increase mortality rate in cases that made it difficult to follow up

Introduction Aim of the work Patients and methods Type of study Exclusion criteria Statistical analysis Research ethics Reference

Septic shock is a serious infectious condition characterized by low blood pressure and multiple organ damage. One of the traditional recommendations is to administer intravenous fluids as the first step to improve blood pressure(1).

However, studies have shown that not every patient benefits from aggressive intravenous hydration (2).

Previous studies have shown that certain parameters may correlate with volume status and others may not to correlate with patient volume status.

Hemodynamic parameters, such as stroke volume variation (SVV) and pleth variability index (PVI) may better predict fluid responsiveness. However, assessments of these parameters require invasive procedures and special monitoring equipment, which limits their clinical application (4).

Echocardiography has been widely adopted to diagnose and monitor cardiac dysfunction leading to hemodynamic instability, and shock pathophysiology in general.

However, the echocardiographic information on macro-hemodynamics is partial, especially as being indirect as concerns vascular tone, and not allowing any inference on end-organ perfusion (5).

Recently, ultrasonography for estimating volume status has been widely recommended because of its non-invasive nature, ease of acquisition, and reproducibility of measurements.

The inferior vena cava (IVC) is a compliant vessel whose size and shape vary with changes in CVP and intravascular volume. Therefore, sonographic measurement of the IVC represents an effective and non-invasive method of estimating CVP.

Respiratory variation in the IVC diameter was used as a guide for fluid therapy in septic shock in both spontaneous breathing and mechanically ventilated patients.

Moreover, the assessment of visceral end-organ perfusion by ultrasound, may offer insights into this facet of shock pathophysiology (5).

Among these ultrasound modalities, corrected flow time (FTc) measured in the carotid artery is a new approach for predicting fluid responsiveness that has shown promising results.

Therefore, although it is a dynamic index, it may be able to adequately evaluate volume status in spontaneously and mechanically breathing patients.

Aim of the work: 1- To evaluate whether carotid FTc as determined by Doppler ultrasound could be a predictor of fluid responsiveness in spontaneously breathing and mechanically ventilated patients.

2- To evaluate the predictive ability of ΔVpeak for fluid responsiveness in spontaneously breathing patients.

3- To detect changes of regional splanchnic hemodynamics by color Doppler resistive index, and its improvement after fluid administration.

4- To evaluate the predictive ability of IVC collapsibility and distensibility indices for fluid responsiveness in septic shock patients.

5- To compare between the predictive ability of the measured Ultrasonographic parameters and the CVP changes in response to intravenous fluid therapy in both spontaneously breathing and mechanically ventilated septic shock patients.

Inclusion Criteria:

1. adult patients age≥18-year-old; written consent will be obtained.
2. septic shocked patients show signs of acute circulatory failure at any time within the first 72 hours.

Exclusion Criteria:

1. Patients confirmed to have cardiogenic shock.
2. History of heart failure or patient known to have moderate to severe valvular heart disease, congenital heart disease.
3. The presence of carotid artery stenosis >50% , newly detected common carotid stenosis >50% during the study period.
4. Non-sinus rhythm.
5. Moderate to severe anemia.
6. Markedly increased intraabdominal pressure as abdominal compartment syndrome, pregnancy.
7. Medically diseased kidneys, ureteric obstruction peri-nephric collection.

After recording these data, the patients will be administered a fluid challenge of a 500 mL fluid bolus of 0.9% normal saline over 10 min and then same haemodynamic parameters will be measured again.

Fluid responsiveness is an increase of stroke volume of 10-15% by echocardiography, after the patient receives 500 ml of crystalloid over 10 min.