This paper considers nursing in the critical care area and more specifically as the main topic, the use of volemic replacement fluids in the broad pathology of shock, applicable by the EMS. Shock is an acute, life-threatening pathological condition of the patient leading to cell and tissue hypoxia resulting in cell death and dysfunction of vital organs. The mechanism leading to such suffering may be decreased intake, increased consumption, improper oxygen utilization, or a combination of these three circumstances. The main cause turns out to be circulatory failure, clinically better known as hypotension. The literature demonstrates how important and critical fluid infusion appears to be in this type of patient. The following review of the bibliography aims to identify and collect the various scientific evidences by evaluating the best solution to infuse, the right dosage, and the target pressor to achieve depending on the type of shock: hypovolemic, distributive, cardiogenic, obstructive. The identification of the best infusible solution is one of the key points of acting in these scenarios as well as the target pressor set (permissive hypotension); it has emerged from the consultations that in the out-of-hospital setting colloids are not recommended because of the consequences compared to crystalloids. In the last decade, special attention is paid to permissive hypotension, that is, the target pressor to be achieved depending on the type of shock, showing how inappropriate fluid administration, in terms of quantity and type of substance to be used, is counterproductive to outcome. The literature shows how an abundant infusion of fluids can alter coagulation or sometimes induce the patient to ARDS; there is also evidence of how in hypovolemic shock the infusion of saline is not recommended, preferring a balanced solution, while in myelic shock saline is preferred.