Altered tissue oxygenation 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 (-0.064 %/s) compared to CVD patients (-0.08 %/s) and healthy subjects (-0.145 %/s) (p < 0.001). After cuff release, slowest speed for reoxygenation was detected in PCS patients at 0.84 %/s compared to CVD patients (1.04 %/s) and healthy controls (CG: 2.07 %/s) (p < 0.001). The differences between PCS patients and CVD patients during ischemia remained significant also after correction for risk factors. Analyses of complications during acute infection, persistence of PCS symptoms (time after acute infection), or PCS severity (number of lead symptoms) as confounding factors did not reveal a significant effect. 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.

Exercise intolerance associated with impaired oxygen extraction in patients with long COVID.

OBJECTIVE: Chronic mental and physical fatigue and post-exertional malaise are the more debilitating symptoms of long COVID-19. The study objective was to explore factors contributing to exercise intolerance in long COVID-19 to guide development of new therapies. Exercise capacity data of patients referred for a cardiopulmonary exercise test (CPET) and included in a COVID-19 Survivorship Registry at one urban health center were retrospectively analyzed. RESULTS: Most subjects did not meet normative criteria for a maximal test, consistent with suboptimal effort and early exercise termination. Mean O2 pulse peak % predicted (of 79 ± 12.9) was reduced, supporting impaired energy metabolism as a mechanism of exercise intolerance in long COVID, n = 59. We further identified blunted rise in heart rate peak during maximal CPET. Our preliminary analyses support therapies that optimize bioenergetics and improve oxygen utilization for treating long COVID-19.

Cardiopulmonary Exercise Testing in Post-COVID-19 Patients: Where Does Exercise Intolerance Come From? / Teste Cardiopulmonar em Pacientes Pós-COVID-19: De Onde vem a Intolerância ao Exercício?

BACKGROUND: Post-COVID-19 exercise intolerance is poorly understood. Cardiopulmonary exercise testing (CPET) can identify the underlying exercise limitations. OBJECTIVES: To evaluate the source and magnitude of exercise intolerance in post-COVID-19 subjects. METHODS: Cohort study assessing subjects with different COVID-19 illness severities and a control group selected by propensity score matching. In a selected sample with CPET prior to viral infection, before and after comparisons were performed. Level of significance was 5% in the entire analysis. RESULTS: One hundred forty-four subjects with COVID-19 were assessed (median age: 43.0 years, 57% male), with different illness severities (60% mild, 21% moderate, 19% severe). CPET was performed 11.5 (7.0, 21.2) weeks after disease onset, with exercise limitations being attributed to the peripheral muscle (92%), and the pulmonary (6%), and cardiovascular (2%) systems. Lower median percent-predicted peak oxygen uptake was observed in the severe subgroup (72.2%) as compared to the controls (91.6%). Oxygen uptake differed among illness severities and controls at peak and ventilatory thresholds. Conversely, ventilatory equivalents, oxygen uptake efficiency slope, and peak oxygen pulse were similar. Subgroup analysis of 42 subjects with prior CPET revealed significant reduction in only peak treadmill speed in the mild subgroup and in oxygen uptake at peak and ventilatory thresholds in the moderate/severe subgroup. By contrast, ventilatory equivalents, oxygen uptake efficiency slope, and peak oxygen pulse did not change significantly. CONCLUSIONS: Peripheral muscle fatigue was the most common exercise limitation etiology in post-COVID-19 patients regardless of the illness severity. Data suggest that treatment should emphasize comprehensive rehabilitation programs, including aerobic and muscle strengthening components.

