Medical Explanation For Pots Heat Intolerance?

[spinner]

We live in South Carolina, it hits 95 and above for a couple months straight during the summer. Its also very humid. I always hated extreme heat being from Ohio but these days I can barely even function outside. I mow the lawn in two consecutive days after the sun goes down.

Ive read a lot about heat intolerance, but havn't really heard a medical explanation for it. For me, its like im stuck in a sauna breathing through a straw. My face flushes, lymph nodes clinch up, and my tachy starts wildly out of control. Im dreading the day i ever get a flat tire in it on the highway when its almost 100, because unless I got into a cool environment, id probably end up in the ER.

Anybody have any links to scientic explanations? Or some theory?

Or at least does it start as a respiratory problem, BP problem, hypothalmus problem, or even

some kind of shock problem? If I had my way, I'd live way up in Vermont on Lake Champlain. Family ties here.

[brethor9]

I feel the same way in the heat ...... I rarely get outside...makes me way too symptomatic.... I always thought it may be due to being over vasodilated which causes worse pooling which then causes more adrenaline compensation (tachy) , dehydration, and unable to properly regulate temp changes which the autonomic system has control over. I live in Canada and Fall is finally upon us and I have never been happier to see cooler temps....although I don't do great in the extreme cold either never a happy medium is there?

[spinner]

Can you explain vasodilation as far as what your various body systems do when that happens? It makes sense that your heart would spike, and if theres histamine, adrenaline or shock involved you'd start having breathing problems which would spike your heart even more and make you weak real fast.

Im from cleveland, not far from canada. Id honestly trade that, but now were heading into about six or seven months of fairly moderate so no big problems. But around april 1 i start to literally get very nervous for the prospect of just making it through summer. Those with POTS know thats all you can do. I wonder if anyones ever moved north to escape the swamps.

[Katybug]

I have all the same symptoms in heat, too. I agree with Bren on the causes. It was 77 and very low humidity today here in Baltimore and I was fine in the shade but I still struggled in the direct sunlight. My body can not adjust to even small changes in temp like going from the shade to the sun. I am starting to feel like a vampire with the sun...I can't wait until its only about 40 outside so I can actually enjoy the sun again.

[Kellysavedbygrace]

I live in FL so this is a big issue for me. My HR will range anywhere between 105-180 when in direct sunlight/ or summer heat so I avoid the sun as much as possible.

The way I understand it is that there are two major probs w heat and the POTS Pt.

1. Heat brings blood to surface of skin causing further pooling away from the heart, lungs, brain, vital organs- thus as more pressure for heart to compensate and less flow to brain causing more symptoms.

2. For some of us we also have autonomic dysfunction of our sweat glands. This is why one of the diagnostic tests they recommend at Cleveland Clinic for some Dysautonomia patients is the Thermoregulatory Sweat Test (TST.). I have very irregular sweat patterns. For instance when exercising intensely (indoors in the gym) I will sweat in the small inside of my elbows but my arms will be completely dry. Thus, because our sweat glands are not working normally, our bodies are not cooling as easily as the should. This is why some us cooling vests to compensate. I make sure to over hydrate and drink lots of cold fluids.

[spinner]

Thanks, I'll have to study that out more. My own sweat patterns seem to have obviously changed since POTS but I also avoid getting into the situation of being overheated. I seem to either flare up and go into a profuse "cold sweat" at my core (abdomen) or i simply dont sweat at all. Im like a thermostat on a car, on or off.

The one time I think i experienced what you describe as blood rushing to my sweat glands, i was in the garage changing a tire but in the heat of the day, 95, but out of the sun. I got the lug nuts off, but my body gave me that familiar warning that I was about to have a meltdown---you all know the drill.

I put the lug nuts back on, and got back in the AC and straight into the shower. I felt VERY shaky in there. Im always afraid of fainting or falling in there, and i keep the water cool, not hot. Then straight into bed after popping a klonapin. My entire body was unable to cool itself, and as you say all the other organs reacted accordingly. Adrenaline, histamine, increased heart rates are normal things in their proper contexts but our bodies cooling mechanisms simply dont work anymore.

[imapumpkin]

Just had the same problem when I spent the summer in DC. For people with pots we already have low bp and low blood volume, and heat dilates your veins making bp even lower so your symptoms increase. It also increases your chances of becoming dehydrated which is really bad for POTS patients. It got so bad for me I had to have someone bring me back to the Northeast.

[futurehope]

I was at Charleston in July and Myrtle Beach in August. Not good. 30 seconds outside in it and I would quickly deteriorate into a "weak" attack. I would feel too fatigued to talk, to move, to do anything. There is nothing to do but to prevent it. I blame it on my mast cell disease, and that my mast cells trigger in the heat. I am useless in heat. If I am very lucky, I can get myself wet and stay that way before having a meltdown. Avoidance is the key. If I did need to remain outside in it, I would wind up on a stretcher at the ER.

[sue1234]

Same here. Cannot tolerate heat at all. I sweat on my upper abdomen, kind of around my liver. And that's about it. The rest of my upper body gets real hot and itchy, but no sweat.

Futurehope, I get that same reaction when hot. It's like my cognition "melts" and my eyesight gets blurry. I get more and more in my own little world until I cool down. That reaction is so similar to people with MS. I would love to know what the mechanism is that gives us that similarity. My new IM thinks I may have MS, but I just think it's POTS.

[peregrine]

Interesting - I have bad heat intolerance too (ideal is about 65F, above 75F I start having trouble functioning). I do sweat - in fact I sweat too much (hyperhidrosis) in the normal spots; even if it's 70F out I have rivulets of sweat running down my chest. I guess the vasodilation is to blame in my case, since the sweating is if anything overly active!

[Millerla]

Sorry if anybody already explained this, but I'm too exhausted to read through everybody's comments.

A big reason is actually because heat causes your blood vessels to relax, which makes blood pooling even worse. I was told to not wear too many layers, especially on my legs, because then I'd warm them up and let our already weak blood vessels relax more.

But for me, cold is actually sometimes worse. I'm more dizzy in the heat, but more nauseous and weak in the cold. I think our systems are just really wacked out and any changes wack us out further.

[Guest maia]

No idea, but i sure wish someone would figure it out! Oddly, this was the first symptom to dissappear when i took flagyl and evereything but the increased heart rate disappeared. Thats back now too, but it was sure nice to have a summer where i didnt even notice the temp fluctuations, let alone the heat!

[troythe8th]

Im with Millerla on this one. Heat is hard on me sometimes worse than other times. Its never consistant as to my reaction to the heat. Its hiut me hard enough to make me have heat stroke like reactions at times when i didnt think it was that hot. Other times in extreme heat i have had very little reaction if any.

Cold is very hard on me all the time. Ive lost alot of weight and have close to zero body fat. My veins are very close to the surface so i cool quickly. The problem for me is below 60 i need a jacket and cooler than that and i shake like a leaf on a tree especially my legs which weakens and tires me quickly. Winter seems to be the toughest on me. I get very run down and find it hard to do anything.

I also have SFN which has alot to do with temp control as well.