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Periphral neural block uday

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Periphral neural block uday

  1. 1. Peripheral Nerve Blocks • Advancement in needle delivery devices, safer local anesthetics, and development of indwelling catheters for postoperative perineural infusion have led to a transformation in regional anesthesia; the focus has shifted from providing intraoperative regional anesthesia to providing intraoperative anesthesia and postoperative regional analgesia. • Fundamental to the success of regional anesthesia is the correct positioning of the needle tip in the perineural sheath, prior to injection of local anesthetic. • In the past, this was accomplished either by eliciting a paresthesia with the needle tip or, in the case of an axillary nerve block, by using the transarterial approach. • Either out of fear of persistent paresthesias or arterial injury, or because of advancement of the specialty and development of newer technologies, anesthesiologists today commonly employ a nerve stimulator to help define needle tip location. • The use of nerve stimulators is not risk free, as morbidities have been reported with these devices, leaving providers in search of the optimal tool. Other technologies that are being studied are ultrasound, Doppler, and sensory nerve stimulation. Currently the best way to establish needle tip location is based on a motor response to nerve stimulation; a motor response at approximately 0.5 mA indicates that the needle is in the appropriate position and local anesthetic can be injected
  2. 2. • The disadvantages of peripheral nerve blocks, although uncommon, include the toxicity of local anesthetics, chronic paresthesias and nerve damage, and, depending on the nerves being anesthetized (interscalene block, supraclavicular block, etc), respiratory failure due to phrenic nerve blockade, and seizures due to intraarterial injection • when performing a block, the anesthesiologist must weigh the toxicity of the agent to be used and the characteristics of individual local anesthetics such as time to onset and duration of action, degree of sensory versus motor block, and the cardiac toxicity of large volumes of local anesthetics delivered into the perineural sheaths.
  3. 3. Upper Extremity Blocks • Successful regional anesthesia of the upper extremity requires knowledge of brachial plexus anatomy from its origin, where the nerves emerge from the intervertebral foramina, to its termination in the peripheral nerves. • Also important is an understanding of the side effects and complications of upper extremity regional techniques, as well as the clinical application of available local anesthetics for these blocks. • role of appropriate sedation during placement of the block and during the surgical procedure should not be underestimated. Many a “perfect” regional anesthetic technique has been undone by inadequate management of sedation. Anatomy- brachial plexus is formed by the union of the anterior primary divisions (ventral rami) of the fifth through the eighth cervical nerves and the first thoracic nerves . Contributions from C4 and T2 are often minor or absent. • As the nerve roots leave the intervertebral foramina, they converge, forming trunks, divisions, cords, and then finally terminal nerves. • Three distinct trunks are formed between the anterior and middle scalene muscles. Because they are vertically arranged, they are termed superior, middle, and inferior. • superior trunk is predominantly derived from C5–6, the middle trunk from C7, and the inferior trunk from C8–T1.
  4. 4. conti.... • As the trunks pass over the lateral border of the first rib and under the clavicle, each trunk divides into anterior and posterior divisions. • As the brachial plexus emerges below the clavicle, the fibers combine again to form three cords that are named according to their relationship to the axillary artery: lateral, medial, and posterior • lateral cord is the union of the anterior divisions of the superior and middle trunks; • medial cord is the continuation of the anterior division of the inferior trunk; and • posterior cord is formed by the posterior division of all three trunks. • At the lateral border of the pectoralis minor muscle, each cord gives off a large branch before terminating as a major terminal nerve. • lateral cord gives off the lateral branch of the median nerve and terminates as the musculocutaneous nerve; • medial cord gives off the medial branch of the median nerve and terminates as the ulnar nerve; and the • posterior cord gives off the axillary nerve and terminates as the radial nerve.
  5. 5. Techniques for Brachial Plexus Block • fascial sleeve that is derived from the prevertebral and scalene fascia encloses the brachial plexus. This sheath extends from the intervertebral foramina to the upper arm and serves as the anatomic basis for brachial plexus blocks. • Injection into this sheath at any point allows local anesthetic to spread and block the C5–T1 nerve roots. • degree of neural blockade, however, may vary somewhat depending on the level of injection. interscalene approach is most optimal for procedures on the shoulder, arm, and forearm. • Injection at the interscalene level tends to produce a block that is most intense at the C5–C7 dermatomes and least intense in the C8–T1 dermatomes. • interscalene approach may therefore not provide optimal surgical anesthesia for procedures in the ulnar nerve distribution. • In contrast, the axillary approach to the brachial plexus is most optimal for procedures from the elbow to the hand. This approach tends to produce the most intense block in the distribution of C7–T1 (ulnar nerve) but is usually inadequate for procedures on the shoulder and upper arm (C5–C6). • The supraclavicular and infraclavicular approaches to the brachial plexus result in a more even distribution of local anesthetic and can be used for procedures on the arm, forearm, and hand
  6. 6. Interscalene Brachial Plexus Block Anatomy-cervical spinal nerves blend into trunks between the anterior and middle scalene muscles. This interscalene groove lies at the level of the cricoid cartilage and is a relatively easy place to enter the brachial plexus sheath to elicit a paresthesia or obtain an evoked motor response with a nerve stimulator. Technique-Palpation of the interscalene groove is usually accomplished with the patient supine and the head rotated 30° or less to the contralateral side. • The external jugular vein often crosses the interscalene groove at the level of the cricoid cartilage. • The interscalene groove should not be confused with the groove between the sternocleidomastoid and the anterior scalene muscle, which lies more anterior. • Having the patient lift and turn the head against resistance often helps delineate the anatomy. • After injection of a skin wheal with a 25-gauge needle at the level of the cricoid cartilage, a 22-gauge, 1.5-in B-bevel needle is introduced nearly perpendicular to the skin and advanced in slightly medial and caudal directions until a paresthesia or evoked muscle contraction in the arm is elicited.
  7. 7. conti........ • If a nerve stimulator is used, activity of the phrenic nerve suggests the needle is too "anterior," whereas stimulation of the trapezius muscle indicates the needle may be too "posterior.“ • Motor activity of the arm, wrist, or hand should be elicited, but success has been reported with a response noted in the deltoid or pectoralis muscles, with subsequent local anesthetic injection. • Some clinicians apply proximal pressure on the sheath to favor distal spread of local anesthetic. A total of 30–40 mL of local anesthetic solution is injected. • For some surgical procedures such as total shoulder arthroplasty, catheters may be inserted and kept in place postoperatively for pain control. Such catheters are placed via an insulated stimulating Tuohy needle. • Compared to needle insertion for a single-shot block, insertion should begin slightly more cephalad and advancement of the needle is more medial.
  8. 8. Complications • Interscalene blocks have a multitude of potential side effects. • The proximity of the stellate ganglion, the phrenic nerve, and the recurrent laryngeal nerve to this location explains their high rate of incidental blockade. • The phrenic nerve is commonly blocked, which may lead to respiratory failure in patients with inadequate pulmonary reserve. • Patients may display a Horner's syndrome (myosis, ptosis, and anhidrosis), dyspnea, and hoarseness, respectively. • The proximity of the vertebral artery to the injection site increases the risk of an intraarterial injection. Even a very small amount (1–3 mL) of local anesthetic injected into a vertebral artery can produce a seizure because the entire amount goes directly to the brain. • Venous injection and rapid absorption can result in a slower onset of central nervous system toxicity. Inadvertent epidural, subarachnoid, or subdural injection can occur because of the close proximity of the cervical neural foramina and the presence of dural sleeves on nerve roots. • Advancing the needle too far, particularly in a lateral direction, can result in puncture of the pleura and a pneumothorax.