FUNDAMENTO: A intolerância ao exercício pós-COVID-19 não é bem entendida. O teste de esforço cardiopulmonar (TECP) pode identificar as limitações ao exercício subjacentes. OBJETIVOS: Avaliar a etiologia e a magnitude da intolerância ao exercício em sujeitos pós-COVID-19. MÉTODOS: Estudo de coorte que avaliou sujeitos com níveis de gravidades diferentes da doença COVID-19 e um grupo de controle selecionado por pareamento por escores de propensão. Em uma amostra seleta com TECP anterior à infecção viral disponível, foram realizadas comparações antes e depois. O nível de significância foi de 5% em toda a análise. RESULTADOS: Foram avaliados cento e quarenta e dois sujeitos com COVID-19 (idade mediana: 43 anos, 57% do sexo masculino), com níveis de gravidade de doença diferentes (60% leve, 21% moderada, 19% grave). O TECP foi realizado 11,5 (7,0, 21,2) semanas após o aparecimento da doença, com as limitações ao exercício sendo atribuídas aos sistemas muscular periférico (92%), pulmonar (6%), e cardiovascular (2%). Menor valor mediano do consumo de oxigênio pico percentual foi observado no subgrupo com níveis graves de doença (72,2%) em comparação com os controles (91,6%). O consumo de oxigênio foi diferente entre os grupos com diferentes níveis de gravidade de doença e o controle no pico e nos limiares ventilatórios. Inversamente, os equivalentes ventilatórios, a inclinação da eficiência do consumo de oxigênio, e o pico do pulso de oxigênio foram semelhantes. A análise do subgrupo de 42 sujeitos com TECP prévio revelou uma redução significativa no pico de velocidade da esteira no subgrupo com nível leve de doença, e no consumo de oxigênio no pico e nos limiares ventilatórios nos subgrupos com níveis moderado/grave. Por outro lado, os equivalentes ventilatórios, a inclinação da eficiência do consumo de oxigênio e o pico do pulso de oxigênio não apresentaram alterações significativas. CONCLUSÕES: A fadiga do músculo periférico foi a etiologia de limitação de exercício mais comum em pacientes pós-COVID-19 independentemente da gravidade da doença. Os dados sugerem que o tratamento deve enfatizar programas de reabilitação abrangentes, incluindo componentes aeróbicos e de fortalecimento muscular.

Effect of COVID-19 Lockdown on Cardiovascular Health in University Students.

BACKGROUND: A decrease in physical activity levels among university students during the COVID-19 pandemic is well-documented in the literature. However, the effect of lockdown restrictions on cardiovascular fitness has not been thoroughly investigated. METHODS: The aim of the study was to assess the possible changes in cardiovascular fitness among university students during a 14-week period of the COVID-19 pandemic. Thirteen female and seven male tourism and recreation students participated in the study. Examinations were conducted in November 2020 and in February/March 2021. Students performed the PWC170 test on a cycling ergometer. Maximal oxygen consumption was calculated based on the PWC170 test results. Blood pressure and heart rate were measured at rest, as well as in the 1st and 5th minute of post-exercise recovery. RESULTS: No substantial changes were observed in maximal oxygen consumption level when comparing autumn and winter indices. Male students presented elevated blood pressure whereas female students presented normal blood pressure. Heart-rate and blood-pressure indices did not show substantial alternations in examined students during analyzed period. CONCLUSIONS: Fourteen weeks of lockdown had little effect on the cardiovascular health of tourism and recreation students.

Oxygen uptake kinetics and chronotropic responses to exercise are impaired in survivors of severe COVID-19.

