Does oxygen pulse represent a reliable surrogate for stroke volume during exercise? Insights from cardiopulmonary exercise test combined with echocardiography or invasive measurements
Notice bibliographique
Résumé
Abstract Background While interpreting the mechanisms underlying exercise limitation in cardiopulmonary exercise testing (CPET), oxygen pulse (O2pulse) is often assumed to be a surrogate for stroke volume (SV). However, in the rearranged Fick’s equation, O2pulse represents the product of SV and arteriovenous oxygen difference (a-vO2diff). Consequently, interpreting O2pulse exclusively as a reflection of SV can be misleading, as it disregards one of its key determinants. Purpose To assess the effort response of the determinants of O2pulse (SV and a-vO2Diff) by simultaneous CPET and echocardiography (CPETecho) or invasive CPET (iCPET). Methods This observational study analysed the O2pulse in CPETecho and iCPET examinations conducted between July/15 and May/24. SV in CPETecho was measured using the ultrasound velocity time integral of the left ventricular outflow tract, and with VO2, a-vO2diff was calculated. For iCPET, a-vO2diff was directly measured using arterial and mixed-venous blood gas analyses, while SV was calculated. During CPETecho, measurements were taken at rest, intermediate, and peak exercise, whereas during iCPET, at rest, at 3, 6, 9 minutes, and at peak exercise. Variables were compared using one-way ANOVA with post hoc Tukey tests, with statistical significance set at p < 0.05. Results CPETecho: A total of 1,866 exams were analyzed (54.1% male; age: 65.4±13.9 y). The main indication was heart failure with preserved ejection fraction (HFpEF, 39.7%), valvular heart disease (35.5%), myocardial ischemia (6.3%), and others (18.5%). O2pulse increased significantly from rest to intermediate and peak (4.0±1.9, 9.0±3.3, and 10.9±3.9 mL/beat, respectively; p<.0001; Figure 1). SV increased from rest to intermediate load (70.2±18.1 vs. 84.5±20.9 mL/beat; p<.0001), with no further significant increase from intermediate to peak exercise (84.5±20.9 vs. 85.1±21.3 mL/beat; p=.07). In contrast, a-vO2 diff increased progressively from rest to intermediate and peak (p<.001). iCPET: A total of 68 exams were analyzed, primarily conducted in suspected HFpEF (age: 64.1±10.6 y). O2pulse increased progressively from rest to peak (p<.0001; Figure 2). SV significantly increased from rest to the 6-minute measurement, with no further significant changes thereafter. In contrast, a-vO2diff showed a continuous progressive increase from rest to peak exercise. Conclusion Analysis of the determinants of O2pulse (SV and a-vO2diff) using both CPETecho and iCPET demonstrated that the increase in O2pulse from intermediate to peak exercise is primarily driven by a rise in a-vO2diff, while SV remains relatively constant. Therefore, in cardiac patients, changes in O2pulse should not be assumed to reliably reflect changes in SV alone but rather represent the combined effects of SV and peripheral oxygen extraction. For a definitive interpretation of the O2pulse response during exercise, performing measurement of either SV or a-vO2diff is essential.Figure 1.Variables measured by CPETechoFigure 2.Variables measuredf by iCPET
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,002 | 0,001 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».