Lecture number 13. Local anesthesia

1. Surface anesthesia

This type of anesthesia is carried out by contact of the anesthetic substance with one or another organ, its surface. For this purpose, a 1-3% solution of cocaine, a 0,25-2% solution of dicaine, a 1-2% solution of lidocaine, a 1-5% solution of trimecaine and a 0,5-2% solution of pyromecaine solution. Most local anesthetics bind to inactivated sodium channels, preventing their activation and sodium entry into the cell during membrane depolarization, thus achieving an analgesic effect.

The technique of surface anesthesia is simple and consists in lubricating, instilling a solution or spraying it using special spray guns. The onset of action of the anesthetic is pH dependent, with low pH taking longer to take effect than at high pH. The duration of action of the anesthetic depends on the degree of its binding to proteins. This type of anesthesia is used in diagnostic manipulations and in ophthalmology, otorhinolaryngology.

2. Regional anesthesia

Regional anesthesia includes plexus, conduction, epidural, paravertebral and other types of anesthesia. Unlike general anesthesia, regional anesthesia provides adequate surgical analgesia due to peripheral blockade of pain impulses while maintaining normal vital functions. Regional anesthesia is technically difficult, and requires accurate knowledge of the anatomical and topographic location of the nerve plexus or nerve conductor, a clear orientation in permanent identification points (bone protrusions, arteries, muscles), the ability to assess tissue resistance and patient sensations. To turn off pain sensitivity, it is enough to introduce a 1% solution of trimecaine (lidocaine), and to turn off proprioceptive sensitivity and achieve muscle relaxation, you need to use more concentrated local anesthetic solutions (for example, trimecaine 2-2,5%). The restoration of sensitivity goes in the reverse order, i.e., first muscle tone and proprioceptive sensations appear, and then pain and temperature sensations.

It is important to take into account that with an increase in the concentration and amount of local anesthetic, its toxicity increases. The most widely used solutions are trimecaine 1-2%, lidocaine 1-2% and bupivocaine 0,75-0,5%. Local anesthetics block myelin-free and thin myelin fibers more easily and quickly (all vegetative, as well as conducting temperature and pain stimuli). The thick myelin fibers going to the skeletal muscles, tactile receptors and proprioceptors are highly resistant to anesthesia, since they are affected by local anesthesia in the area of ​​Ranvier's intercepts. Diffusion of the anesthetic into the lipoid part of the nerve fiber is rapid, but only until the concentration outside the nerve is higher than in the nerve itself. After this ratio changes, the anesthetic diffuses in the opposite direction from the nerve into the surrounding tissues. Weakly concentrated anesthetic solutions, administered in large volumes, spread widely, but their diffusion is negligible. Concentrated solutions introduced in small volumes have a good degree of diffusion.

The effect of anesthesia depends on the amount of anesthetic penetrating transperineurally and causing an adequate threshold block. Doubling the concentration of the injected anesthetic prolongs anesthesia by 1/3, and the introduction of a double volume - only by 3-9%.

Local anesthetics often lead to anaphylactic reactions. Trimecaine: duration of action is 1-1,5 hours, the maximum single dose is 800-1000 mg. Lidocaine (xicaine) is used in a 1-2% solution, the duration of anesthesia is up to 2,5-3 hours. Bupivocaine (marcaine) used in a 0,5-0,75% solution in a maximum single dose of 150-170 mg, duration of action 8-12 hours. For the use of long-acting anesthetics, the addition of lidocaine clearly accelerates the onset of the effect, reducing the latent period.

When conducting regional anesthesia, you need to know and follow the general rules:

1) clearly know the anatomical and topographic features of the nerve plexuses and conductors in the area of ​​the proposed anesthesia, as well as the technique of performing anesthesia;

2) choose the right local anesthetic, determine its concentration, total dose and method of delivery to the nerve plexus or conductor;

3) assess the patient's condition and find out the allergic and pharmacotherapeutic background;

4) warn the patient about the possible preservation of deep tactile and proprioceptive sensitivity during conduction and plexus anesthesia;

5) to constantly monitor the patient's hemodynamics and respiration after anesthesia;

6) before or immediately after anesthesia, perform venipuncture and take measures to prevent possible complications;

7) carry out in compliance with aseptic and antiseptic measures, and carefully remove chemically active substances (iodine, chlorhexidine, etc.) from the skin surface before puncture;

8) before the introduction of a local anesthetic, it is imperative to conduct an aspiration test to prevent the needle from entering the arterial vessel;

9) remember that the paresthesia felt by the patient during regional anesthesia is a prerequisite for the success of obtaining analgesia; its absence indicates a possible failure;

10) to facilitate the finding of the nerve conductor or plexus, it is advisable to apply electrical stimulation by applying a negative impulse to the needle, and a positive impulse (anode) to the indifferent pole of the electrode, which is fixed on the patient's skin.