  9. 9. Supraclavicular Block Anatomy-At the lateral border of the anterior scalene muscle, the brachial plexus passes down between the first rib and clavicle to enter the axilla. • The trunks are tightly oriented vertically on top of the first rib just posterior to the subclavian artery. Because the plexus is so compacted here, blockade achieves excellent anesthesia of the entire arm, including the hand. Technique- patient is placed in a supine position with the head turned away from the side to be blocked. The far as possible. • In the classic technique, the midpoint of the clavicle should be identified and marked. • The posterior border of the sternocleidomastoid can be palpated easily when the patient raises the head slightly. • arm to be anesthetized should be adducted, and the hand should be extended along the side toward the ipsilateral knee as The palpating fingers can then roll over the belly of the anterior scalene muscle into the interscalene groove, where a mark should be made approximately 1.5 to 2.0 cm posterior to the midpoint of the clavicle. Palpation of the subclavian artery at this site confirms the landmark.
  10. 10. • After appropriate preparation and development of a skin wheal, the anesthesiologist stands at the side of the patient facing the patient's head. • A 22-gauge, 4-cm needle is directed in a caudad, slightly medial, and posterior direction until a paresthesia or motor response is elicited or the first rib is encountered. If a syringe is attached, this orientation causes the needle shaft and syringe to lie almost parallel to a line joining the skin entry site and the patient's ear. • If the first rib is encountered without elicitation of a paresthesia, the needle can be systematically walked anteriorly and posteriorly along the rib until the plexus or the subclavian artery is located . • Location of the artery provides a useful landmark; the needle can be withdrawn and reinserted in a more posterolateral direction, which generally results in a paresthesia or motor response. On localization of the brachial plexus, aspiration for blood should be performed before incremental injections of a total volume of 20 to 30 mL of solution.
  11. 11. conti..... • The rib is usually contacted at a needle depth of 3 to 4 cm; however, in an obese patient or in the presence of tissue distortion from hematoma or injection of solution, the depth may exceed the length of the needle. • Nonetheless, before the needle is advanced farther, gentle probing in the anterior and posterior directions should be done at the 2- to 3-cm depth if paresthesias are not obtained • Multiple injections may improve the quality or may shorten the onset of blockade. Modified plumb-bob approach uses similar patient positioning, although the needle entry site is at the point where the lateral border of the sternocleidomastoid muscle inserts into the clavicle. 1. After preparation and raising of a skin wheal, a 22-gauge, 4-cm needle is inserted while mimicking a plumb-bob suspended over the needle entry site . 2. Frequently, a paresthesia or motor response is elicited before contacting the first rib or artery. 3. If no paresthesia or motor response is elicited, the needle is reinserted while angling the tip of the needle cephalad and then caudad in small steps until the first rib is contacted. •
  12. 12. Side Effects and Complications OF Supraclavicular Block • Although the block is more difficult in obese patients , there does not appear to be an increased frequency of complications. • prevalence of pneumothorax after a supraclavicular block is 0.5% to 6% and diminishes with experience. The onset of symptoms is usually delayed and may take up to 24 hours. Routine chest radiography after the block is not justified. • supraclavicular approach is best avoided when the patient is uncooperative or cannot tolerate any degree of respiratory compromise because of underlying disease. • Other complications include frequent phrenic nerve block (40% to 60%), Horner's syndrome, and neuropathy. The presence of phrenic or cervical sympathetic nerve blockade normally requires only reassurance. Although nerve damage can occur, it is uncommon and usually self-limited.
  13. 13. Infraclavicular Block • Clinical Applications • An infraclavicular block provides anesthesia to the arm and hand. • Blockade occurs at the level of the cords and offers the theoretical advantages of avoiding pneumothorax while affording block of the musculocutaneous and axillary nerves. No special arm positioning is required. A nerve stimulator or ultrasound visualization is required because there are no palpable vascular landmarks to aid in directing the needle. • Technique • The needle is inserted 2 cm below the midpoint of the inferior clavicular border and advanced laterally, and a nerve stimulator is used to identify the plexus. • Marking a line between the C6 tubercle and the axillary artery with the arm abducted is helpful in visualizing the course of the plexus. Incremental injection of 20 to 30 mL of solution is sufficient after the needle is correctly placed. The success rate is improved with a distal motor response. However, more lateral insertion site may result in the absence of blockade of the musculocutaneous nerve, thus removing the major advantage of this approach over the simpler axillary block.
  14. 14. • Side Effects and Complications • Because of the necessarily blind approach to the plexus, the incidence of intravascular injection may be increased. Exaggerated medial needle direction may result in pneumothorax. Other rare complications such as infection and hematoma.
  15. 15. Axillary Block • Clinical Applications • The axillary approach to the brachial plexus is the most popular because of its ease, reliability, and safety. • Blockade occurs at the level of the terminal nerves. Although blockade of the musculocutaneous nerve is not always produced with this approach, it can be supplemented at the level of the axilla or at the elbow. • Indications for axillary block include surgery on the forearm and hand and elbow procedures .This block is ideally suited for outpatients and is easily adapted to the pediatric population. • However, an axillary block is unsuitable for surgical procedures on the upper part of the arm or the shoulder, and the patient must be able to abduct the arm to perform the block.
  16. 16. Technique of axillary Block • Anatomic concepts that should be considered before an axillary block include the following: • The neurovascular bundle is multicompartmental . • The axillary artery is the most important landmark; the nerves maintain a predictable orientation to the artery. • The median nerve is found superior to the artery, the ulnar nerve is inferior, and the radial nerve is posterior and somewhat lateral • At this level, the musculocutaneous nerve has already left the sheath and lies in the substance of the coracobrachialis muscle. • The intercostobrachial nerve, a branch of the T2 intercostal nerve, is usually blocked by the skin wheal overlying the artery; however, adequate anesthesia for the tourniquet can be ensured by extending the wheal 1 to 2 cm caudad and cephalad • The patient should be in the supine position with the arm to be blocked placed at a right angle to the body and the elbow flexed to 90 degrees. The dorsum of the hand rests on the bed or pillow; hyperabduction of the arm with placement of the hand beneath the patient's head is not recommended because this position frequently obliterates the pulse.
  17. 17. • The axillary artery is palpated, and a line is drawn tracing its course from the lower axilla as far proximally as possible. The artery is then fixed against the patient's humerus by the index and middle fingers of the left hand, and a skin wheal is raised directly over the artery at a point in the axilla approximating the skin crease. Proximal needle placement and maintenance of distal pressure facilitate proximal spread of the solution. • Method of Needle Localization • Several methods of identifying the axillary sheath have been described. Overall, paresthesias are unnecessary. • 1. Paresthesias can be sought with a 25-gauge, 2-cm needle, beginning deeply (i.e., radial nerve) or with the nerves supplying the surgical site. Needles longer than 2 cm are rarely needed to reach the neurovascular bundle; smaller needles and a short needle bevel may be associated with a lower incidence of nerve damage.Each paresthesia is injected with 10 mL of local anesthetic.
  18. 18. • 2. A nerve stimulator can also be used with an insulated needle to locate the nerves. This technique obviates the need for paresthesias. • 3. A short-beveled needle can be advanced until the axillary sheath is entered, as evidenced by a fascial click, after which 40 to 50 mL of solution is injected after negative aspiration. • 4. A transarterial technique can be used whereby the needle pierces the artery and 40 to 50 mL of solution is injected posterior to the artery; alternatively, half of the solution can be injected posterior and half injected anterior to the artery. Great care must be taken to avoid intravascular injection with this technique, particularly because the pressure of injection within the compartments of the axillary sheath may move anatomic structures in relation to the immobile needle. Some practitioners avoid intentional arterial puncture in the belief that it is unnecessarily traumatic. • 5. Field block of the brachial plexus with a fanlike injection of 10 to 15 mL of local anesthetic solution on each side of the artery is a variation of the sheath technique. Paresthesias, though not sought, are often encountered with this technique and provide evidence of correct placement.
  19. 19. • Classically, it was recommended that on completion of the injection, the arm should be adducted and returned to the patient's side to prevent the humeral head from obstructing proximal flow of the solution. However, a more recent study reported that maintaining the arm in abduction decreases onset time and prolongs both sensory and motor blockade. • Side Effects and Complications • Nerve injury and systemic toxicity are the most significant complications associated with the axillary approach. • Injection of large volumes of local anesthetic, particularly via the transarterial approach, increases the risk for intravascular injection and systemic toxicity of local anesthetics. • Hematoma and infection are rare complications.
