Local anesthesia

Surface and infiltration anesthesia

The simplest type of local anesthesia is terminal (application or irrigation). It is widely used in ophthalmology, urology, and otorhinolaryngology. High-concentration solutions are used for this purpose: cocaine (1–10%), tetracaine (0.25–3%), lidocaine (1–2%), or procaine (5–10%). For example, during bronchography, it is safer to use 5–10% procaine. It is important to remember that mucous membranes rapidly absorb drugs, so the risk of toxic complications here is extremely high.

Infiltration anesthesia involves the saturation of tissues with an anesthetic (usually 0.25–0.5% procaine) directly in the surgical area. Procaine is convenient because it does not accumulate and is rapidly degraded in the liver and blood, allowing large volumes to be administered.

The technique is performed layer by layer from the outside in:

1. Intradermally with a fine needle along the line of the future incision, a wheal is created — a "lemon peel".
2. During the surgery, tissues are infiltrated layer by layer.
3. The lateral sides of the surgical wound must be blocked to intercept the approaching nerve trunks.

A variation of the method is fascial compartment anesthesia, where the entire cross-section of a limb is blocked (often used in amputations).

A. V. Vishnevsky method

This is a unique domestic technique of tight layer-by-layer creeping infiltrate. It is based on the administration of a 0.25% procaine solution under pressure into fascial and aponeurotic compartments.

The solution mechanically spreads through natural anatomical spaces, contacting nerves and receptors. During the procedure, the surgeon works alternately with the syringe and the scalpel.

The main advantage of the method is hydraulic tissue dissection. The fluid injected under pressure pushes anatomical structures apart by itself, which tremendously facilitates the isolation of organs or adhesions. Despite the huge consumption of anesthetic (up to 1.5–3 liters per surgery), intoxication does not occur: a significant portion of the fluid simply flows out after the tissue is incised.

Conduction (regional) anesthesia

With this method, the anesthetic is injected proximal to the surgical site into the zone where sensory nerve conduction is interrupted. The target area for the solution is the perineural adipose tissue.

Safety guidelines: since large nerve trunks are often accompanied by major blood vessels, the needle is advanced toward the nerve strictly without a syringe to avoid accidentally injecting the drug into the bloodstream. A sure sign that the needle has reached the nerve is the patient experiencing a sharp, shooting pain.

The onset speed of the effect depends on precision:

• With endoneural administration (directly into the nerve, 1–2% solution), the block sets in within 3–5 minutes.
• With perineural administration (around the nerve) — within 10–15 minutes.

The method is indispensable in dentistry (tooth extraction), hand surgery (Lukashevich–Oberst finger anesthesia), rib fractures (intercostal block), and as an adjunct in thoracic surgeries (blockade of the vagus nerve, splanchnic nerves, or sympathetic trunk).

Intraosseous and intravascular limb anesthesia

Intraosseous anesthesia is used for interventions on the limbs. First, the limb is elevated to ensure blood outflow, then a tourniquet is applied proximal to the surgical site (until the pulse completely disappears). Using a shortened Bier needle with a stylet, the cortical layer of the bone is punctured, penetrating 1–1.5 cm into the spongy substance. After that, the needle is slightly pulled back and procaine (0.25–2%) is injected. For example, to anesthetize the foot, the tourniquet is applied to the lower leg, and the needle is inserted into the calcaneus, injecting 50–60 ml of the solution.

Venous and arterial anesthesia is used for osteomyelitis, dislocations, or injuries.

1. The limb is exsanguinated with an elastic bandage.
2. Two tourniquets are applied: one at the upper and one at the lower boundary of the operative field.
3. The elastic bandage is removed.
4. In this space isolated between the two tourniquets, a vein or artery is exposed, and 0.5% procaine is injected into it (50 ml for the hand, 80–100 ml for the foot). The effect develops in 10–15 minutes.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Methods of controlling body functions in modern anesthesiology (hypothermia, artificial hibernation, controlled hypotension)
• Topographic anatomy and technique of Lukashevich–Oberst anesthesia
• Fascial compartment anesthesia: indications and anatomical rationale
• Spinal and epidural anesthesia: similarities and differences
• Intercostal neuralgia and technique of intercostal block

Other topics in the section "General Operative Surgery. Equipment, Instruments. Anesthesia"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.