3. Anesthesia of the cervical plexus (ASP)

ACS, performed on one or both sides, allows you to perform all operations on the neck, thyroid gland, brachiocephalic vessels in case of gunshot wounds, injuries and tumor diseases. The cervical plexus (Plexus cervicalis) is formed from the anterior branches of the four upper cervical nerves (C₁-FROM₄) at their exit from the intervertebral foramina. It is located on the anterior surface of the middle scalene muscle and the muscle that lifts the scapula, lateral to the transverse processes of the cervical vertebrae. The motor nerves of the cervical plexus innervate the muscles of the neck, and the sensory nerves innervate the skin of the occipital region of the head, the anterior and lateral surfaces of the neck, the subclavian region to the level of I and II ribs and the auricle. The largest nerve of the cervical plexus is the phrenic (p. prenicus), which is formed from C₃-FROM₄ and less often due to an additional branch from C₅. Most sensory nerves exit in the middle from under the posterior edge of the sternocleidomastoid muscle and diverge in the superficial layers of the neck, skin of the occipital region of the head and upper chest.

When anesthesia of the sensitive nerves of the cervical plexus along the posterior edge in the middle of the sternocleidomastoid muscle, a number of operations on the neck can be performed, but it should be remembered that anesthesia must be bilateral, since the nerves anastomose along the midline of the neck. For large operations in the deep layers of the neck (strumectomy, removal of neck tumors, laryngectomy, carotid endarterectomy, etc.), it is necessary to anesthetize the cervical plexus with an anterior approach. With lateral access, there is a risk of serious complications (introduction of an anesthetic solution into the subdural space), so it is not used.

To perform an ASS with an anterior approach, it is necessary that the patient lie on his back with a small roll under the neck. The head should lie flat, straight in the midline without turning or be slightly turned in the direction opposite to the puncture. Hands along the body, the anesthesiologist stands at the head of the puncture. Landmarks: sternocleidomastoid muscle, hyoid bone, internal carotid artery and mandibular angle.

Anesthesia technique

2 cm below the angle of the lower jaw, anterior to the sternocleidomastoid muscle, the pulsation of the internal carotid artery is determined. The horizontal branch of the hyoid bone corresponds to the level of the transverse process of vertebra C₃. The needle injection point is located at the intersection of the line, which is a continuation of the horizontal branch of the hyoid bone, with the anterior edge of the sternocleidomastoid muscle. At this point of intersection, under aseptic conditions, a “lemon peel” is formed, and an injection needle is directed through it from the outside to the inside and from front to back, advancing it medially to the sternocleidomastoid muscle and behind the internal carotid artery (in the gap between the sternocleidomastoid muscle and palpable internal carotid artery) until the patient develops paresthesia or the needle hits the transverse process of vertebra C₃. The depth of the injection does not exceed 2-5 cm. The needle is securely fixed in this position and an aspiration test is performed, determining whether the end of the needle is in the lumen of the vessel.

For anesthesia, 10-12 ml of a 2% solution of trimecaine is injected from both sides. To enhance the anesthesia of the cervical plexus, you can additionally block the superficial branches that go to the anterior surface of the neck. The place of their exit is the middle of the posterior edge of the sternocleidomastoid muscle. The needle is injected at the point of their exit under the superficial fascia of the neck. A solution of 2% trimecaine is administered in an amount of 3-5 ml cranially and caudally (fan-shaped). Adequate anesthesia occurs after 8-12 minutes and provides effective pain relief in most patients within 1,5-2 hours.

Complications

Horner's syndrome, phrenic nerve block, recurrent nerve paresis, hypotension with intravascular injection of anesthetic. Hoarseness is the main symptom of cervical plexus block. The most dangerous complication with lateral access is the development of high spinal anesthesia and the ingress of anesthetic into the cavity of the IV ventricle, the symptoms of which are paralysis of the bulbar centers, pupil dilation, lowering blood pressure, respiratory failure and muscle atony. Absolute contraindications to anesthesia of the cervical plexus are paresis of the phrenic nerve on the opposite side, damage to the nerves of the cervical plexus.

4. Anesthesia of the brachial plexus (APS)

APS allows you to perform all operations on the upper limb, shoulder joint, shoulder, forearm and hand: amputations, surgical treatment of wounds with reposition and fixation of bone fragments, operations on blood vessels and nerves, reduction of shoulder dislocation, etc. High frequency of surgical interventions on the upper limb, especially in wartime, raises the question of rational methods of anesthesia during these operations.

