Isotonic crystalloid solutions can sustain hemodynamic function and deliver adequate oxygenation in healthy patients who have lost as much as 30% of their total blood volume. Still, controversy remains over the use of crystalloid or colloid therapy for the initial therapy of hypovolemic shock.

Proponents of crystalloid therapy argue that both intravascular and interstitial fluid losses occur in hypovolemic shock and that these can be readily replaced with crystalloids. Another benefit of crystalloids is the decrease in blood viscosity that might enhance perfusion. A particular advantage to lactated Ringer solution is that lactate is metabolized to bicarbonate, which can help buffer the acidosis. Finally, the cost of crystalloid is much less than that of colloid. Because crystalloid leaves the intravascular space and enters the interstitial space, large quantities are needed, and some feel that these quantities lead to both pulmonary and peripheral edema, although studies have not confirmed this.

Proponents of colloid therapy argue that much less volume is needed to counteract hypovolemic shock and that early colloid therapy can prevent the complications associated with large-volume crystalloid resuscitation such as dilutional coagulopathy, hyperchloremic acidosis, and edema. Colloids maintain oncotic pressure and hold fluids in the intravascular space, which can possibly prevent pulmonary edema. If leaky alveolar-capillary membranes are seen within the lung, colloids might worsen pulmonary edema. Despite the potential benefits of colloid administration, there is a lack of quality evidence showing a decreased mortality among patients who receive colloid for hypovolemic shock.

The best resuscitative fluid to treat hemorrhagic shock is whole blood. It provides a balanced resuscitation, reversing shock and coagulopathy, by containing all components of blood: hematocrit of 38% to 50%, plasma clotting factors, fibrinogen, and 150 to 400 10³/µL platelets. A major advantage whole blood possesses over crystalloid and colloid is that it does not promote dilutional coagulopathy. From a logistical standpoint, it requires limited processing. In terms of its safety profile, administration of uncrossmatched, cold-stored, low-titer (low levels of anti-A and anti-B immunoglobulins M), type O whole blood is well tolerated, without causing hemolysis or transfusion reactions.

References

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• Griffee MJ, Deloughery TG, Thorborg PA. Coagulation management in massive bleeding. Curr Opin Anaesthesiol. 2010;23:263-268.
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• Seheult JN, Bahr M, Anto V, et al. Safety profile of uncrossmatched, cold-stored, low-titer, group O+ whole blood in civilian trauma patients. Transfusion. 2018;58:2280-2288.
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