In general, for all patients requiring resuscitation, fluid replenishment can be divided into discrete phases. Vincent and De Baker[14] divided resuscitative methods into four stages, referring to the purposes of each stage of therapy, as follows;

• Rescue or salvage
• Optimization 
• Stabilization 
• De-escalation

The first is the 'rescue phase' during which the resuscitation is aimed at re-establishing the minimum perfusion necessary to sustain life in the setting of a life-threatening hypovolemic shock. Next, the 'optimization phase' is aimed at preventing decompensation after the patient has been rescued from life-threatening shock. This helps ensure an optimal cardiac output for appropriate tissue perfusion. The 'stabilization phase' aims at maintaining a patient's normal physiologic systolic and mean arterial pressures. Then, 'de-escalation' aims at slowing down and removing fluid administration in order to evaluate a patient's independent stability following supportive therapy and fluids. Permissive hypotension has generally been used only in the initial rescue and optimization phases of recovery. 

Different guidelines can be applied when determining what initial infusion volume and with which rate to begin before resuscitation. There have been animal models attempting to determine the most appropriate method in which hypotensive resuscitation could be standardized in humans.[15][16] Research favors resuscitation at a rate of 60 mL/kg/h to 80 mL/kg/h to maintain systolic pressures of 80 mmHg to 90 mmHg or a MAP of 40 mmHg to 60 mmHg.[17] However, there lacks standardized, conclusive data corroborating a numerical cutoff in pressure or a discrete algorithmic approach to the rate and method of pressure stabilization. Many sources are in agreement that permissive hypotension can be achieved in many patients who have either a MAP of around the target number of 50 mmHg or systolic pressure around 80 mmHg to 90 mmHg.[1][2][18][19][20] Fluid infusions around 100 mL to 200 mL at a time, while evaluating the response of the periodic infusions using the mean arterial pressure or systolic blood pressures can be applied to ensure a patient is in a permissible pressure range.[11] 

The method of injury may also play a role in resuscitative efforts. It has been noted that different forms of injury require different systolic blood pressure control. Penetrating traumas may require a systolic blood pressure ranging from 60 mmHg to 70 mmHg. Patients with brain injury may require resuscitation methods that manage systolic pressures ranging between 80 mmHg to 90 mmHg. Finally, those with both traumatic brain injury blunt force trauma should be managed in non-hypotensive conditions with systolic blood pressures ranging between 100 mmHg to 110 mmHg based on age.[21] The overall management of systolic pressures should ultimately be based on the clinical improvement of the patient pursuant to the initial resuscitation methods employed. 

The use of crystalloid versus colloid solutions in initial resuscitation has been debated. Evidence supporting the initial use of crystalloid may have either a positive or no effect on promoting coagulation during the initial resuscitation of a patient undergoing a hypovolemic hemorrhagic bleed.[22][23][24] Reports show that early use of colloid solutions may have either a positive, neutral, or negative effect on early coagulation.[25][26][27] It can be noted that the use of crystalloid 0.9% saline to allow for permissive hypotension has shown to have some pro-coagulatory effects when used in moderation.[28] Only a few solutions should not be used or may be used with great caution during resuscitation. The use of colloid solutions of dextrans or hydroxyethyl starch could hamper coagulation when 1.5 or more liters are administered during resuscitation efforts.[29] 

In addition, serial laboratory tests should be obtained in order to evaluate the degree of coagulopathy and the degree of anemia. Mild to moderate hypovolemic episodes may not require blood products, whereas patients with severe blood loss and rapid decompensation may require the early administration of such products.[30] A hemoglobin level of below 7 g/dL should warrant the transfusion of packed red blood cells. Generally, a 1:1:1 ratio of units of plasma, packed red blood cells, and platelets are used to prevent early coagulopathy and address anemia during early resuscitation.[30] Prothrombin, partial thromboplastin time, bleeding time, and the international normalized ratio should be reviewed in order to assess the adequacy of the transfusion products administered.

After the initial rescue and optimization of resuscitation, hydration can then be managed with urine output checks to evaluate appropriate maintenance fluids. Physicians should also take note of the physical markers of the patient's hydration status. Physicians should check for capillary refill and peripheral pulses, in conjunction with monitoring both the patient's heart rate and blood pressure. Although such measures are not as accurate as serial re-checks in urine output, quick physical exams offer a quick measure to gauge fluid status. 

Timing plays an important role in the initial stabilization of a patient’s vital signs. Prehospital (PH) administration of fluids in those patients with major hemorrhagic shock has been shown to be an effective strategy in stabilizing patients before intra-operative procedures and in helping to reduce mortality.[1][31][32] In general, the prehospital administration of intravenous fluid is associated with increased survival in trauma patients. However, the benefits of prehospital fluid administration may not be applicable to all patients with hemorrhage loss. Prehospital fluid crystalloid administration more than 500 mL in patients without PH hypotension has been shown to have worse outcomes.[32] A goal-directed resuscitation based on the presence or absence of PH hypotension should be adopted. In those with severe, life-threatening hemorrhage. Such practice allows early venous access to permit the administration of appropriate fluid administration, and any other necessary resuscitation agents that may be acutely administered in the hospital setting.[33][34]

Employing the practice of hypotensive resuscitation prevents a compensatory loss of blood by mitigating a vasodilatory effect and by preventing the over-dilution of the coagulation cascade factors, decreasing the need for administration of other blood products such as fresh frozen plasma to preserve clotting function. With caution, permissive hypotension can be a much more cost-effective method of resuscitation. As this method of fluid resuscitation is more thoroughly elaborated in the future, it is already apparent that such a strategy can positively improve patient recovery and expedite discharge while reducing post-hospitalization complications.

The management of permissive hypotension can be a complex endeavor. The procedure allows the medical team to maintain those body fluid pressures appropriate for organ function in the setting of a hemorrhagic shock, due to trauma. Proper coordination and communication must be carefully choreographed within the medical team, in order to adequately evaluate any variable that may alter the management protocol. It is of great importance that first responders quickly garner information regarding the mechanism of injury, in order to better determine the amount and rate of fluid administration.[1][2] In addition, the severity of the volume loss must be assessed in order not only to evaluate the amount of fluids needed; but also to estimate the need for prehospital fluid administration.[1][31][32][35] A patient's pre-existing conditions must then be assessed in order to determine if there are any contraindications to management before fluids are administered. 

Based upon retrospective data collection studies in the trauma setting, reports have suggested that permissive hypotension can generally be achieved in many patients, if the mean arterial pressure is close to the target number of 50 mmHg, or if the systolic pressures are between 80 mmHg to 90 mmHg.[1][2][18][19][20] [Level 4] The fluid resuscitation strategy should depend on the mechanism of injury. Penetrating traumas may require a systolic blood pressure ranging from 60 mmHg to 70 mmHg. Patients with brain injury may require resuscitation methods with systolic pressures between 80 mmHg to 90 mmHg. Those with both traumatic brain injury and blunt trauma should be managed in non-hypotensive conditions with systolic blood pressures ranging between 100 mmHg to 110 mmHg and adjusted based on age.[21] [Level 4] Evidence-based guidelines however have yet to clearly elucidate adjustment of systolic and mean arterial pressures based on other aspects of the patient's background, such as age, weight, height, and gender. It is, therefore, of great importance that nurses and physicians closely monitor the patient's mentation and vitals once initial fluids are started. Following the initial rescue phase, blood pressure may be gradually raised and urine output may be monitored in determining the patient's establishing homeostasis.