VO2 – American ME and CFS Society

Differential Cardiopulmonary Hemodynamic Phenotypes in PASC Related Exercise Intolerance

Abstract:

Background Post-acute sequelae of COVID-19 (PASC) affects a significant portion of patients who have previously contracted SARS-CoV-2, with exertional intolerance being a prominent symptom.

Study Objective This study aimed to characterize the invasive hemodynamic abnormalities of PASC-related exertional intolerance using a larger data set from invasive cardiopulmonary exercise testing (iCPET).

Study Design & Intervention Fifty-five patients were recruited from the Yale Post-COVID-19-Recovery-Program, with most experiencing mild acute illness. Supine right heart catheterization (RHC) and iCPET were performed on all participants.

Main results The majority (75%) of PASC patients exhibited impaired peak systemic oxygen extraction (pEO₂) during iCPET in conjunction with supranormal cardiac output (CO) (i.e., PASC alone group), On average, the PASC alone group exhibited a “normal” peak exercise capacity, VO₂ (89±18% predicted). Approximately 25% of patients had evidence of central cardiopulmonary pathology (i.e., 12 with resting and exercise HFpEF and 2 with exercise PH). PASC patient with HFpEF (i.e., PASC HFpEF group) exhibited similarly impaired pEO₂ with well compensated PH (i.e., peak VO₂ and cardiac output >80% respectively) despite aberrant central cardiopulmonary exercise hemodynamics. PASC patients with HFpEF also exhibited increased body mass index of 39±7 kg·m⁻². To examine the relative contribution of obesity to exertional impairment in PASC HFpEF, a control group compromising of obese non-PASC group (n=61) derived from historical iCPET cohort was used. The non-PASC obese patients with preserved peak VO₂ (>80% predicted) exhibited a normal peak pulmonary artery wedge pressure (17±14 versus 25±6 mmHg; p=0.03) with similar maximal voluntary ventilation (90±12 versus 86±10%predicted; p=0.53) compared to PASC HFpEF patients. Impaired pEO₂ was not significantly different between PASC patients who underwent supervised rehabilitation and those who did not (p=0.19).

Conclusions This study highlights the importance of considering impaired pEO₂ in PASC patients with persistent exertional intolerance unexplained by conventional investigative testing. Results of current study also highlights the prevalence of a distinct high output failure HFpEF phenotype in PASC with a primary peripheral limitation to exercise.

Source: Peter A. Kahn, Phillip Joseph, Paul M. Heerdt, Inderjit Singh. Differential Cardiopulmonary Hemodynamic Phenotypes in PASC Related Exercise Intolerance. ERJ Open Research Jan 2023, 00714-2023; DOI: 10.1183/23120541.00714-2023 https://openres.ersjournals.com/content/early/2023/12/07/23120541.00714-2023 (Full text available as PDF file)

Maximal Oxidative Capacity During Exercise is Associated with Muscle Power Output in Patients with Long coronavirus disease 2019 (COVID-19) Syndrome. A Moderation Analysis

Abstract:

Background & Aims: Long COVID syndrome (LCS) involves persistent symptoms experienced by many patients after recovering from coronavirus disease 2019 (COVID-19). We aimed to assess skeletal muscle energy metabolism, which is closely related to peak fat oxidation rates during exercise, in patients with LCS compared with healthy controls. We also examined whether muscle power output mediates the relationship between COVID-19 and skeletal muscle energy metabolism.

Methods: In this cross-sectional study, we enrolled 71 patients with LCS and 63 healthy controls. We assessed clinical characteristics such as body composition, physical activity, and muscle strength. We used cardiopulmonary exercise testing to evaluate substrate oxidation rates during graded exercise. We performed statistical analyses to compare group characteristics and peak fat oxidation differences based on power output.

