Detecting Orthostatic Intolerance in Long COVID in a Clinic Setting, 2023, Isaac et al.

SNT Gatchaman

SNT Gatchaman

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Detecting Orthostatic Intolerance in Long COVID in a Clinic Setting
Isaac, Robert Oliver; Corrado, Joanna; Sivan, Manoj

Introduction:
A likely mechanism of Long COVID (LC) is dysautonomia, manifesting as orthostatic intolerance (OI). In our LC service, all patients underwent a National Aeronautics and Space Administration (NASA) Lean Test (NLT), which can detect OI syndromes of Postural Tachycardia Syndrome (PoTS) or Orthostatic Hypotension (OH) in a clinic setting. Patients also completed the COVID-19 Yorkshire Rehabilitation Scale (C19-YRS), a validated LC outcome measure. Our objectives in this retrospective study were (1) to report on the findings of the NLT; and (2) to compare findings from the NLT with LC symptoms reported on the C19-YRS.

Methods:
NLT data, including maximum heart rate increase, blood pressure decrease, number of minutes completed and symptoms experienced during the NLT were extracted retrospectively, together with palpitation and dizziness scores from the C19-YRS. Mann-Witney U tests were used to examine for statistical difference in palpitation or dizziness scores between patients with normal NLT and those with abnormal NLT. Spearman’s rank was used to examine the correlation between the degree of postural HR and BP change with C19-YRS symptom severity score.

Results: Of the 100 patients with LC recruited, 38 experienced symptoms of OI during the NLT; 13 met the haemodynamic screening criteria for PoTS and 9 for OH. On the C19-YRS, 81 reported dizziness as at least a mild problem, and 68 for palpitations being at least a mild problem. There was no significant statistical difference between reported dizziness or palpitation scores in those with normal NLT and those with abnormal NLT. The correlation between symptom severity score and NLT findings was <0.16 (poor).

Conclusions:
We have found evidence of OI, both symptomatically and haemodynamically in patients with LC. The severity of palpitations and dizziness reported on the C19-YRS does not appear to correlate with NLT findings. We would recommend using the NLT in all LC patients in a clinic setting, regardless of presenting LC symptoms, due to this inconsistency.

Link | PDF (International Journal of Environmental Research and Public Health)
 
It's interesting that the conclusion from the poor correlation between results on the NASA lean test and OI symptoms seems to be to believe the veracity of the test rather than the symptoms.

A more logical conclusion is surely that the NASA test is inadequate and shouldn't be relied on for assessing the cause of OI in a patient as it will miss lots of genuine cases.

I think it should be checked out with tilt table testing. I'm sure we've seen other research that showed 10 minutes NASA lean test is not reliable at picking up many OI cases.

Also, POTS and orthostatic hypotension aren't the only forms of genuinely physiological OI.
 
Trish said:
Also, POTS and orthostatic hypotension aren't the only forms of genuinely physiological OI.
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Yes. One study showing this:
Cerebral blood flow is reduced in ME/CFS during head-up tilt testing even in the absence of hypotension or tachycardia: A quantitative, controlled study using Doppler echography
C Linda M C van Campen et al. Clin Neurophysiol Pract. 2020.
https://pubmed.ncbi.nlm.nih.gov/32140630/
 
Trish said:
A more logical conclusion is surely that the NASA test is inadequate and shouldn't be relied on for assessing the cause of OI in a patient as it will miss lots of genuine cases.
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I thought they covered that in discussion and conclusion. Ref [14] is the study @Dolphin posted above. [6] is Long-Haul COVID Patients: Prevalence of POTS Are Reduced but Cerebral Blood Flow Abnormalities Remain Abnormal with Longer Disease Duration (2022).

Transcranial Doppler ultrasound has been used to measure CBF in other settings. In one study of 510 patients diagnosed with ME/CFS, Van Campen et al. demonstrated that OI, as manifested by a significant decrease in cerebral blood flow on postural challenge, was present even in those with no significant HR or BP abnormalities [14]. The same team also described significant decreases in cerebral blood in patients with LC with no diagnosable postural signs [6]. These data show the advantage of more direct measurements of physiological parameters in symptomatic patients. Some of the disadvantages of this test include accessibility on a large scale, and obtaining sufficient image quality may limit the use in certain patients [14].
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This retrospective study found evidence of OI patients with LC, with impact on daily functioning. The NLT can be used to detect OI in a clinic setting. We would recommend using this test for all patients with LC and not just patients with classical OI symptoms, due to the high prevalence of OI in LC. Further confirmatory tests of OI including HUT and CBF would be ideal; however, accessing these tests in a community setting is difficult. Further work is required to evaluate the sensitivity and specificity of NLT for OI in LC.
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