Topographically, there are 2 parts of the brachial plexus: supraclavicular and subclavian. Branches extend from the supraclavicular part to the deep muscles of the neck and muscles of the shoulder girdle. The subclavian part of the brachial plexus consists of three trunks covering the axillary artery from the inner, back and outer sides. Long nerves originate from the trunks, going to the free part of the upper limb, and one short nerve to the shoulder girdle. From the inner trunk depart the ulnar nerve and the lower root to the median nerve; the radial and axillary nerves depart from the posterior trunk, and the musculocutaneous nerve and the upper root of the median nerve depart from the external trunk. Therefore, anesthesia of the brachial plexus is possible in various ways using supraclavicular, axillary and subclavian approaches. Of the supraclavicular approaches, the methods of anesthesia in the interstitial space are most widely used as the most simple, reliable and having fewer complications.

Brachial plexus anesthesia by Winnie

The patient lies on his back, his head is turned in the opposite direction from the puncture site, the chin is brought to the contralateral shoulder girdle. The hand from the side of the puncture lies along the body, slightly pulled down. Landmarks: sternocleidomastoid muscle, scalenus anterior, interstitial space, external jugular vein, clavicle, cricoid cartilage.

Anesthesia technique. The skin is treated with an antiseptic solution. Behind the sternocleidomastoid muscle, which clearly contours with a slight rise of the head, at the level of the cricoid cartilage, the fingertips of the left hand are placed on the anterior scalene muscle. With further displacement of the fingers laterally by 0,5-1,5 cm between the anterior and middle scalene muscles, the interscalene gap is probed. It becomes more distinct with a deep breath, as this tenses the scalene muscles. In the depth of the interstitial space, the transverse processes of the cervical vertebrae are palpated (feeling of firm resistance), and with increased pressure with the tip of the finger, paresthesia in the shoulder or shoulder girdle is often caused; more caudally, in the interstitial space, the subclavian artery can be palpated. The interstitial space in the upper section is crossed by the external jugular vein. The needle injection point is located in the upper part of the interstitial space at the level of the cricoid cartilage. At this point, a "lemon crust" is formed, and through it the needle is directed medially and somewhat downward, from front to back (in the dorsal direction) to the transverse process C₆ at an angle of 30° to the sagittal plane. When the needle is advanced inward at a distance of 1,5-4 cm, paresthesia occurs, and the tip of the needle rests on the transverse process of the 6th cervical vertebra. In this position, the needle is fixed or pulled up by 1-2 mm, and after the aspiration test, 30-40 ml of a 2% solution of trimecaine (lidocaine) or a 0,5-0,75% solution of bupivocaine (marcaine) is injected. During the introduction of the first milliliters of local anesthetic solution, the patient experiences a short-term pain ("electric shock"), indicating the correct location of the needle tip. In the absence of paresthesia, the position of the needle tip can be checked by introducing 0,5 ml of a 0,9% sodium chloride solution taken from the refrigerator. The appearance of a feeling of ache in the upper limb indicates the contact of a cold solution with a nerve.

Contraindications: paresis of the recurrent or phrenic nerve on the opposite side, damage to the nerves of the brachial plexus. Possible complications: intravascular injection of a local anesthetic solution, especially into the vertebral artery, the rapid diffusion of which leads to CNS intoxication; subarachnoid administration of an anesthetic solution causes a total spinal block; epidural administration results in high epidural anesthesia.

Anesthesia of the brachial plexus in the interstitial space according to the method of S. V. Gavrilin and L. G. Tikhonov

The main difference of this method from others is that there are no dome of the pleura and large blood vessels at the puncture site. The patient lies on his back, his head is turned in the opposite direction from the puncture site, the chin is brought to the contralateral shoulder girdle. A small roller is placed under the shoulders, the arm from the side of the puncture lies along the body. Landmarks: clavicle, sternocleidomastoid muscle.

Anesthesia technique. The needle injection point is located at the top of the perpendicular, restored from the upper edge of the middle of the clavicle, the length of which is equal to ¼ of the length of the sternocleidomastoid muscle. At this point, a “lemon peel” is formed, the intramuscular injection needle is inserted at an angle of 60 ° to the skin surface, while the needle and an imaginary or drawn perpendicular should be in the same plane. The needle is inserted in the direction of the transverse process of the 6th cervical vertebra until paresthesia appears in the upper limb. In the absence of paresthesia, the needle is advanced all the way into the transverse process of the 6th cervical vertebra, and after pulling it towards itself by 1-2 mm, 30-40 ml of a 2% solution of trimecaine or lidocaine is injected. The needle insertion depth is 2-5 cm.

