High Respiratory Quotient

[TXPOTS]

Has anyone out there had a cardiometabolic stress test?

I've had this test performed twice in the past 6 months and have had very unusual results. As part of the test, it measures and resting and working respiratory quotient. The respiratory quotient is CO2 eliminated/ O2 inhaled. My O2 inhaled is normal, while my CO2 eliminated is very high. This is at rest. As soon as I start exercising, my respiratory quotient goes back to the normal range. My RQ at rest is very high (1.3). My doctors says I am like an anaerobic animal at rest. The test was performed twice in 6 months and both times I have gotten this result and have been fasting as instructed. My POTS specialist does not know what the result means, which is very frustrating. He told us to find a pulmonologist, but we have yet to find one that has a clue what this is. I am better physical shape than most of the population, but the problems for me start when I stop moving. I cannot sit or stand without head support. My pulmonary function tests are normal, and I am not short of breath.

[firewatcher]

I had a pulmonary function test a year or so ago and had a lung diffusion capacity of 230% of predicted. The only medical research that shows physiologic changes like this are free-divers and people living at high elevations (basically low oxygen environments.) My hematocrit and RBC are also high, but not high enough to create this type of change. I think that we are more anaerobic than normal people. The only time I have a hard time breathing is when my HR is higher than 160, at 180 the black spots and sparkles start dancing and above that I'm dry heaving. Unfortunately I go from 160 to 180+ within a minute or so. 90 seconds on a treadmill above 4mph and I'm shooting off the back!

[TXPOTS]

Firewatcher,

Thank you for the reply. I am still trying to get my hands on the official results of the PFTs, but I will be interested to see my lung diffusion capacity. You brought up some very interesting thoughts. My POTS began the last Saturday in May 2008 after an intensive swimming work out. I had symptoms from May-October 2008, but in the beginning, the symptoms only occurred after my mornings of swimming. To this day, I swear the swimming had something to do with triggering my POTS. I swam pretty intensively, and I wonder if I made myself hypoxic after these swims. My hematocrit and RBCs also run high. It has been this way since I have been 16, which is around the time I started displaying symptoms of DI.

Speaking of high elevations, I often describe my illness as constantly living with altitude sickness to my family. This is the closest I can come to a simple explanation for how I feel on a daily basis.

I'm sorry your HR is shooting up so high when exercising. This was me back in December, but now although my heart rate shoots up quickly, it stays pretty stable, despite a high intensity exercise program. I am baffled that I am able to exercise the way that I can, but I can not sit up straight. In fact, my respiratory quotient immediately improved when I started exercising. Weird.

[gackedo]

I also had a high resp quotient on my last cardiometabolic stress test and no one has been able to explain it to me. I've searched the internet and have not been able to come up with an explanation.

[TXPOTS]

I also had a high resp quotient on my last cardiometabolic stress test and no one has been able to explain it to me. I've searched the internet and have not been able to come up with an explanation.

Thanks so much for reply. I was disappointed when my POTS specialist could not come up with an explanation, and I am even more frustrated that we can not find a pulmonologist who has encountered this. The POTS specialist thinks this is my main issue and claims he has only seen one other patient with this result back in the 90s who he was unable to help. I just don't understand why a physician would perform a test without being prepared to research/ explain an abnormal test. It annoyed me that he suspects this is my main problem, but basically told me to go find someone out there in the medical universe to interpret it.

[firewatcher]

Firewatcher,

Thank you for the reply. I am still trying to get my hands on the official results of the PFTs, but I will be interested to see my lung diffusion capacity. You brought up some very interesting thoughts. My POTS began the last Saturday in May 2008 after an intensive swimming work out. I had symptoms from May-October 2008, but in the beginning, the symptoms only occurred after my mornings of swimming. To this day, I swear the swimming had something to do with triggering my POTS. I swam pretty intensively, and I wonder if I made myself hypoxic after these swims. My hematocrit and RBCs also run high. It has been this way since I have been 16, which is around the time I started displaying symptoms of DI.

Speaking of high elevations, I often describe my illness as constantly living with altitude sickness to my family. This is the closest I can come to a simple explanation for how I feel on a daily basis.

I'm sorry your HR is shooting up so high when exercising. This was me back in December, but now although my heart rate shoots up quickly, it stays pretty stable, despite a high intensity exercise program. I am baffled that I am able to exercise the way that I can, but I can not sit up straight. In fact, my respiratory quotient immediately improved when I started exercising. Weird.

