The aim of the study is to assess carotid ultrasounds measurements, namely corrected flow time (FTc), velocity time integral (VTI) and respirophasic variation in carotid artery blood flow peak velocity (ΔVpeak), as a predictor of fluid responsiveness in septic shock patients.

Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection . Early identification and appropriate management in the initial hours after the development of sepsis improve outcomes.

For patients with sepsis-induced hypoperfusion or septic shock it is recommended to give IV crystalloid fluid within the first 3 hr of resuscitation . However, fluid responsiveness varies widely between cases. Determining the optimal amount of fluid to be administered remains a critical issue in clinical practice and research. Recent studies have shown that not every patient advantages from intravenous hydration, only 40% of hypotensive patients with sepsis benefit, and the others who do not respond are liable to develop pulmonary edema with high associated mortality . Studies have shown that aortic blood peak velocity had high sensitivity and specificity to predict fluid responsiveness, however, measurements of aortic blood flow velocity need a transesophageal ultrasound which is an invasive procedure . Measurement of left ventricular outflow tract velocity time integral (LVOTVTI), derived stroke volume (SV), and cardiac output reliably predicts fluid responsiveness in critically ill patients but it is difficult and dependent on operator and echo windows . There is a need to find a non-invasive accurate and easy method to assess fluid responsiveness in septic shock patients. Different Measurements of carotid artery flow have been suggested recently to predict fluid responsiveness. A promising measurements are corrected flow time (FTc), velocity time integral (VTI) and respirophasic variation in carotid artery blood flow peak velocity (ΔVpeak).

Inclusion Criteria:

• Adult patients (18-75 year old) diagnosed with septic shock (MAP >65mmHg), within 6 hours of admission or development of septic shock if previously admitted with other diagnoses.

Exclusion Criteria:

• patients have any of these conditions: Carotid artery stenosis ≥50%, known heart failure (Ejection fraction ≤45%) or End Stage Kidney Disease requiring haemodialysis.

All recruited patients aged between 18 and 75 year old suspected to have septsis and septic shock are to be assessed at time of admission by history taking, thorough physical examination, laboratory workup. ECG, haemodynamic parameters and abdominal ultrasound including inferior vena cava (IVC) dimeter and collapsibility. Sequential Organ failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation (APACHE-II) score to diagnose septic shock and eligibility to enter the study .