The post-acute phase of coronavirus disease 2019 (COVID-19) is often marked by several persistent symptoms and exertional intolerance, which compromise survivors' exercise capacity. This was a cross-sectional study aiming to investigate the impact of COVID-19 on oxygen uptake (V̇o2) kinetics and cardiopulmonary function in survivors of severe COVID-19 about 3-6 mo after intensive care unit (ICU) hospitalization. Thirty-five COVID-19 survivors previously admitted to ICU (5 ± 1 mo after hospital discharge) and 18 controls matched for sex, age, comorbidities, and physical activity level with no prior history of SARS-CoV-2 infection were recruited. Subjects were submitted to a maximum-graded cardiopulmonary exercise test (CPX) with an initial 3-min period of a constant, moderate-intensity walk (i.e., below ventilatory threshold, VT). V̇o2 kinetics was remarkably impaired in COVID-19 survivors as evidenced at the on-transient by an 85% (P = 0.008) and 28% (P = 0.001) greater oxygen deficit and mean response time (MRT), respectively. Furthermore, COVID-19 survivors showed an 11% longer (P = 0.046) half-time of recovery of V̇o2 (T1/2V̇o2) at the off-transient. CPX also revealed cardiopulmonary impairments following COVID-19. Peak oxygen uptake (V̇o2peak), percent-predicted V̇o2peak, and V̇o2 at the ventilatory threshold (V̇o2VT) were reduced by 17%, 17%, and 12% in COVID-19 survivors, respectively (all P < 0.05). None of the ventilatory parameters differed between groups (all P > 0.05). In addition, COVID-19 survivors also presented with blunted chronotropic responses (i.e., chronotropic index, maximum heart rate, and heart rate recovery; all P < 0.05). These findings suggest that COVID-19 negatively affects central (chronotropic) and peripheral (metabolic) factors that impair the rate at which V̇o2 is adjusted to changes in energy demands.NEW & NOTEWORTHY Our findings provide novel data regarding the impact of COVID-19 on submaximal and maximal cardiopulmonary responses to exercise. We showed that V̇o2 kinetics is significantly impaired at both the onset (on-transient) and the recovery phase (off-transient) of exercise in these patients. Furthermore, our results suggest that survivors of severe COVID-19 may have a higher metabolic demand at a walking pace. These findings may partly explain the exertional intolerance frequently observed following COVID-19.

The Evaluation of Functional Abilities Using the Modified Fullerton Functional Fitness Test Is a Valuable Accessory in Diagnosing Men with Heart Failure.

The assessment of functional abilities reflects the ability to perform everyday life activities that require specific endurance and physical fitness. The Fullerton functional fitness test (FFFT) seems to be the most appropriate for assessing physical fitness in heart failure (HF) patients. The study group consisted of 30 consecutive patients hospitalized for the routine assessment of HF with a reduced ejection fraction (HFrEF). They formed the study group, and 24 healthy subjects formed the control group. Each patient underwent a cardiopulmonary exercise test (CPET), transthoracic echocardiography and FFFT modified by adding the measurement of the handgrip force of the dominant limb with the digital dynamometer. The HF patients had significantly lower peak oxygen uptake (peakVO2), maximal minute ventilation, and higher ventilatory equivalent (VE/VCO2). The concentrations of B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) were significantly higher in the study group. The results of all the FFFT items were significantly worse in the study group. FFFT parameters, together with the assessment of the strength of the handgrip, strongly correlated with the results of standard tests in HF. FFFT is an effective and safe tool for the functional evaluation of patients with HFrEF. Simple muscle strength measurement with a hand-held dynamometer can become a convenient and practical indicator of muscle strength in HF patients.

COVID-19 and physical activity in sedentary individuals: differences in metabolic, cardiovascular, and respiratory responses during aerobic exercise performed with and without a surgical face masks.

BACKGROUND: The Coronavirus-19 (COVID-19) impairs metabolic, cardiovascular, and pulmonary functions in human metabolism, and wearing face masks is recommended for the prevention of contracting or exposing others to cardio-respiratory infections. Since the effect of wearing a surgical face mask (SFM) on cardiopulmonary exercise capacity has not been systematically reported we aimed to determine the effects of wearing SFM during an incremental walking test on metabolic, cardiovascular, and pulmonary gas exchange responses in sedentary individuals. METHODS: The evaluations were performed using a repeated measures study design. Seven sedentary males (age: 40 years, height: 178 cm, weight: 88 kg, BMI: 28 kg/m2, VO2max: 32.7±3.9 mL/kg/min) and 7 sedentary female participants (age: 34 years, height: 169 cm, weight: 62 kg, BMI: 22 kg/m2, VO2max: 32.1±6.8 mL/kg/min) volunteered to participate in the current study. Anthropometric parameters were measured using a Bioelectrical impedance analysis prior to each testing session. The measures of lung function assessed by spirometry, breathing pattern, maximal exercise capacity with-and-without mask were measured with a breath-by-breath automated exercise metabolic system during incremental Bruce protocol on a treadmill with two consecutive sessions with 48-h intervals. Blood pressure values (systolic and diastolic pressure) of the individuals were taken and recorded within 1 minute at the end of every ten minutes, without speed changes. RESULTS: VO2, VCO2, and VE were significantly lower during exercise performed with SFM (P<0.001). Heart rate, systolic and diastolic blood pressure were also found significantly higher during exercise performed with SFM (P<0.01). CONCLUSIONS: Wearing a SFM during incremental walking predispose a decrease in oxygen delivery while increasing pulmonary ventilation in sedentary individuals. Thus, it could be speculated that surgical face masks have a negative impact on oxygen delivery during exercise which results in decreased exercise performance due to the restricted ventilatory conditions.