I also explain "altitude sickness" to my docs. It fits my labs perfectly with what is going on. If I were living in the Andes, my labs would be normal.

I have had it explained to me as my body's adaptation to my brain's constant lack of oxygen due to vasoconstriction (just like my reduced kidney function.) I have wondered what would happen if I were to get O2. You probably feel better during exercise because of the systemic vasodilation and the increased stroke volume of your heart. If you are volume depleted from the "DI" like I am, it would make sense that exercise keeps things moving to your brain instead of settling in your lower half. I just wish my HR stabilized like yours with exercise. It is better if I am up and moving around at a leisurely pace, but once I push it , it seems like everything goes into overdrive.

[juliegee]

Hey Texas-

I don't have anything to add, I just wanted you to know that I'm following & wish I had answers for you. I wonder if your abnormal result explains WHY running is "easy" for you- easy being a relative term- easier than standing still .

Sounds like you've always been athletic. I have seem other members who have been stricken at the height of their fitness as well.

Out of curiosity, what kind of a pace are you running? I wonder if you could do a rehab program & run it backwards . For instance, if you are running at a 6 MPH pace, over time try slowing it down to 5.5MPH, then 5MPH, then a fast walking pace until you are able to walk without crazy symptoms..... Just a thought.

I'm still running, but it's an effort for me in this heat. Before 8AM or on the treadmill for now. My pace and stamina are much worse with heat & humidity.

Hope you get answers-

Julie

[TXPOTS]

I agree with the theory of vasodilation and increased stroke volume during exercise. My POTS doc does as well. I wonder if the high expelled CO2 at rest is simply lack of oxygen rich blood being filtered out of the lungs at rest from reduced venous return? I don't understand the mechanics of the pulmonary circulation well. My physician claims to perform many of the metabolic stress tests on POTS patients and does not see my result. On the other hand, I am in better shape (during exercise) than the majority of POTS patients. I imagine this is due to the specific mechanism behind my particular POTS because I know many patients with POTS simply can not exercise or get much, much worse. I was in bad shape back in December. My heart rate was up in the 160s just standing up. I would try walking up and down our street to get moving. I was crying, gagging, and blacking out. My mom bought me a recumbent bike with a high back that was adjustable, and the improvement started relatively quickly from there. Never in my wildest dreams did I think I would be exercising for 2 hours a day. I feel great for about an hour afterwards and during my exercises, but at rest I am still so debilitated. Have you ever tried a rowing machine? It took me awhile to get used to it, but it barely raises my heart rate, and feel really wonderful while rowing. I think the seated position is helpful for POTSies.

It's interesting that we both have DI, high blood counts, excessive constriction, and 2 boys . Do you also have low aldosterone as well? I am on Florinef, but I can only take 0.1mg due to my blood pressure getting too high on a higher dose. Are you still on Inderal? I haven't tried a beta blocker, but I'm skeptical because I did not respond well to clonidine, which was a big surprise to all.

[firewatcher]

I agree with the theory of vasodilation and increased stroke volume during exercise. My POTS doc does as well. I wonder if the high expelled CO2 at rest is simply lack of oxygen rich blood being filtered out of the lungs at rest from reduced venous return? I don't understand the mechanics of the pulmonary circulation well. My physician claims to perform many of the metabolic stress tests on POTS patients and does not see my result. On the other hand, I am in better shape (during exercise) than the majority of POTS patients. I imagine this is due to the specific mechanism behind my particular POTS because I know many patients with POTS simply can not exercise or get much, much worse. I was in bad shape back in December. My heart rate was up in the 160s just standing up. I would try walking up and down our street to get moving. I was crying, gagging, and blacking out. My mom bought me a recumbent bike with a high back that was adjustable, and the improvement started relatively quickly from there. Never in my wildest dreams did I think I would be exercising for 2 hours a day. I feel great for about an hour afterwards and during my exercises, but at rest I am still so debilitated. Have you ever tried a rowing machine? It took me awhile to get used to it, but it barely raises my heart rate, and feel really wonderful while rowing. I think the seated position is helpful for POTSies.

It's interesting that we both have DI, high blood counts, excessive constriction, and 2 boys . Do you also have low aldosterone as well? I am on Florinef, but I can only take 0.1mg due to my blood pressure getting too high on a higher dose. Are you still on Inderal? I haven't tried a beta blocker, but I'm skeptical because I did not respond well to clonidine, which was a big surprise to all.