  20. 20. Median Nerve Block • Blockade of the median nerve provides anesthesia of the palmar aspects of the thumb and index finger, the middle finger and radial half of the ring finger, and the nail beds of the same digits. • Motor block includes the muscles of the thenar eminence, the lumbrical muscles of the first and second digits, and in the case of a block at the elbow, the median-innervated wrist flexor muscles of the forearm. • Technique at the Elbow • With the patient's arm placed in the anatomic position (i.e., palm up), a line is drawn connecting the medial and lateral epicondyles of the humerus. • The major landmark for this technique is the brachial artery, which is found medial to the biceps tendon at the intercondylar line. The median nerve lies medial to the artery, and can be blocked with 3 to 5 mL of solution after eliciting a paresthesia. If no paresthesia is obtained, the solution can be injected in a fanlike pattern medial to the palpated artery.
  21. 21. • Technique at the Wrist • The median nerve is located between the flexor carpi radialis and palmaris longus tendons and can be blocked at a point 2 to 3 cm proximal to the wrist crease . (The palmaris longus tendon is congenitally or postsurgically absent from some patients.) Loss of resistance is felt as the needle passes through the flexor retinaculum, at which point 2 to 4 mL of solution should be injected. A superficial palmar branch supplying the skin of the thenar eminence can be blocked by injecting 0.5 to 1 mL of solution subcutaneously above the retinaculum. Paresthesias should not be sought because of confinement of this nerve within the carpal tunnel.
  22. 22. Radial Nerve Block • Blockade of the radial nerve provides anesthesia to the lateral aspect of the dorsum of the hand (i.e., thumb side) and the proximal portion of the thumb, index, middle, and lateral half of the ring finger. • Technique at the Elbow • The radial nerve can be blocked at the elbow as it passes over the anterior aspect of the lateral epicondyle. The intercondylar line and lateral edge of the biceps tendon are marked. A 22-gauge, 3- to 4-cm needle is inserted at a point 2 cm lateral to the biceps tendon and advanced until bone is encountered . Three to 5 mL of solution is injected in a fanlike fashion. • Technique at the Wrist • The radial nerve block at the wrist is a field block of the multiple peripheral branches descending along the dorsum and radial side of the wrist. The extensor pollicis longus tendon can be identified when the patient extends the thumb. The needle insertion site is over this tendon at the base of the first metacarpal, and the solution is injected superficial to the tendon. A volume of 2 mL of local anesthetic is injected proximally along the tendon, and an additional 1 mL is injected as the needle passes at a right angle across the anatomic snuffbox .
  23. 23. Ulnar Nerve Block • Blockade of the ulnar nerve provides anesthesia to the ulnar side of the hand, the little finger, the ring finger, and all the small muscles of the hand, except those of the thenar eminence and the first and second lumbrical muscles. • Technique at the Elbow • ulnar nerve is easily accessible at its subcutaneous position posterior to the medial epicondyle, blockade at this site is associated with a high incidence of neuritis. Because the nerve is surrounded by fibrous tissue at this point, intraneural injection is required for successful blockade. • Use of a very fine needle along with a small volume of solution (1 mL) diminishes the risk; however, the nerve can be satisfactorily blocked with 5 to 10 mL of solution at a site 3 to 5 cm proximal to the elbow. The local anesthetic should be injected in a fanlike fashion without elicitation of a paresthesia. • Technique at the Wrist • ulnar nerve lies beneath the flexor carpi ulnaris tendon between the ulnar artery and the pisiform bone. Nerve can be approached by directing the needle medially from the radial side of the tendon or, alternatively, by directing the needle radially from the ulnar side of the tendon . After eliciting a paresthesia, 3 to 5 mL of anesthetic solution is injected or spread in a fanlike fashion.
  24. 24. Intravenous Regional Blocks • Intravenous regional blocks were first described by a German surgeon, August Bier, in 1908.Early methods involved two tourniquets and the first synthetic local anesthetic, procaine. The technique lost popularity as reliable methods of blocking the brachial plexus evolved. • Clinical Applications • The Bier block has multiple advantages, including ease of administration, rapidity of recovery, rapid onset, muscular relaxation, and controllable extent of anesthesia. It is an excellent technique for short (<90 minutes) open surgical procedures and for closed reduction of bony fractures. • Technique • An intravenous cannula is placed in the upper extremity to be blocked as far distally as possible; the patient should also have an intravenous cannula in the nonoperative upper extremity for administration of fluids and other drugs. Traditionally, a double tourniquet is placed on the operative side; both cuffs should have secure closure and reliable pressure gauges. • After exsanguination of the arm, the proximal cuff is inflated to approximately 150 mm Hg more than systolic pressure, and absence of a radial pulse confirms adequate tourniquet pressure.
  25. 25. • The total dose of local anesthetic is based on the patient's weight, and it is injected slowly (3 mg/kg of 0.5% prilocaine or lidocaine, without epinephrine). • The use of bupivacaine for intravenous regional anesthesia has been associated with local anesthetic toxicity and death and therefore is not recommended. However, dilute solutions (0.125% levobupivacaine) of long-acting amides, as well as the addition of adjuvants (tramadol, ketorolac, clonidine), have been used to prolong sensory blockade and analgesia after deflation of the tourniquets. • The onset of anesthesia usually occurs within 5 minutes. When the patient complains of tourniquet pain, the distal tourniquet, which overlies anesthetized skin, is inflated, and the proximal tourniquet is released. Use of a single wide cuff allows lower inflation pressures to be used during intravenous regional anesthesia. • The postulated advantage is that the lower pressures will decrease the incidence of neurologic complications related to the high inflation pressures with the narrow double cuffs. The tourniquet may be safely released after 25 minutes, but the patient should be closely observed for local anesthetic toxicity for several minutes after release of the tourniquet. Slow injection of local anesthetic solutions at a distal site has been shown to lower the risk for toxicity.
  26. 26. • Side Effects and Complications • Technical problems with this block include tourniquet discomfort, rapidity of recovery leading to postoperative pain, difficulty providing a bloodless field, and the necessity of exsanguination in the case of a painful injury. • Accidental or early deflation of the tourniquet or use of excessive doses of local anesthetics can result in toxic reactions. • Cyclic deflation of the tourniquet at 10-second intervals has been shown to increase the time to peak arterial lidocaine levels and may decrease any potential toxicity. • Other rare complications associated with this technique include phlebitis (with 2- chloroprocaine), the development of a compartment syndrome, and loss of a limb
  27. 27. Digital Nerves • Digital Nerves • These nerve blocks are used for minor operations on the fingers and to supplement brachial plexus blocks. • Anatomy • Sensory innervation of each finger is provided by four small digital nerves that enter each digit at its base in each of the four corners. • Technique • A 23- to 25-gauge needle is inserted at the medial and lateral aspects of the base of the selected digit. A total of 2–3 mL of local anesthetic without epinephrine is injected on each side near the periosteum. Addition of a vasoconstrictor (epinephrine) can seriously compromise blood flow to the digit. Complications • Nerve injury is the primary risk of a digital block.
  28. 28. Somatic Blockade of the Lower Extremity Anatomy The lumbar and the lumbosacral plexi are the major nerve distributions to the lower extremities. The lumbar plexus is derived from the ventral rami of L1–4, with some occasional contribution from T12 The lumbar plexus, primarily from L2 to L4, forms three major nerves that innervate the lower extremity: the lateral femoral cutaneous, femoral, and obturator nerves. These nerves predominantly supply motor and sensory innervation to the anterior portion of the lower extremity and the cutaneous sensory portion of the medial lower leg (saphenous nerve). The lumbosacral plexus is derived from the nerve roots of L4–5 and S1–3 and primarily forms the sciatic nerve, which courses posteriorly and supplies both motor and sensory innervation to the posterior aspect of the lower extremity and foot, largely as its terminal branches into the tibial and the common peroneal nerves. is a simplified schematic of the global innervation of the lower extremity. Note that the posterior cutaneous nerve (S1–3) is highlighted but the sciatic nerve is not; it courses with the sciatic nerve as it emerges around the piriformis muscle and subsequently it too is blocked when a proximal sciatic nerve block is performed.
