brachial plexus blocks

brachial plexus blocks

1. BRACHIAL PLEXUS BLOCK Dr.Charulatha.R MD Fellowship in Regional A naesthesia

2. ANATOMY BRACHIAL PLEXUS Anterior primary divisions (ventral rami ) of 5 th Cervical nerves to 1 st Thoracic nerves . Contributions from C4 and T 2 are often minor or absent. Leaving 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. The superior trunk is predominantly derived from C 5–6 , the middle trunk from C7, and the inferior trunk from C8–T 1 . As the trunks pass over the lateral border of the first rib and under the clavicle, each trunk divides into anterior and posterior divisions.

3. ANATOMY BRACHIAL PLEXUS

4. 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. The lateral cord is the union of the anterior divisions of the superior and middle trunks; the medial cord is the continuation of the anterior division of the inferior trunk; and the 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. The lateral cord gives off the lateral branch of the Median nerve - Musculocutaneous nerve ; The Medial cord gives off the medial branch of the median nerve - Ulnar nerve. The Posterior cord gives off the Axillary nerve and terminates as the Radial nerve

5. DERMATOMES

6. Brachial Plexus Block

7. ELICITATION OF PARAESTHESIA When a needle makes direct contact with a sensory nerve, a paresthesia is elicited in its area of sensory distribution. Needle should contact with the nerve rather than penetrating it, and that the injection is in proximity to the nerve ( perineural ) rather than within its substance ( intraneural ). The high pressures generated by a direct intraneural injection can cause hydrostatic (ischemic) injury to nerve fibers. A Perineural injection may produce a brief accentuation of the paresthesia , whereas an Intraneural injection produces an intense, searing pain that serves as a warning to immediately terminate the injection and reposition the needle.

8. NERVE STIMULATION One lead of a low-output nerve stimulator is attached to a needle and the other lead is grounded elsewhere on the patient. The special needles that are used are insulated and permit current flow only at the tip for precise localization of nerves , whereas the nerve stimulators used deliver a linear, constant current output of 0.1–6.0 mA . Muscle contractions occur and increase in intensity as the needle approaches the nerve and diminish when the needle moves away. Moreover, the evoked contractions require much less current as the needle approaches the nerve. Optimal positioning produces evoked contractions with 0.5 mA or less, but successful blocks can often be obtained with needle positions that produce contractions with as much as 1  mA . Characteristically, the evoked response rapidly diminishes (fades) after injection of 1–2 mL of local anesthetic

9. INTERSCALENE BLOCK Interscalene block (classic anterior approach) is especially effective for surgery of the Shoulder or Upper arm. The roots of the brachial plexus are most easily blocked with this technique. This block is ideal for reduction of a dislocated shoulder and often can be achieved with as little as 10 to 15 mL of local anesthetic. The block also can be performed with the arm in almost any position and thus can be useful when brachial plexus block needs to be repeated during a prolonged upper extremity procedure

10. Surface Anatomy Surface anatomy of importance to anesthesiologists includes that of the larynx, sternocleidomastoid muscle, and external jugular vein. Interscalene block is most often performed at the level of the C6 vertebral body, which is at the level of the cricoid cartilage. Thus, by projecting a line laterally from the cricoid cartilage, the level at which one should roll the fingers off the sternocleidomastoid muscle onto the belly of the anterior scalene and then into the interscalene groove can be identified. With firm pressure, it is possible to feel the transverse process of C6 in most individuals, and in some people it is possible to elicit a paresthesia by deep palpation .

11. INTERSCALENE BLOCK SURFACE ANATOMY

12. ANATOMY It is always important to visualize what lies under the palpating fingers, and again the key to carrying out successful Interscalene block is identifying the Interscalene groove. We should make out from the surface anatomy, how closely the lateral border of the anterior scalene muscle deviates from the border of the Sternocleidomastoid . . The anterior scalene muscle and the Interscalene groove are oriented at an oblique angle to the long axis of the Sternocleidomastoid muscle.

13. APPLIED ANATOMY INTERSCALENE BLOCK Vertebral artery beginning its route towards the brain at the level of the C6 through the root of the transverse process of Cervical vertebrae .

14. POSITONING The patient lies supine with the neck in the neutral position and the head turned slightly opposite the site to be blocked. The anesthesiologist then asks the patient to lift the head off the table to tense the sternocleidomastoid muscle and allow identification of its lateral border. The fingers then roll onto the belly of the anterior scalene muscle and subsequently into the interscalene groove. This maneuver should be carried out in the horizontal plane through the cricoid cartilage—that is, at the level of C6. To roll the fingers effectively , the operator should stand at the patient’s side.

