A Funny Turn On Thursday
Because of my endoscopy at five on Thursday, I had a quiet day. I wasn’t allowed to eat anything for eight hours before or drink anything but water for four hours.
About one in the afternoon, I was sitting at my computer, typing a post into my blog.
And then everything, went rather fuzzy and words were coming out garbage. Often each letter was replaced by one of the next on the keyboard.
I was also a bit unsteady on my feet and as I was alone in my house, I decided to go out, so that if it was something worse and I collapsed, there would be someone to help me.
As I got to the bus stop, which is about fifty metres away, a violent thunderstorm broke out.
On the bus to The Angel, I tried to check my phone to get the time. It didn’t respond and I couldn’t unlock it. And even with help from the EE Shop and a guy on the bus, the phone wouldn’t respond to my fingers.
At the Angel, I did at least have a sensible conversation with an assistant about a clothes purchase, but in the end I bought nothing.
I left the Angel earlier than I’d intended and as I was on a 38 bus, which starts my journey to Homerton Hospital, I gave up on the idea of going home for some water.
I had a long change at Dalston Junction for the 242 bus for the hospital, but at least the rain had stopped somewhat and I was by now steady on my feet.
My phone was also working, so I was able to read the instructions about where to go at the hospital.
So what had happened to me at one in the afternoon?
Was there a low pressure before the storm, that sucked all the water out of my body and in the process made my fingers dry, so they didn’t work the phone?
Interestingly, I lost 0.9 of a Kg between 08:00 on Thursday and 08:00 on Friday. Was that just the fasting?
My INR also dropped from 2.4 at 08:00 on Thursday to 2.0 at 08:00 on Saturday. Was that because of all the fluid I lost, thickened my blood?
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.
Northern Lights Stun UK In Spectacular Display
The title of this post, is the same as that of this article on the BBC.
This is the sub-heading.
The Northern Lights have made a rare appearance across the UK, delighting sky watchers up and down the country.
These three paragraphs add more detail.
Excited onlookers shared pictures of the lights, also known as aurora borealis, visible right across the country, including the south coast of England – and if you missed it you are likely to have a chance to see it again on Saturday night.
They could be seen after one of the strongest geomagnetic storms for years hit Earth, with the US National Oceanic and Atmospheric Administration (NOAA) issuing a rare solar storm warning.
Such storms increase people’s chances of seeing the lights.
But how did the weather effect me?
- Yesterday, my INR was 2.4.
- I then had a terrible night, as I tossed and turned.
- I even had to get up twice in the middle of the night to remake the bed.
- This is so unlike me.
- In the morning my INR was 2.2.
Was the reduction because low pressure sucked the water out of my body?
That is nnot in itself dangerous, but I do think, that there will have been a lot of strokes last night.
I wrote about this in Do Thunderstorms Cause Strokes?.
AstraZeneca Withdraws Covid Vaccine After Drop In Demand
The title of this post, is the same as that of this article on The Times.
This is the first paragraph.
AstraZeneca is withdrawing its Covid-19 vaccine worldwide, citing a “surplus of available updated vaccines” since the pandemic that target newer variants of the virus.
This was my experience of the vaccine.
I am coeliac and have a very strong immune system, as it gets all the fuel it needs.
When I had my first AZ vaccine, my immune system started to attack the chimpanzee adenovirus-based viral vector vaccine.
I felt dreadful and I’ve now been advised by doctors, not to have any more viral vector vaccines.
Interestingly, I had no reaction to the second dose, so my immune system had probably decided it was a friend.
When I had that second dose, there was all the controversy raging, about whether the AZ vaccine causes blood clots.
So I did an experiment, which I described in My INR Readings Before And After My Second AstraZeneca Jab.
I found that my INT bounced all over place, just as when a wheel hits a pothole.
Conclusion
I shall not be taking the AstraZeneca Vaccine for COVID-19 again and would think twice before allowing myself to be injected with a viral vector vaccine.
Did A Day In A Class 350 Train Lower My INR?
Yesterday, I went to Birmingham to take pictures of the rebuilt Birmingham University station.
- I travelled by West Midlands Trains catching the 11:23 to Birmingham New Street station, where it arrived at 13:45.
- Coming home, I caught the 15:36 from Birmingham New Street station, which arrived in Euston at 17:49.
So I spent nearly four and a half hours in the train.
This morning, when I measured my INR, it was only 1.8.
Did the weather and the train’s air-conditioning conspire to lower my INR by removing water from my body?
Application Of Control Engineering Principles To The Calculation Of Pharmaceutical Drug Doses
Today, I was asked by an eminent cardiologist to give my opinion on this scientific paper in the Journal of the American Heart Association, which was entitled Personalized Antihypertensive Treatment Optimization With Smartphone‐Enabled Remote Precision Dosing of Amlodipine During the COVID‐19 Pandemic (PERSONAL‐CovidBP Trial).