Longitudinal assessment of cardiorespiratory fitness and body mass of young healthy adults during COVID-19 pandemic.

Physical activity was reduced during the COVID-19 pandemic, especially when lockdowns were mandated; however, little is known about the impact of these lifestyle changes on objective measures of cardiorespiratory fitness. To address this knowledge gap, we evaluated the cardiorespiratory fitness of 14 young healthy adults (4 women, age: 27 ± 6 yr) just before the pandemic and after ∼1 yr of public health measures being in place. During fitness assessments, participants performed submaximal pseudorandom cycling exercise to assess cardiorespiratory kinetics, and a 25 W·min-1 ramp-incremental cycling test to determine peak oxygen uptake (V̇o2). Cluster analysis identified two subgroups of participants: those who had reduced peak V̇o2 at the 1-yr follow-up (-0.50 ± 0.17 L·min-1) and those whose peak V̇o2 was maintained (0.00 ± 0.10 L·min-1). Participants with reduced peak V̇o2 also exhibited slower heart rate kinetics (interaction: P = 0.01), reduced peak O2 pulse (interaction: P < 0.001), and lower peak work rate (interaction: P < 0.001) after 1 yr of the pandemic, whereas these variables were unchanged in the group of participants who maintained peak V̇o2. Regardless of changes in peak V̇o2, both subgroups of participants gained body mass (main effect: P = 0.002), which was negatively correlated with participants' level of self-reported physical activity level at the follow-up assessment (mass: ρ = -0.59, P = 0.03) These findings suggest that some young healthy individuals lost cardiorespiratory fitness during the pandemic, whereas others gained weight, but both changes could potentially increase the risk of adverse health outcomes and disease later in life if left unaddressed.NEW & NOTEWORTHY Some young healthy adults experienced cardiovascular deconditioning during the COVID-19 pandemic, with measurable reductions in cardiorespiratory fitness, whereas others experienced no change in fitness but gained body mass, which was related to self-reported physical activity during the pandemic.

Mild-to-moderate COVID-19 impact on the cardiorespiratory fitness in young and middle-aged populations.

The goal of the present study was to compare pulmonary function test (PFT) and cardiopulmonary exercise test (CPET) performance in COVID-19 survivors with a control group (CG). This was a cross-sectional study. Patients diagnosed with COVID-19, without severe signs and symptoms, were evaluated one month after the infection. Healthy volunteers matched for sex and age constituted the control group. All volunteers underwent the following assessments: i) clinical evaluation, ii) PTF; and iii) CPET on a cycle ergometer. Metabolic variables were measured by the CareFusion Oxycon Mobile device. In addition, heart rate responses, peak systolic and diastolic blood pressure, and perceived exertion were recorded. Twenty-nine patients with COVID-19 and 18 healthy control subjects were evaluated. Surviving patients of COVID-19 had a mean age of 40 years and had higher body mass index and persistent symptoms compared to the CG (P<0.05), but patients with COVID-19 had more comorbidities, number of medications, and greater impairment of lung function (P<0.05). Regarding CPET, patients surviving COVID-19 had reduced peak workload, oxygen uptake (V̇O2), carbon dioxide output (V̇CO2), circulatory power (CP), and end-tidal pressure for carbon dioxide (PETCO2) (P<0.05). Additionally, survivors had depressed chronotropic and ventilatory responses, low peak oxygen saturation, and greater muscle fatigue (P<0.05) compared to CG. Despite not showing signs and symptoms of severe disease during infection, adult survivors had losses of lung function and cardiorespiratory capacity one month after recovery from COVID-19. In addition, cardiovascular, ventilatory, and lower limb fatigue responses were the main exercise limitations.