15. INTERSCALENE BLOCK When the interscalene groove has been identified and the operator’s fingers are firmly pressing into the interscalene groove, the needle is inserted in a slightly caudal and slightly postero -medial direction . As a further directional help, if the needle for this block is imagined as being quite long and if it is inserted deeply enough, it would exit the neck posteriorly in approximately the midline at the level of the C7 or T1 spinous process

16. DIFFICULT SURFACE ANATOMY If there is difficulty identifying the anterior scalene muscle, one maneuver is to have the patient maximally inhale while the anesthesiologist palpates the neck. During this maneuver the scalene muscles should contract before the sternocleidomastoid muscle , which may allow clarification of the anterior scalene muscle in the difficult-to-palpate neck. If the right side of the neck is divided into a 180 -degree arc, the needle entry site should be approximately 60 degrees from the sagittal plane to optimize the block .

17. Injection CONFIRMATON : 1. By Eliciting paraesthesia in the arm. 2 . If using a nerve stimulater , activity of the Phrenic nerve indicates needle is too anterior, whereas stimulation of Trapezius – needle is too posterior. Motor activity of the arm, wrist or hand should be sought . After confirmation & negative aspiraton inject the L.A. slowly in a free flowing manner. If there is any resistance to the flow, u might be injecting in the nerve bundle.

18. INTERSCALENE BLOCK Most of the injection difficulties that result in complications of the block can be avoided if one remembers that it should be an extremely “superficial” block; if the palpating fingers apply Sufficient pressure, no more than 1 to 1.5 cm of the needle should be necessary to reach the plexus. Local Anaesthetic : Bupivacaine 0.5 %, Ropivacaine 0.5 % with Adr ( 1 : 200000 ). Volume 35-40 ml . Duration : 12-18 Hrs Potential Problems : Common - Phrenic nerve palsy ( dyspnoea ), Honer syndome , Recurrent LN Block (Hoarseness) Rare - Vertebral artery injection ( Siezures ) , Pneumothorax , Inadvertant spninal & epiduralBlock . Contraindications : Pt. with Sigificant Lung Ds.

19. Supraclavicular approach Supraclavicular block provides anesthesia of the entire upper extremity in the most consistent, time-efficient manner of any brachial plexus technique. It is the most effective block for all portions of the upper extremity and is carried out at the “division” level of the brachial plexus .

20. SUPRACLAVICULAR BLOCK

21. ANATOMY As the Subclavian artery and brachial plexus pass over the first rib, they do so between the insertion of the anterior and middle scalene muscles onto the first rib . The nerves lie in cephaloposterior relation to the artery ; thus, paresthesia may be elicited before the needle contacts the first rib. At the point where the artery and plexus cross the first rib, the rib is broad and flat, sloping in a caudad direction as it moves from posterior to anterior; although the rib is a curved structure, there is a distance of 1 to 2 cm through which a needle can be walked in a parasagittal anteroposterior direction. Remember that immediately medial to this first rib is the cupola of the lung; and when the needle angle is too medial, pneumothorax may result

22. SUPRACLAVICULAR BLOCK Position Patient supine, arm at side, head turned away Technique 1 . Classical Approach (Winnie ) Subclavian perivascular : Needle inserted 2 cm posterior to the midpoint of the clavicle, Parallel to the neck , towards the ipsilateral nipple. Paraesthesia is elicited & after negative aspiration L.A is injected slowly without moving the needle

23. 2. “ Plumb-bob” approach Needle insertion: immediately superior to the clavicle, just lateral to the point where the Sternomastoid is inserted into the clavicle. Angle of needle entry is 90 deg to the table. Higher risk of Pneumothorax Phrenic nerve palsy Volume of L.A : 25-30 ml

24. SUPRACLAVICULAR BLOCK The most feared complication of the supraclavicular block is pneumothorax . Its principal cause is a needle/syringe angle that “aims” toward the cupola of the lung. Special attention should be directed toward walking the needle in a strictly anteroposterior direction

25. SITTING POSITION With the patient in the semi-sitting position and the shoulder down, the lateral (posterior) border of the SCM muscle is identified and followed distally to the point where it meets the clavicle. This particular point is marked on the skin over the clavicle

26. A parasagital line (parallel to the midline) is drawn at this level to recognize an area at risk of pneumothorax risk medial to it .

27. The point of needle entrance is found lateral to this parasagital plane separated by a distance k/a “margin of safety”. This distance is about 1 inch ( 2.5 cm) lateral to the insertion of the SCM in the clavicle or one “thumb breadth” lateral to the SCM

28. The needle is inserted immediately cephalad to the palpating finger and advanced first perpendicularly to the skin for 2-5 mm (depending on the amount of subcutaneous tissue in the patient) and then turned caudally under the palpating finger to advance it in a direction that is parallel to the midline.

29. SUPRACLAVICULAR BLOCK Phrenic nerve block occurs in probably 30 % to 50 % of patients, and the block’s use in patients with significantly impaired pulmonary function must be carefully weighed. The development of Hematoma after Supraclavicular block, as a result of puncture of the subclavian artery, usually requires only observation .

