What can a CPET do to diagnose ME, OI, mitochondrial disease, heart conditions, etc.?

[Sasha]

Just wondering about this. We tend to be familiar with the 2-day CPET (cardiopulmonary exercise test) showing that, unlike other people, PWME do worse on Day 2.

But is a one-day CPET useful for flagging up co-morbid conditions or possible alternative diagnoses?

I speak as one who doesn't actually know what gets measured, or whether the measurements taken vary according to the suspected diagnosis.

 

[Valentijn]

But is a one-day CPET useful for flagging up co-morbid conditions or possible alternative diagnoses?

I don't think it's specific enough by itself. But a bad enough value on a single CPET does exclude deconditioning/sedentary lifestyle.

It also could depend on what else is being measured at the same time. My specialist is also a cardiologist, so did an ECG with my CPET. Combined with tests of lung or heart function it also might rule things out - my heart and lungs are fine, for example, which might suggest my abysmal score was due to problems with energy production or other aspects of circulation or oxygen utilization.

 

[Ryan31337]

Hi @Sasha,

Here's a graphic that I find useful:



That is taken from an excellent, albeit heavy-going review here: http://circ.ahajournals.org/content/122/2/191

If you want a briefer overview, I found this quite useful (it lists normal ranges too): https://www.ucl.ac.uk/anaesthesia/research/CPEx_Interpretation.pdf

Finally, if you're interested in exploring mitochondrial myopathy presentation in more detail, this blog post is very helpful: https://www.pftforum.com/blog/diagnosing-mitochondrial-myopathies/

As Valentijn said, its indicative rather than diagnostic. From what I gather even invasive CPETs can't really differentiate between autonomic dysfunction and MM (which is where most of us would show anomalies).

Hope it helps,
Ryan

 

[JaimeS]

Hi @Sasha,

Here's a graphic that I find useful:

In the words of Tumblr, this is the high quality stuff I want to see on my dash.

Incredibly useful, @Ryan31337

 

[JaimeS]

But is a one-day CPET useful for flagging up co-morbid conditions or possible alternative diagnoses?

Yesssss.

I'm one of those pwme who had a really weird / unusual single-day CPET. VO2 low, lactic acidosis and breathing problems afterwards. Memorably, the neuro who looked at my exercise test said, "totally normal... great!... if you were 80+ years old." I was in my late 20s early 30s at the time.

I've encountered a few other patients who've said the same, on the Other Forum. Though we seem to be a smaller subset.

 

[Ryan31337]

Yeah, same here, ~50% of predicted VO2max, crazy high RER. My AT was low enough that I would've exceeded it walking to the lab. My heart rate didn't get over 150bpm that day, I was on a very low dose of bisoprolol and it was doing me no good it seems.

I repeated it 2x weeks later off bisoprolol and things were less crazy, normal heart rate response and I got to 65% VO2max. Still falling way short of the 80% 'just deconditioned' minimum, with low O2 pulse and exaggerated CO2 still.

Third test was some months later after switching to ketogenic diet, which brought about a big improvement subjectively. Objectively I had no improvement in workload, my O2 pulse was still poor but CO2 /RER was far lower and I just scraped 80% VO2max, so was obviously then told 'nothing to see here'...

 

[JaimeS]

I just scraped 80% VO2max

Mine was 67% of normal VO2. I'd been working full time at a very active full-time job up until a few months before, but they still decided that meant I was just deconditioned. The doctor's notes urge me to exercise for 30 minutes a day!

80% is meant to be 'just deconditioned'? Wow, Mayo really failed me in almost every way.

[Edit: except that neuro who told me 'sure it's normal if you were 80 yrs old'. He actually gave me a lot of great advice as well as having a good bedside manner... I've said about Mayo before, you could see a great deal of difference between the 'old guard' and the new, and he was the 'old guard'.]

 

[Dechi]

Hi @Sasha,

Here's a graphic that I find useful:

View attachment 587

That is taken from an excellent, albeit heavy-going review here: http://circ.ahajournals.org/content/122/2/191

If you want a briefer overview, I found this quite useful (it lists normal ranges too): https://www.ucl.ac.uk/anaesthesia/research/CPEx_Interpretation.pdf

Finally, if you're interested in exploring mitochondrial myopathy presentation in more detail, this blog post is very helpful: https://www.pftforum.com/blog/diagnosing-mitochondrial-myopathies/

As Valentijn said, its indicative rather than diagnostic. From what I gather even invasive CPETs can't really differentiate between autonomic dysfunction and MM (which is where most of us would show anomalies).

Hope it helps,
Ryan

I am impaired in all 3 categories. My VO2 max is between 60%-75% of normal values.

