The Benefits of Oral Rehydration on Orthostatic Intolerance in Children with Postural Tachycardia Syndrome (2019) Marvin S Medow, et al

ahimsa said:
But I'm wondering about more general autonomic measurements? Does the lower body negative pressure testing measure things that are not in the patient's control?

It's related to my earlier question about that graph. What is does the y-axis mean when it says, "normalized orthostatic index"?
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Very good question. I don't know either. Maybe I will have time to look at the methodology in more detail later but often in these studies it is not easy to cut through the jargon.
 
Jonathan Edwards said:
Very good question. I don't know either. Maybe I will have time to look at the methodology in more detail later but often in these studies it is not easy to cut through the jargon.
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I found a lot of references to orthostatic index in autonomic research studies but it was hard for me to find how it is measured.

After looking for quite a while I found this equation in an appendix:

Orthostatic Index Formula.png

Assuming this is the same orthostatic index (I hope there's only one?) this is an equation based on autonomic measurements (blood pressure, heart rate).

Hope this is helpful.
 
I find ORS slightly helpful with OI symptoms, but I found that taking ORS at consistent intervals through the day led to troughs in between the doses during which my symptoms were markedly worse.

Once a pattern of taking ORS was established (about 2 weeks) my system seemed to compensate - or over-compensate - for the ORS, so that my symptoms between doses were worse than they had been before. This phenomenon was so pronounced (fainting while prone if I elevated my head onto a single pillow) that I stopped ORS completely until my OI symptoms returned to their milder, pre-ORS severity.

I have since moved to a deliberately irregular ORS regimen, taking ORS as needed rather than on a fixed schedule. This seems to reduce the unwanted compensatory effect. Since salt balance is partially a periodic process over days or even weeks (https://www.ncbi.nlm.nih.gov/pubmed/23312287) which responds only gradually to external stimuli, there could be some logic to my experience.
 
TiredSam said:
To tell us anything at all they should compare it with giving the children beer and crisps.
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Or peanuts and beer. Perpetual motion within mankind's grasp. Eat a peanut, get thirsty for beer. Drink beer, want more salty peanuts. Perpetual. Motion.

(So sad that many of you are not aware of Jean-Claude Van Damme's many wisdoms, dude is unwittingly so hilarious)
 
SallyC said:
I found info from other patients and tried drinking a decent amount of water in the early morning before I got up and it made a big difference to how I felt.
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I agree that if a dose response study showed a specific physiological benefit it would be sensible to allow patients to find their own optimum. But there is a danger that patients will end up taking in large amounts of salt and sugar for no reason.

Note that you found benefit from drinking WATER. Rehydration with water and replenishment of blood compartment with saline are two quite different things. We do not want people to poison themselves because one is confused with the other.
 
Jonathan Edwards said:
I agree that if a dose response study showed a specific physiological benefit it would be sensible to allow patients to find their own optimum. But there is a danger that patients will end up taking in large amounts of salt and sugar for no reason.

Note that you found benefit from drinking WATER. Rehydration with water and replenishment of blood compartment with saline are two quite different things. We do not want people to poison themselves because one is confused with the other.
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Yes, completely. Current POTS advice is to 'increase salt intake' which is so vague and has great potential to do harm. There definitely needs to be studies of ideal concentrations/solutions. This goes back to the urine studies, it is worth simultaneously checking excretion products to see if solutes are being lost at the same rate as fluids. Usually rehydration solutions are recommended to compensate for losses due to certain conditions such as vomiting/diarrhoea/excess sweating during exercise. Is this happening during POTS?
 
SallyC said:
Current POTS advice is to 'increase salt intake' which is so vague and has great potential to do harm. There definitely needs to be studies of ideal concentrations/solutions....
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It would be great to have more studies! But at least the NIH is doing a study now, referenced above -
https://www.clinicaltrials.gov/ct2/show/study/NCT02854683

Can you explain a bit about the harm you're concerned about? Anything, even aspirin or acetaminophen, can cause serious harm in certain situations - wrong dosage, patient is allergic, or some other problem.

All patients should work with their doctor(s) to figure out what is the right treatment for them, yes? And what might cause great harm for one patient (due to allergies, immune system problems, or whatever) won't cause another patient any harm at all, and vice versa.

I would hope that any patient with POTS and orthostatic intolerance (OI) would not simply start drinking ORS without talking with their doctor first, whether it's their primary care doctor, their cardiologist, or some other doctor who is managing their POTS/OI.
 
ahimsa said:
I would hope that any patient with POTS and orthostatic intolerance (OI) would not simply start drinking ORS without talking with their doctor first, whether it's their primary care doctor, their cardiologist, or some other doctor who is managing their POTS/OI.
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I think there are a lot of people out there who are very isolated from their doctors/medical professionals who may just try things out themselves. I am speaking from a UK perspective in this. Given that ORS can be bought in shops etc they may be seen as a benign thing. My point about salt is that without any guidance whatsoever someone could easily be taking far too much. Oral rehydration solutions are meant to replace lost electrolytes etc and it's not completely clear that we are 'losing' anything other than fluids. It would be very easy to end up with sodium or potassium imbalances.

But as you say, hopefully most people will seek medical advice and their doctors will engage with them properly. :)

ETA: The point about ORS and IV saline solutions is that generally they are meant for fixing short-term situations, not for ongoing long-term use, which is the situation most POTS patients will find themselves in. That is what concerns me. I don't know if any research has been done into this sort of thing. Sorry for the addition, my brain isn't firing well.
 
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ahimsa said:
Assuming this is the same orthostatic index (I hope there's only one?) this is an equation based on autonomic measurements (blood pressure, heart rate).

Hope this is helpful.
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I don't understand this at all. I cannot see what the basis for this peculiar equation is.
Also it looks to me as if it would be a measure of OI - I.e. high in people with OI. But in the results it seems they think a high level is good.
I am totally confused.
 
Jonathan Edwards said:
I don't understand this at all. I cannot see what the basis for this peculiar equation is.
Also it looks to me as if it would be a measure of OI - I.e. high in people with OI. But in the results it seems they think a high level is good.
I am totally confused.
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I think a doctor (cardiologist?) who has experience with autonomic system testing (eg. tilt table testing, lower body negative pressure testing, etc.) might be able to answer these questions.
 
It's always cool when old threads pop up that I had forgotten all about :)

Hutan said:
The study assessed OI one hour after IV or oral intake. That raises the question of how long any benefit lasts. If you have to drinking oral rehydration solution every two hours, that might cause problems and two-hourly IV is even more problematic.
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I thought everyone knew that drinking electrolyte solutions (ORS) only provides a temporary benefit?

But yeah, I'm not sure how many hours it lasts for the average patient. It seems like longer than two hours for me - maybe 4 hours? Perhaps the max benefit is at 1 hour and that's why they tested at that point?

Just FYI, this other thread (from 2022) has a screen shot from a video where one of the authors discussed this study:

https://www.s4me.info/threads/salt.25279/#post-415851
 
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