Usual investigations [complete blood count (CBC), C reactive protein (CRP), serum procalcitonin, serum lactate, arterial blood gases (ABG), blood culture, electrocardiogram (ECG) and liver and renal function tests] will be done.

Once the diagnosis of sepsis is definite and the patient develops hypotension, all patients will undergo simultaneous measurement by (EC) using the ICON_ device and (TTE).

Electrical cardiometry (EC) measurements: by the ICON_ hemodynamic monitor (ICON Cardiotronics, Inc., La Jolla, CA 92307; Osyka Medical GmbH, Berlin, and Germany, model C3, Serial no: 1725303). Four sensors of (EC) will be applied (1st: 5 cm above the base of the neck, 2nd: on the base of the neck, 3rd: lower thorax at the level of the xiphoid and 4th: 5 cm below the 3rd electrode at the level of the anterior axillary line). The ICON continuously displays heart rate, stroke volume, and cardiac output.

Transthoracic echocardiography (TTE) measurements: will be performed by using Philips (CX50 - Extreme edition) equipped with echo probe. SV of the left ventricle will be calculated using LVOT diameter (D) just below the aortic valve from parasternal long-axis view and velocity time integral (VTI) measured in left ventricle outflow tract (LVOT) from apical 5 chamber view (by pulsed wave Doppler), respectively. The machine's built-in software uses the formula ''(πD2/4) × VTI × HR'' to calculate CO.

Management of sepsis will be done according to surviving sepsis campaign guidelines in 2016 and its update 2018.

Fluid resuscitation will be 30 mL/kg of intravenous infusion of lactated ringer to be given within the first 3 h (≈5 mL/kg/30 min) guided by fluid responsiveness (fluid responder if SV increases by > 10% after the fluid challenge). If the patient becomes fluid non-responder, vasopressor infusion (norepinephrine 0.05-0.3µg/kg/min) will start. The end of the study is when mean arterial blood pressure > 65 mmHg (either by fluid or both fluid and vasopressor).

• Electrical Cardiometry
• Transthoracic Echocardiography
• Fluid Responsiveness
• Sepsis
• Stoke Volume

• fluid responders
  fluid responder if stroke volume increases by > 10% after the fluid challenge
  Intervention: Device: Electrical Cardiometry
• fluid non responders
  fluid responder if stroke volume increases by <= 10% after the fluid challenge
  Intervention: Device: Electrical Cardiometry

Inclusion Criteria:

• Age from 19 to 65 years old.
• Clinical criteria of sepsis [acute change in sepsis-related organ failure assessment (SOFA) variables ≥ 2 points consequent to the infection which include: PaO2/FiO2 ratio < 300, Glasgow Coma Scale score < 15, mean arterial pressure (MAP) < 70 mmHg, serum creatinine >1.2 mg/dl or urine output < 0.5 ml/kg/h, serum bilirubin > 1.2 mg/dL, platelet count < 150 X 103 /µl].
• Developing hypotension (mean arterial blood pressure ≤ 65 mmHg).

Exclusion Criteria:

• Other causes of shock
• Previous cardiac disease
• Rhythm other than sinus rhythm or heart rate > 140 beats/min
• Chronic renal failure.