01 Apr 08
Cardiovascular response to dobutamine stress predicts outcome in severe sepsis and septic shock
By A Kumar, E Schupp, E Bunnell, A Ali, B Milcarek and J E Parrillo
During septic shock, resistance to the hemodynamic effects of catecholamine vasopressors/inotropes is a well-recognized marker of mortality risk. However, the specific cardiovascular/metabolic response elements that are most closely associated with outcome have not been well defined. The objective of this study was to assess cardiovascular/metabolic responses to dobutamine as correlates of outcome in patients with severe sepsis/septic shock.
Methods
A prospective, non-randomized, non-blinded interventional study of graded dobutamine challenge (0, 5, 10, and 15 ug/kg/min) in adult patients who had undergone pulmonary artery catheterization within 48 hours of onset of severe sepsis or septic shock (8 survivors/15 non-survivors) was performed. Radionuclide cineangiography during graded infusion was used to determine biventricular ejection fractions at each increment of dobutamine.
Results
In univariate analysis, a variety of cardiovascular/hemodynamic and oxygen transport/metabolic variables (at the point of maximum cardiac index response for a given subject) were associated with survival including increased stroke volume index (p=0.0003), right ventricular end-diastolic volume index (p=0.0047), left ventricular stroke work index (p=0.0054), oxygen delivery index (p=0.0084), cardiac index (p=0.0093), systolic blood pressure/left ventricular end-systolic volume index ratio (sbp/lvesvi) (p=0.0188), left ventricular ejection fraction (p=0.0160), venous oxygen content (p=0.0208), mixed venous oxygen saturation (p=0.0234) and pulse pressure (p=0.0403); and decreased pulmonary artery diastolic pressure (p=0.0133), systemic vascular resistance index (p=0.0154), extraction ratio (p=0.0160) and pulmonary vascular resistance index (p=0.0390). Increases of SVI of greater than or less than 8.5 ml/m2 were concordant with survival or death in 21 of 23 cases. Multivariate profile construction showed stroke volume index as the dominant discriminating variable for survival with the sBP/LVESVI ratio alone among all other variables significantly improving the model.
Conclusions
Survivors maintain cardiac responsiveness to catecholamine stimulation during septic shock. Survival from severe sepsis/septic shock is associated with increased cardiac performance and contractility indices during dobutamine infusion. Further studies are required to determine whether these parameters are predictive of outcome in a larger severe sepsis/septic shock population.