**4.1. Composition of resuscitation fluids**

There is no ideal fluid used for resuscitation of shock patients. At least the fluid used has a similar chemical composition to the plasma and can eliminate shock signals without adding fluid extravasation to the interstitial cavity. Currently, the fluid used is colloidal fluid and crystalloid fluid [19].

Crystalloids are more recommended as first-line therapy to restore hemodynamics in patients with shock [20]. Crystalloids are made up of ions with various tonicities and can be freely distributed. The saline liquor is more isotonic to the plasma but has a higher concentration of chloride and is more at risk of hyperchloremic metabolic acidosis and increases the risk of kidney failure [18]. The fluid such as the ringger is more hypotonic than the extracellular fluid and is also associated with hyperchloremia but has a pH that is more similar to plasma pH [19–21].

Colloid is a fluid containing macromolecules with the usefulness of increasing the oncotic pressure and maintaining the amount of fluid that already exists in the vascular and even absorb fluid in extracellular to intracellular [5, 8]. Colloids are classified according to natural (albumin) and artificial (gelatin, dextran, and hydroxyethyl starch (HES)) [7]. In contrast to the crystalloid fluid distributed among compartments, the colloidal fluid will remain in the vascular cavity for more than 16 h [8].

Gelatins, a polypeptide derived from collagen bovine, have the same extravascular extension as albumin but are associated with the risk of renal damage. HES is a high-molecular weight synthetic polymer and is associated with high incidence of renal failure and coagulation disease [8].

A study comparing the effects of crystalloid with HES found that the use of HES could reduce the amount of fluid intake (30% less than crystalloid), increasing CVP faster, decreasing the incidence of shock but increasing chances for RRT and increasing mortality [22].