This was the background to the study.
The objective of the PERSONAL‐CovidBP (Personalised Electronic Record Supported Optimisation When Alone for Patients With Hypertension: Pilot Study for Remote Medical Management of Hypertension During the COVID‐19 Pandemic) trial was to assess the efficacy and safety of smartphone‐enabled remote precision dosing of amlodipine to control blood pressure (BP) in participants with primary hypertension during the COVID‐19 pandemic.
These were the methods and the results.
This was an open‐label, remote, dose titration trial using daily home self‐monitoring of BP, drug dose, and side effects with linked smartphone app and telemonitoring. Participants aged ≥18 years with uncontrolled hypertension (5–7 day baseline mean ≥135 mm Hg systolic BP or ≥85 mm Hg diastolic BP) received personalized amlodipine dose titration using novel (1, 2, 3, 4, 6, 7, 8, 9 mg) and standard (5 and 10 mg) doses daily over 14 weeks. The primary outcome of the trial was mean change in systolic BP from baseline to end of treatment. A total of 205 participants were enrolled and mean BP fell from 142/87 (systolic BP/diastolic BP) to 131/81 mm Hg (a reduction of 11 (95% CI, 10–12)/7 (95% CI, 6–7) mm Hg, P<0.001). The majority of participants achieved BP control on novel doses (84%); of those participants, 35% were controlled by 1 mg daily. The majority (88%) controlled on novel doses had no peripheral edema. Adherence to BP recording and reported adherence to medication was 84% and 94%, respectively. Patient retention was 96% (196/205). Treatment was well tolerated with no withdrawals from adverse events.
These were the conclusions.
Personalized dose titration with amlodipine was safe, well tolerated, and efficacious in treating primary hypertension. The majority of participants achieved BP control on novel doses, and with personalization of dose there were no trial discontinuations due to drug intolerance. App‐assisted remote clinician dose titration may better balance BP control and adverse effects and help optimize long‐term care.
About Myself
I am a Graduate Control Engineer, who graduated from the University of Liverpool in 1968.
I then worked at ICI in Runcorn for eighteen months, before moving to ICI Plastics Division, because of the untimely death of my father-in-law.
One of my tasks at Welwyn, was to look at control algorithms for chemical plants. For this I often used a PACE 231-R analogue computer.
Note.
- These computers could solve up to a hundred simultaneous differential equations at one time.
- They were programmed by wiring the various amplifiers and potentiometers together to simulate the equations.
- There were only a few transistors in these powerful machines, as all electronics were thermionic valves.
- Two of these machines wired together, were used to calculate the trajectories of the Apollo missions.
They were the unsung heroes of bringing Jim Lovell and Apollo 13 home safely.
Determining Control Algorithms
In a typical problem, I would model the a section of a chemical plant and the control system around it.
This would then lead to recommendations, as to the design and operation of the plant, so that it performed as required.
It could be argued that the body of an animal, is a very complicated integrated chemical plant, with a sophisticated control system.
For instance, if sensors around the body, say you are slightly low on fluids, your brain determines you should have a drink.
Many control loops on a chemical plant are controlled by proportional–integral–derivative controllers, which are commonly known as three-term controllers.
This is the first two paragraphs of the Wikipedia entry for three-term controllers.
A proportional–integral–derivative controller (PID controller or three-term controller) is a control loop mechanism employing feedback that is widely used in industrial control systems and a variety of other applications requiring continuously modulated control. A PID controller continuously calculates an error value
PID systems automatically apply accurate and responsive correction to a control function. An everyday example is the cruise control on a car, where ascending a hill would lower speed if constant engine power were applied. The controller’s PID algorithm restores the measured speed to the desired speed with minimal delay and overshoot by increasing the power output of the engine in a controlled manner.
I wouldn’t be surprised that the app in the smartphone used in the PERSONAL‐CovidBP Trial contained a form of three-term controller.
These are some points about three-term control algorithms.
Changing Of External Factors
One that was the villain in a problem, I dealt with, also affects my body – the weather.
I was asked to look at the problem of a chemical reaction, that overheated in hot weather. But the plant operators solved it by better insulation and ventilation of the plant and the standard three-term controller adjusted itself automatically to the new conditions.
After my stroke, I am on Warfarin for life. I test my own INR with a Roche meter and I have noticed that atmospheric pressure affects my INR. I change my deose accordingly, using a simple algorithm, of my own design.
The More You Test The More Precise The Control
If you take the cruise control example used by Wikipedia, speed is monitored continuously, as I hope, it would be if you were driving yourself.
But obviously, in many systems, where you are using an input with discrete values to control a system, you can’t be as precise as the data you collect.
