Fluid therapy is an essential component of the management of patients with acute circulatory failure. Nevertheless, unnecessary administration of fluids in non-responders is harmful. Thus, the concept of fluid responsiveness has been suggested to guide fluid administration in critically ill patients to avoid either over or under-transfusion. The aim of this work is to investigate the ability of peripheral perfusion index to predict the hemodynamic response to mini-fluid challenge in patients with septic shock .

The concept of fluid responsiveness has been suggested to guide fluid administration in critically ill patients to avoid either over or under-transfusion.

Several methods have been suggested to detect fluid responsiveness. Mini fluid challenge with concomitant monitoring of stroke volume is one of the most robust methods for pre-load challenge.

The main foreshortening of mini fluid challenge method is the need for a real-time cardiac output monitor, to track the instantaneous change of stroke vole with changing body position. Finding a surrogate to cardiac output to trace the effect of mini fluid challenge would make the test more applicable without the need for advanced hemodynamic monitors.

There is a growing interest in the use of perfusion indices in assessment of fluid responsiveness. Perfusion indices are measures for adequacy of oxygen delivery in peripheral tissues; thus, they were hypothesized to be possible surrogates of cardiac output. Peripheral perfusion index represents "the ratio between the pulsatile and non-pulsatile component of the light reaching the pulse oximeter" . Peripheral perfusion index has been considered as a numerical non-invasive measure for peripheral perfusion. PPI has the advantage over other perfusion indices that it a non-invasive, user-friendly monitor.

The aim of this work is to investigate the ability of peripheral perfusion index to predict the hemodynamic response to mini-fluid challenge in patients with septic shock.

Mini-fluid challenge test will be performed by infusion of 200 mL Lactated Ringer's solution over 1 minute. Velocity time integral will be monitored using Transthoracic echocardiography at the left ventricular outflow tract at the apical five-chamber view. Cardiac output will be calculated, and the patient will be considered fluid-responder if cardiac output increased by 10% after fluid challenge.

Inclusion Criteria:

• Septic shock patients

Exclusion Criteria:

• Evident blood loss
• Peripheral vascular disorders
• Upper limb injury or burns

The study will include septic shock patients undergoing fluid resuscitation. Patients will be enrolled during evaluation of fluid responsiveness.