Depending on the cause of hypovolemia (loss of blood, plasma or fluids), the patient is transfused respectively with blood, plasma (or plasma expanders Like dextran solution) or isotonic saline solutions (replacement therapy). Dextran molecules do not pass through the capillary pores. It therefore promotes osmosis of water from the interstitial to the intravascular spaces, thereby increasing the plasma volume.
In neurogenic shock, sympathomimetic drugs fulfill the physiological role of the sympathetic nervous system which is severely depressed. In anaphylactic shock, sympathomimetic drugs act as physiological antagonists to histamine which is largely responsible in the pathogenesis of the shock.
In hemorrhagic shock, the sympathetic system is already maximally active, and therefore, sympathomimetic drugs have limited value. The sympathomimetic drug of choice is dopamine because it produces renal vasodilatation and at the same time, produces vasoconstriction elsewhere in the body. It also has a positive inotropic effect on the heart.
When the pressure falls too low especially hemorrhagic and neurogenic shock, placing the patient with the head 30 cm lower than the feet (the Trendelenberg position) helps in promoting venous return and thereby increasing cardiac output.
Oxygen therapy may be beneficial in some instances. However, the response is not marked because the hypoxia of shock is of the anemic and/or stagnant type. Oxygen is beneficial mostly in hypoxic hypoxia.
Glucocorticoids are frequently given to patients in severe shock for several reasons. They increase the strength of the heart in the late stages of shock. They stabilize the lysosomal membranes and prevent release of lysosomal enzymes into the cytoplasm of the cells, thus preventing deterioration from this source. They also aid in the metabolism of glucose by the severely damaged cells.