Sclerosis, or surgically due to something like head and neck cancer. We learned quite early on in my course that 'Swallowing is the most complex reflex in the body, employs about 25 separate muscles, and once initiated it cannot be stopped.' If any part of the reflex is damaged, whether by a brain injury or surgery to tissue and muscles in the mouth or neck, there is a risk that the swallow will fail, and food will either remain in the mouth, or pass into the lungs (called 'aspiration').

Speech and Language Therapists (SLTs) not only deal with communication in these patients, but are also in charge of the pathway from the mouth to the stomach, which is not reflected in their professional title. Maybe one day they will become Speech, Language and Swallow Therapists. Anyway, they are the ones who investigate and assess the risk of aspiration, using sips of fluid and bites of food, cameras put down the throat (FEES = Fibre-optic Endoscopic Examination of Swallow) and videofluoroscopy using barium drinks, where the internal process of swallowing and route of a liquid can be watched 'live' from various angles.

The treatment they have at their disposal includes both exercise (if the problem is muscular or neurological) and texture modification of food and fluids. Fluid is easier to control in the mouth and to swallow when it is thickened, and presents a lower risk of aspiration. Similarly, removing the lumps from food and reducing it to a puree consistency can reduce the risk of choking. It is not an exact science, and sometimes things 'go down the wrong way.' For many patients, this would provoke a fit of coughing, alerting onlookers that something is wrong. Some do not cough, however, and this 'silent aspiration' manifests itself as a wet voice, 'chestiness', or a drastic drop in blood oxygen saturation as the lungs fill with food or fluid.

Not that long ago, an attempt was made to standardise the classifications of texture modified food and fluids, and the latest reference document is freely available. It contains only the descriptors for food - those for fluids are still under review, although previous standards are still available. The two sets meet in the middle - food is progressively softened and pureed into something approaching a liquid, while drinks are progressively thickened to something approaching a solid.

In the hospital where I work, alongside the normal menu are two 'texture modified' menus, offering Texture C (thick puree) and Texture E (fork mashable) food. Fluids can be thickened to Stage 1 (thin custard) and Stage 2 (thick custard). Each patient is assessed by an SLT, and the most suitable texture is recommended. When any such texture modification of food or fluid is advised, a referral to a Dietitian should ensue (but it doesn't always happen).

The main reason for the Dietitian getting involved is because it is almost impossible for a patient to meet his or her full nutritional requirements on a texture-modified diet or fluids. The thought of thickened fluids - imagine a custard-thick cup of tea or coffee - is enough to put most people off drinking anything, although fruit juice and squash seem much more acceptable in a thickened form. If food is pureed to the right consistency it often has to have water or other liquid added, which dilutes the nutrient content, and many patients who have a compromised swallow will have a small appetite to start with. They simply can't eat enough to provide the protein and energy they need, and again, pureed food on a plate is not the most appetising sight (although I would contend that the taste isn't too bad if you can get past the look of it).

So we ride to the rescue, the Dietitian on the steed of food fortification and nutritional supplements. But hang on - most of the supplements we use are in liquid form, and by virtue of the complex composition which makes them nutritionally complete (i.e. containing all the essential protein, carbs, fat, vitamins and minerals), they are impossible to thicken successfully. There are pre-thickened supplements on the market, but they are not available in the hospital on our contract with the supplier, due to their high price. And the kitchen in this hospital doesn't provide a fortified menu, let alone a fortified puree menu...

To be continued

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