Anesthesia of the brachial plexus in the modification of V. S. Sokolovsky

The patient lies on his back, the head is located in the midline, the arms lie along the body. Landmarks: sternocleidomastoid muscle and clavicle.

Anesthesia technique. To facilitate finding a point on the skin of the neck, a triangle is built with a vertex in the area of ​​the sternoclavicular joint on the side of anesthesia. The rays of the triangle are the axis of the clavicle and a straight line connecting the mastoid process with the sternoclavicular joint. A perpendicular is restored to the bisector of the angle ABC from the middle of the clavicle. The point of intersection is the point of injection of the needle, which advances at an angle of 45° relative to the horizontal plane of the operating table and perpendicular to the axis of the cervical spine. At a depth of 2-3 cm, after receiving paresthesia and conducting an aspiration test, 30-40 ml of a 2% solution of trimecaine (lidocaine) is injected. Anesthesia occurs in 10-12 minutes. When inconclusive paresthesia is obtained, it is desirable to use electrical stimulation to identify the nerve trunk of the cervical plexus.

5. Anesthesia of peripheral nerves in the wrist area

For operations on the hand, it is necessary to anesthetize the ulnar, median and radial nerves. In all cases, the needle is injected at the level of the proximal fold of the wrist. During anesthesia, the patient lies on his back, in the area of ​​\uXNUMXb\uXNUMXbthe wrist, the arm is supinated and slightly bent. Landmarks: Ulna styloid, pisiform, flexor carpi ulnaris tendon, and flexor carpi longus tendon.

Anesthesia of the ulnar nerve

Topography of the ulnar nerve. In the lower third of the forearm, the ulnar nerve runs lateral to the flexor ulnar tendon and medial to the ulnar artery. At the level of the wrist or on the flexor surface of the forearm, 3-5 cm proximal to the wrist, the ulnar nerve divides into two branches - dorsal and palmar. The dorsal branch is sensitive, goes under the tendon of the ulnar flexor of the hand and exits into the subcutaneous tissue of the rear of the hand at approximately the level of the wrist joint. Anastomosing with the branches of the radial nerve, it innervates 2 ½ fingers. The palmar branch of the ulnar nerve is mixed and at the level of the pisiform bone it is divided into two branches - deep and superficial. The latter is sensitive and innervates the hypothenar region of the 5th finger and the ulnar side of the ring finger.

Technique for anesthesia of the palmar branch of the ulnar nerve. The point of injection of the needle is at the level of the proximal fold of the wrist medial to the tendon of the ulnar flexor of the hand. The needle to a depth of 1-2 cm is passed through the subcutaneous tissue towards the pisiform bone. After the appearance of paresthesia and with a negative aspiration test, the needle is fixed and 3-5 ml of a 2% trimecaine solution is injected. In the absence of paresthesia, the needle is advanced until it comes into contact with the bone, and when it is removed, the tissues are infiltrated with a 2% trimekia solution.

Technique for anesthesia of the dorsal branch of the ulnar nerve. The point of injection of the needle is at the level of the intersection of the proximal fold of the wrist with the medial edge of the tendon of the flexor ulnaris muscle. The needle is directed to the styloid process of the ulna. To obtain paresthesia, 3-5 ml of a 2% solution of trimecaine is injected. In the absence of paresthesia, the needle is removed, and 5-10 ml of a 2% trimecaine solution is infiltrated into the tissues. There are no complications.

median nerve anesthesia

The patient lies on his back, the arm is supinated and straightened. Landmarks: tendon of the long palmar muscle, tendon of the radial flexor of the hand and proximal skin fold of the wrist. Topography. In the lower third of the forearm, the median nerve passes in the medial groove very close to the surface of the skin, located under the fascia, and approximately 4-5 cm above the distal skin fold. The medial groove is formed from the outside by the tendon of the radial flexor of the hand, on the ulnar side - by the tendon of the long flexor of the hand. The branches of the median nerve innervate the 1st, 2nd, 3rd fingers and the outer surface of the 4th finger, as well as the thenar muscles.

Anesthesia technique. The needle injection point is located on the line of the proximal skin fold of the wrist between the tendon of the long palmar muscle and the radial flexor of the hand. After perpendicular advancement of the needle through the subcutaneous tissue to a depth of 0,5-1 cm and obtaining paresthesia, the needle is fixed and 3-5 ml of a 2% lidocaine solution is injected. If it is not possible to achieve paresthesia at a depth of 1 cm, the tissues are fan-shaped infiltrated with 5-10 ml of a 2% trimecaine solution while slowly withdrawing the needle.

