The study aims to evaluate the accuracy of fluid responsiveness assessment with non-invasive cardiometry compared to ultrasound guided inferior vena cava (IVC) collapsibility for management of critically ill septic patients with hemodynamic instability.

Prospective Randomized observational comparative single blinded study will be conducted at intensive care unit at Benha University Hospitals after obtaining approval of the ethical committee and informed written consent from first degree relatives will be issued. The blindness will be performed to the patients.

The study will be conducted according to CONSORT 2010 statement. Enrolment of eligible patients will occur within 8 h of meeting the criteria for septic shock. All patients will be randomized using the computer-generated software of randomization and sealed closed envelopes to allocate them to one of two groups (30 patients each). Routine measurements and investigations will be taken at admission to intensive care unit; history, vital signs, routine laboratory investigation.

Inclusion Criteria:

1. ASA class I and II
2. Age 18-65 years old of both genders.
3. Fulfilment criteria of sepsis as defined according to the standard Surviving Sepsis Campaign criteria using the Sequential (sepsis-related) Organ Failure Assessment (SOFA) score (SOFA score ≥ 2 indicated organ dysfunction).
4. Patients within 8 h of meeting the criteria for septic shock.

Exclusion Criteria:

1. Lack of consent
2. Age below 18 and above 65 years old.
3. acute coronary syndrome
4. major cardiac dysrhythmia,
5. valvular or congenital heart disease
6. Massive bilateral pleural effusion
7. Severe anaemia
8. End-stage kidney disease (ESKD) patients with Creatinine clearance (CrCl) <50ml/min.
9. Child B and Child C hepatic patients
10. impaired systolic function according to the ejection fraction (EF) (EF < 40% indicated impaired systolic function)
11. Severe ARDS (acute respiratory distress syndrome).
12. Tense ascites
13. Mechanical ventilation.

Enrolment of eligible patients will occur within 8 h of meeting the criteria for septic shock. All patients will be randomized using the computer-generated software of randomization and sealed closed envelopes to allocate them to one of two groups (30 patients each). Routine measurements and investigations will be taken at admission to intensive care unit; history, vital signs, routine laboratory investigation.