Aerobic capacity of professional soccer players before and after COVID-19 infection.

This investigation aimed to assess the aerobic capacity of professional soccer players pre-and post-COVID-19 infection. Twenty-one division-1 elite soccer players (age 24.24 ± 5.75 years, height 178.21 ± 5.44 cm, weight 74.12 ± 5.21 kg) participated in this study. This observational study compared the same players' aerobic capacity pre-, and 60-days post COVID-19 recovery. The statistical analysis demonstrated that the infected players had significantly lower VO2max values [t(20) = 5.17, p < 0.01, d = 0.613 (medium effect)], and significantly lower VO2 values at respiratory compensation point (RC) [t(20) = 2.97, p < 0.05, d = 0.39 (small effect)] after recovery. Furthermore, results indicated a significantly lower running time (RT) on the treadmill [t(20) = 4.84, p < 0.01, d = 0.46 (small effect)] when compared to the results that were obtained before they got infected. In addition, velocity at VO2max (VVO2max) was significantly lower [t(20) = 2.34, p < 0.05, d = 0.41 (small effect)] and the heart rate values at ventilatory threshold (VT) [t(20) = -2.79, p < 0.01, d = 0.55 (medium effect)] and RC [t(20) = -3.72, p < 0.01, d = 0.52 (medium effect)] were significantly higher post-recovery. The aforementioned findings indicate that post COVID-19 soccer players may not reach full recovery at two months. Therefore, our results highlight that further adaptations and improvements are needed with regard to aerobic capacity before soccer players return to professional games.

Obese patients with long COVID-19 display abnormal hyperventilatory response and impaired gas exchange at peak exercise.

Aim: To analyze the impact of obesity on cardiopulmonary response to exercise in people with chronic post-COVID-19 syndrome. Patients & methods: Consecutive subjects with chronic post-COVID syndrome 6 months after nonsevere acute infection were included. All patients received a complete clinical evaluation, lung function tests and cardiopulmonary exercise testing. A total of 51 consecutive patients diagnosed with chronic post-COVID-19 were enrolled in this study. Results: More than half of patients with chronic post-COVID-19 had a significant alteration in aerobic exercise capacity (VO2peak) 6 months after hospital discharge. Obese long-COVID-19 patients also displayed a marked reduction of oxygen pulse (O2pulse). Conclusion: Obese patients were more prone to have pathological pulmonary limitation and pulmonary gas exchange impairment to exercise compared with nonobese COVID-19 patients.

In this study, the cardiopulmonary response to exercise in people with chronic post-COVID-19 syndrome was analyzed. More than half of patients diagnosed with chronic post-COVID-19 had reduced exercise capacity 6 months after hospital discharge. In addition, patients with chronic post-COVID-19 syndrome who were overweight or obese displayed exaggerated hyperventilation along with an impairment of oxygenation at peak exercise.

Laminar flow ventilation system to prevent airborne infection during exercise in the COVID-19 crisis: A single-center observational study.

Particulate generation occurs during exercise-induced exhalation, and research on this topic is scarce. Moreover, infection-control measures are inadequately implemented to avoid particulate generation. A laminar airflow ventilation system (LFVS) was developed to remove respiratory droplets released during treadmill exercise. This study aimed to investigate the relationship between the number of aerosols during training on a treadmill and exercise intensity and to elucidate the effect of the LFVS on aerosol removal during anaerobic exercise. In this single-center observational study, the exercise tests were performed on a treadmill at Running Science Lab in Japan on 20 healthy subjects (age: 29±12 years, men: 80%). The subjects had a broad spectrum of aerobic capacities and fitness levels, including athletes, and had no comorbidities. All of them received no medication. The exercise intensity was increased by 1-km/h increments until the heart rate reached 85% of the expected maximum rate and then maintained for 10 min. The first 10 subjects were analyzed to examine whether exercise increased the concentration of airborne particulates in the exhaled air. For the remaining 10 subjects, the LFVS was activated during constant-load exercise to compare the number of respiratory droplets before and after LFVS use. During exercise, a steady amount of particulates before the lactate threshold (LT) was followed by a significant and gradual increase in respiratory droplets after the LT, particularly during anaerobic exercise. Furthermore, respiratory droplets ≥0.3 µm significantly decreased after using LFVS (2120800±759700 vs. 560 ± 170, p<0.001). The amount of respiratory droplets significantly increased after LT. The LFVS enabled a significant decrease in respiratory droplets during anaerobic exercise in healthy subjects. This study's findings will aid in exercising safely during this pandemic.