Anesthesia of the radial nerve

Landmarks: styloid process of the radius, radial artery, "anatomical snuffbox". Topography. The superficial branch of the radial nerve first goes to the forearm along with the radial artery, and then in the lower third of the forearm at a distance of about 8 cm from the wrist joint, the nerve crosses with the tendon of the brachioradialis muscle and passes to the posterior surface of the forearm, where it goes distally and posteriorly, crossing the long abductor of the large finger and its short extensor. At the level of the wrist at the top of the "anatomical snuffbox" it divides into terminal branches that innervate fingers 1, 2 and the outer surface of fingers 3. The branches of all three nerves often anastomose with each other at the forearm, wrist, and hand.

Anesthesia technique. The injection point is located at the level of the proximal skin fold of the wrist lateral to the radial artery on the projection of the top of the "anatomical snuffbox". It is injected, and the needle is directed towards the "snuffbox". When paresthesia occurs, the needle is fixed, with a negative aspiration test, 3-5 ml of a 2% trimecaine solution is injected. In the absence of paresthesia, 5-10 ml of a 2% solution of trimecaine is fan-shapedly injected into the underlying tissues, creating an infiltration "bracelet" 3-3,5 cm long from the tendons of the short extensor and long abductor of the thumb on one side, to the long extensor of the thumb - with another.

6. Anesthesia of the lower extremities

To perform surgical interventions on the lower limb, it is necessary to anesthetize all four major nerves. Three of them - the femoral, obturator and external cutaneous nerve of the thigh - originate from the lumbar plexus, and the sciatic nerve is formed partly from the lumbar and three branches of the sacral plexus. Each nerve innervates certain areas of the lower limb: the femoral nerve - the anterior surface of the thigh, the anterior inner surface of the lower leg and rear of the foot; ischial - rear and lateral surface of the lower leg, plantar surface of the foot and its outer edge, obturator - inner surface of the thigh; external cutaneous nerve of the thigh - the lateral surface of the thigh. Zones of deep sensitivity coincide with the innervation of the skin zones. All muscles of the lower limb receive motor fibers from the femoral and sciatic nerves, except for the group of abductors innervated by the obturator nerve. The knee joint and its anterior surface are innervated by the femoral nerve, the inner surface by the obturator, the lateral by the external cutaneous and sciatic, and the posterior by the posterior cutaneous, femoral and sciatic nerves.

Anesthesia of the lumbar plexus by anterior (inguinal) access

The patient lies on his back. Landmarks: inguinal ligament and femoral artery.

Topography. The lumbar plexus is formed by the anastomosing anterior branches of the L roots.₁-L₂-L₃ and partly by the anterior branches of Th₁₂ and L₄ nerves. The plexus is located in front of the transverse processes of the lumbar vertebrae between the square muscle of the lower back - dorsally, the psoas major muscle - ventrally, the bodies of the vertebrae - medially, gives off muscle branches and goes down in the fascial bed. The lumbar spinal nerves have connecting branches with the lumbar nodes of the sympathetic trunks, contain motor, sensory and sympathetic nerve fibers. The largest nerves of the lumbar plexus are the external femoral cutaneous nerve (L₂-L₃), obturator (L₂-L₄) and femoral (L₂-L₄) nerves. The latter is a continuation of the lumbar plexus, extends to the thigh under the pupart ligament through the muscular lacuna, being separated from the medially located femoral artery by the iliopectineal ligament. The width of the femoral nerve in this place is about 0,7-0,8 cm. The depth of the femoral nerve is on average 1,8-3 cm. -0,5 cm. Below the inguinal ligament, the nerve forms two bundles. The branches of the anterior bundle innervate the quadriceps femoris muscle, the middle and medial side of the knee joint and pass into the saphenous nerve, which innervates the medial surface of the lower leg and the inner ankle.

Anesthesia of the sciatic nerve makes it possible to operate in any area below the knee joint, to reduce all fractures of the bones of the lower limb, excluding a fracture of the femoral neck.

Anesthesia technique. The skin is treated with a disinfectant solution. A "lemon peel" is formed with an anesthetic solution, after which the needle is injected under the inguinal ligament 1-1,5 cm below the latter and 0,5-1 cm lateral to the palpable femoral artery. The needle is directed through the subcutaneous tissue somewhat in the proximal direction under the inguinal ligament, where at a depth of 3-4 cm after puncture of the fascia, the needle fails with loss of resistance and paresthesia may occur, extending to the anterior surface of the thigh. In this position, the needle is fixed with the thumb and forefinger of the left hand, and the edge of the palm of the left hand is pressed with force on the soft tissues of the thigh distal to the needle and 35-40 ml of a 1,5% trimecaine solution is injected. Pressure on soft tissues lasts 1,5-2 minutes. Thus, anesthesia of the femoral nerve with clamping turns into anesthesia of the lumbar plexus, performed from the anterior approach. The action of anesthesia lasts 2-2,5 hours.