There were 8 different anomalies found, some of which were severe.

For disability purposes, this is gold. I recommend it if you need to prove you’re disabled, if you think you can manage it. it took me six weeks to recover, but then I started going downhill and I am at least 30% more impaired since doing it, if not 50%.

 

[Valentijn]

Mine was 11.9, or 34% of what it should be for a woman my age. My RER was well above the minimum threshold needed to objectively indicate maximum effort.

 

[Sasha]

it took me six weeks to recover, but then I started going downhill and I am at least 30% more impaired since doing it, if not 50%.

Very sorry to hear that, Dechi.

 

[Ryan31337]

80% is meant to be 'just deconditioned'? Wow, Mayo really failed me in almost every way.

Yeah, 80% VO2max appears to be the agreed cut off for 'normal' in guidelines.

But unless there's a really bleeding obvious primary limitation it seems like a low score just puts docs back into "meh, could be anything" mode. Which is even more frustrating when you learn that people with confirmed mitoD can still occasionally have 80%+ VO2max and other normal parameters!

 

[Ryan31337]

@Valentijn was that 11.9 score your VO2max or AT? Whichever, I hope you've improved a bit since, that's really harsh

If VO2Max I really wonder how useful this test becomes, because you must be over your AT just sitting on the bike. Pretty sure I was in similar situation in my first test, near maximal exertion just getting to the hospital lab. It must muddy the results.

 

[Rossy191276]

Thankyou Ryan for putting up that article regarding mitochondrial myopothies...it was my understanding that a large body of research suggests that an acquired mitochondrial myopathy is a major part of ME and therefore it seems strange to me that people with ME would have normal results on the 1st day CPET...

 

[Valentijn]

@Valentijn was that 11.9 score your VO2max or AT? Whichever, I hope you've improved a bit since, that's really harsh

VO2 max. I seem to be doing a bit better since starting IgG 5 months ago.

If VO2Max I really wonder how useful this test becomes, because you must be over your AT just sitting on the bike. Pretty sure I was in similar situation in my first test, near maximal exertion just getting to the hospital lab. It must muddy the results.

Yeah, my "resting" heart rate was already high at the start, at 91. When I'm really rested it'll be around 75-80. I think that can throw off the VO2max calculations, but from what I recall it would have lowered my score even further to use my normal resting heart rate.

 

[JaimeS]

near maximal exertion just getting to the hospital lab. It must muddy the results.

Sometimes I think that the reason I reacted as I did to a single-day CPET is because it was only technically a 'single-day'. I'd been at Mayo for nearly a week already. The tests there were stressful, and Mayo itself is a giant industrial complex greatly resembling an oversized shopping mall. Luckily none of the testing seemed more than 15 minutes from any of the other testing, but 15 minutes of continual exercise was my absolute limit at the time.

 

[Trish]

That has struck me about the 2 day CPET too. I can't see how it can be a valid or useful test if the activity of the participants over the days before and between the two tests is variable. I think it should ideally be done in patients who can rest for a few days beforehand and not have a demanding journey to the test centre. Otherwise they may already be effectively on day 2 on their first day.

 

[Jenny TipsforME]

Surely it’s just not a viable test for many pwme? Not just thinking of @Dechi style of experience, but people who are already too ill to even choose to risk it.

It’s useful in the occasional research study to evidence the nature of biological abnormalities, but should we be reluctant to accept this test as the gateway to diagnosis or benefits?

 

[Mij]

@Dechi did Dr.Moreau do this test for you? You don't have to answer if you don't want. I'm having difficulty understanding the mechanism behind his "massage machine" he uses to measure levels of PEM etc. thx

Perhaps someone else has more insight on this.

 

[Sasha]

It’s useful in the occasional research study to evidence the nature of biological abnormalities, but should we be reluctant to accept this test as the gateway to diagnosis or benefits?

I don't think it's necessary in the diagnosis of ME, but can be useful if you might have cardiovascular problems on top of it.

 

[Dechi]

@Dechi did Dr.Moreau do this test for you? You don't have to answer if you don't want. I'm having difficulty understanding the mechanism behind his "massage machine" he uses to measure levels of PEM etc. thx

Perhaps someone else has more insight on this.

Yes, I am part of this study.

This machine is like a BP cuff. For about an hour or so, maybe 2, I can’t remember, it inflates and squeezes your arm at different intervals, most likely disrupting blood circulation and causing muscle fatigue. Meanwhile, blood is regularly drawn.

I did experience more pronounced fatigue a few days afterwards, but not full blown PEM. Since we get no feedback, I don’t know what results Dr Moreau is getting from it.