I actually talked to my PT about all this. She says that the high hematocrit will cause high diffusion and increased O2 turnover.....at a point. If I exercise, my HR goes too high and I get the double problem of a HR so high that there is actually less O2 available, plus (as my PT put it) your cerebral arteries are constricting in an effort to protect the brain from a "paradoxical state of too much 02." Basically, when I start out, exercise causes my HR to go up and because of the high RBC, I am good at O2 turnover. That high O2 turnover confuses the brain into thinking that I am hyperventilating and clamps down on my brain blood flow, which causes signals to speed the HR up further to compensate which actually does reduce the O2, at which point the brain shuts everything down......off the back I go! thud

I have lower than "normal" aldosterone and undetectable ADH. Two docs have said DI and two have said no. I am on a tiny dose of Inderal (20 mg once a day) but it doesn't do much for my HR when I exercise. I can get it up to 180 pretty quick, even supine (Pilates.) I have always been this way (aerobic exercise intolerant) for as long as I can remember. It never really stopped me till 2007 though. If I could just get back to before that point, I'd be happy. It takes me four days to recover from 50 minutes of exercise. I know muscle pain and fatigue, but this is ridiculous!

[TXPOTS]

Wow, how frustrating for you!!! Still, the pilates is enough to keep your heart and skeletal muscle from becoming deconditioned, so why push it?. I think you know your body best and have found a way to stay in shape without putting yourself in jeopardy. Hopefully, you will eventually get back to where you were in 2007. I find the progress in POTS to be super slow and variable. I don't even know if I am really making progress, but just learning what works and does not work for me. I had 2 endocrinologists tell me DI and one endocrinologist doubted it, but I went with the endocrinologist who specializes in DI. The formal water dep test confirmed it, but it was a tricky diagnosis because my aldosterone was unmeasurable and hence I was never hypernatriemic.

[firewatcher]

The Hypernatremic issue was what they used for my no-diagnosis too.

Here's something from Wiki that explains the cerebral vasoconstriction and your issues as well:

Hyperventilation

[TXPOTS]

Thanks firewatcher, I'll give it a read.

[ramakentesh]

C02 is implicated or plays a part in many forms of OI. Postural Hypocapnia is present in nearly 50% of patients for a start...

[Noreen]

Rana-

Thanks as always for educating us.

If anyone else is ignorant as to the term hypocapnia.

http://www.ncbi.nlm.nih.gov/pubmed/16565300

[TXPOTS]

Regarding hypocapnia...

Well, that's what I initially thought, but my POTS doc claims he has only seen this result once back in the 90s (a high RQ that normalized with exercise). He performs many of these cardiometabolic stress tests on POTS patients. His staff also claimed that I did not appear to be hyperventilating. I do not breath rapidly to my knowledge, but I may be breathing too deeply. I swear there is something OFF with my breathing when upright. Would breathing too deeply expel too much CO2? I have no idea whether the cardiometabolic stress test measures rate or depth of respiration. Regardless, I'm going with the hypocapnia theory because it makes the most sense to me. Stewart's research suggests that this is a common finding with POTS, so I am baffled why my physician does not routinely see this. I lost faith when my physician was unable to interpret the result and told us to find a pulmonologist who knew what it meant. Well, that has been totally unsuccessful. I guess there is nothing more to do with this other than except it as part of POTS? I looked into an impedance type breathing apparatus that may help OI, but it looks like it is only designed for emergencies and orthostatic hypotension. It requires a prescription. Thanks everyone!!! You guys are wonderful when I have a difficult question.

[Chaos]

I've been watching this post with interest but have been too brain fogged to try to comment (probably still am for that matter ). I too have similar issues although haven't had a cardiometabolic test. My PFT's have been normal or above normal. When I have a TTT or a relapse, I definitely have symptoms of hyperventilation but without hyperventilating. Doctors and nurses have all commented "well, you're not hyperventilating" even though I seem to have all the symptoms of it. And yes, maybe breathing too deeply is part of it. When I'm in a bad state, even talking gives me the same symptoms which would seem to indicate hypocapnia although I don't think I talk any differently at that time than I do at any other time.???...

During a recent episode a nurse put O2 on me, even though my 02 sats were 95% or greater. It didn't help with the light-headedness of being upright but after a bit I was able to talk without getting so short of breath. It didn't (and still doesn't) make sense to me. I'm still trying to figure out why it would have helped. (Don't know if the placebo effect could account for it, since I was SURE it wasn't going to help in the first place. )

I've done yoga for years so controlled breathing hasn't been a problem for me in the past. I too had looked at the impedence breathing devices but it didn't seem like something that would be beneficial to me at this point.