Results: The two-way analysis of covariance (ANCOVA) results, adjusted for covariates, showed that the patients with LCS had lower absolute maximal fatty acid oxidation (MFO), relative MFO/fat-free mass (FFM), absolute carbohydrates oxidation (CHox), relative CHox/FFM, and oxygen uptake (VO₂) at maximum fat oxidation (mL∙min⁻¹) than the healthy controls (P < 0.05). Moderation analysis indicated that muscle power output significantly influenced the relationship between LCS and reduced peak fat oxidation (interaction β = −0.105 [95% confidence interval −0.174; −0.036]; P = 0.026). Therefore, when muscle power output was below 388 W, the effect of the LCS on MFO was significant (62% in our study sample P = 0.010). These findings suggest compromised mitochondrial bioenergetics and muscle function, represented by lower peak fat oxidation rates, in the patients with LCS compared with the healthy controls.

Conclusion: The patients with LCS had lower peak fat oxidation during exercise compared with the healthy controls, potentially indicating impairment in skeletal muscle function. The relationship between peak fat oxidation and LCS appears to be mediated predominantly by muscle power output. Additional research should continue investigating LCS pathogenesis and the functional role of mitochondria.

Source: Robinson Ramírez-Vélez, Sergio Oscoz-Ochandorena, Yesenia García-Alonso, Nora García-Alonso, Gaizka Legarra-Gorgoñon, Julio Oteiza, Ander Ernaga Lorea, Mikel Izquierdo, María Correa-Rodríguez. Maximal Oxidative Capacity During Exercise is Associated with Muscle Power Output in Patients with Long coronavirus disease 2019 (COVID-19) Syndrome. A Moderation Analysis. Clinical Nutrition ESPEN, 2023, ISSN 2405-4577, https://doi.org/10.1016/j.clnesp.2023.10.009. https://www.sciencedirect.com/science/article/pii/S2405457723021666 (Full text)

Structural and functional impairments of skeletal muscle in patients with post-acute sequelae of SARS-CoV-2 infection

Abstract:

Background: Following acute COVID-19, a substantial proportion of patients showed symptoms and sequelae for several months, namely the post-acute sequelae of COVID-19 (PASC) syndrome. Major phenomena are exercise intolerance, muscle weakness and fatigue. We aimed to investigate the physiopathology of exercise intolerance in patients with PASC syndrome by structural and functional analyses of skeletal muscle.

Methods: At least 3 months after infection, non-hospitalized patients with PASC (n=11,ys:54±11; PASC) and patients without long-term symptoms (n=12,ys:49±9; CTRL) visited the laboratory on four non-consecutive days. Spirometry, lung diffusion capacity and quality of life were assessed at rest. Cardiopulmonary incremental exercise test was performed. Oxygen consumption (VO₂) kinetics were determined by moderate-intensity exercises. Muscle oxidative capacity (k) was assessed by near-infrared spectroscopy. Histochemical analysis, O₂ flux (JO₂) by high-resolution respirometry, and quantification of key molecular markers of mitochondrial biogenesis and dynamics were performed in vastus lateralis biopsies.

Results: Pulmonary and cardiac functions were within normal range in all patients. VO₂_peak was lower in PASC than CTRL (24.7±5.0vs32.9±7.4mL*min^-1*kg^-1, respectively, P<.05). VO₂ kinetics was slower in PASC than CTRL (41±12vs30±9s^-1, P<.05). k was lower in PASC than CTRL (1.54±0.49vs2.07±0.51min^-1, P<.05). Citrate synthase, PGC1alfa and JO₂ for mitochondrial complex II were significantly lower in PASC vs CTRL (all P<.05).

Conclusion: In our cohort of patients with PASC, we showed limited exercise tolerance mainly due to “peripheral” determinants. Substantial reductions were observed for biomarkers of mitochondrial function, content, and biogenesis. PASC syndrome appears to negatively impact skeletal muscle function, although the disease is an heterogenous condition.

Source: Colosio M, Brocca L, Gatti M, Neri M, Crea E, Cadile F, Canepari M, Pellegrino MA, Polla B, Porcelli S, Bottinelli R. Structural and functional impairments of skeletal muscle in patients with post-acute sequelae of SARS-CoV-2 infection. J Appl Physiol (1985). 2023 Sep 7. doi: 10.1152/japplphysiol.00158.2023. Epub ahead of print. PMID: 37675472. https://journals.physiology.org/doi/abs/10.1152/japplphysiol.00158.2023 (Full text available as PDF file)

Reduced exercise capacity, chronotropic incompetence, and early systemic inflammation in cardiopulmonary phenotype Long COVID

Abstract:

Background: Mechanisms underlying persistent cardiopulmonary symptoms following SARS-CoV-2 infection (post-acute sequelae of COVID-19 “PASC” or “Long COVID”) remain unclear. This study sought to elucidate mechanisms of cardiopulmonary symptoms and reduced exercise capacity.

