Uncoupling between cerebral perfusion and oxygenation during incremental exercise in an athlete with postconcussion syndrome: a case report

High‐intensity exercise may pose a risk to patients with postconcussion syndrome (PCS) when symptomatic during exertion. The case of a paralympic athlete with PCS who experienced a succession of convulsion‐awakening periods and reported a marked increase in postconcussion symptoms after undergoing a graded symptom‐limited aerobic exercise protocol is presented. Potential mechanisms of cerebrovascular function failure are then discussed

The physiological burden of the 6-minute walk test compared with cardiopulmonary exercise stress test in patients with severe aortic atenosis

Background Management of aortic stenosis (AS) relies on symptoms. Exercise testing is recommended for asymptomatic patients with significant AS but is often experienced as forbidding and/or technically unrealistic for patients who are often frail, deconditioned, and intimidated by the exercise test. We compared the physiological burden assessed with gas exchange assessments to gauge and respiratory exchange ratio (RER) of a 6-minute walk test (6MWT) to a cardiopulmonary exercise stress test (CPET) in patients with severe AS. peak oxygen utilization Methods Adults with equivocal symptoms and severe AS (1-aortic valve area [AVA] ≤ 1.0 cm2 or AVA index ≤ 0.6 cm2/m2, 2-peak aortic jet velocity ≥ 4.0 m/sec, 3-mean transvalvular pressure gradient ≥ 40 mm Hg by rest or dobutamine stress echocardiography, or 4-aortic valve calcification ≥ 1200 in women or ≥ 2000 AU in men) were studied. All participants completed both a 6MWT and symptom-limited progressive bicycle exercise testing. Breath-by-breath gas analysis and 12-lead electrocardiography were completed during 6MWT and CPET. Results: Eleven patients were studied. Patients walked on average 330 ± 75 m during the 6MWT and achieved a maximal workload of 48 ± 14 watts during the CPET. During the 6MWT, peak maximal oxygen uptake (O2peak) was 12.8 ± 2.5 vs 10.8 ± 4.2 mL/kg/min during the CPET. Respiratory exchange ratio exceeded 1.1 in both the 6MWT and CPET indicating similarly high exertion. Compared with the CPET, a larger proportion of the 6MWT was performed at a high intensity level (78% ± 28% vs 33% ± 24% at > 85% V̇O2peak; P = 0.004). Conclusions The 6MWT with breath-by-breath gas analysis was well tolerated and able to achieve a physiological intense RER and O2peak that are similar to symptom-limited CPET in patients with severe AS.Introduction La prise en charge de la sténose aortique (SA) dépend des symptômes. L’épreuve d’effort est recommandée aux patients asymptomatiques qui ont une SA significative, mais elle est souvent perçue comme dangereuse et/ou théoriquement irréaliste chez ces patients qui sont souvent fragiles, en mauvaise forme et craintifs par l’épreuve d’effort. Nous avons comparé le fardeau physiologique calculé par la consommation maximale de l’oxygène (O2max) et le quotient respiratoire (QR) d’un test de marche de 6 minutes (TM6) et d'une épreuve d’effort maximal chez des patients avec une SA sévère. Méthodes Tous les patients présentaient une SA symptomatique et sévère (1-aire valvulaire aortique [AVA] ≤ 1,0 cm2 ouAVA ≤ 0,6 cm2/m2, 2-une vélocité maximale du flux aortique ≥ 4,0 m/sec, 3-un gradient de pression transvalvulaire moyen ≥ 40 mmHg au repos ou à l’échocardiographie à l’effort sous dobutamine ou 4-une calcification valvulaire aortique (AU) ≥ 1200 chez les femmes ou ≥ 2000 AU chez les hommes). Les participants ont effectué un TM6 et une ’épreuve d’effort maximal de type rampe sur vélo. L’analyse des échanges gazeux respiration par respiration et un électrocardiogramme à 12 dérivations ont été effectués durant le TM6 et l'épreuve d'effort maximal. Résultats Un total de 11 patients ont participé à l'étude. Les patients ont marché en moyenne 330 ± 75 m durant le TM6 et ont atteint une charge de travail maximale de 48 ± 14 watts durant l’épreuve d'effort maximal. Durant le TM6, le O2max était de 12,8 ± 2,5 vs 10,8 ± 4,2 ml/kg/min durant l’épreuve d'effort maximal. Le QR était supérieur à 1,1 au TM6 ainsi qu'à l’épreuve d'effort maximal. Comparativement à l’épreuve d'effort maximal, un pourcentage plus important au TM6 a été réalisée à une intensité élevée (78 % ± 28 % vs 33 % ± 24 % à > 85 % V̇O2max; P = 0,004). Conclusions Le TM6 avec mesure directe des échanges gazeux était bien toléré et susceptible d’atteindre des valeurs physiologiques d'intensité élevée pour le QR et le O2max. Les valeurs atteintes au TM6 étaient semblables à celles de l'épreuve d'effort maximal chez les patients avec une SA sévère

Development of a Constant Rate Step Test to Assess Exertional Dyspnea in the Primary Care Setting in Patients with COPD Ashley Rycroft

