Blood Volume Deficit in POTS Assessed by Semi-Automated Carbon Monoxide Rebreathing [preprint], 2024, Kulapatana et al

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kushami

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Some of you may remember me blabbing on about a new(ish) method for measuring blood volume becoming available as an off-the-shelf device.

This paper uses the research version of the device to look at blood volume in POTS. The medical version of the device is approved and for sale in Europe, with other countries/jurisdictions hoped to follow soon.

Note: direct PDF link.

https://assets-eu.researchsquare.co...xQvYFzb8qhCLREAgKQ_aem_rLreawDPMoRc2-4eKBGXGw


Abstract
Purpose: Semi-automated carbon monoxide (CO) rebreathing method has been introduced as a non-invasive and radioactive-free blood volume estimation method. We tested whether the semi-automated CO rebreathing method can detect the blood volume deficit in postural orthostatic tachycardia syndrome (POTS). In addition, we explored the relationship between blood volume estimated from the CO rebreathing and body impedance.

Methods: We recruited 53 subjects (21 POTS females, 19 healthy females, 13 healthy males) to record blood volumes and hemodynamic data. Blood volumes were measured by the CO rebreathing and the segmental body impedance. Linear regression models to predict normal volume of red blood cell volume (RBCV), plasma volume (PV), and blood volume (BV) were developed. Percentage deviations from the predicted normal volumes were calculated.

Results: POTS had lower RBCV (25.18±3.95 vs. 28.57±3.68 mL/kg, p=0.010, POTS vs. healthy females), BV (64.53±10.02 vs. 76.78±10.00, p<0.001), and BV deviation (-13.92±10.38% vs. -0.02±10.18%, p<0.001). POTS had higher supine heart rate (HR) (84±14 vs. 69±11 bpm, p<0.001) and upright HR (123±23 vs. 89±22 bpm, p<0.001). We found a correlation between BV deviation and upright HR in POTS (r=-0.608, p=0.003), but not in healthy [controls]. Volumes from the CO rebreathing and body impedance were well correlated (r=0.629, p<0.001).

Conclusion: The CO rebreathing method can detect BV deficit, as well as the RBCV deficit in POTS. The negative correlation between BV deviation and upright HR indicates that hypovolemia is one of POTS’ pathophysiological causes. Correlations between body impedance and CO rebreathing volume suggest the usefulness for measurements of volume changes.
 
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kushami

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The study mentions measuring blood volume using “body impedance”, a technique I haven’t heard of before.

I haven’t managed to read about it yet. If anyone knows about it and can provide or link to a brief explanation of how it works that would be much appreciated.
 
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kushami

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I suppose ideally the study would have compared the CO rebreathing method to the radioactive tracer method to see whether they gave similar results. However, getting access to that method is hard, and I believe it is reserved for crucial patient testing, e.g. for rare blood cancers.
 
sb4

sb4

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Results
Patients with POTS had lower RBCV (25.18 ± 3.95 versus 28.57 ± 3.68 mL/kg, p = 0.008, patients with POTS versus healthy female participants), BV (64.53 ± 10.02 versus 76.78 ± 10.00 mL/kg, p < 0.001), and BV deviation (−13.92 ± 10.38% versus −0.02 ± 10.18%, p < 0.001). Patients with POTS had higher supine heart rate (HR) (84 ± 14 versus 69 ± 11 bpm, p < 0.001) and upright HR (123 ± 23 versus 89 ± 22 bpm, p < 0.001). We found a correlation between BV deviation and upright HR in patients with POTS (r = −0.608, p = 0.003), but not in healthy participants. Volumes from the CO rebreathing and body impedance were well correlated (r = 0.629, p < 0.001).
Click to expand...
 
Mary

Mary

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kushami said:
The study mentions measuring blood volume using “body impedance”, a technique I haven’t heard of before.

I haven’t managed to read about it yet. If anyone knows about it and can provide or link to a brief explanation of how it works that would be much appreciated.
Click to expand...

I wonder if this has anything to do with impedance cardiography?

https://en.wikipedia.org/wiki/Imped...ography (ICG) is a,), pre-ejection period and

https://www.sciencedirect.com/science/article/abs/pii/S1551713608001633

https://pubmed.ncbi.nlm.nih.gov/12920435/ -

Abnormal impedance cardiography predicts symptom severity in chronic fatigue syndrome - this is a very interesting article. I had IC testing done in 2007 and my results were not good, in accordance with this article. I believe for some reason cardiologists stopped doing this testing and the machines which do it were going unserviced or hard to get parts for. ​


This test might actually be the equivalent of a biomarker for ME/CFS . . .
 
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