ObjectiveTo explore the influence of norepinephrine on the prediction of fluid responsiveness by passive leg raising (PLR) during septic shock. MethodsForty-six septic shock patients in intensive care unit of Nanjing Drum Tower Hospital were prospectively observed from September to November 2012. Among which 36 septic shock patients were enrolled with a positive PLR test (defined by an increase in stroke volume index ≥10%). A PLR test was performed at baseline (PLR1). A second PLR test (PLR2) was performed at returning to supine position for 10 min and the dose of norepinephrine was increased to maintain MAP ≥65 mmHg for 20 min. The changes of heart rate(HR),mean arterial pressure(MAP),central venous pressure(CVP),cardiac index(CI),stroke volume index(SVI),index of systemic vascular resistance(SVRI),global end-diastolic volume index(GEDVI),and cardiac function index(CFI) were monitored by transpulmonary thermodilution technique (PiCCO). ResultsPLR1 significantly increased SVI by (20.54±9.63)%,CI by (20.57±9.89)%,MAP by (7.64±5.77)%,and CVP by (25.83±23.39)%. As the dose of norepinephrine increased,SVI was increased by (16.97±9.06)%,CI by (16.78±8.39)%,GEDVI by (9.08±4.47)%,MAP by (28.07±12.48)%,and CVP by (7.86±8.52)%. PLR2 increased SVI by (13.74±8.79)%,CI by (13.79±9.08)%,MAP by (2.93±5.06)%,and CVP by (13.36±14.74)%. The PLR2 and the dose increase of norepinephrine augmented SVI to a significantly lesser extent than the PLR1 performed at baseline (both P<0.05). However,SVI increased by <10% in 6 patients while the baseline PLR was positive in these patients. ConclusionIn septic patients with a positive PLR at baseline,norepinephrine increases cardiac preload and cardiac output and influences the fluid responsiveness.