Indications and choice of administration route
Infusion therapy is used to correct various life-threatening conditions. Hemodynamic blood substitutes (e.g., medium molecular weight dextrans 30,000–40,000) are used for shock of various origins, acute blood loss, purulent intoxication, and microcirculation disorders. Electrolyte solutions, trometamol, and sodium bicarbonate are used to correct water-electrolyte balance and acidosis.
The primary route of administration is intravenous. Other accesses are used in specific situations:
- Subcutaneous: used as a rare exception due to low efficiency. In shock, it does not provide a rapid increase in circulating blood volume (CBV), and proteins are assimilated extremely poorly. A single dose is limited to 500 ml; preliminary tissue infiltration with 0.5% procaine solution is required.
- Administration via a tube (into the intestine): indicated for protein hydrolysates when the patient cannot be fed enterally after gastric or esophageal surgery.
Assessment of solution suitability and equipment
Before assembling the infusion set, the physician must perform a macroscopic inspection of the drug. Administration is prohibited in case of any deviations from the norm. The following are evaluated:
- Expiration date and storage conditions: absence of signs of freezing or overheating.
- Hermetic seal: integrity of the closure, absence of microcracks on the glass vial.
- Visual properties: absolute transparency, absence of film, flakes, and atypical sediment.
For a classic transfusion, it is necessary to prepare a sterile tray, a disposable drip set, a venipuncture needle, a tourniquet, gauze balls, and alcohol. The rate of drop administration is regulated by clamps (e.g., Mohr clamps).
Performing a biological test
A biological test is strictly mandatory before the transfusion of protein hydrolysates, fat emulsions, and high-molecular-weight dextran (av. mol. weight 50,000–70,000).
- Standard procedure (for protein media): the solution is administered intermittently according to the scheme "5 ml → 10 ml → 15 ml". The interval between each administration is exactly 3 minutes.
- For dextran (polyglucukin): 10 ml is administered first, a 3-minute break is taken, then another 30 ml is administered, and another 3-minute wait follows.
- Extended test (for fat emulsions): for the first 10 minutes, the drug is dripped extremely slowly — 10–20 drops/min. If there are no reactions, the rate is increased.
Criteria for a successful test include stable blood pressure, steady pulse, absence of dyspnea, hyperemia, itching, or rash.
Administration rate and monitoring
The choice of infusion rate depends on the clinical situation and the composition of the blood substitute:
- Emergency anti-shock therapy: begins with a bolus administration for rapid restoration of CBV, after which it switches to drip (60–70 drops/min).
- Detoxification and electrolyte media: the optimal rate is 40–50 drops/min.
- Protein solutions and amino acids: require a slow rate — from 20 to 40 drops/min. Forced administration (up to 100 drops/min) leads to a sharp decrease in amino nitrogen assimilation and frequent toxic reactions.
Throughout the procedure, the physician subjectively and objectively monitors the patient's condition. If tachycardia, anxiety, headache, or tachypnea occurs, the infusion must be immediately slowed down or stopped. Upon completion of the transfusion, the type of drug, its volume, and the presence of reactions must be recorded in the medical history and transfusion log.
Briefly: answers to topical questions
What are the groups of blood substitutes according to their functional purpose and mechanism of action?
According to their functional purpose and mechanism of action, several main groups of blood substitutes are distinguished.
- Hemodynamic (anti-shock) blood substitutes — used for various types of shock and acute blood loss; the goal in emergency situations is the rapid restoration of circulating blood volume.
- Detoxification blood substitutes — used for toxicosis.
- Parenteral nutrition preparations — prescribed when enteral nutrition is impossible or restricted, including in hypoproteinemia and states with significant protein breakdown.
- Agents for the correction of water-electrolyte and acid-base balance — used for dehydration, electrolyte imbalance, and acidosis.
- Oxygen carriers — this group includes perftoran and pernfukal.
Which specific drugs belong to the group of hemodynamic (anti-shock) blood substitutes?
The group of hemodynamic (anti-shock) blood substitutes includes:
- Dextrans:
- dextran with an average molecular weight of 50,000–70,000;
- dextran with an average molecular weight of 30,000–40,000.
- Gelatin preparations.
- Preparations based on hydroxyethyl starch — hydroxyethyl starch.
These drugs are used in anti-shock therapy; dextrans are indicated as drugs of choice for shock, acute blood loss, and acute vascular insufficiency. Dextran with an average molecular weight of 30,000–40,000 is also used for microcirculation disorders, vascular surgeries, purulent intoxication, and traumatic shock.
The "5-10-15" rule for a standard biological test of protein solutions: sequentially administer 5 ml, then 10 ml, then 15 ml with a mandatory 3-minute pause after each dose.
Class and exam questions
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.
What are the absolute contraindications for any blood substitutes?
General restrictions include acute liver failure, cardiac decompensation, as well as diagnosed thrombosis and embolism. Unfavorable allergological and transfusiological history must always be taken into account.
Is it permissible to transfuse protein blood substitutes to patients with nephritic syndrome?
Acute glomerulonephritis is a specific contraindication for the administration of protein preparations. Chronic nephritis is considered a relative contraindication for transfusion therapy in general.
What else to study on this topic
- Mechanism of action and differences of dextrans with various molecular weights
- Specific contraindications for protein hydrolysates
- Parenteral nutrition in purulent processes and extensive burns
- Preparations for the correction of water-electrolyte and acid-base balance
- Complications of transfusion therapy and algorithms for their management
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Other topics of "CHAPTER 7. BLOOD SUBSTITUTES"
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