Background: There is a need to develop a field test to evaluate exertional dyspnea in the primary care setting. This study examined the applicability of a 3-minute constant rate step test in patients with COPD. Methods: This test involved 4 stepping rates (18, 22, 26, 32 steps.min-1) equivalent to approximately 4.5, 5.3, 6.0, and 7.2 MET with the ultimate goal that in its final development, the assessment will be made a single stepping rate based on disease severity. Stable COPD patients (N= 43; 65 ± 6.5 years; FEV1= 49 ± 16% pred.; SpO2 (%) rest: 95± 2) were equipped with a portable Jaeger Oxycon Mobile® metabolic system and followed an audio signal for stepping up and down a single 20 cm step for 3 minutes. Borg dyspnea scores were obtained at the end each stepping bout. A 10-min rest was given between each stepping bout. Results: O f the 43 patients, 80% completed stages 1 and 2, 74 and 37% stages 3 and 4 while no patient of MRC class 4 or 5 (n=8) completed stage 1. Breathing frequency (breaths.min-1) spanned from 26.5± 4.1 to 39.0±6.4 but VT (L) remained unchanged (1.4± 0.3 vs. 1.5±0.4) from stage 1 to 4 while Borg scores were 3 ± 1, 4 ± 1, 5 ± 2, 6 ± 3 respectively and SpO2 (%) were 92±5, 91±4, 91±4 and 90±4. Conclusions: Preliminary findings indicate that a 3-min constant rate step test may present a feasible alternative to laboratory testing to assess exertional dyspnea in moderately severe COPD. In this population, a stepping rate of 26 steps·min-1 could be sustained by the majority of patients while producing a level of dyspnea potentially amenable to therapy

Development of a Constant Rate Step Test to Assess Exertional Dyspnea in the Primary Care Setting in Patients with COPD Ashley Rycroft

Background: There is a need to develop a field test to evaluate exertional dyspnea in the primary care setting. This study examined the applicability of a 3-minute constant rate step test in patients with COPD. Methods: This test involved 4 stepping rates (18, 22, 26, 32 steps.min-1) equivalent to approximately 4.5, 5.3, 6.0, and 7.2 MET with the ultimate goal that in its final development, the assessment will be made a single stepping rate based on disease severity. Stable COPD patients (N= 43; 65 ± 6.5 years; FEV1= 49 ± 16% pred.; SpO2 (%) rest: 95± 2) were equipped with a portable Jaeger Oxycon Mobile® metabolic system and followed an audio signal for stepping up and down a single 20 cm step for 3 minutes. Borg dyspnea scores were obtained at the end each stepping bout. A 10-min rest was given between each stepping bout. Results: O f the 43 patients, 80% completed stages 1 and 2, 74 and 37% stages 3 and 4 while no patient of MRC class 4 or 5 (n=8) completed stage 1. Breathing frequency (breaths.min-1) spanned from 26.5± 4.1 to 39.0±6.4 but VT (L) remained unchanged (1.4± 0.3 vs. 1.5±0.4) from stage 1 to 4 while Borg scores were 3 ± 1, 4 ± 1, 5 ± 2, 6 ± 3 respectively and SpO2 (%) were 92±5, 91±4, 91±4 and 90±4. Conclusions: Preliminary findings indicate that a 3-min constant rate step test may present a feasible alternative to laboratory testing to assess exertional dyspnea in moderately severe COPD. In this population, a stepping rate of 26 steps·min-1 could be sustained by the majority of patients while producing a level of dyspnea potentially amenable to therapy

Test-retest Reproducibility of Constant Rate Step and Shuttle Walk Test for the Assessment of Exertional Dyspnea in patients with COPD

Background: Alternatives for laboratory exercise testing are needed to better reflect symptoms of physical activities of daily living in chronic disease. Such a tool should accurately set the exercise intensity and show good reproducibility. This study examined the reproducibility of constant rate walking (CRWT) and stepping tests (CRST) to assess exertional dyspnea in patients with COPD. Methods: Stable COPD patients (n=43; 65 ± 6.5 yr; FEV1= 49 ± 16% pred.) equipped with a portable Jaeger Oxycon Mobile® metabolic system completed both the CRWT and the CRST. Each test included four 3-min constsant rate stages separated by a 10-min rest period on two occasions separated by 7 to 14 days. For both exercise modalities the selected rates targeted intensities between 25 and 80% VO2 peak for moderately-severe COPD patients. Ventilation (VE) and gas exchange were obtained during the third minute and the Borg dyspnea score at the end of each exercise bout. Results: An equal proportion of patients (35%) completed stage 4 of the CRWT and of the CRST. The test-retest correlation coefficients for dyspnea scores ranged from 0.79 to 0.95 for stages 1 through 4 for theCRWTand from 0.88 to 0.85 for the CRST while those for VE (L·min-1) ranged from 0.95 to 0.98 and 0.91 to 0.95 respectively. Conclusion: These results show both the CRWT and the CRST to be highly reproducible for the assessment of exertional dyspnea in patients with moderate-severe COPD. However, a better linearity in VE and VO2 with exercise stages was seen for the CRST than for the CRWT since patients complied more easily to the imposed external load with stepping than with walking