My hematocrit seems to swing from high to anemic levels without much that would account for it. Wonder how much that plays into all of this...

"Tis a puzzlement..."

[TXPOTS]

A puzzlement indeed.

Chaos, have you found an effective treatment plan? They also measured my CO2 emitted during my TTT, and it was high. The PA and technician who performed the test said I did not appear to be hyperventilating. I was trying to calm myself by taking slow, deep breaths because I started to feel panicky on the tilt. I didn't last for more than 10 minutes, which was better than the 6 minutes I lasted back in December. No more tilts for me.

[ramakentesh]

The postural hypocapnia encountered by Stewart and Medow was attributed if I remember to carotid chemoreceptors unloading from excessive splanchinc pooling or sympathetic drive. A consequence of POTS rather than the primary cause. There was an earlier study that postulated that all POTs dizziness was related to hypocapnia - http://stroke.ahajournals.org/cgi/content/full/29/9/1876

Also stewart connected the hypocapnia with excessive peripheral resistance which is usually found in 'hyper' patients.

Postural hypocapnia is associated with feelings of anxiety.

[TXPOTS]

Thank you Rama.

This makes sense in my particular case because they have determined I have increased peripheral resistance. I appear to over-constrict. They are postulating this may be why my RAAS has shut down. I failed a trials of clonidine, L-arginine, and nitroglycerin. My blood pressure fluctuates from low/normal to high, which makes this hard to treat. I have a prescription for losartan, but I am afraid to try it because my renin and aldosterone were very low (measured pre-Florinef). My angiotensin II is already low/normal. I have only been able to tolerate 0.1mg of Florinef, else I am too wired and my bp shoots up. Balancing POTS is for the birds. I greatly appreciate everyone's comments and support.

[Chaos]

It's interesting that the article notes "Hyperventilation that consists of an increased depth without an increased rate only occurs during orthostatic stress...." Seems to be what both TXPOTS and I have experienced. What I haven't experienced is getting relief of symptoms with rebreathing CO2. I've only tried it once, but it didn't seem to help. I actually did better with just slow focused timed breathing. I also don't recall a feeling of anxiety in those situations as much as just feeling REALLY BAD! I definitely get the paresthesias and tetany they mentioned in the article.

TXPOTS- No unfortunately I haven't found any particular treatment plan that has solved everything. I am better on my meds but still have days where I feel, as my children say, "I've been sniped". (As in shot by a sniper... as in I was doing well for a few days and then I feel like my wheels have been shot out from under me and I'm back in bed for a few days.) I have the same feeling you report of feeling like my breathing "is just OFF" many days. I find myself having a sense of needing to take frequent deep breaths/heavy sighs much of the time.

I haven't had CO2 measured on TTT. Wish it would have been but I've done 3 TTT that have all been miserable so don't want to repeat it again. Wish they would have done a transcranial doppler that some people on here have mentioned having done on TTT also.

My peripheral resistance was reported to be abnormally low in supine and "quite good" in upright. Not sure how that would relate to this situation.

I see the endocrinologist the end of August so am hoping he will test the angiotensn II, renin and aldosterone for me.

Still find this a very interesting topic. Thanks for all the input!

[TXPOTS]

It's interesting that the article notes "Hyperventilation that consists of an increased depth without an increased rate only occurs during orthostatic stress...." Seems to be what both TXPOTS and I have experienced. What I haven't experienced is getting relief of symptoms with rebreathing CO2. I've only tried it once, but it didn't seem to help. I actually did better with just slow focused timed breathing. I also don't recall a feeling of anxiety in those situations as much as just feeling REALLY BAD! I definitely get the paresthesias and tetany they mentioned in the article.

TXPOTS- No unfortunately I haven't found any particular treatment plan that has solved everything. I am better on my meds but still have days where I feel, as my children say, "I've been sniped". (As in shot by a sniper... as in I was doing well for a few days and then I feel like my wheels have been shot out from under me and I'm back in bed for a few days.) I have the same feeling you report of feeling like my breathing "is just OFF" many days. I find myself having a sense of needing to take frequent deep breaths/heavy sighs much of the time.

I haven't had CO2 measured on TTT. Wish it would have been but I've done 3 TTT that have all been miserable so don't want to repeat it again. Wish they would have done a transcranial doppler that some people on here have mentioned having done on TTT also.

My peripheral resistance was reported to be abnormally low in supine and "quite good" in upright. Not sure how that would relate to this situation.