Complications: rather rapid resorption of the anesthetic solution is possible when anesthesia of the lumbar plexus is combined with anesthesia of the sciatic nerve, when the total single dose exceeds 1 g of the drug.

Anesthesia of the lumbar plexus can be performed by the posterior approach, while simultaneously anesthetizing the femoral (L₂-L₄) and obturator nerves (L₂-L₃), genitofemoral nerve (L₁-L₂) and the lateral femoral cutaneous nerve (L₂-L₃). The position of the patient during anesthesia is on a healthy side with bent legs. Landmarks: spinous process of the 4th lumbar vertebra (line connecting the iliac crests behind); 3 cm caudal along the crests of the spinous processes from the spinous process of the 4th lumbar vertebra and 5 cm lateral from the last point. Anesthesia technique. From the spinous process of the 4th lumbar vertebra in the caudal direction, a line 3 cm long is drawn, from the end of which a perpendicular 5 cm long is laterally restored upward. The end point of the perpendicular, lying near the iliac crest, is the needle injection point. After creating a "lemon peel", a 12-15 cm long needle is inserted perpendicular to the skin until it contacts the transverse process of the 5th lumbar vertebra. Cranially, sliding off the transverse process of the 5th lumbar vertebra, the needle enters the thickness of the square psoas muscle. At the same time, resistance is felt to the introduction of a solution into it with a syringe (or springy resistance occurs with deformation of the air bubble in the syringe). The needle is passed to a depth where there is a feeling of "loss of resistance" (or the air bubble is not deformed). This test indicates that the needle is in the fascia between the quadrate psoas and psoas major. The needle is fixed at this depth and 35-40 ml of a 1,5-2% trimecaine (lidocaine) solution is injected to achieve anesthesia.

Possible complications: intramuscular injection of a local anesthetic solution with the wrong position of the needle, as well as rapid resorption of the anesthetic into the blood when a concentrated solution is injected.

Anesthesia of the sciatic nerve from the anterior approach

Topography. The sciatic nerve originates from the sacral plexus (L₄-S₃). It is formed in the small pelvis and leaves the pelvic cavity through the piriform opening along with the artery. Medial to it, the posterior cutaneous nerve passes, as well as the neurovascular bundle, consisting of the internal pudendal artery, vein, and pudendal nerve. In the gluteal region, the sciatic nerve lies under the gluteus maximus, behind the gemellis, obturator internus, and quadratus femoris muscles. On the latter, it is located approximately at an equal distance from the ischial tuberosity and the greater trochanter of the femur. As a rule, in the upper part of the popliteal fossa, the nerve divides into terminal branches: the tibial and common peroneal nerves. The tibial nerve passes through the middle of the popliteal fossa, located lateral and superficial to the popliteal vein and artery, and, together with the vessels, enters the ankle-popliteal canal. The tibial nerve innervates the posterior muscle group of the lower leg, all the muscles of the sole of the foot, the skin of the posterior surface of the lower leg, heel and lateral edge of the foot. Branches from the sciatic nerve to the hip joint. In the region of the gluteal fold, it lies superficially under the broad fascia of the thigh outward from the long head of the biceps femoris. The common peroneal nerve runs along the lateral side of the popliteal fossa, around the head of the fibula. From it there are branches to the knee joint and the skin of the lateral surface of the lower leg, it also innervates the muscles of the lower leg, the back muscles of the foot and the skin of the rear of the toes. Anesthesia of the sciatic nerve is performed from the anterior approach. Landmarks: anterior superior iliac axis and the most protruding part of the greater trochanter of the femur.

Anesthesia technique. The patient lies on his back. The anterior superior iliac spine and the most protruding point of the greater trochanter of the femur are connected by a straight line, and a perpendicular to the anterior surface of the thigh is restored from the last point. The length of the perpendicular is equal to the distance between the anterior superior iliac spine and the greater trochanter of the femur. The end of this perpendicular is the projection point. In the physiological position of the lower limb, after treating the skin with a disinfectant solution and creating a "lemon peel", a 12-15 cm long needle is directed vertically down until it rests against the lesser trochanter of the femur. After the needle slips off the lesser trochanter, without changing the main direction, the needle is carried even deeper - 4-5 cm until paresthesia occurs. If it is not possible to achieve paresthesia, the needle is returned to the bone and, turning the limb inward by 7-10 °, the needle is advanced again until paresthesia appears in the patient.