  29. 29. • Spinal and epidural anesthesia are most often employed for regional anesthesia of the lower extremities. Peripheral nerve blocks in the lower extremity can also provide excellent surgical anesthesia for some procedures but require multiple injections and may be technically more challenging in some cases. Ankle block is the easiest and most commonly used lower extremity block; it is typically used for foot surgery. • Four major nerves innervate the lower extremities: the femoral (L2–4), obturator (L2–4), lateral femoral (L1–3), and sciatic nerves (L4–S3). The first three nerves are part of the lumbar plexus; they lie within the substance of the psoas muscle and emerge within a common fascial sheath that extends into the proximal thigh. The common peroneal and tibial nerves are continuations of the sciatic nerve in the lower leg.
  30. 30. Lumbar Plexus (Psoas) Block • Anatomy • The lumbar plexus is derived from the ventral rami of the lumbar nerve roots. The plexus courses via the "psoas compartment" as defined by the fascia of the psoas muscle (which lies anterior to the plexus) and the fascia of the quadratus laborum (which lies posterior to the plexus). • Technique • The patient should lie in a lateral decubitus position with the side to be blocked in the nondependent position. Both iliac crests are identified and a line is drawn connecting the crests. This line generally crosses the lumbar body of L4. The posterior superior iliac spine is identified and a line is drawn cephalad, parallel to the vertebral column. The intersection of the two lines indicates the most lateral location of the lumbar plexus. Generally, the insertion point is 4 cm from the midline or two-thirds the distance between the spinous processes of the lumbar vertebrae and this intersection . • Psoas block for anesthetizing the lumbar plexus. The site of entry is 4 cm lateral to the spinous processes on a line drawn between the iliac crests. PSIS, posterior superior iliac spine. .
  31. 31. • A 4-in, 21-gauge insulated stimulating needle is advanced in a perpendicular plane at this insertion site. When the needle has entered the psoas compartment (70–90 mm), a quadriceps motor response is noted. After reducing the stimulation to < 0.5 mA, witnessing fade of motor activity after injection of 1 mL of local anesthetic and a negative aspiration of blood, 25–40 mL of local anesthetic is delivered. Early descriptions of this block employed a "loss of resistance" technique (similar to epidural placement) when the needle tip entered the psoas compartment • Indications • A psoas block anesthetizes the lateral femoral cutaneous, femoral, and obturator nerves. This block is useful for procedures involving the knee, anterior thigh, and hip. Catheter placement and a continuous infusion administered for postoperative analgesia are common for patients recovering from total hip arthroplasty and occasionally total knee arthroplasty. • Complications • Local anesthetic toxicity and nerve damage from an intraneural injection or hematoma have been reported from this block
  32. 32. Femoral Nerve & "Three-in-One" Block • A femoral nerve block can be used to provide anesthesia for the anterior thigh, knee, and a small part of the medial foot. It is typically used in conjunction with other lower extremity blocks. It may also be used for postoperative pain relief following knee surgery. • Anatomy • After passing through the psoas compartment, the femoral nerve enters the thigh lateral to the femoral artery just below the inguinal ligament. Distal to this point, motor branches to the quadriceps, sartorius, and pectineus muscles arise as well as numerous sensory branches to the medial and anterior thigh. The nerve is encased in a sheath that extends from the psoas muscle to just below the inguinal ligament. • Technique • The inguinal ligament should first be identified (by drawing a line connecting the anterior superior iliac spine and the superior-lateral corner of the pubic tubercle). The operator approximates the midpoint along this line and palpates for the femoral pulse. Once the femoral pulse is identified, the insertion point for the femoral nerve block is located 2 cm lateral to the femoral artery pulse and 2 cm distal to the inguinal ligament line. With the nerve stimulator technique, a 2-in, 22- gauge stimulating needle is advanced seeking a quadriceps twitch or "patellar snap." Once identified, and after reducing the stimulation to < 0.5 mA, witnessing fade of motor activity after injection of 1 mL of local anesthetic and a negative aspiration of blood, 20–30 mL of local anesthetic is delivered.
  33. 33. • Femoral nerve block. The insertion site should be 1.5–2.0 cm lateral to the femoral pulse, 2 cm inferior to a line drawn between the pubic symphysis and the anterior superior iliac spine (which overlies the inguinal ligament). Indications • A femoral nerve block is very useful in numerous procedures involving the thigh and knee, such as skin grafting, knee arthroscopy, and patellar surgery, or as an adjunct to procedures distal to the knee that require anesthesia to the medial aspect of the lower leg (saphenous distribution). An increasingly common practice in many centers is the insertion of an indwelling femoral catheter for continuous perineural infusion along with an accompanying sciatic nerve block for patients recovering from total knee arthroplasty. • This block is often referred to as Winnie's "3-in-1 block." As first described, placement of sufficient local anesthetic, directed proximally and with distal compression, blocked not only the femoral nerve, but the obturator and the lateral femoral cutaneous nerves as well, thus the "3-in-1." There have been many conflicting reports on the effectiveness of this approach as a true "3-in-1 block." Many practitioners view this as a femoral nerve only block with little ability to provide additional nerve coverage. • Complications • Careful aspiration and incremental dosing help avoid intravascular injection and systemic local anesthetic toxicity.
  34. 34. Fascia Iliaca Block • Anatomy • A fascia iliaca block takes advantage of the fact that the femoral nerve and, to a certain degree, the lateral femoral cutaneous, the obturator, and the genitofemoral nerves course posterior to the fascia iliaca and delivery of local anesthetic behind the fascia may result in a "compartment" block. The so-called "fascia iliaca compartment" is a potential space bordered anteriorly by the fascia iliaca (which is overlaid by the fascia lata) and posteriorly by the iliopsoas muscle. • Technique • In performing this block, the landmarks are similar to those used to identify the femoral nerve; a line is drawn from the anterior superior iliac spine and connected to the outer corner of the pubic tubercle. This line is then divided into thirds and the outer and middle third junction is identified. Two centimeters distal from this junction is the needle insertion site. In performing the block, it is preferable to use a B-bevel needle to accentuate the tactile sensation, as this block is not performed with a nerve stimulator. Commonly a 3.5-in, 22-gauge Whitacre spinal needle may be used (recognizing that other products are also available). As the needle is inserted, two "pops" will be felt. The first occurs as the needle passes through the fascia lata and the second as it passes through the fascia iliaca. Following negative aspiration of blood, approximately 25–30 mL of local anesthetic is injected.
  35. 35. Fascia iliaca block. Indications • There has been a recent surge of interest in fascia iliaca blocks. Because it does not require a nerve stimulator, it can be performed very quickly, it is not very stimulating, and patients often do not require sedation. It is useful in procedures involving the hip, thigh, and knee. A catheter for continuous infusion may be placed for analgesia in the postoperative period. • Complications • Some anesthesiologists have reservations regarding the block's consistency, reliability, and adequacy. Complications for this block are similar to those for other peripheral nerve blocks.
  36. 36. Lateral Femoral Cutaneous Block • Anatomy • The lateral femoral cutaneous nerve (L2–3) departs from the lumbar plexus, transverses laterally from the psoas muscle, and courses anterolaterally along the iliacus muscle. It emerges inferior and medial to the anterior superior iliac spine to supply the cutaneous sensory innervation of the lateral thigh. • Technique • (Figure 17–24) The block is performed via a field injection technique with 10–12 mL of local anesthetic at a mark approximately 2 cm distal and 2 cm medial to the anterior iliac spine. With insertion of a 2-in, 22-gauge needle, a "pop" may be felt as the needle passes through the fascia lata. This block is accomplished by repeatedly reinserting the needle while injecting local anesthetic above and below the fascia in a lateral to medial direction. • Lateral femoral cutaneous nerve block. Indications • This nerve may be blocked concurrently with a femoral nerve block or a fascia iliaca block and certainly is included with a lumbar plexus block. For a skin or muscle biopsy or a harvest site for a skin graft from the lateral thigh, an isolated block of this nerve may be performed. • Complications • Complications with this block are few as the amount of local anesthetic injected is small, and the chance of intraneural injection unlikely, as would be for an intravascular injection.
