Preserving cardiac output with beta-adrenergic receptor blockade and inhibiting the Bezold-Jarisch reflex during resuscitation from hemorrhage.
J Trauma
; 63(1): 26-32, 2007 Jul.
Article
em En
| MEDLINE
| ID: mdl-17622865
ABSTRACT
BACKGROUND:
Successful fluid resuscitation after severe hemorrhage may be limited by activation of the Bezold-Jarisch reflex. We postulated that pharmacologic inhibition of this reflex would restore cardiovascular hemodynamics more effectively than would volume repletion alone during resuscitation for hemorrhagic shock.METHODS:
We measured mean arterial pressure (MAP), heart rate (HR), and cardiac output (CO) during fluid resuscitation after hemorrhaging laboratory rats until their CO had decreased by 90% to 95%. To block distinct components of the Bezold-Jarisch reflex, animals received capsazepine, yohimbine, or propranolol before iso-osmotic volume repletion.RESULTS:
Hemorrhage decreased MAP and CO; despite an initial tachycardia, HR fell significantly in response to this large volume blood loss. The degree of hemorrhage-induced bradycardia mediated by the Bezold-Jarisch reflex predicted resuscitation MAP. Capsazepine-treated animals had greater resuscitation-induced increases in MAP (values in mm Hg +/- SEM), 130 +/- 12, when compared with the saline-only animals, 90 +/- 7 (p = 0.004). The capsazepine group also had a greater increase in systemic vascular resistance over baseline values during resuscitation (86% +/- 19%) compared with vehicle-treated animals (26% +/- 14%, p = 0.02). Capsazepine had no effect on cardiac dynamics. On the other hand, yohimbine increased HR and diminished CO, and propranolol dramatically increased stroke volume by 30%.CONCLUSION:
Inhibition of the Bezold-Jarisch reflex may aid fluid resuscitation after hemorrhage only if stroke volume is restored. Beta-adrenergic receptor antagonists such as propranolol may prove the most salutary of these agents in enhancing fluid resuscitation in patients with severe hemorrhage.
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Base de dados:
MEDLINE
Assunto principal:
Reflexo
/
Pressão Sanguínea
/
Débito Cardíaco
/
Antagonistas Adrenérgicos beta
/
Hidratação
/
Frequência Cardíaca
/
Hemorragia
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article