Anesthesia of the sciatic nerve from the posterior approach

Anesthesia technique. The patient lies on a healthy side, the anesthetized limb is bent at the hip and knee joints at an angle of 45-60°. From the most protruding part of the greater trochanter of the femur, a straight line is drawn to the posterior superior iliac spine, from the middle of which a perpendicular 4-5 cm long is lowered in the caudal direction. The end of the perpendicular serves as a projection point for the sciatic nerve. The needle is injected at an angle of 90° to the frontal plane of the patient's body and advanced until paresthesia or contact with the bone is obtained. If necessary, the needle is pulled up and inserted approximately 0,5 cm lateral or medial to the original injection. Getting paresthesia is a must. Enter 20-25 ml of a 2% solution of lidocaine (trimecaine). The technique of anesthesia will not change if the patient lies on his stomach.

Anesthesia in the popliteal fossa

For surgical interventions on the lower leg and foot, it is sufficient to anesthetize the tibial and peroneal nerves in the popliteal fossa. The position of the patient - on a healthy side or on the stomach. Landmarks: tendons of the biceps, semimembranosus and semitendinosus muscles of the thigh, patella, calf muscle. Topography. The popliteal fossa contains fiber, blood vessels, nerves and lymph nodes. The upper outer border is formed by the tendon of the biceps femoris muscle, the upper inner border is formed by the tendons of the semimembranosus and semitendinosus muscles, the lateral head of the gastrocnemius muscle is below and outside, and the lower internal is the medial head of the gastrocnemius muscle. The projection of the upper angle of the popliteal fossa mostly corresponds to the upper edge of the patella in the upper corner of the rhomboid fossa of the sciatic nerve and is divided into the tibial and common peroneal nerves. The latter from the upper edge goes to the lateral edge of the gastrocnemius and wraps around the neck of the head of the fibula semi-spirally. In the popliteal fossa, the tibial nerve passes most superficially along the midline, a vein lies deeper and medially from it, and even deeper and medially, closer to the bone, is the popliteal artery.

Anesthesia technique. The upper corner of the rhomboid fossa is at the level of the upper edge of the patella. The injection point lies 1-1,5 cm below the upper angle on the bisector lowered from this angle, formed from the outside by the tendon of the biceps femoris, from the inside by the tendons of the semimembranosus and semitendinosus muscles of the thigh. The direction of movement of the needle is strictly vertical with the patient in the prone position until paresthesia of the tibial nerve is obtained. In the absence of paresthesia, the needle is directed fan-shaped, pulling it up each time to the level of subcutaneous tissue. After an aspiration test, 5-10 ml of a 2% solution of trimecaine is injected. To block the common peroneal nerve from the same point, the needle is directed laterally at an angle of 30-45° to the frontal plane. After receiving paresthesia, 5-10 ml of a 2% solution of trimecaine is injected. There are no complications or contraindications.

Complications of regional anesthesia

During RA, complications occur quite rarely, and they can be divided into two groups.

1. Specific, which are more related to the technical errors of the methodology:

1) erroneous injection of a local anesthetic into the spinal canal or epidural space, intravenously or intra-arterially (with anesthesia of the cervical plexus, anesthesia of the lumbar plexus with inguinal access);

2) puncture of cavities and organs (pleural cavity, lung);

3) the formation of a hematoma with a neglect of puncture and damage to a large vessel; hematoma compresses the surrounding tissue or neurovascular bundle;

4) prolonged and severe hypotension that occurs with rapid resorption of the local anesthetic;

5) trauma to the nerve plexus or conductor with the end of the injection needle during rough manipulation;

6) the absence of an analgesic effect after plexus or conduction anesthesia.

2. Nonspecific, manifested mainly by general and local reactions of the body to the action of a local anesthetic in the form of toxic and allergic reactions. Non-specific complications may develop depending on the time, dose and site of administration of the anesthetic. In this case, lesions of the central nervous or cardiovascular systems predominate. Complications from the CNS can be mild (limited only to central excitation) or severe, which is manifested by CNS inhibition with possible total paralysis.

The nature of non-specific complications:

1) an overdose of anesthetic with the simultaneous administration of a large dose (more than 1 g) of trimecaine or lidocaine intraarterially or intravenously. With intravascular injection of a local anesthetic, toxic reactions appear immediately, and with overdoses of the drug - after 10-15 minutes. Severe toxic reactions with excessive dosages of local anesthetics are extremely rare. Much more often (up to death) they are observed with intravascular administration of a highly concentrated solution of local anesthetic;

2) allergic reactions to the introduction of a local anesthetic, characterized by a symptom complex of disorders of the central nervous and cardiovascular systems: anxiety, impaired consciousness, speech disorders, muscle twitches, convulsions, deep breathing, heart rhythm disturbance, QR expansion, lowering blood pressure, tachycardia, apnea , asystole;

3) infectious complications due to poor-quality processing of the surgical field at the site of anesthesia, insufficient sterilization of syringes, needles and solutions, as well as in the presence of a local skin infection (pyoderma) in the area of ​​the intended manipulation;

4) the development of hypotension with plexus and conduction anesthesia is much less common than with epidural and spinal anesthesia, but this does not reduce the importance of correcting hypovolemia;

5) with the introduction of concentrated solutions of local anesthetics in a small percentage of cases, the development of bradycardia is noted, which is well stopped by atropine sulfate. Cases of ventricular fibrillation and cardiac arrest are extremely rare.