  37. 37. Obturator Nerve Block • An obturator nerve block provides anesthesia to the medial thigh and muscle relaxation of the adductor muscles of the hip. It may be used for an adductor release procedure. • Anatomy • The obturator nerve exits the pelvis and enters the medial thigh through the obturator foramen, which lies beneath the superior pubic ramus. It supplies sensation to the medial thigh and the hip joint and motor innervation to the adductor muscles of the thigh. • Technique • A 4-in, 21-gauge needle is inserted through a skin wheal 1.5 cm lateral and 1.5 cm inferior to the pubic tubercle. As the needle is advanced in a posterior direction toward the superior pubic ramus, small amounts of local anesthetic are injected to decrease patient discomfort. Upon contacting bone, the needle is redirected in a lateral and caudal direction another 2–4 cm to enter the obturator foramen. An adductor motor response should be elicited. Once identified, and after reducing the stimulation to < 0.5 mA, witnessing fade of motor activity after injection of 1 mL of local anesthetic and a negative aspiration of blood, 15–20 mL of local anesthetic is administered.
  38. 38. • Obturator nerve block. Indications • This block is commonly performed as a compliment to additional blocks performed for knee surgery (eg, femoral and sciatic nerve blocks). Its role as an isolated block is limited, although it may be useful in the diagnosis of hip pain or to treat spasticity of the thigh adductors. • Complications • Careful aspiration and incremental dosing help avoid intravascular injection and systemic local anesthetic toxicity
  39. 39. Sciatic Nerve Block • Anatomy • The sciatic nerve originates from the lumbosacral trunk and is composed of nerve roots L4–5 and S1–3. It supplies sensory fibers to the posterior hip capsule as well as the knee. It provides motor activity to the hamstrings and to all the lower extremity muscles distal to the knee. It also provides all the sensory innervation to the lower extremity distal to the knee except along the anteromedial aspect, which is provided by the saphenous nerve. • Techniques • Classic or Posterior Approach • The patient is placed in a lateral decubitus position (Sim's position) with the operative extremity nondependent. Landmarks are the greater trochanter, the posterior superior iliac spine, and the sacral hiatus. A line is drawn from the greater trochanter to the posterior superior iliac spine and a second line is drawn from the greater trochanter to the sacral hiatus. The midpoint along the line of the greater trochanter–posterior superior iliac spine is marked and a perpendicular line is drawn caudad. The intersection of this line and the greater trochanter–sacral hiatus line (approximately 5 cm) is the insertion point for the block.
  40. 40. • Sciatic nerve block, posterior approach. PSIS, posterior superior iliac spine. The operator advances a 4-in, 21-gauge insulated stimulating needle in a direction perpendicular to the skin. After encountering gluteal muscle stimulation, the needle is inserted further as a motor response is sought in the distal ankle, foot, or toes. Once identified, and after reducing the stimulation to < 0.5 mA, witnessing fade of motor activity after injection of 1 mL of local anesthetic and a negative aspiration of blood, 20–25 mL of local anesthetic is delivered. This approach readily accommodates placement of a perineural catheter for continuous infusion in the postoperative setting. • Lithotomy Approach • As the sciatic nerve courses from the pelvis to the leg, it characteristically travels between the ischial tuberosity and the greater trochanter. Taking advantage of this consistent course and the nerve's relatively superficial location, the patient is placed in a supine position with the hip and knee flexed (lithotomy position). In this position, the midpoint between the ischial tuberosity and the greater trochanter is identified and marked. A 4-in, 21-gauge insulated stimulating needle is inserted at the mark and advanced perpendicular to the skin.
  41. 41. • A motor response is sought in the distal ankle, foot, or toes. Once identified, and after reducing the stimulation to < 0.5 mA, witnessing fade of motor activity after injection of 1 mL of local anesthetic and a negative aspiration of blood, 15–20 mL of local anesthetic is delivered. • Sciatic nerve block, lithotomy approach. Anterior Approach • The sciatic nerve can also be blocked using an anterior thigh approach. This approach minimizes patient movement, requires less preparation time (as it is often combined with the same preparation for a femoral block), and therefore theoretically can be placed more quickly. However, this approach is technically more challenging. Of all the procedures used to block the sciatic nerve, this involves the greatest distance the needle must travel to reach its target, thus making the time needed to perform this block, particularly for the inexperienced, much longer. To perform this block the patient is placed in a supine position with the legs in a slight internal rotation (this maneuver rotates the lesser trochanter posteriorly and out of the line of sight for needle passage). A common approach begins by identifying landmarks similar to those used for a femoral nerve block. The inguinal ligament is identified and marked (drawing a line between the anterior superior iliac spine and the pubic tubercle). A second line is drawn parallel to the inguinal ligament starting from the greater trochanter and going medially across the anterior thigh (this line connects the greater and the lesser trochanter). •
  42. 42. • The inguinal ligament line is then divided into thirds. At the junction of the medial and middle thirds a perpendicular line is drawn that intersects the greater trochanter line at a right angle. At this point of intersection, a 4-in, 21-gauge insulated stimulating needle is inserted.. • As the needle is advanced, a motor response is sought in the distal ankle, foot, or toes. Once identified, and after reducing the stimulation to < 0.5 mA, witnessing fade of motor activity after injection of 1 mL of local anesthetic and a negative aspiration of blood, 15–20 mL of local anesthetic is delivered • Sciatic nerve block, anterior approach. Indications • Blockade of the sciatic nerve is useful for many surgical procedures involving the hip, knee, or distal lower extremity. The nerve can be successfully blocked at numerous sites along its course. • Complications • Partial block due to an injection distal to the branching of the sciatic nerve and intraneural injection are the most frequent complications
  43. 43. Popliteal Block • Anatomy • The sciatic nerve divides into the tibial and common peroneal nerves, high in the popliteal fossa. The upper popliteal fossa is bounded laterally by the biceps femoris tendon and medially by the semitendinosus and semimembranosus tendons. Cephalad to the flexion crease of the knee, the popliteal artery is immediately lateral to the semitendinosus tendon. The popliteal vein is lateral to the artery, and the tibial and common peroneal nerves (within a sheath) are just lateral to the vein and medial to the biceps tendon, 4–6 cm deep to the skin. The tibial nerve continues deep behind the gastrocnemius muscle, whereas the common peroneal nerve leaves the popliteal fossa by passing between the head and neck of the fibula to supply to the lower leg. • Techniques • There are two main approaches for performing this block: the posterior approach and the lateral approach. • Posterior Approach • This is the traditional approach used to block the sciatic nerve at this level. The block is performed after placing the patient in the prone position. The popliteal fossa is identified as a triangle by outlining the borders of the biceps femoris laterally, the semitendinosus and semimembranosus medially, and the popliteal crease inferiorly.
  44. 44. • At the midpoint along the popliteal crease, a perpendicular line is drawn cephalad approximately 8–10 cm in length, bisecting the popliteal triangle. A mark is made 1 cm from the apex and 1 cm lateral for needle insertion. At this mark, a 2-in, 22- gauge insulated stimulating needle is inserted. As the needle is advanced, a motor response is sought in the distal ankle, foot, or toes. Once identified, and after reducing the stimulation to < 0.5 mA, witnessing fade of motor activity after injection of 1 mL of local anesthetic and a negative aspiration of blood, 30–40 mL of local anesthetic is delivered. • Lateral Approach • An advantage of this approach is that the patient remains supine for the procedure. The lateral approach is performed by palpating the intertendinous groove between the vastus lateralis and the biceps femoris muscles approximately 10–12 cm proximal to the superior notch of the patella. With a 4-in, 21-gauge insulated stimulating needle advanced at 30°, posteriorly angled, a motor response is sought in the distal ankle, foot, or toes. Once identified, and after reducing the stimulation to < 0.5 mA, witnessing fade of motor activity after injection of 1 mL of local anesthetic and a negative aspiration of blood, 30–40 mL of local anesthetic is injected.
