Substitutes plasma, and other blood components
Substitutes plasma, and other blood components intended for volume replacement, saving its state of aggregation, the substitution of certain functions of the blood (leukocyte weight, preparations of plasma, thrombocyte concentrate), maintain water and electrolyte balance, oncotic pressure of the blood, correction of acid-base balance. Drugs in this group are used as detoksiciruuschee funds (see FUNDS DETOXIFYING, INCLUDING ANTIDOTES), having the ability to bind various toxic substances and hasten their excretion from the body and also to reduce the aggregation of blood corpuscles in capillaries.
The actual plasma substitutes perform only one function — maintaining BCC. They must meet certain requirements:
- not pass through gistogematicalkie barriers and do not penetrate from vessels in the tissue;
- maintain sufficient and stable osmotic pressure;
- have a minimum and prolonged metabolism, accompanied by the formation of neutral products or metabolites involved in a conventional exchange reaction, or intense filtered urine;
- not to possess antigenic properties and pyrogenicity.
Substitutes of plasma are the plasma of donor blood (natural plazmozamenitel), dextrans, and salts of electrolytes (solutions of crystalloids).
Plasma contains all the components of the liquid portion of human blood, but require special methods of storage and care for the donor organism to antigenic relationship.
The dextran — solutions of the polysaccharides from cultures of several bacteria, their antigenic properties. The dextran may have varying degrees of polymerization and, consequently, different molecular weight; these can be obtained by plasma-substituting solutions for various applications. Solutions containing dextran with a high molecular weight, are used primarily as a means of hemodynamic, but with a lower molecular weight as a corrector of rheological properties of blood. When injected into the blood dextrans increase the oncotic pressure and increase the displacement of fluid from the tissues into the bloodstream. They increase the diuresis and thus the detoxification processes. Because in the body the partial hydrolysis of the dextrans are excreted mainly by the kidneys (renal failure is a limitation to their use).
Solutions of crystalloids (ringer's, ringer-acetate, Hartman) contain various combinations of salts (sodium chloride, sodium bicarbonate, sodium acetate, calcium chloride, potassium chloride), and glucose in concentrations close to physiological. The salt solutions are aimed at correcting dehydration, electrolyte content, concentration of hydrogen ions, and thus KHS (see REGULATORS WATER-ELECTROLYTE BALANCE AND KHS). In the absence of a significant loss of electrolytes to correct hypovolaemia impose 5% (isotonic) dextrose solution.
A number of pathological conditions (obstruction of the esophagus, the violation of suction from the intestines, severe intoxication, etc.), operations on the stomach and intestines necessitate parenteral administration of nutrients, primarily proteins. Plasma-substituting agents (albumin 20-25%, dextrose 20-50% solution) can be used in such situations as preparations for parenteral nutrition (see TOOLS FOR ENTERAL AND PARENTERAL NUTRITION). Proteins (see PROTEINS AND AMINO acids) provide the substrate for many enzyme processes, the dextrose is an energy exchange. Note, however, that parenteral administration of proteins may cause sensitization with the development of anaphylactic reactions with repeated injections.
Substitutes plasma, and other blood components used mainly for the treatment and prevention of shock different origins, AD normalization and improvement gemodinamicakih indicators. They are used in blood loss, burns, and other conditions involving dehydration and hypovolemia, for the prevention of postoperative and post-traumatic embolism, intoxication of different Genesis. Drugs dextrose (20-40% solution) are also used for the correction of hypoglycemic States. To parenteral nutrition these drugs are used for current consumption and the body regenerative processes in the cells, when food naturally for a number of reasons impossible.