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Altered Tissue Oxygenation in Patients with Post COVID-19 Syndrome 2023 Schäfer et al

Discussion in 'Long Covid research' started by Andy, Mar 18, 2023.

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  1. Andy

    Andy Committee Member

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    Hampshire, UK
    For published version see
    Altered tissue oxygenation in patients with post COVID-19 syndrome (2023, Microvascular Research)
    ********************
    Pre-Print     https://www.researchgate.net/public...ation_in_Patients_with_Post_COVID-19_Syndrome

    Background: Post COVID-19 syndrome (PCS) is a complex condition with partly substantial impact on patients’ social and professional life and overall life quality. Currently, the underlying cause(s) of PCS are unknown. Since PCS-specific symptoms could be associated with systemic alterations in tissue oxygen supply, we aimed to investigate changes in tissue oxygenation in patients with PCS.

    Methods: A case-control study including 30 PCS patients (66.6 % males, 48.6 ± 11.2 years, mean time after (first) acute infection: 324 days), 16 cardiologic patients (CVD) (65.5 % males, 56.7 ± 6.3 years) and 11 young healthy controls (55 % males, 28.5 ± 7.4 years) was conducted. Near infrared spectroscopy (NIRS) was used to assess changes in tissue oxygenation during an arterial occlusion protocol on the non-dominant forearm (brachioradialis, 760/850 nm, 5 Hz). The protocol included 10-min rest, a 2-min baseline measurement followed by a 3-min ischemic period (upper-arm cuff, 50 mmHg above resting systolic blood pressure) and a 3-min reoxygenation period. PCS patients were grouped by presence of arterial hypertension and elevated BMI to assess the impact of risk factors.

    Results: No differences in mean tissue oxygenation in the pre-occlusion phase existed between groups (p ≥ 0.566). During ischemia, comparisons of linear regressions slopes revealed slower oxygen desaturation for PCS patients (-3.8 %/min) compared to CVD patients (-4.8 %/min) and healthy subjects (-8.7 %/min) (p < 0.001). After cuff release, slowest speed for reoxygenation was detected in PCS patients at 50.2 %/min compared to CVD patients (62.4 %/min) and healthy controls (CG: 124.2 %/min) (p < 0.001). The differences between PCS patients and CVD patients during ischemia remained significant also after correction for risk factors.

    Conclusions: This study provides evidence that the rate of tissue oxygen consumption is persistently altered in PCS and that PCS patients show an even slower decline in tissue oxygenation during occlusion than CVD patients. Our observations may at least partly explain PCS-specific symptoms such as physical impairment and fatigue.
     
    Last edited by a moderator: Jun 15, 2023
    Andy, Mar 18, 2023
    #1
    obeat, RedFox, Binkie4 and 12 others like this.
  2. Mij

    Mij Senior Member (Voting Rights)

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    Silent hypoxia
     
    Mij, Mar 18, 2023
    #2
    Amw66, RedFox, Jacob Richter and 3 others like this.
  3. SNT Gatchaman

    SNT Gatchaman Senior Member (Voting Rights)

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    SNT Gatchaman, Jun 15, 2023
    #3
    Amw66, RedFox, Binkie4 and 4 others like this.
  4. Hutan

    Hutan Moderator Staff Member

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    There isn't detail on PCS diagnostic criteria - just that there are persistent symptoms for more than 12 weeks. The PCS group have high levels of fatigue though (table 1).
    It looks as though efforts were made to reduce confounding factors e.g. measurement done in the morning, attention was given to the temperature of the room, caffeine and nicotine intake, and more.

    Screen Shot 2023-06-15 at 8.25.15 pm.png

    It's definitely interesting, but the control groups are small, there is no healthy post-infection control group of a similar age, and there is quite a complicated picture of Covid complications and medication use among the PCS and cardiac participants.

    The paper suggests that the finding (both the slow decline in oxygenation after occlusion and the slow increase upon release) might be due to a reduced concentration of micro vessels and/or an issue with mitochondria.

    I assume this sort of investigation would be easy to replicate. I hope the study is replicated.
    Shame about the assumptions the researchers make about appropriate treatment:
     
    Hutan, Jun 15, 2023
    #4
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  5. SNT Gatchaman

    SNT Gatchaman Senior Member (Voting Rights)

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    Ref is Mitochondria and oxygen homeostasis (2022, The FEBS Journal). Senior author is Paul Hwang (looking at WASF3 and HIF-1, endoplasmic reticulum stress, unfolded protein response etc). See this comment.
     
    Last edited: Aug 20, 2023
    SNT Gatchaman, Jul 30, 2023
    #5
    Mij, RedFox, Amw66 and 1 other person like this.

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