When my son was dying from pancreatic cancer, he was fitted with a morphine pump, that he could adjust himself to dull the immense pain he was enduring.
- His nerves and his brain ascertained the pain level.
- He then adjusted the morphine level.
- He could get very precise control of his pain, because he was measuring it continuously.
But he was only using simple one-term control (proportional).
Derivative Control Can Be Difficult To Get Right And Can Even Go Unstable
Derivative control is mainly to stop overshoot, but sometimes you will find that it can go unstable, so two-term(proportional+integral) controllers will be used.
How I Control My INR
As I said earlier, I am on Warfarin for life and test my INR with a Roche meter.
The NHS typically tests patients about once every six weeks, which in my opinion as a Control Engineer is too infrequent.
I usually test myself a couple of times a week.
But every so often, I evaluate what daily dose gives me an equilibrium INR level of 2.5.
For the last three years, I have found a dose of 3.75 mg keeps me more or less on 2.5.
- As Warfarin comes in 1, 3, 5 and 10 mg. tablets, I alternate 3.5 and 4 mg.
- Warfarin tablets are easily cut in half using a sharp knife.
- I record INR and dose in a spreadsheet.
I have been doing this now for over ten years.
Is This A Unique Property Of Warfarin?
In this time, I have had five medical procedures, where surgeons were worried, that as I was on Warfarin, I might bleed too much.
For the first, which was to remove a lump from my mouth, the private surgeon wanted to charge extra for an anaesthetist. In the end, I asked what INR he wanted and he said 2.1 should be OK!
- So I reduced the Warfarin level and tested every day.
- I judged it correctly and had an INR of 2.1 on the day of the operation.
- The operation went incredibly well and I went home on public transport.
- The lump turned out to be benign.
- I’ve not had another lump.
After the operation, I increased the Warfarin level and tested every day, until it regained a level of 2.5.
On analysing my doses through the date of the operation, I found that the total amount of Warfarin, I didn’t take to reduce my INR to 2.1, was the same as I took to bring it back up again to 2.5.
Is this a unique property of Warfarin?
Since then I’ve had two cataract operations performed in a private hospital, where the NHS paid. Interestingly, they wouldn’t trust my own INR readings, so I had to get my GP to take the measurement.
I’ve also had gallstones removed by endoscopy at the local Homerton NHS hospital.
- For cases like mine, the hospital hire in a surgeon from the posh Wellington private hospital for one day a week, who brings the specialist tools needed.
- I wrote about this in Goodbye To My Gallstones.
- As it was a more serious procedure, I reduced my INR to a requested 1.0.
Interestingly, I still have my gall bladder, but the surgeon put it on notice to behave.
Conclusion
I would totally agree with the conclusion given in the PERSONAL‐CovidBP Trial.
Personalized dose titration with amlodipine was safe, well tolerated, and efficacious in treating primary hypertension. The majority of participants achieved BP control on novel doses, and with personalization of dose there were no trial discontinuations due to drug intolerance. App‐assisted remote clinician dose titration may better balance BP control and adverse effects and help optimize long‐term care.
I would add some conclusions of my own.
- The app used in the PERSONAL‐CovidBP Trial, seems to have had a good algorithm.
- I suspect the app could also be Internet-based.
These are some general conclusions.
- If you are on Warfarin and have access to a Roche meter, it is possible to lower your INR to the value required by a surgeon for an operation or a procedure.
- Since starting to take Warfarin, I have had four operations or procedures, where others would have had anaesthetic or a sedative.
- In those four operations, I was able to go home on public transport. If I still drove a car, I could have driven home afterwards.
- Private hospitals like to use an anesthetist, as it pumps up the bill.
- Avoiding anaesthesia must save hospitals money.
Well designed apps, based on Control Engineering principles, that help the patient take the best dose of a drug will become more common.
A Funny Wet Week
I’ve had a funny few days as regards my health.
Tursday morning, my INR was 2.1.
On Friday night, I wasn’t sleeping very well and got up at three on Saturday morning. But after a couple of mugs of tea, I was feeling a lot better.
I had my usual Saturday morning breakfast in Leon on Moorgate, but I did get slightly confused with my shopping in Marks & Spencer. I put this down to my eyesight having an off day. Is that normal after two cataract operations?
I slept better on Saturday night! But was this because I went to bed before instead of after Match of the Day and then watched it on Sunday morning.
On Sunday morning, I went out to do a bit of shopping, but it was really just to get out and then it was walking in the pouring rain.
Monday was a quiet day, after breakfast in Leon on Moorgate, I wrote for most of the day. My INR was a bit low at 2.2.