Comparison of Ratings of Perceived Exertion and Target Heart Rate-Based Exercise Prescription in Cardiac Rehabilitation: A RANDOMIZED CONTROLLED PILOT STUDY.

PURPOSE: Although ratings of perceived exertion (RPE) are widely used to guide exercise intensity in cardiac rehabilitation (CR), it is unclear whether target heart rate ranges (THRRs) can be implemented in CR programs that predominantly use RPE and what impact this has on changes in exercise capacity. METHODS: We conducted a three-group pilot randomized control trial (#NCT03925493) comparing RPE of 3-4 on the 10-point modified Borg scale, 60-80% of heart rate reserve (HRR) with heart rate (HR) monitored by telemetry, or 60-80% of HRR with a personal HR monitor (HRM) for high-fidelity adherence to THRR. Primary outcomes were protocol fidelity and feasibility. Secondary outcomes included exercise HR, RPE, and changes in functional exercise capacity. RESULTS: Of 48 participants randomized, four patients dropped out, 20 stopped prematurely (COVID-19 pandemic), and 24 completed the protocol. Adherence to THRR was high regardless of HRM, and patients attended a median (IQR) of 33 (23, 36) sessions with no difference between groups. After randomization, HR increased by 1 ± 6, 6 ± 5, and 10 ± 9 bpm ( P = .02); RPE (average score 3.0 ± 0.05) was unchanged, and functional exercise capacity increased by 1.0 ± 1.0, 1.9 ± 1.5, 2.0 ± 1.3 workload METs (effect size between groups, ηp2 = 0.11, P = .20) for the RPE, THRR, and THRR + HRM groups, respectively. CONCLUSIONS: We successfully implemented THRR in an all-RPE CR program without needing an HRM. Patients randomized to THRR had higher exercise HR but similar RPE ratings. The THRR may be preferable to RPE in CR populations for cardiorespiratory fitness gains, but this needs confirmation in an adequately powered trial.

Hemodynamic response to positive end-expiratory pressure and prone position in COVID-19 ARDS.

BACKGROUND: Use of high positive end-expiratory pressure (PEEP) and prone positioning is common in patients with COVID-19-induced acute respiratory failure. Few data clarify the hemodynamic effects of these interventions in this specific condition. We performed a physiologic study to assess the hemodynamic effects of PEEP and prone position during COVID-19 respiratory failure. METHODS: Nine adult patients mechanically ventilated due to COVID-19 infection and fulfilling moderate-to-severe ARDS criteria were studied. Respiratory mechanics, gas exchange, cardiac output, oxygen consumption, systemic and pulmonary pressures were recorded through pulmonary arterial catheterization at PEEP of 15 and 5 cmH2O, and after prone positioning. Recruitability was assessed through the recruitment-to-inflation ratio. RESULTS: High PEEP improved PaO2/FiO2 ratio in all patients (p = 0.004), and significantly decreased pulmonary shunt fraction (p = 0.012), regardless of lung recruitability. PEEP-induced increases in PaO2/FiO2 changes were strictly correlated with shunt fraction reduction (rho=-0.82, p = 0.01). From low to high PEEP, cardiac output decreased by 18 % (p = 0.05) and central venous pressure increased by 17 % (p = 0.015). As compared to supine position with low PEEP, prone positioning significantly decreased pulmonary shunt fraction (p = 0.03), increased PaO2/FiO2 (p = 0.03) and mixed venous oxygen saturation (p = 0.016), without affecting cardiac output. PaO2/FiO2 was improved by prone position also when compared to high PEEP (p = 0.03). CONCLUSIONS: In patients with moderate-to-severe ARDS due to COVID-19, PEEP and prone position improve arterial oxygenation. Changes in cardiac output contribute to the effects of PEEP but not of prone position, which appears the most effective intervention to improve oxygenation with no hemodynamic side effects.

