Fluid replacement is considered the cornerstone of hemodynamic management in critically ill patients especially in patients with septic shock. However, only about 50% of critically ill hemodynamically unstable patients are responsive to fluids. Consequently, the resuscitation of critically ill patients requires an accurate assessment of the patients' intravascular volume status and their volume responsiveness. In this study, we will compare the efficacy of carotid artery flow to echo left ventricular end diastolic volume as a predictive value for fluid resuscitation in septic shock patients.