  45. 45. • Indications • A popliteal nerve block is very useful for foot and ankle surgery and can result in complete anesthesia of the limb distal to the knee if a separate saphenous nerve block (terminal nerve of the femoral nerve) is also included. This block can accommodate placement of a catheter for continuous perineural infusion for postoperative analgesia and in an increasing number of ambulatory centers patients may be dismissed home with such infusions. • Complications • Intravascular or intraneural injections are possible
  46. 46. Saphenous Nerve Block • Anatomy • The saphenous nerve is the terminal extension of the femoral nerve and provides sensory innervation along the medial aspect of the lower leg between the knee and the medial malleolus. • Technique • Infiltrate subcutaneously 7–10 mL of local anesthetic starting from the tibial tuberosity and directed medially, completing the infiltration near the posterior aspect of the leg. • Saphenous nerve block. • Indications • This is not commonly performed as an isolated block, but rather in conjunction with a popliteal block to complete the anesthesia for procedures done below the knee. • Complications • Complications are the same as for other field blocks.
  47. 47. Nerve Blocks at the Ankle • Four of the five individual nerves that can be blocked at the ankle to provide anesthesia of the foot are terminal branches of the sciatic nerve: the posterior tibial, sural, superficial peroneal, and deep peroneal branches. The sciatic nerve divides at or above the apex of the popliteal fossa to form the common peroneal and tibial nerves. The common peroneal nerve descends laterally around the head of the fibula, where it divides into the superficial and deep peroneal nerves. • The tibial nerve divides into the posterior tibial and sural nerves in the lower part of the leg. The posterior tibial nerve becomes superficial at the medial border of the Achilles tendon near the artery of the same name, and the sural nerve emerges lateral to the Achilles tendon. • Clinical Applications • Ankle blocks are simple to perform and offer adequate anesthesia for surgical procedures on the foot that do not require a tourniquet above the ankle.
  48. 48. Technique • Posterior Tibial Nerve • The posterior tibial nerve can be blocked with the patient in either the prone or the supine position. The posterior tibial artery is palpated, and a 25-gauge, 3-cm needle is inserted posterolateral to the artery at the level of the medial malleolus ( Fig. 52-23A and B ). A paresthesia is often elicited but is not necessary for a successful block. If a paresthesia occurs, 3 to 5 mL of local anesthetic should be injected. Otherwise, 7 to 10 mL of solution should be injected as the needle is slowly withdrawn from the posterior aspect of the tibia. Blockade of the posterior tibial nerve provides anesthesia to the heel, plantar portion of the toes, and the sole of the foot, as well as some motor branches in the same area. • Sural Nerve • The sural nerve is located superficially between the lateral malleolus and the Achilles tendon. A 25-gauge, 3-cm needle is inserted lateral to the tendon and directed toward the malleolus as 5 to 10 mL of solution is injected subcutaneously . This block provides anesthesia to the lateral part of the foot and the lateral proximal aspect of the sole of the foot.
  49. 49. • Deep Peroneal, Superficial Peroneal, and Saphenous Nerves • The deep peroneal, superficial peroneal, and saphenous nerves can be blocked through a single needle entry site . A line is drawn across the dorsum of the foot connecting the malleoli. The extensor hallucis longus tendon is identified by having the patient dorsiflex the big toe. The anterior tibial artery lies between this structure and the tendon of the extensor digitorum longus muscle and is palpable at this level. A skin wheal is raised just lateral to the pulsation between the two tendons on the intermalleolar line. A 25-gauge, 3-cm needle is advanced perpendicular to the skin entry site, and 3 to 5 mL of local anesthetic is injected deep to the extensor retinaculum to block the deep peroneal nerve. This technique anesthetizes the skin between the first and second toes and the short extensors of the toes. • The needle is directed laterally through the same skin wheal while injecting 3 to 5 mL of solution subcutaneously, which blocks the superficial peroneal nerve and results in anesthesia of the dorsum of the foot, excluding the first interdigital cleft. The same maneuver can be performed in the medial direction to anesthetize the saphenous nerve, a terminal branch of the femoral nerve that supplies a strip along the medial aspect of the foot.
  50. 50. • Side Effects and Complications • The multiple injections required for some techniques result in discomfort for the patient. Persisting paresthesias may occur, but they are self-limited. The presence of edema or induration in the area of the ankle block can make palpation of landmarks difficult. Intravascular injection is possible but unlikely if aspiration for blood is negative. The volume of local anesthetic used is small, thereby decreasing the risk for local anesthetic toxicity.
  51. 51. Somatic Blockade of the Trunk • Superficial Cervical Plexus Block • The superficial cervical plexus block is performed for unilateral procedures on the neck, such as carotid endarterectomy. This block is also done as an adjunct to an interscalene block used for shoulder surgery, particularly with very anterior incisions. • Anatomy • The cervical plexus is formed from the anterior rami of C1–4, which emerge from the platysma muscle posterior to the sternocleidomastoid muscle. It supplies sensation to the jaw, neck, the occiput posteriorly, and areas of the chest and shoulder close to the clavicle. • Technique • The patient is positioned supine with the neck slightly turned, and the posterior border of the sternocleidomastoid muscle is identified. A 22-gauge spinal needle is selected; the sternocleidomastoid is divided into thirds, and at the junction of the upper and middle thirds, a skin wheal is raised. The spinal needle is directed cephalad toward the mastoid along the posterior border of the sternocleidomastoid in a subcutaneous plane and injected with 2–3 mL of local anesthetic as the needle is withdrawn. Care is taken to avoid entering the external jugular vein. As the needle reaches the wheal, it is rotated 180° and directed subcutaneously caudad toward the clavicle along the posterior border of the sternocleidomastoid. A similar amount of local anesthetic is injected as the needle is withdrawn. • Complications • Rapid systemic absorption and intravascular injection of local anesthetic.
  52. 52. Intercostal Block • Intercostal blocks are rarely employed as the sole anesthetic technique for surgery. commonly used as postoperative analgesia following thoracic and upper abdominal surgery, and for relief of pain associated with rib fractures, herpes zoster, and cancer. • Anatomy • The intercostal nerves arise from the dorsal and ventral rami of the thoracic spinal nerves. They exit from the spine at the intervertebral foramen and enter a groove on the underside of the corresponding rib, running with the intercostal artery and vein; the nerve is generally the most inferior structure in the neurovascular bundle. Branches are given off for sensation in the correct dermatome from the midline dorsally all the way to across the midline ventrally. • Technique • With the patient in the lateral decubitus or supine position, the level of each rib is palpated and marked in the mid and posterior axillary line. A skin wheal is raised over the inferior border at the selected ribs, and a 22- to 25-gauge needle is inserted down to the inferior edge of the rib and "walked-off" until it steps off the rib inferiorly. The needle is advanced 0.5 cm underneath the rib, and following a negative aspiration (for blood or air), 3–5 mL of local anesthetic is injected at each level.
  53. 53. • Complications • Intercostal blocks result in the highest blood levels of local anesthetic per volume injected of any block in the body. Care must be taken to avoid toxic levels of local anesthetic. Careful aspiration may help prevent intravascular injection. The risk of pneumothorax is obvious, and any indication of entering the chest should be investigated with a chest radiograph.
  54. 54. Celiac Plexus Block • Clinical Applications • A celiac plexus block can be combined with an intercostal block to provide anesthesia for intra-abdominal surgery. Because it results in blockade of the autonomic nervous system, this block may help reduce stress and endocrine responses to surgery. • Anatomy and Technique • The celiac plexus contains visceral afferent and efferent fibers derived from T5 to T12 by means of the greater, lesser, and least splanchnic nerves. The plexus has no somatic fibers and is composed of a number of ganglia and nerve fibers. It innervates most of the abdominal viscera. Knowledge of the surrounding structures is important for correct needle placement. The plexus lies in close relation to the L1 vertebra. The vena cava lies anteriorly to the right, and on the left anteriorly is the aorta. The kidneys lie laterally, with the pancreas anterior. The number of ganglia varies from one to five, and each ganglion is 0.5 to 4.5 cm in diameter. Left-sided ganglia are usually lower than those on the right.
