The aim of this study is to compare the effect of resuscitation guided by Left ventricular outflow tract-velocity time integral (LVOT-VTI) variation versus the effect of resuscitation guided by inferior vena cava (IVC) variation on time to normalization of the capillary refill time in adult patients with septic shock, amount of resuscitation fluids, rate of vasopressor and ICU length of stay.

Capillary refill time will be measured by applying firm pressure to the ventral surface of the right index finger distal phalanx with a glass microscope slide. The pressure will be increased until the skin is blank and then maintained for 10 seconds. The time for return of the normal skin color will be registered with a chronometer. A CRT > 3 seconds will be considered abnormal.

Patients with normal CRT at baseline will proceed to periodic monitoring (every hour/6 hours) and start the algorithm if CRT becomes abnormal at any of these timepoints. Patients with abnormal CRT will follow the loop when fulfilling the Sepsis-3 definition of septic shock.

Sepsis time 0 is defined as the time of admission to the ICU for sepsis treatment upon the inclusion criteria. For patients already in the ICU, sepsis time 0 is considered the earliest time at which the patients satisfy the inclusion criteria.

Fluid responsiveness FR will be assessed using a structured approach. Dynamic predictors of FR will be evaluated depending on the individual status, i.e., considering if under MV or spontaneous breathing, Vt, respiratory rate (RR), respiratory system compliance and the presence of arrhythmias.

Passive leg raise PLR is performed by tilting a patient from a 45-degree semi-recumbent head-up position to a 30-45° degree leg-up position or by lifting the legs passively from the horizontal position. This maneuver transfers up to 300 mL of blood from the lower limbs and the splanchnic territory into the intrathoracic compartment and induces significant changes in cardiac preload, mean systemic pressure and the upstream pressure of systemic venous return. It is reliable and can be implemented in either spontaneously breathing or mechanically ventilated patients and can often be repeated. A method that has been recommended by the Surviving Sepsis Campaign, and is appraised by the European Society of Intensive Care Medicine.

After informed consent is obtained from the caregiver, transthoracic two-dimensional 2D, M-mode, and Doppler echocardiography will be performed on commercially available echocardiographic equipment (Mindray, M7 Premium) using a (SP5-1s) probe. Echocardiography will be performed to measure the LVOT diameter measured in the long-axis parasternal view, and the time-velocity integral of the flow wave across the aortic valve (VTI) will be obtained by pulsed wave Doppler and averaged over the whole respiratory cycle. Synchronization of the measurements with the different times of the ventilatory cycle will be verified by insertion of a pressure signal.

For the spontaneously breathing patients, the images will be obtained over 1 respiratory cycle, inspiration and expiration will be defined by the biggest and smallest size, respectively. Multiple ECHO images will be obtained and the 3 most consistent will be averaged off-line.

LVOT-VTI variation and IVC diameter variation will be measured twice at least for every patient in both groups at baseline and post PLR. The 3 most consistent recordings will be chosen and averaged at baseline and post PLR for the sake of precision of values.

IVC Collapsibility diameter < 21 mm and index ≥ 50% indicates fluid responsiveness in spontaneously breathing patients. IVC distensibility index > 18% indicates fluid responsiveness in mechanically ventilated patients. Passive leg raising test > 12% increase in SV indicates fluid responsiveness.

Inclusion Criteria:

• adult patients ( ≥ 18 years) of either gender with septic shock according to the Sepsis-3

Exclusion Criteria:

• Known history of any cardiac pathology, acute coronary syndrome, cardiac dysrhythmias (as a primary diagnosis), acute pulmonary edema or known poor systolic cardiac function (left ventricular ejection fraction < 50%).
• Body mass index ≥ 35 kg/m2 .
• Concomitant acute respiratory distress syndrome) or high PEEP (> 10 cmH2O) requirements on mechanical ventilation (MV).
• Child B or C liver cirrhosis.
• End-stage renal disease with or without dialysis.
• Pregnancy.
• Multi-organ system failure.
• Active hemorrhage.
• Head trauma.
• Intra-abdominal hypertension (> 15 mmHg).
• Declined to consent.

Both participants and outcome assessors will be blinded to the groups