Are Bodies Cleverer Than We Think?
Because, I had a serious stroke thirteen years ago, I am on Warfarin for life to thin my blood, so that I don’t have another stroke.
INR is short for International Normalized Ratio, which diverts on Wikipedia to the Wikipedia entry for Prothrombin Time, where these is the first two paragraphs.
The prothrombin time (PT) – along with its derived measures of prothrombin ratio (PR) and international normalized ratio (INR) – is an assay for evaluating the extrinsic pathway and common pathway of coagulation. This blood test is also called protime INR and PT/INR. They are used to determine the clotting tendency of blood, in such things as the measure of warfarin dosage, liver damage, and vitamin K status. PT measures the following coagulation factors: I (fibrinogen), II (prothrombin), V (proaccelerin), VII (proconvertin), and X (Stuart–Prower factor).
PT is often used in conjunction with the activated partial thromboplastin time (aPTT) which measures the intrinsic pathway and common pathway of coagulation.
That is very technical and complicated, but what does it mean practically?
Those on Warfarin to thin their blood are generally supposed to keep their INR between 2 and 3.
I test the INR myself with a Coaguchek meter from Roche and have done so for nearly ten years.
Every, so often, I discuss the level of Warfarin with my GP and we adjust the level accordingly.
Typically, NHS patients on Warfarin have their INR checked every few weeks.
But as I am a Graduate Control Engineer, who has written control strategies for chemical plants, I feel this checking every few weeks, is not enough.
At times, I have checked at a higher frequency.
Four times, I have had minor operations.With the first operation, I agreed with the surgeon, that I would lower my INR to 2.1 for the operation and raise it back to 2.5 after the operation.
It all went well and I repeated the exercise for the three other minor operations.
I have checked daily since about the beginning of April, before which, I generally tested on Mondays and Thursdays.
There were two reasons for the change of frequency.
- Regular storms seemed to roll in and for some reason, they tended to lower my INR.
- I also wrote Do Thunderstorms Cause Strokes?, after reading a paper from the United States about the relationship between thunderstorms and strokes.
So I took the prudent decision to test my INR daily.
Then on the 30th May, disaster struck.
My Coaguchek meter found out it had the wrong firmware and Roche implored me to change it.
But I am not a hardware person, so I was left unable to check my INR.
Luckily, I remembered a story from the 1960s about one of ICI’s chemical plants.
This plant was one of the first fully-digitally controlled plants controlled by an IBM 1800 computer.
It also ran 24 hours a day, seven days week.
So in the middle of the night, the plant operators got out all the computer printouts, which showed how the computer had set all the valves and controllers.
One-by-one they reset all the controls on the plant to the settings that the computer had used for the last few days.
Using, this computer-assisted mode the plant was kept running, until engineers could fix the computer.
On the 30th May, my INR was a little bit high at 2.9 and I was using a dosage of Warfarin of 4 mg. one day and 3.5 mg. the next.
The strange dosage was one, that I know from experiment over time produces an INR of 2.5.
My actual average Warfarin dose was 3.73 over the last thirty days and my INR, as measured most days was 2.6 over the same period.
So, I did what the engineers did on the chemical plant, kept calm and carried on.
Yesterday my son fixed the Coaguchek meter and I was able to take my first reading for 17 days. It was 2.7 and only 0.1 higher than the 30-day average on the 30th May.
I had successfully jumped the gap in the readings.
Conclusion
Most systems have an equilibrium. Make sure you know it.
The Anonymous Widower 