Persistent Exertional Intolerance After COVID-19: Insights From Invasive Cardiopulmonary Exercise Testing.

BACKGROUND: Some patients with COVID-19 who have recovered from the acute infection after experiencing only mild symptoms continue to exhibit persistent exertional limitation that often is unexplained by conventional investigative studies. RESEARCH QUESTION: What is the pathophysiologic mechanism of exercise intolerance that underlies the post-COVID-19 long-haul syndrome in patients without cardiopulmonary disease? STUDY DESIGN AND METHODS: This study examined the systemic and pulmonary hemodynamics, ventilation, and gas exchange in 10 patients who recovered from COVID-19 and were without cardiopulmonary disease during invasive cardiopulmonary exercise testing (iCPET) and compared the results with those from 10 age- and sex-matched control participants. These data then were used to define potential reasons for exertional limitation in the cohort of patients who had recovered from COVID-19. RESULTS: The patients who had recovered from COVID-19 exhibited markedly reduced peak exercise aerobic capacity (oxygen consumption [VO2]) compared with control participants (70 ± 11% predicted vs 131 ± 45% predicted; P < .0001). This reduction in peak VO2 was associated with impaired systemic oxygen extraction (ie, narrow arterial-mixed venous oxygen content difference to arterial oxygen content ratio) compared with control participants (0.49 ± 0.1 vs 0.78 ± 0.1; P < .0001), despite a preserved peak cardiac index (7.8 ± 3.1 L/min vs 8.4±2.3 L/min; P > .05). Additionally, patients who had recovered from COVID-19 demonstrated greater ventilatory inefficiency (ie, abnormal ventilatory efficiency [VE/VCO2] slope: 35 ± 5 vs 27 ± 5; P = .01) compared with control participants without an increase in dead space ventilation. INTERPRETATION: Patients who have recovered from COVID-19 without cardiopulmonary disease demonstrate a marked reduction in peak VO2 from a peripheral rather than a central cardiac limit, along with an exaggerated hyperventilatory response during exercise.

Dysautonomia following COVID-19 is not associated with subjective limitations or symptoms but is associated with objective functional limitations.

BACKGROUND: Individuals who contract coronavirus disease 2019 (COVID-19) can suffer with persistent and debilitating symptoms long after the initial acute illness. Heart rate (HR) profiles determined during cardiopulmonary exercise testing (CPET) and delivered as part of a post-COVID recovery service may provide insight into the presence and impact of dysautonomia on functional ability. OBJECTIVE: Using an active, working-age, post-COVID-19 population, the purpose of this study was to (1) determine and characterize any association between subjective symptoms and dysautonomia; and (2) identify objective exercise capacity differences between patients classified "with" and those "without" dysautonomia. METHODS: Patients referred to a post-COVID-19 service underwent comprehensive clinical assessment, including self-reported symptoms, CPET, and secondary care investigations when indicated. Resting HR >75 bpm, HR increase with exercise <89 bpm, and HR recovery <25 bpm 1 minute after exercise were used to define dysautonomia. Anonymized data were analyzed and associations with symptoms, and CPET outcomes were determined. RESULTS: Fifty-one of the 205 patients (25%) reviewed as part of this service evaluation had dysautonomia. There were no associations between symptoms or perceived functional limitation and dysautonomia (P >.05). Patients with dysautonomia demonstrated objective functional limitations with significantly reduced work rate (219 ± 37 W vs 253 ± 52 W; P <.001) and peak oxygen consumption (V̇o2: 30.6 ± 5.5 mL/kg/min vs 35.8 ± 7.6 mL/kg/min; P <.001); and a steeper (less efficient) V̇e/V̇co2 slope (29.9 ± 4.9 vs 27.7 ± 4.7; P = .005). CONCLUSION: Dysautonomia is associated with objective functional limitations but is not associated with subjective symptoms or limitation.

Maximal exercise outcomes with a face mask: the effects of gender and age differences on cardiorespiratory responses.