Methods: We conducted cardiopulmonary exercise testing (CPET), cardiac magnetic resonance imaging (CMR) and ambulatory rhythm monitoring among adults > 1 year after confirmed SARS-CoV-2 infection in a post-COVID cohort, compared those with or without symptoms, and correlated findings with previously measured biomarkers.

Results: Sixty participants (median age 53, 42% female, 87% non-hospitalized) were studied at median 17.6 months following SARS-CoV-2 infection. On CPET, 18/37 (49%) with symptoms had reduced exercise capacity (<85% predicted) compared to 3/19 (16%) without symptoms (p = 0.02). Adjusted peak VO2 was 5.2 ml/kg/min lower (95%CI 2.1-8.3; p = 0.001) or 16.9% lower percent predicted (95%CI 4.3-29.6; p = 0.02) among those with symptoms. Chronotropic incompetence was common. Inflammatory markers and antibody levels early in PASC were negatively correlated with peak VO2 more than 1 year later. Late-gadolinium enhancement on CMR and arrhythmias were absent.

Conclusions: Cardiopulmonary symptoms >1 year following COVID-19 were associated with reduced exercise capacity, which was associated with elevated inflammatory markers early in PASC. Chronotropic incompetence may explain exercise intolerance among some with cardiopulmonary Long COVID.

Source: Durstenfeld MS, Peluso MJ, Kaveti P, Hill C, Li D, Sander E, Swaminathan S, Arechiga VM, Lu S, Goldberg SA, Hoh R, Chenna A, Yee BC, Winslow JW, Petropoulos CJ, Kelly JD, Glidden DV, Henrich TJ, Martin JN, Lee YJ, Aras MA, Long CS, Grandis DJ, Deeks SG, Hsue PY. Reduced exercise capacity, chronotropic incompetence, and early systemic inflammation in cardiopulmonary phenotype Long COVID. J Infect Dis. 2023 May 11:jiad131. doi: 10.1093/infdis/jiad131. Epub ahead of print. PMID: 37166076. https://academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiad131/7159960 (Full text available as PDF file)

Post-acute Sequelae of SARS Co-V2 and Chronic Fatigue/Myalgic Encephalitis Share Similar Pathophysiologic Mechanisms of Exercise Limitation

Abstract:

Abstract available online: https://www.atsjournals.org/doi/abs/10.1164/ajrccm-conference.2023.207.1_MeetingAbstracts.A6470

Source: S. Jothi, G. Claessen, M. Insel, S. Kubba, E. Howden, S.-R. Carmona, F.P. Rischard. Post-acute Sequelae of SARS Co-V2 and Chronic Fatigue/Myalgic Encephalitis Share Similar Pathophysiologic Mechanisms of Exercise Limitation. https://www.atsjournals.org/doi/abs/10.1164/ajrccm-conference.2023.207.1_MeetingAbstracts.A6470

Sex Differences in Hemodynamic Response to Exercise in Patients With Myalgic Encephalomyelitis: Insights From Invasive Cardiopulmonary Exercise Testing

Abstract:

Abstract available online: https://www.atsjournals.org/doi/10.1164/ajrccm-conference.2023.207.1_MeetingAbstracts.A2995

Source: K. Wichmann Madsen, J. Squires, M.C. Stovall, S. Al-Zayer, C.-J. Chang, W. Xiao, R. Pari, P. Joseph, D.M. Systrom. Sex Differences in Hemodynamic Response to Exercise in Patients With Myalgic Encephalomyelitis: Insights From Invasive Cardiopulmonary Exercise Testing. American Journal of Respiratory and Critical Care Medicine 2023;207:A2995 https://www.atsjournals.org/doi/10.1164/ajrccm-conference.2023.207.1_MeetingAbstracts.A2995