  55. 55. • Bony surface landmarks can be used reliably for needle placement. With the patient in the prone position and a pillow beneath the abdomen, lines are drawn connecting the spine of T12 with points 7 to 8 cm laterally at the lower edges of the 12th ribs. These lines form a flattened isosceles triangle, the equal sides of which serve as directional guides for the needles ( Fig. 52-33B ). A 20-gauge, 10- to 15-cm needle is inserted on the left side through a skin wheal at a 45-degree angle toward the body of T12 or L1. Bone contact should be made at an average depth of 7 to 9 cm. The needle is then withdrawn and reinserted to allow the tip to slide off the vertebral body anterolaterally. The needle is advanced 1.5 to 2 cm past this point; aortic pulsations can be felt as they are transmitted along the needle when it is correctly placed (see Fig. 52-33 ). After this depth is ascertained, the right-sided needle is inserted in similar fashion to a depth of 1.0 to 1.5 cm farther (see Fig. 52- 33A ). When the needles are in position, observation for leakage of blood, urine, or cerebrospinal fluid is made before careful aspiration. A 3- to 5-mL test dose of local anesthetic is given before injection of 20 to 25 mL of solution through each needle. • Side Effects and Complications • Side effects associated with celiac plexus blockade include hypotension; spinal, epidural, or intravascular injection; pneumothorax; puncture of viscera, such as the kidney, ureter, or gut; and retroperitoneal hematoma.
  56. 56. Paravertebral Nerve Blocks • Initially described in the early 1900s, paravertebral blocks were popularized in the 1930s as a means to provide analgesia for labor. Although this approach was largely replaced with more effective alternate treatments for labor, today paravertebral nerve blocks are being increasingly used as an effective technique for postoperative analgesia following mastectomy, inguinal hernia repair, and several procedures involving the chest and body wall. • Anatomy • Each spinal nerve emerges from the intervertebral foramina and divides into two rami: a larger anterior ramus, which innervates the muscles and skin over the anterolateral body wall and limbs, and a smaller posterior ramus, which reflects posteriorly and innervates the skin and muscles of the back and neck. The thoracic paravertebral space is defined posteriorly by the superior costotransverse ligament, anterolaterally by the parietal pleura, medially by the vertebrae and the intervertebral foramina, and inferiorly and superiorly by the heads of the ribs.
  57. 57. • Technique • The paravertebral nerve block is performed first by having the patient placed in a sitting position, similar to that for a sitting epidural. The spinous processes are identified, starting with the most obvious lower cervical vertebra in the neck, C7 or "vertebra prominens." Each process is marked along its superior aspect. From the midpoint of the superior aspect of each spinolus process, it is necessary to measure 2.5 cm laterally and mark these points. These are the insertion points for the blocks and because of the pronounced inferior angulation of the thoracic spinous processes these marks generally overlie the transverse process of the next vertebrae below, ie, a mark across from the T4 spinous process overlies the transverse process of T5.
  58. 58. • At each insertion point a 22-gauge Tuohy needle is advanced in a perpendicular fashion approximately 3 cm initially, seeking to contact the transverse process. If bone is encountered (transverse process), the needle is withdrawn and redirected caudad and advanced an additional 1 cm. A "pop" may be felt as the needle passes through the costotransverse ligament. Following a negative aspiration, 4 mL of local anesthetic is delivered. This step is repeated for each level being blocked. If bone is not encountered with the initial pass, the needle is withdrawn and redirected caudad and inserted the same distance (ie, 3 cm), again seeking contact with the transverse process. Failure to contact bone with this pass requires redirection of the needle in a cephalad angulation, again inserting it the same depth while searching for bone contact. Failure to contact bone after this three-pass sequence (midline, caudad, and cephalad at the same depth) necessitates repeating this sequence at an added depth of 1 cm. This three-pass sequence with the addition of 1 cm in depth may be repeated until contact with bone is achieved. Once bone contact is made, from that site and depth, the needle is withdrawn and redirected caudad and advanced an additional 1 cm to enter the paravertebral space. Subsequent levels are approximately similar in depth, except for the upper thoracic, which tends to lie deeper. Lumbar paravertebral blocks are performed in a similar fashion. However, the transverse processes are thinner than their thoracic counterparts; therefore, after making bone contact and redirecting the needle caudad, the needle is advanced only an additional 0.5 cm in depth.
  59. 59. • Indications • Paravertebral nerve blocks require individual injections delivered at the various vertebral levels that correspond to the area of body wall to be anesthetized. For example, a simple mastectomy would require blocks at levels T3–6; for axillary node dissection, additional injections should be made at T1 and T2. For inguinal hernia repair, blocks should be performed at T10 through L1. • Complications • The most common complication of thoracic paravertebral block is pneumothorax, which is related to the number of levels and the experience of the operator. If air is aspirated, a chest radiograph is mandatory. Intravascular injection and failed block are other possible problems.
  60. 60. Inguinal Nerve Block • Anatomy • The ilioinguinal and iliohypogastric nerves arise primarily from L1 but may derive fibers from T12. The iliohypogastric nerve splits into two branches prior to becoming cutaneous. The lateral branch is sensory to the lateral aspect of the buttock and hip. The anterior branch becomes superficial just medial to the anterior superior iliac spine, where it sends off a network of branches that innervates the lower abdomen. The ilioinguinal nerve follows the same course and exits the peritoneum to enter the inguinal canal, where it provides sensation to the scrotum, penis, and medial thigh in the male, or an equivalent area of the labia and mons pubis in the female. Both nerves pierce the transversalis abdominis and internal oblique muscles approximately 2 cm medial to the anterior superior iliac spine. The genitofemoral nerve is derived from L1 and L2. Its femoral branch travels with the femoral artery to provide cutaneous sensation just below the inguinal ligament, whereas its genital branch travels in the inguinal canal to supply the scrotum in men and the labium majus in women. •
  61. 61. • Technique • A skin wheal is raised 2 cm medial to the upper aspect of the anterior superior iliac spine, and a 22-gauge, 3.5-in spinal needle is inserted perpendicular to the skin until it is just under the fascia, and 8–10 mL of anesthetic is injected fanwise to block both the ilioinguinal and iliohypogastric nerves. The genital branch of the genitofemoral nerve is blocked with 2–3 mL of local anesthetic injected just lateral to the pubic tubercle; the femoral branch can be anesthetized with 3–5 mL of local anesthetic injected subcutaneously just below the inguinal ligament. • Indications • Ilioinguinal and iliohypogastric blocks can be used for inguinal or genital operations, such as inguinal herniorrhaphy or orchiopexy, or for postoperative pain relief. Supplementation with a genitofemoral nerve block may be necessary. • Complications • Patient discomfort and persistent paresthesia from intraneural injection are potential sequelae.
  62. 62. • Penile Block • Anatomy • Innervation of the penis is derived from the pudendal nerve, which gives off the dorsal nerve of the penis bilaterally. It enters the penis deep to Buck's fascia and divides into dorsal and ventral branches. The genitofemoral and ilioinguinal nerves may additionally provide sensation to the base of the penis via subcutaneous branches. • Technique • A fan-shaped (triangular) field block with 10–15 mL of local anesthetic injected at the base of the penis and 2–4 cm lateral to the base on both sides of the penis can block the sensory nerves without risk of vascular injury. If more profound block is necessary, or if extensive surgery is planned, the dorsal nerve is blocked just lateral to the base of the penis bilaterally with a 25-gauge, ¾- to 1-in needle just penetrating Buck's fascia at the 10:30 and 1:30 o'clock positions; 1 mL of local anesthetic is injected on each side, with care taken to avoid pressure. Epinephrine or other vasoconstrictors should be avoided to prevent end artery spasm and ischemic injury.
  63. 63. • Indications • Penile block is performed for penile surgery or postoperative pain relief afterward. • Complications • Careful aspiration is necessary to avoid intravascular injection. Injecting large volumes of local anesthetic or epinephrine-containing solutions may compromise blood flow to the penis.
