Dynamic arterial elastance predicts mean arterial pressure decrease associated with decreasing norepinephrine dosage in septic shock

INTRODUCTION: Gradual reduction of the dosage of norepinephrine (NE) in patients with septic shock is usually left to the physician’s discretion. No hemodynamic indicator predictive of the possibility of decreasing the NE dosage is currently available at the bedside. The respiratory pulse pressure variation/respiratory stroke volume variation (dynamic arterial elastance (Ea(dyn))) ratio has been proposed as an indicator of vascular tone. The purpose of this study was to determine whether Ea(dyn) can be used to predict the decrease in arterial pressure when decreasing the NE dosage in resuscitated sepsis patients. METHODS: A prospective study was carried out in a university hospital intensive care unit. All consecutive patients with septic shock monitored by PICCO(2) for whom the intensive care physician planned to decrease the NE dosage were enrolled. Measurements of hemodynamic and PICCO(2) variables were obtained before/after decreasing the NE dosage. Responders were defined by a >15% decrease in mean arterial pressure (MAP). RESULTS: In total, 35 patients were included. MAP decreased by >15% after decreasing the NE dosage in 37% of patients (n = 13). Clinical characteristics appeared to be similar between responders and nonresponders. Ea(dyn) was lower in responders than in nonresponders (0.75 (0.69 to 0.85) versus 1 (0. 83 to 1.22), P <0.05). Baseline Ea(dyn) was correlated with NE-induced MAP variations (r = 0.47, P = 0.005). An Ea(dyn) less than 0.94 predicted a decrease in arterial pressure, with an area under the receiver-operating characteristic curve of 0.87 (95% confidence interval (95% CI): 0.72 to 0.96; P <0.0001), 100% sensitivity, and 68% specificity. CONCLUSIONS: In sepsis patients treated with NE, Ea(dyn) may predict the decrease in arterial pressure in response to NE dose reduction. Ea(dyn) may constitute an easy-to-use functional approach to arterial-tone assessment, which may be helpful to identify patients likely to benefit from NE dose reduction.