Reproducibility of Measurements Obtained During Cardiopulmonary Exercise Testing in Individuals With Fatiguing Health Conditions – A Case Series

Abstract:

Purpose: Measurements obtained during maximal cardiopulmonary exercise testing (CPET) demonstrate high test–retest reliability, which indicates low error variance. However, measurements obtained from people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) may depart from typically observed high reproducibility, which could represent functionally relevant biological variability that is characteristic of the underlying pathophysiology. The purpose of this case series was to document individual experiences with test–retest variability in CPET measurements in individuals with ME/CFS compared with other fatiguing health conditions.

Methods: In this case series, 6 women matched for age and body mass index underwent 2 maximal CPETs spaced 24 hours apart. Clients comprised 1 sedentary individual without fatigue, 1 active individual without fatigue, 1 individual with multiple sclerosis (MS), 1 individual diagnosed with HIV, 1 individual with ME/CFS and low maximal volume of oxygen consumed (VO₂max), and 1 high-functioning individual with ME/CFS and high VO₂max. Percent change in CPET measurements between tests was calculated for each client.

Results: Nondisabled clients and clients with MS and HIV reproduced or improved in their volume of oxygen consumed (VO₂), workload (WL), heart rate (HR), and minute ventilation (VE) at ventilatory anaerobic threshold (VAT) and at peak exercise (except peak WL and VE for the individual with HIV). Neither individual with ME/CFS reproduced VO₂, WL, HR, or VE at VAT within literature estimates.

Conclusions: Measurements during CPET for individual patients may relate to potential condition-specific deficits in cardiac, pulmonary, and metabolic functioning.

Source: Larson, Benjamin PT, DPT¹; Davenport, Todd E. PT, DPT, MPH, OCS^2,3; Stevens, Staci R. MA³; Stevens, Jared BS³; Van Ness, J. Mark PhD^3,4; Snell, Christopher R. PhD³. Reproducibility of Measurements Obtained During Cardiopulmonary Exercise Testing in Individuals With Fatiguing Health Conditions: A Case Series. Cardiopulmonary Physical Therapy Journal: October 2019 – Volume 30 – Issue 4 – p 145-152 doi: 10.1097/CPT.0000000000000100 https://journals.lww.com/cptj/Abstract/2019/10000/Reproducibility_of_Measurements_Obtained_D%20uring.4.aspx

Cardiopulmonary responses to exercise in an individual with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome during long-term treatment with intravenous saline: A case study

Abstract:

BACKGROUND:Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) causes significant impairment in daily activities, including the ability to pursue daily activities. Chronotropic intolerance is becoming better characterized in ME/CFS and may be the target of supportive treatment.

OBJECTIVE:To document the effect of repeated intravenous (IV) saline administration on cardiovascular functioning and symptoms in a 38-year old female with ME/CFS.

METHODS:The patient received 1 L of 0.9% IV saline through a central line for a total of 675 days. Single CPETs were completed periodically to assess the effect of treatment on cardiopulmonary function at peak exertion and ventilatory anaerobic threshold (VAT). An open-ended symptom questionnaire was used to assess subjective responses to CPET and self-reported recovery time.

RESULTS:Improvements were noted in volume of oxygen consumed (VO2), heart rate (HR), and systolic blood pressure (SBP) at peak and VAT. Self-reported recovery time from CPET reduced from 5 days to 1–2 days by the end of treatment. The patient reported improved quality of life related, improved capacity for activities of daily living, and reduced symptoms.

CONCLUSIONS:IV saline may promote beneficial effects for cardiopulmonary function and symptoms in people with ME/CFS, which should be the focus of formal study.