  64. 64. Blocks of the Head and Neck • Regional anesthesia of the head and neck has become less popular as safer methods of general anesthesia have been developed. • Trigeminal Nerve Block • The trigeminal nerve divides into three main branches in the middle cranial fossa. These divisions—the ophthalmic, maxillary, and mandibular nerves—provide sensation to the eye and forehead, midface and upper jaw, and lower jaw, respectively ( Fig. 52-25A ). With the exception of motor fibers to the muscles of mastication, carried by the mandibular nerve, these nerves are wholly sensory. • A gasserian ganglion block, approached classically through the foramen ovale, is infrequently used for producing surgical anesthesia. In the past, it was primarily applied for the diagnosis and treatment of trigeminal neuralgia; however, the increasing popularity and safety of thermocoagulation for ablation of the ganglion have rendered neurolytic blocks obsolete. • Clinical Applications • Blockade of the second and third divisions of the trigeminal nerve, as well as blockade of the peripheral branches, is occasionally useful in the diagnosis and management of pain syndromes and for discrete surgical procedures in selected patients
  65. 65. • Technique: Mandibular and Maxillary Nerves • The mandibular and maxillary nerves, two divisions of the trigeminal nerve, can be blocked through the same needle entry site (see Fig. 52-25B ). The maxillary nerve (i.e., second division) is blocked as it exits the skull through the foramen rotundum and crosses the pterygopalatine or infratemporal fossa between the skull and the upper jaw. The nerve terminates as the infraorbital nerve as it exits through the infraorbital foramen, where it can also be anesthetized. • The coronoid notch of the mandible is located, and with the patient's mouth closed, a 22-gauge, 8-cm needle is inserted at the inferior edge of the coronoid notch perpendicular to the skin entry site. The needle contacts the lateral pterygoid plate at a depth of about 5 cm. It is then withdrawn and redirected anteriorly and superiorly to walk off the plate and is subsequently advanced approximately 0.5 cm into the pterygopalatine fossa (see Fig. 52-25C ). Between 3 and 5 mL of local anesthetic solution produces anesthesia of the upper jaw and skin of the lower eyelid, cheek, and upper lip. • The mandibular nerve (i.e., third division) leaves the cranium through the foramen ovale and innervates the skin of the lower jaw and the skin anterior and superior to the ear by its posterior division. Peripheral sensory branches of cranial nerve V3 include the buccal, auriculotemporal, lingual, and inferior alveolar (terminating in the mental nerve) nerves. The anterior division supplies motor innervation to the muscles of mastication. • The mandibular nerve is blocked through the same entry site as the maxillary nerve. The needle is advanced along the inferior margin of the coronoid notch until the bone of the lateral pterygoid plate is contacted (about 5 cm). The needle is withdrawn and redirected to walk off the posterior border of the pterygoid plate, and it is advanced in an attempt to elicit a paresthesia. The needle should not be inserted farther than 0.5 cm past the plate (see Fig. 52-25D ). Injection of 3 to 5 mL of local anesthetic solution at this site is adequate. • Side Effects and Complications • Blockade of the maxillary nerve can be associated with hematoma formation and spread of the local anesthetic solution to the optic nerve, thereby causing temporary blindness. A mandibular nerve block is not associated with major complications. If the needle is advanced past the pterygoid plate more than the recommended 0.5 cm, the pharynx may be entered, which increases the risk of contaminating the infratemporal fossa. Rarely, subarachnoid spread of local anesthetic may occur and result in brainstem anesthesia
  66. 66. • Cervical Plexus Blockade • The cervical plexus is derived from the C1, C2, C3, and C4 spinal nerves and supplies branches to the prevertebral muscles, strap muscles of the neck, and phrenic nerve. The deep cervical plexus supplies the musculature of the neck segmentally and the cutaneous sensation of the skin between the trigeminally innervated face and the T2 dermatome of the trunk. Blockade of the superficial cervical plexus results in anesthesia of only the cutaneous nerves. • Clinical Applications • Blockade of the cervical plexus is easy to perform and provides anesthesia for surgical procedures in the distribution of C2 to C4, including lymph node dissection, plastic repair, and carotid endarterectomy. The ability to monitor the awake patient's neurologic status continuously is an advantage of this anesthetic technique for the latter procedure and has resulted in an upsurge in popularity of this technique.[74] Bilateral blocks can be used for tracheostomy and thyroidectomy. • Technique
  67. 67. • Technique • Superficial Cervical Plexus • The superficial cervical plexus is blocked at the midpoint of the posterior border of the sternocleidomastoid muscle. A skin wheal is raised at this point, and a 22-gauge, 4-cm needle is advanced while injecting 5 mL of solution along the posterior border and medial surface of the sternocleidomastoid muscle ( Fig. 52-27 ). It is possible to block the accessory nerve with this injection, which results in temporary paralysis of the ipsilateral trapezius muscle. • Deep Cervical Plexus • The deep cervical plexus block is a paravertebral block of the C2 to C4 spinal nerves as they emerge from their foramina in the cervical vertebrae ( Fig. 52-28 ). The traditional approach involves the use of three separate injections at C2, C3, and C4. The patient lies supine with the neck slightly extended and the head turned away from the side to be blocked. A line is drawn connecting the tip of the mastoid process and the Chassaignac tubercle (i.e., transverse process of C6); a second line is drawn 1 cm posterior to the first line. The C2 transverse process lies 1 to 2 cm caudad to the mastoid process, where it can usually be palpated. The C3 and C4 transverse processes lie at 1.5-cm intervals along the second line. After skin wheals are raised over the transverse processes of C2, C3, and C4, three 22-gauge, 5-cm needles are advanced perpendicular to the skin entry site at a slight caudad angulation. The transverse process is contacted at a depth of 1.5 to 3 cm. If a paresthesia is obtained, 3 to 4 mL of solution is injected after careful aspiration for blood and cerebrospinal fluid. If no paresthesia is elicited initially, the needle is walked along the transverse process in the anteroposterior plane until a paresthesia is obtained.
  68. 68. • This block can also be performed with a single injection of 10 to 12 mL at the C4 transverse process.[75] Cephalad spread of the local anesthetic usually anesthetizes the C2 and C3 nerves. Cervical plexus anesthesia can also be observed after injection at the interscalene level for brachial plexus blockade. Maintenance of distal pressure and a horizontal or slightly head-down position may facilitate the onset of cervical plexus blockade via the interscalene technique. • Side Effects and Complications • Although these blocks are technically straightforward, needle placement for a deep cervical block allows injection of local anesthetic in close proximity to a variety of neural and vascular structures. Reported complications and side effects include intravascular injection, blockade of the phrenic and superior laryngeal nerve, and spread of local anesthetic solution into the epidural and subarachnoid spaces.
  69. 69. • Stellate Ganglion Block • Clinical Applications • Blockade of the stellate ganglion is used primarily for the treatment of upper extremity sympathetic dystrophy and to increase blood flow to this area ( Chapter 58 ). • Technique • The patient lies supine with the neck extended slightly. The most prominent cervical transverse process—the Chassaignac tubercle (C6)—is palpated between the sternocleidomastoid muscle and the trachea. The C6 tubercle is palpated between the index and middle fingers and the carotid artery is pushed laterally. A skin wheal is raised between the fingers over the tubercle, and a 22-gauge, 4-cm short-beveled needle with a 12-mL syringe attached is inserted in a perpendicular direction until the tip contacts the C6 transverse process ( Fig. 52-31 ). The needle is then withdrawn 3 mm and fixed. After careful aspiration, 8 to 12 mL of local anesthetic solution is injected. Signs of a successful stellate ganglion block include Horner's syndrome, anhidrosis, injection of the conjunctiva, nasal stuffiness, vasodilation, and increased skin temperature. • Side Effects and Complications • Because of the proximity of several major neural and vascular structures to the site of needle insertion, side effects and complications can occur, including block of the brachial plexus and recurrent laryngeal nerves, hematoma formation, intravascular injection resulting in convulsions, and epidural and subarachnoid injection.[80]

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