Tuesday morning, it was a repeat of Friday night and I got up at four and had a couple of mugs of tea. It was another breakfast in Leon on Moorgate and a visit to M & S. After I returned, I wrote for most of the day, as it was too wet to go outside.
In the afternoon, I started to get a bit unsteady on my feet and even thought about calling 999. But after two mugs of tea and a can of Adnams, I regained my balance and never fell. My blood pressure was fine and the only unusual thing, was that my left food was quite red. But it does this sometimes.
Wednesday was uneventful and I had lunch with a friend at Cote in Sloane Square.
Today, Thursday my INR is down to 2.
I feel OK, but it does seem, that for some reason my INR has tended to slump during the week.
I just wonder if my leaky skin, just lets water out, which surely must lower the INR.
Does my foot go red, as the red blood corpuscles are too big to get through my skin?
The Weather And My INR
I measure my own INR and adjust my levels of Warfarin accordingly.
I typically take 4 mg of Warfarin one say and 3.5 mg the next, as this average dose of 3.75 mg, seems to keep my INR around the required 2.5.
Recent readings have been as follows.
- 18th December – 2.5
- 21st December – 2.5
- 25th December – 2.7
- 28th December – 1.9
Note.
- I test on Mondays and Thursdays.
- Today’s test was a bit low at 1.9.
- I should also say my left humerus was uncomfortable. Was it because bone was unhappy being in a dry body?
Today I took 5 mg of Warfarin to kick the INR the right way. I shall also test my INR tomorrow, just to be sure.
So why did my IRN drop by an unusual amount between Monday and Thursday?
We have just had storm Gerrit (Who thinks up these names? Donald, Nigel or Vladimir would be better, as they’re Low-life!)
So does the the low pressure suck the water out of my body, thus lowering the INR? And bring pain to my injured arm?
Do Thunderstorms Cause Strokes?
On Saturday evening, we had a severe thunderstorm in North London.
All day long, I’d been drinking heavily, but as it was only tea and low-alcohol Adnams Ghost Ship 0.5 %, the worst that could happen is an accident on an extra visit to the toilet.
I came to the conclusion though, that most of the fluids was leaving my body through my skin.
Does this lower my INR? I do know that in hot and humid weather, I have difficulty raising it. In the last week or so, it has been hovering around 2.2, but yesterday, it was a very safe 2.7.
But as I test regularly, this may well help to protect me from another stroke.
Typing “Thunderstorms and Strokes” into Google, I found this paper on the National Library of Medicine, which is entitled Relationship Between Weather Conditions And Admissions For Ischemic Stroke And Subarachnoid Hemorrhage.
It is an interesting read.
This was the aim of the study.
To assess impacts of different weather conditions on hospitalizations of patients with ischemic strokes and subarachnoid hemorrhages (SAH) in South Florida.
And this was the conclusion.
Higher number of ischemic stroke and SAH cases can be expected with the daily lowest and highest air pressure, highest air temperature. Presence of hurricanes or tropical storms increased the risk of ischemic stroke but not the SAH. These findings can help to develop preventive health plans for cerebrovascular diseases.
From my own observations on INR for nearly ten years, I certainly believe that INR moves up and down with the weather because of the laws of physics.
Next time a severe thunderstorm is forecast, I will track my INR throughout the day.
Biarritz And My Family
I am coeliac and I am fairly sure, my father was too, as he had all the wind, I had at fifty, which was something that led to my being diagnosed as coeliac.
But as my father was born in 1904, there was not really any tests for the disease.
I was one of many, who were diagnosed at Addenbrooke’s Hospital in the 1990s, where I am certain, they were testing out, the genetic test for the disease.
How else could I go in on a Monday and have a very short chat and give some blood for testing and then get a letter on the Wednesday saying I was probably coeliac and it would be confirmed by endoscopy.
I never met my paternal grandfather, as he died in 1929 at around fifty.
My father told me a lot about his father. He had been very affected by his father’s heavy drinking and alcoholism. I suspect, it was part of his plan to make sure, that I didn’t go the way of his father.
In fact now at 76, I am virtually teetotal, although I do drink a lot of bottles of 0.5 % alcohol real ale. But this doesn’t affect my gut or my INR.
I know little about my grandfather’s health, but he did suffer from asthma and that was what killed him.
Was he coeliac? From my father’s descriptions of his father, it was highly likely.
My grandfather had a profitable printing business, which even in the 1920s had around a hundred employees according to what my father told me.
My father also remembered going to see Spurs at White Hart Lane in a pony and trap. That at least showed a certain status.
My paternal grandparents also used to go to Biarritz for at least part of the winter.
My father did say a couple of times, that it did improve my grandfather’s health.
But when I went to Biarritz ten years ago, it certainly made me feel better.
I wrote Would I Go Back To Biarritz Again?.
The Anonymous Widower 