Contraindications to

Contraindications are as follows.

1. Hysteria.

2. Tendency to aggravate.

3. Neurological complications: hemiplegia and hemiparesis of the proposed area of ​​anesthesia, diseases of the spinal cord, multiple sclerosis, diseases of the peripheral nerves.

4. Infection of the skin in the area of ​​the needle injection point.

5. Septicemia.

6. Tendency to bleeding and severe hypovolemia after massive blood loss.

7. Pernicious anemia (relative contraindication).

7. Epidural anesthesia

Its essence lies in the blockade of the spinal nerves and their roots with an anesthetic introduced into the epidural space.

The technique of conducting and the zone of anesthesia are indicated in lecture No. 2.

Doses and duration of analgesia

1. Lidocaine is injected in a volume of 4 ml (2%), the duration of anesthesia is 4 hours.

2. Marcaine is administered at a dose of 6-10 ml (0,5%), the duration of anesthesia is 6-8 hours.

3. Naropin is administered at a dose of 4-6 ml (1%), the duration of anesthesia is 4-6 hours.

With this type of anesthesia, hemodynamics suffers, there is a sharp decrease in blood pressure. Therefore, when using this type of anesthesia, constant monitoring of the patient's pressure and, if necessary, its correction is necessary.

8. Lumbar anesthesia

This type of anesthesia is achieved by injecting an anesthetic into the spinal canal.

The technique of lumbar puncture is described in lecture No. 2. Features are that the level of puncture is higher (T₁₂-L₁, L₁-L₂) and after removing the mandrin from the needle, an anesthetic is immediately injected. The volume of anesthetic is 3-5 ml. Naropin is administered in 0,5% concentration, lidocaine - in 2%, marcaine - in 0,5%. The duration of anesthesia is 4-6 hours. This type of anesthesia also causes severe hypotension. With a high level of anesthesia (T₁₂-L₁) may cause respiratory problems. The most common complication is headache.

9. Cervical vagosympathetic blockade according to A. V. Vishnevsky

The patient is placed on the table on his back so that the hand on the side of the proposed blockade hangs over the edge of the table. The sternocleidomastoid muscle should be relaxed. A roller is placed under the shoulder girdle, the head is retracted in the opposite direction; in this position, the anatomical contours of the neck are well outlined. The field is treated with lubrication with alcohol and iodine. The doctor stands on the side of the blockade of the same name. The injection site is the angle formed by the intersection of the posterior edge of the sternocleidomastoid muscle with a vein. The index finger of the left hand is placed at the posterior edge of the sternocleidomastoid muscle, above the place where it crosses with the external jugular vein. Strongly pressing a finger on this place, they try to move the neurovascular bundle to the midline. In this case, the finger easily feels the anterior surface of the cervical vertebrae. The injection of the needle and its advancement should be done slowly, upward and inward, all the while focusing on the anterior surface of the spine. The needle moves along the 2% novocaine solution sent in small portions (3-0,25 cm), which ensures the safety of the injection. The syringe during the injection is repeatedly removed from the needle for the purpose of control (blood). Having brought the needle to the vertebra, they feel how it rests against it. Then the pressure on the needle is weakened, due to which it moves away by 1-2 mm, after which 40 to 60 ml of a solution is injected, which, spreading in a creeping infiltrate along the prevertebral aponeurosis, covers the vagus, sympathetic, and often phrenic nerves, interrupting ( blocking) transmission of irritations from the pleuropulmonary region. The effectiveness of vagosympathetic blockade is evidenced by the appearance of Horner's symptom (narrowing of the pupil, narrowing of the palpebral fissure and retraction of the eyeball). The respiratory rhythm and pulse become less frequent, shortness of breath and cyanosis decrease, and the general condition improves.

To avoid getting the needle into the vessels of the neck, the sternocleidomastoid muscle with the underlying neurovascular bundle should be moved strongly enough with the index finger to the midline. It is important to direct the needle up and inward, since moving it in a horizontal direction threatens to introduce a solution under the prevertebral aponeurosis and subsequent complication in the form of a pain syndrome that does not stop during the day.

Author: Kolesnikova M.A.

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