Determinants of the Y Descent and its Usefulness as a Predictor of Ventricular Filling
Notice bibliographique
Résumé
Our objective was to determine if the magnitude of the Y descent in the central venous pressure tracing could be used to determine which patients have restrictive hemodynamics. To better understand the determinants of the Y descent, we also examined the effects of changes in blood volume, changes in pleural pressure, and respiratory maneuvers on its magnitude. Studies were performed in both humans and dogs. In six anesthetized dogs, we examined the effect on the Y descent in central venous pressure (CVP) of an infusion of normal saline, a decrease in pleural pressure produced by having animals perform a Mueller maneuver, and the combination of a Mueller maneuver and volume loading. Observations were made with the chest closed, chest open, and chest and pericardium open. The state of the chest did not effect the Y descent. The Y descent was only significantly increased when a Mueller maneuver was combined with volume loading. There was a significant inverse relationship between the magnitude of the decrease in esophageal pressure and the Y descent. There was also a linear relationship between the CVP and Y descent. For the human studies, we examined patients undergoing routine cardiac surgery. They were examined during spontaneous breathing before intubation, with positive pressure breathing and closed chest, with positive pressure breathing and open chest, with an open pericardium, with a closed chest and positive pressure breathing postsurgery, and with spontaneous breathing after extubation following surgery. The Y descent was greater in spontaneous breaths postsurgery compared to before surgery, and this was associated with an increase in CVP. However, the magnitude of CVP did not correlate with the magnitude of the Y descent. A restrictive pattern in cardiac filling was identified by a lack of respiratory variation in right atrial pressure during spontaneous breaths. All patients with large Y descents had a restrictive pattern, but many patients with restrictive filling patterns did not have a large Y descent. The magnitude of the Y descent is affected by the volume status, the magnitude and direction of the changes in pleural pressure, and the compliance of the pericardial compartment. A large Y descent indicates a restrictive cardiac state, but a small Y descent does not rule out a restrictive condition because of the many interacting variables.
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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 | 0,000 | 0,003 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 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 ».