I see the endocrinologist the end of August so am hoping he will test the angiotensn II, renin and aldosterone for me.

Still find this a very interesting topic. Thanks for all the input!

Chaos,

Did your endo test renin, aldosterone, and ang II? at the end of Aug. Curious, since we both have the breathing and CO2 issues. My renin and aldosterone were very low. My ang II was considered normal, but on the low end of the spectrum.

[Chaos]

It's interesting that the article notes "Hyperventilation that consists of an increased depth without an increased rate only occurs during orthostatic stress...." Seems to be what both TXPOTS and I have experienced. What I haven't experienced is getting relief of symptoms with rebreathing CO2. I've only tried it once, but it didn't seem to help. I actually did better with just slow focused timed breathing. I also don't recall a feeling of anxiety in those situations as much as just feeling REALLY BAD! I definitely get the paresthesias and tetany they mentioned in the article.

TXPOTS- No unfortunately I haven't found any particular treatment plan that has solved everything. I am better on my meds but still have days where I feel, as my children say, "I've been sniped". (As in shot by a sniper... as in I was doing well for a few days and then I feel like my wheels have been shot out from under me and I'm back in bed for a few days.) I have the same feeling you report of feeling like my breathing "is just OFF" many days. I find myself having a sense of needing to take frequent deep breaths/heavy sighs much of the time.

I haven't had CO2 measured on TTT. Wish it would have been but I've done 3 TTT that have all been miserable so don't want to repeat it again. Wish they would have done a transcranial doppler that some people on here have mentioned having done on TTT also.

My peripheral resistance was reported to be abnormally low in supine and "quite good" in upright. Not sure how that would relate to this situation.

I see the endocrinologist the end of August so am hoping he will test the angiotensn II, renin and aldosterone for me.

Still find this a very interesting topic. Thanks for all the input!

Chaos,

Did your endo test renin, aldosterone, and ang II? at the end of Aug. Curious, since we both have the breathing and CO2 issues. My renin and aldosterone were very low. My ang II was considered normal, but on the low end of the spectrum.

Still waiting for my results..... I think he ran ACTH along with a bunch of other stuff but I don't think he included the renin, aldosterone etc in this go round. My cardio had sent me over there for reactive hypoglycemia (to rule out other causes for it) so he wasn't looking too much at helping me sort out the POTS part of all this- at least at that first appt.

What are they doing about your results?

[Chaos]

Got a copy of my labs today. My CO2 was 30 (ref range 16-30), Anion gap was 5 (ref range 6-16) and low insulin with normal fasting glucose. ACTH was normal.

So would the CO2 and anion gap (which shows a disturbance in acid/base balance) somehow fit in with the hypo/hypercapnia issue that Ramakentesh refers to?

I made a follow up appt with the endo for Friday so we'll see if he can shed any light on any of this.

Hmmmm.....

[TXPOTS]

Got a copy of my labs today. My CO2 was 30 (ref range 16-30), Anion gap was 5 (ref range 6-16) and low insulin with normal fasting glucose. ACTH was normal.

So would the CO2 and anion gap (which shows a disturbance in acid/base balance) somehow fit in with the hypo/hypercapnia issue that Ramakentesh refers to?

I made a follow up appt with the endo for Friday so we'll see if he can shed any light on any of this.

Hmmmm.....

Definitely ask your endo, but I believe hypocapnia/ hypercapnia would be detected in arterial blood (arterial blood gases). The base metabolic profile CO2 is a sampling of venous blood. I only know that I expel high amounts of CO2 via respiration when upright, but I have no idea what the CO2 reads in my arterial blood. I have no intention of finding a pulmonologist to place an arterial line to test CO2 in various positions as suggested by my cardiologist. I am bunt out of all the testing for now. Was your albumin normal? Did they test venous pH? I have thought of bringing this CO2 issue up with my endo as well.

I caught myself holding my breath today while upright. There is something funny with my breathing when upright which should be unconscious. This must be related to OI.

[sue1234]

It's odd. I don't think I hold my breath when upright, but I have definitely noticed I "tense" my ribcage. This in turn keeps me from expanding well when breathing.

I have started doing a step machine I have. I quit when I get short of breath, which is pretty fast, like in two minutes. The one thing I have noticed is when I get to that point of getting short of breath, I don't seem to be breathing really deep or really fast. I thought that was kind of odd.

So, maybe something is "off" biochemically to begin with that keeps us from getting the extra O2 we need when needed? I would be interested in what y'all find out with your doctors appts.