BACKGROUND: Surgical masks have become an important accessory of physical activity in daily life due to the COVID-19 pandemic. AIMS: To determine the effects of the surgical mask on respiratory gas exchange parameters, dyspnoea, and hemodynamic responses during maximal exercise in different age groups and gender. METHODS: Twenty-six healthy participants between 18 and 65 years (mean 37.35 ± 15.99) performed a maximal exercise test twice randomly, with and without a mask. To determine the respiratory gas exchange parameters (peak oxygen consumption (VO2peak), minute ventilation (VE), energy expenditure (EE), respiratory rate), and hemodynamic responses, each participant underwent a maximal exercise test with Bruce protocol on the treadmill. The modified Borg scale (MBS) was used to determine the dyspnoea before and after exercise test. RESULTS: Test duration (min), metabolic equivalents (MET), VO2peak ml/kg/min, respiratory rate, and peak heart rate (HRpeak) of young participants after exercise test with and without a mask were higher than in middle-aged participants (p < 0.01). There was no significant difference between males and females in test duration, VO2peak ml/kg/min, VO2peak ml/min, MET, VE l/min, respiratory rate, MBS, and EE in masked tests (p > 0.05). CONCLUSION: The surgical mask use affected the maximal exercise capacity of middle-aged participants more than young participants. Although males performed better than females in tests without masks, the decrease in exercise capacity with mask use was greater than in females. Advanced age and male gender may be factors that need more attention during exercise with mask use. TRIAL REGISTRATION NUMBER AND DATE: NCT04498546-02/17/2021.

Continuous monitoring of changes in cerebral oxygenation during hemodialysis in a patient with acute congestive heart failure.

A 71-year-old man undergoing hemodialysis (HD) was admitted to our hospital with congestive heart failure (CHF) and pneumonia. After admission, ultrafiltration with HD was urgently performed because of a lack of respiratory improvement despite the use of noninvasive positive pressure ventilation. During HD, cerebral regional saturation of oxygen (rSO2) was monitored by INVOS 5100c oxygen saturation monitor (Covidien Japan, Japan) to evaluate changes in tissue oxygenation. At HD initiation, cerebral rSO2 was very low at 34% under the fraction of inspiratory oxygen (FiO2) of 0.4. Ultrafiltration was performed at the rate of 0.5 L/h thereafter, cerebral rSO2 gradually improved even as inhaling oxygen concentration decreased. At the end of HD, cerebral rSO2 improved at 40% under a FiO2 of 0.28 as excess body fluid was removed. After pneumonia and CHF improved, he was discharged. Reports of the association between cerebral oxygenation and acute CHF status in patients undergoing HD are limited; therefore, in our experience with this case, cerebral oxygenation deteriorated with the CHF status but was improved by adequate body-fluid management during HD.

COVID-19: the new cause of dyspnoea as a result of reduced lung and peripheral muscle performance.

This study aimed to evaluate the cardiopulmonary function and impairment of exercise endurance in patients with COVID-19 after 3 months of the second wave of the pandemic in Turkey. A total of 51 consecutive COVID-19 survivors, mostly healthcare providers, still working in the emergency room and intensive care units of the hospital after the second wave of Covid 19 pandemia were included in this study. Cardiopulmonary exercise stress test was performed. The median of the exercise time of the COVID-19 survivors, was 10 (4.5-13) minutes and the mean 6.8 ± 1.3 Mets was achieved. The VO2max of the COVID-19 survivors was 24 ± 4.6 ml kg-1min-1which corresponds the 85 ± 10% of the predicted VO2max value. The VO2WRs value which was reported about 8.5-11 ml min-1per watt in healthy individuals as normal was found lower in Covid 19 survivors (5.6 ± 1.4). The percentage of the maximum peak VO2calculated according to the predictable peak VO2of the COVID-19 survivors, was found significantly lower in male patients (92 ± 9.5% vs 80 ± 8.5%,p: 0.000). Also, there was a positive correlation between the percentage of the maximum predicted VO2measurements and age (r: 0.320,p: 0000). The peak VO2values of COVID-19 survivors decreased, and simultaneously, their exercise performance decreased due to peripheral muscle involvement. We believe that COVID-19 significantly affects men and young patients.