7 topics with concise reviews: definitions, key facts, and class questions.
This section is dedicated to one of the fundamental topics in general surgery—infusion therapy and blood-substituting fluids. Choosing the right solution often determines the treatment outcome, whether it is stabilizing blood pressure in shock or providing metabolic support to a depleted patient.
Here, the classification and mechanisms of action of hemodynamic blood substitutes and basic electrolyte solutions are examined in detail. Special attention is paid to the principles of parenteral nutrition and the agents used for it. The practical part of the chapter describes step-by-step the technique of transfusion of blood substitutes, as well as the recognition and management of complications of infusion therapy.
What is most commonly asked in classes? Instructors typically expect a clear understanding of the difference between colloids and crystalloids, indications for their use, and rules for calculating infusion volume. Be prepared to answer questions on transfusion safety techniques and emergency response algorithms for complications (e.g., anaphylactic shock or acute volume overload).
No. A blood-substituting fluid replaces only a specific function of blood (e.g., volume or nutrition). For a comprehensive effect, it is necessary to administer mixtures or use products sequentially.
Why should medium-molecular-weight dextran not be administered during ongoing bleeding?
The drug is a potent hemodiluent. It rapidly draws fluid into the vessels and raises blood pressure, which can dislodge a blood clot and increase internal bleeding.
Why is regular dextrose not always suitable in diabetes mellitus or shock?
Glucose assimilation is impaired in these conditions. In such cases, fructose and sorbitol become the drugs of choice, as their hepatic metabolism does not depend on insulin production.
Why cannot saline solutions be used as the sole treatment in severe shock?
Due to their low molecular weight, they very quickly leave the vascular bed and pass into the interstitium. Therefore, to maintain vascular pressure, they must be combined with colloidal solutions or blood products.
Why are blood substitutes, rather than donor blood, used initially in shock and acute blood loss?
Whole blood transfusion requires 20–30 minutes for blood typing and compatibility testing, which is unacceptable in emergency shock. Furthermore, in shock, microcirculation is impaired, blood viscosity is increased, and there is a risk of microthrombosis—whole blood transfusion will only exacerbate these disorders, whereas dextrans will rapidly restore BCC.
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