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Besides crystalloids, colloids are used for the treatment of hypovolemia and shock. They are high-molecular-weight proteins of bovine origin with properties of more rapid replacement of circulating blood volume. Iso-oncotic character provides the volume effect (approximately equal to 100%) close to the volume intravenously infused with the duration of action for 2-4 hours. Gelatin solutions are excreted with urine and feces in unchanged form without prolonged fixation in organism. Even in case of acute renal failure, gelatin peptides do not accumulate due to increased activity of proteolytic enzymes; therefore, they are the first-choice colloids. Gelatin solutions do not change coagulation as other colloids; just they may cause hemodilution as crystalloids do, so they are safe in case of hemorrhage and thrombocytopenia. There is a decreased risk of bleeding when gelatin solutions are used in surgery as compared with other colloids; in addition, they protect from hypotension due to vasodilatation in epidural or spinal analgesia. Gelatin solutions may cause compensatory hyperemia and increase of cardiac output, cardiac index, myocardial contractility, mean arterial blood pressure, and diuresis; in addition, oxygen delivery to the tissues improves. The dosage depends on clinical condition of a patient, and it is suggested to be 100-2000 mL and even more, for isovolemic hemodilution--20 mL/kg of body weight. Adverse reactions such as anaphylactoid or anaphylactic to gelatin derivates are rare and similar to other colloids.