Comparison between Central Venous Pressure and Aortic Flow Time in Guiding Fluid Therapy in Septic Shock Patients

Background: Aortic corrected flow time (FTc) is easily measured by Doppler techniques. Recent data using transoesophageal Doppler suggest that it may predict fluid responsiveness in critical care. This use of FTc has not previously been evaluated in septic shock, only one preliminary study have incorporated transcutaneously measured FTc. Denoting its importance in prediction of fluid responsiveness in septic patient furthermore, no comparison has been made between transesopahgeal FTc and central venous pressure. Aim of the Work: The aim of our study was to compare flow time corrected to heart rate (FTc) and Central Venous Pressure (CVP); as predictors of fluid responsiveness in septic shock patients and significance of (CVP) measurement on morbidity and mortality at 12 hours post resuscitation. Subjects and Methods: This was a prospective study of 46 consecutive adult septic shock patients (in sinus rhythm; 44 out of 46 patients were mechanically ventilated) treated with intravenous fluid challenge (500ml over 15 minutes) guided with CVP in control group and guided by FTC in Doppler group in a surgical tertiary intensive care unit. There were no statistically significant differences between the two groups at baseline, except for lower APACHE (p=0.039) levels in the Doppler group than in the control group. Haemodynamic assessment incorporating transesophageal aortic Doppler (CardioQ®) measurements occurred shortly before and 1,6, 12 hours after fluid challenge. Concurrent with initial assessment, blood samples were withdrawn and laboratory measurements documented 1,6,12 hours after fluid challenge and in 3 consecutive days. Results: Five patients demonstrated an increase in stroke volume 10% (responders). Percent change in stroke volume strongly correlated with baseline FTc (r=-0.6831,p=0.000) but not central venous pressure (r=-0.0864,p=0.56). Baseline FTc 332ms discriminated responders from non-responders [AUC=0.989, 95% confidence interval=0.954 to 1.023; p=0.01)]. Our data support Low CVP 5mmHg at 12 hours