30. INFRA CLAVICULAR BOCK Block at the level of the cords Anesthesia or analgesia with this technique results in a “high” Axillary block Classical Infraclavicular Approach Needle inserted 2 cm Below the midpoint of the inferior clavicular border and advanced laterally towards the axilla at an angle 45 deg , until a paraesthesia is elicited

31. Coracoid (vertical) approach

32. With the arm abducted at the shoulder, the coracoid process is identified by palpation and a skin mark placed at its most prominent portion. The skin entry mark is then made at a point 2.5 cm medial and 2 cm caudad to the previously marked coracoid process . Deeper infiltration is performed with a 25 -gauge, 5 -cm needle while directing the needle from the insertion site in a vertical parasagittal plane . Then a 6 to 9.5 cm, 20 to 22 gauge needle is inserted in a direction similar to that taken by the infiltration needle.

33. If a Paresthesia technique is used, a distal upper extremity paresthesia is sought. If a nerve stimulator technique is used, a distal upper extremity motor response is sought. If needle redirection is needed , should be redirected in a Cephalocaudad arc . The depth of contact with the brachial plexus depends on body habitus and needle angulation ; It ranges from 2.5 to 3 cm in slender patients, 4-5 cm in larger pts.

34. INFRA CLAVICULAR BOCK Minimal risk of pneumothorax Radial & musculocutaneous nerves are reliably blocked Plain Bupivacaine 0.5 % and Ropivacaine 0.5 % produce surgical anesthesia lasting 4 to 6 hours; the addition of Epinephrine may prolong this period to 8 to 12 hours . Volume of LA: 20 - 30 ml

35. Continuos catheter tech.

36. Continuos Catheter Tech. Once a catheter is placed, the Infraclavicular catheter secured at its insertion site is much more effective than any other brachial plexus continuous catheter technique. This reason alone makes the Infraclavicular block, a preferred technique for continuous catheter brachial plexus analgesia

37. STIMULATING CATHETER

38. Axillary Approach Blocks the terminal branches Easy, reliable & safe Anatomy: Neurovascular bundle is multi compartmental Median, Ulnar & Radial nerves lie in close relation to the Axillary artery Musculocutaneous nerve lies in the substance of the Coracobrachialis , can be missed.

39. Axillary approach The Musculocutaneous nerve is found in the 9 to 12 o’clock quadrant in the substance of the Coracobrachialis muscle. The Median nerve is most often found in the 12 to 3 o’clock quadrant; The Ulnar nerve is “inferior” to the median nerve in the 3 to 6 o’clock quadrant; and The Radial nerve is located in the 6 to 9 o’clock quadrant

40. Position Supine position, arm to be blocked placed at right angle to the body with E lbow flexed to 90 deg Needle entry : Just superior to the pulsation of the axillary artery at the lateral border of pectoralis major muscle Musculocutaneous blocked by injecting LA in the belly of the coracobrachialis Transarterial technique : Hematoma Multiple injection techniques : I ncreases success in blocking musculocutaneous but H igher risk of neuropraxia

41. Axillary approach The axillary artery is identified with two fingers, and the needle is inserted superior And inferior to it. An effective axillary block is achieved by utilizing the axillary artery as an anatomic landmark and infiltrating the tissue around it in a fan-like manner

42. Axillary approach Local Anaesthetic : Bupivacaine 0.5 % with Adr . Volume 35-40 ml Anaesthesia duration: 5-6 hrs Analgesia : 12-24 hrs Problems : Neuropraxia , Intravascular injection, Haemtoma

43. CONINUOUS CATHETER TECH.

44. ASSESSMENT OF BLOCK

45. QUICK ASSESSMENT OF BLOCK “push, pull, pinch, pinch” To check the FOUR peripheral nerves of interest during a brachial plexus block. Ask the patient to resist the anesthesiologist’s pulling the forearm away from the upper arm, motor innervation to the Biceps muscle can be assessed. If this muscle has been weakened, one can be certain that the local anesthetic has reached the Musculocutaneous nerve. Likewise, by asking the patient to attempt to extend the forearm by contracting the Triceps muscle , one can assess the Radial nerve . Finally, pinching the fingers in the distribution of the Ulnar or Median nerve—that is, at the base of the fifth or second digit, respectively—can help to assess the adequacy of the block of both the ulnar and median nerves. Typically, if these maneuvers are performed shortly after a Brachial plexus block, motor weakness is evident before the sensory block.

46. Local Anaesthetic L.A with Latency Surgical Post op Adr ( Mins ) Anaesthesia Analgesia (Hrs) (Hrs) Lignocaine 1.5-2% 10-20 2- 3.5 3-5 Bupivacaine 0.5 % 15-30 5- 6 12-24 L-Bupivacaine 0.5 % 15-30 5- 6 12-24 Ropivacaine 0.5 % 10-20 3- 4 10-15 Note: Latency (onset of action ) is longer with Axillary than Interscalene Block

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48. INFRA CLAVICULAR BOCK

49. INFRA CLAVICULAR BOCK Vertical Infraclavicular approach Needle entry point is immediately below the clavicle, midway between the sternal notch and the ventral apophysis of the Acromion . Needle advanced in a vertical direction to a maximum. depth of 4 cm, until a paraesthesia is elicited.