Personal experiences of self-monitoring >

Guinea pig and Curry

Evelyn Richardson

In 1988, while on a skiing trip, I was hit very hard on my calf by a swinging chair lift. The next day I travelled home, sitting in a car for 12 hours. A week later I developed a deep vein thrombosis (DVT) in my left leg. After an operation to remove the clot from my groin I was able to become fully mobile again and, much to the surprise of my surgeon, my left leg returned to its normal size fairly quickly with no swelling, not even in the ankle. I was able to return to my very active lifestyle: cycling, swimming, sailing, and keeping fit in a gym. I was on warfarin for six months. I always wear a strong support stocking, which at first was full length, but later I was able to use a knee length one. Despite using a stocking, I have developed varicose veins in my calf but they are not painful.

In 1992, I developed a second DVT after a two and a half hour flight. I sat by the window and enjoyed the view, but forgot to walk about or to take aspirin. This time the DVT was dispelled by streptokinase, which was injected directly into the vein. I had not realised that I was more at risk having already had one DVT. I was told I would have to take warfarin "for the rest of your days."

This necessitated a visit to the surgery every four weeks for a blood test once the international normalised ratio (INR) was fairly stable.

I now monitor my own INR successfully with a portable device. This is particularly important because my husband and I do a lot of travelling to remote parts of the world and spend the summer sailing. I once had to walk 2 miles to a hospital in the Outer Hebrides for a blood test. The blood was then flown up to the main hospital a couple of days later - the plane goes only 3 days a week - for analysis.

Further, I had to call from a telephone box to get my INR results. I had been told that the INR can often be affected by different foods, by taking certain drugs such as antibiotics, and by consuming inconsistent amounts of alcohol. I have found no problem with the alcohol, even if I don't drink for a couple of days and then go to a party the next. I rarely take any medications unless I really need them. However, I have been unable to ascertain the effects of different types of food: a change in diet gives wild variations. For example, when staying with a family in Peru, before I had the portable device, we were fed rice and mashed potato topped by half a guinea pig; no vegetables or fruit. My INR rose alarmingly, as I later discovered when I was able to get to a hospital for a test.

I have also learnt something new about warfarin, even after 13 years. I have recently found that if I have had a stomach upset either from eating rich food, or from a curry or Chinese dish, my INR seems to rise dramatically. When skiing early in 2005, I fell heavily on some ice on the first run and developed a huge haematoma on my thigh. A test at the local clinic revealed that my INR was far too high. I had had a stomach upset for 2 days before departure, but I had not taken the portable device because my INR had been stable for several months. However, in November I went to India, and this time took the portable device and monitored my INR once a week. Despite eating (admittedly mild) curries all the time, I had no stomach upset and my INR remained stable.

I find the machine to be completely accurate relative to itself, although it never quite agrees with the results obtained from our local hospital, which could be because there is a time lag between the blood being taken in the surgery and the testing in the haematology department later in the day.

I would recommend portable monitoring to anyone who travels a lot, who feels able to control their own warfarin dosage, and who does not mind adding the machine, which is rather smaller than a hard-backed book, to their luggage. It gives me freedom and, above all, peace of mind.

Published with kind permission of 'The Lancet': Lancet 2006; 367: 412. See Articles page 404.

Evelyn Richardson is 65. She is a retired music teacher and lives with her husband who is also retired. She is very active and is not in any way troubled by having had two DVTs. She plays chamber music, paints watercolours, and is a very busy grandmother.