Comparison of phenylephrine and norepinephrine in the management of dopamine-resistant septic shock

Introduction: This study aims to compare two vasoconstrictors: - norepinephrine and phenylephrine - in the management of dopamine- resistant septic shock. Materials and Methods: We performed a randomized, prospective, controlled trial in 54 septic shock patients, with persistent hypotension despite adequate volume resuscitation and continued dopamine infusion ~25μg/kg/h. Patients were randomly allocated into two groups to receive either norepinephrine or phenylephrine infusion (n = 27 each) titrated to achieve a target of SBP > 90mm Hg, MAP > 75 mm Hg, SVRI > 1100 dynes.s/cm5m2, CI > 2.8 L/min/m2, DO2I > 550 ml/min/m2, and VO2I > 150 ml/min/m2 for continuous 6 h. All the parameters were recorded every 30 min and increment in dose of studied drug was done in the specified dose range if targets were not achieved. Data from pulmonary arterial and hepatic vein catheterization, thermodilution catheter, blood gas analysis, blood lactate levels, invasive blood pressure, and oxygen transport variables were compared with baseline values after achieving the targets of therapy. Differences within and between groups were analyzed using a one-way analysis of variance test and Fischer′s exact test. Results: No difference was observed in any of the investigated parameters except for statistically significant reduction of heart rate (HR) (P< 0.001) and increase in stroke volume index (SVI) (P< 0.001) in phenylephrine group as compared to nonsignificant change in norepinephrine group. Conclusions: Phenylephrine infusion is comparable to norepinephrine in reversing hemodynamic and metabolic abnormalities of sepsis patients, with an additional benefit of decrease in HR and improvement in SVI.