Anatomical rationale of the method
The technique, developed by A.V. Vishnevsky, is based on a deep understanding of the structure of the fascial formations of the human body. Fasciae form closed anatomical sheaths for muscles and organs.
During the procedure, the local anesthetic solution is purposefully injected into these sheaths under high hydrostatic pressure. This is how the method of creeping infiltrate is implemented: tight accumulations of fluid do not remain at the injection site, but begin to spread (literally "crawl") along the natural boundaries of the sheaths. Gradually, these infiltrates merge with one another, penetrating into deep tissues and thoroughly bathing the nerve trunks and nerve endings passing there.
Principle of alternation and safety
To successfully perform anesthesia, a strict principle of instrument alternation is used. As layers are sequentially traversed, the surgeon alternately uses a syringe to inject the solution and a scalpel to dissect the tissues.
There is an inviolable rule: tight infiltration must be performed exclusively before opening the sheath. If this principle is violated and the fascia is dissected first, the solution will simply leak out into the wound. As a result, creating a tight infiltrate becomes impossible, leading to a lack of adequate anesthesia.
Low concentrations are used as the working solution — 0.25% procaine or lidocaine. Epinephrine (adrenaline) is added as an adjuvant for vasoconstriction at a rate of 3 drops of solution (1:1000) per every 100 ml of anesthetic. Despite the fact that a large volume of fluid (up to 800–1000 ml) may be used during surgery, systemic intoxication does not occur. This is explained by the extremely low concentration of the drug and the fact that a significant portion of the solution safely leaks out into the wound during subsequent dissection of the fascial layers.
Hydraulic tissue preparation
In addition to blocking pain impulses, tight fluid injection performs a crucial surgical function — hydraulic tissue preparation. The solution injected under pressure mechanically separates anatomical layers with a fluid cushion.
Advantages of this effect:
- Blood vessels and nerve trunks begin to be easily identified within the semi-transparent infiltrate.
- Reliable prevention of accidental damage to important anatomical structures by the scalpel is ensured.
- Compression of small capillaries by the tight infiltrate greatly facilitates the surgeon's hemostasis in the surgical wound.
Example: anesthesia in neck surgeries
A classic example of the method's application is the layer-by-layer tissue impregnation during thyroid surgeries (e.g., during its resection). The surgeon requires two syringes of different volumes (2 and 5 ml, or 5 and 10 ml).
Steps of the procedure:
- Skin anesthesia: Performed intradermally with a fine needle along the entire incision line using the "lemon peel" technique. Important nuance: each subsequent injection is made precisely at the edge of the wheal formed by the previous injection.
- Subcutaneous tissue: Administration of procaine is carried out deep into the already infiltrated skin. A reliable criterion for the adequacy of anesthesia at this stage is the visual elevation of the entire area of the future incision in the form of a characteristic ridge.
- Injection beneath the neck muscles: After dissection of the skin, subcutaneous tissue, and platysma (platysma), the solution is injected along the midline to infiltrate the muscles. Then the anesthetic is injected directly beneath the muscles (the needle is directed upward, downward, and to the sides).
- Fascial spread: Injection beneath the muscles causes the anesthetic to independently spread under the middle layer of the cervical fascia. The resulting "creeping infiltrate" in the form of a sheath encompasses the thyroid gland from all sides.
- Additional infiltration: Carried out after the dissection of muscles and careful dislocation of the gland lobe into the wound. The surgeon target-infiltrates tissues at the upper and lower poles of the thyroid gland, as well as along its entire posterior surface.
Briefly: answers to topical questions
What are the absolute contraindications for infiltration anesthesia?
The sources indicate the following contraindications for infiltration anesthesia:
- Intolerance — increased individual sensitivity to anesthetic agents.
- Age — children under 10 years old.
- Psychoneurological status — presence of mental disorders and increased nervous excitability.
- Tissue condition — presence of inflammatory or cicatricial changes preventing the execution of infiltration anesthesia; administration of procaine into a focus of purulent inflammation is strictly not recommended.
- Internal hemorrhage — ongoing bleeding requiring emergency surgery to stop it.
In life-saving surgeries, contraindications become relative.
What systemic complications can develop in case of accidental intravascular administration of a local anesthetic?
Accidental intravascular administration of a local anesthetic can cause systemic reactions: moderately severe hemodynamic and cardiac rhythm disturbances, headache, and nausea. For mepivacaine, central nervous system reactions are also described — euphoria, depression, speech, swallowing, and visual disturbances, convulsions, respiratory depression, coma — as well as cardiovascular reactions — bradycardia and arterial hypotension.
What is the mechanism of blocking the pain impulse at the cellular level upon administration of procaine or lidocaine?
At the cellular level, the mechanism of blocking the pain impulse upon administration of procaine or lidocaine consists of blocking sodium channels in the membranes of nerve fibers. Anesthetics bind to sodium channels in certain conformations. The effectiveness of the blockade depends on the frequency of impulse transmission: the more frequently impulses pass along the nerve, the more effectively the block develops. Since local anesthetics are weak bases, tissue pH is a critical factor for their penetration through the membrane. In an acidic environment, drugs become ionized, and their ability to penetrate inside the fiber decreases.
The "syringe — scalpel" rule: first, tightly fill the entire sheath (syringe), and only then open it (scalpel). If done the other way around, the solution will leak into the wound and the anesthesia will not work.
Class and exam questions
Why doesn't overdose occur when administering up to 1000 ml of anesthetic?
Safety is ensured by two factors: using a very weak concentration of the drug (0.25%) and the fact that a significant volume of fluid mechanically flows out into the surgical wound as the fascial sheaths are opened.
What is the "lemon peel" method?
This is a method of intradermal administration of an anesthetic at the first stage of surgery. Multiple intradermal wheals are created with a fine needle along the incision line, with each new injection made at the edge of the previous one, forming a continuous anesthetized zone.
Why is epinephrine added to the anesthetic solution?
Epinephrine (adrenaline) acts as an adjuvant that causes local vasoconstriction. This reduces tissue bleeding during the incision and slows down the absorption of the anesthetic into the systemic circulation.
What else to study on this topic
- Structure and topography of the fascial sheaths of the neck
- Mechanism of fluid spread under the middle layer of the cervical fascia
- Pharmacodynamics of 0.25% procaine and lidocaine
- Technique of safe dislocation of the thyroid gland lobe
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