Source: Davenport, Todd E., Ward, Michael K., Stevens, Staci R., Stevens, Jared, Snell, Christopher R., VanNess, J. Mark. Cardiopulmonary responses to exercise in an individual with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome during long-term treatment with intravenous saline: A case study. Work, vol. Pre-press, no. Pre-press, pp. 1-7, 2020 https://content.iospress.com/articles/work/wor203214

Physical Activity Measures in Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Correlations Between Peak Oxygen Consumption, the Physical Functioning Scale of the SF-36 Questionnaire, and the Number of Steps From an Activity Meter

Abstract:

Background: Most studies to assess effort intolerance in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) have used questionnaires. Few studies have compared questionnaires with objective measures like an actometer or an exercise test. This study compared three measures of physical activity in ME/CFS patients: the physical functioning scale (PFS) of the SF-36, the number of steps/day (Steps) using an actometer, and the %peak VO2 of a cardiopulmonary stress test.

Methods: Female ME/CFS patients were selected from a clinical database if the three types of measurements were available, and the interval between measurements was ≤ 3 months. Data from the three measures were compared by linear regression.

Results: In 99 female patients the three different measures were linearly, significantly, and positively correlated (PFS vs Steps, PFS vs %peak VO2 and Steps vs %peak VO2: all P < 0.001). Subgroup analysis showed that the relations between the three measures were not different in patients with versus without fibromyalgia and with versus without a maximal exercise effort (RER ≥ 1.1). In 20 patients re-evaluated for symptom worsening, the mean of all three measures was significantly lower (P < 0.0001), strengthening the observation of the relations between them. Despite the close correlation, we observed a large variation between the three measures in individual patients.

Conclusions: Given the large variation in ME/CFS patients, the use of only one type of measurement is inadequate. Integrating the three modalities may be useful for patient care by detecting overt discrepancies in activity and may inform studies that compare methods of improving exercise capacity.

Source: van Campen CMC, Rowe PC, Verheugt FWA, Visser FC. Physical activity measures in patients with myalgic encephalomyelitis/chronic fatigue syndrome: correlations between peak oxygen consumption, the physical functioning scale of the SF-36 questionnaire, and the number of steps from an activity meter. J Transl Med. 2020;18(1):228. Published 2020 Jun 8. doi:10.1186/s12967-020-02397-7 https://pubmed.ncbi.nlm.nih.gov/32513266/

Abnormal blood lactate accumulation during repeated exercise testing in myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Post-exertional malaise and delayed recovery are hallmark symptoms of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Studies on repeated cardiopulmonary exercise testing (CPET) show that previous exercise negatively affects oxygen uptake (VO2 ) and power output (PO) in ME/CFS. Whether this affects arterial lactate concentrations ([Laa ]) is unknown.

We studied 18 female patients (18-50 years) fulfilling the Canadian Consensus Criteria for ME/CFS and 15 healthy females (18-50 years) who underwent repeated CPETs 24 h apart (CPET1 and CPET2 ) with [Laa ] measured every 30th second. VO2 at peak exercise (VO2 peak) was lower in patients than in controls on CPET1 (P < 0.001) and decreased in patients on CPET2 (P < 0.001).

However, the difference in VO2peak between CPETs did not differ significantly between groups. [Laa ] per PO was higher in patients during both CPETs (Pinteraction < 0.001), but increased in patients and decreased in controls from CPET1 to CPET2 (Pinteraction < 0.001). Patients had lower VO2 (P = 0.02) and PO (P = 0.002) at the gas exchange threshold (GET, the point where CO2 production increases relative to VO2 ), but relative intensity (%VO2peak ) and [Laa ] at GET did not differ significantly from controls on CPET1 .

Patients had a reduction in VO2 (P = 0.02) and PO (P = 0.01) at GET on CPET2 , but no significant differences in %VO2peak and [Laa ] at GET between CPETs. Controls had no significant differences in VO2 , PO or %VO2peak at GET between CPETs, but [Laa ] at GET was reduced on CPET2 (P = 0.008).

In conclusion, previous exercise deteriorates physical performance and increases [Laa ] during exercise in patients with ME/CFS while it lowers [Laa ] in healthy subjects.

Source: Lien K, Johansen B, Veierød MB, Haslestad AS, Bøhn SK, Melsom MN, Kardel KR, Iversen PO. Abnormal blood lactate accumulation during repeated exercise testing in myalgic encephalomyelitis/chronic fatigue syndrome. Physiol Rep. 2019 Jun;7(11):e14138. doi: 10.14814/phy2.14138. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6546966/ (Full article)