GENERAL DATA AND INFORMATION

Regional anesthesia (often called peripheral nerve blockade) involves injecting a volume of local anesthetic in specific locations around nerves that supply various parts of the body, rendering them insensate to a surgical stimulus and allowing for pain relief postoperatively. It can be combined with general anesthesia or sedation for surgical procedures or may be the sole anesthetic of a surgical procedure. These techniques can also be used in the treatment of patients with chronic pain syndromes. For the purposes of this chapter, neuraxial techniques (e.g., spinal and epidural anesthesia) will not be mentioned because they are discussed elsewhere in this text.

The benefits of regional anesthesia include faster discharge times at ambulatory surgical centers along with improved early pain postoperative control,¹ reduction in opioid use in the immediate postoperative period, and less nausea and vomiting postoperatively.² Another advantage is the potential to avoid general anesthesia, particularly in higher-risk patients with significant comorbidities.

For these reasons, the use of regional anesthesia techniques may translate to higher patient satisfaction rates, overall lower health care costs, and improved patient outcomes and quality. The role of regional anesthesia will likely continue to expand because there continues to be tremendous growth in ambulatory surgical procedures, as well as continually evolving changes in reimbursement coupled with the safety, effectiveness, portability, and affordability of ultrasound techniques. Its use will likely only continue to rise, and the authors believe it should be an important part of any anesthesiologist’s armamentarium.

GENERAL INDICATIONS AND PATIENT SELECTION

Indications for regional anesthesia are multifactorial. It is most dependent on the type of procedure performed; preexisting patient comorbidities; and the preferences of the patient, surgeon, and anesthesiologist. It is useful when the discussion of the type of anesthesia starts with the surgeon in the office in order to set patient expectations for the day of surgery to include a regional anesthetic.

For indications for each specific type of block, please refer to each individual block.

GENERAL CONTRAINDICATIONS

Absolute

There are very few absolute contraindications to a regional anesthetic block. These include the following:

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  Patient refusal

  
  
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  Active infection at the site where injection of the local anesthetic is to be performed

  
  
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  Presence of a history of true allergy or anaphylactic reaction to the medications to be injected (e.g., local anesthetic)

Relative

Several relative contraindications to regional anesthesia are often related to patient factors. Some of these include:

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  Inability to perform the block because of poor patient tolerance or cooperation (e.g., an awake young child)

  
  
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  Preexisting neurologic deficit or need for immediate neurologic examination after the procedure

  
  
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  Preexisting comorbidities that may worsen with peripheral blockade (e.g., prior respiratory dysfunction would preclude the placement of an interscalene nerve block because of the high incidence of ipsilateral phrenic nerve paralysis)

  
  
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  Surgeon preference for a specific technique (e.g., general anesthesia)

  
  
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  Expertise of the anesthesiologist and available equipment for nerve block

Anticoagulation

The presence of systemic anticoagulation in a patient presenting for a regional anesthetic is one of intense debate and is continuously evolving as newer medications continue to be brought to the market and more evidence emerges regarding existing anticoagulation medications and regional anesthesia. The American Society of Regional Anesthesia (ASRA) has released three versions of its guidelines for neuraxial and peripheral nerve blockade in patients receiving systemic anticoagulation and antithrombotic therapy, most recently in January 2010.³ These guidelines are generally accepted as the gold standard in the United States in assessing the risk of neuraxial and peripheral anesthesia for complications caused by systemic anticoagulation. These complications include mainly hemorrhage and clinically significant hematoma. However, despite these guidelines, many of the data regarding risk remain incomplete or unknown, and often it is left to a discussion among the surgeon, patient, and anesthesiologist to determine the risk versus benefit of performing a regional anesthetic in the presence of systemic anticoagulation.

Few investigations have examined the frequency and severity of hemorrhagic complications after plexus or peripheral blockade in anticoagulated patients. Despite this, a summary of the current recommendations for peripheral nerve blockade is given in this chapter with discussion of several commonly used anticoagulants.

Aspirin and Nonsteroidal Anti-Inflammatory Drugs

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  In general, peripheral nerve blockade in patients receiving systemic aspirin or nonsteroidal anti-inflammatory medications is deemed safe.

Clopidogrel and Ticlopidine

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  Current recommendations suggest waiting 5 to 7 days after the last dose before the performance of a peripheral nerve blockade and 10 to 14 days for ticlopidine, given the half-lives of these drugs and prolonged platelet-altering effect.

Low-Dose Prophylactic Subcutaneous Unfractionated Heparin (e.g., 5000 units)

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  Twice-daily dosing: This is generally considered safe because of its widespread use, no change in clotting parameters, and lack of widespread complications directly related to peripheral nerve blockade.

  
  
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  Thrice-daily dosing or higher doses: Unknown safety. This is mainly attributable to a lack of data of complications involving this dosing. Per the ASRA consensus statement, “A review of relevant literature shows that there are reports that document an increased risk of minor and major bleeding in surgical and in nonsurgical patients receiving thrice-daily subcutaneous unfractionated heparin” (UFH). Also, it is recommended to not check the activated thromboplastin time or platelet count unless there is concern about changes in these values after “prolonged administration” or in patients with “many comorbidities that might influence the pharmacology of subcutaneous UFH.” Therefore, it is left to the discretion of the practitioner and the type of block to be performed, such as a superficial versus a deeper blockade, and it is recommended to closely follow these patients for potential complications.

Low-Molecular-Weight Heparin

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  In patients receiving prophylactic dosing with low-molecular-weight heparin (LMWH) without any other hemostatic-modifying drugs, it is recommended to wait approximately 10 to 12 hours after the last dose before the performance of regional anesthesia. In patients receiving a full anticoagulation dose, 24 hours should elapse after the last dose of LMWH before performance of regional anesthesia.

Oral Anticoagulation (e.g., Warfarin)

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  In patients receiving systemic oral warfarin therapy, it is recommended to stop warfarin 4 or 5 days earlier, and the international normalized ratio should be normalized (<1.5) before placement of a nerve block

The above recommendations are for patients undergoing so-called “deep” versus “superficial” peripheral nerve blocks. These include deep plexus blocks (e.g., lumbar plexus, lumbar sympathetic, paravertebral) and deep peripheral nerve blocks when hematoma formation and hemorrhage may not be readily apparent after peripheral blockade.

For further recommendations regarding systemic anticoagulation and regional anesthesia, refer to the general ASRA evidence-based guidelines.

PREOPERATIVE ASSESSMENT AND PREPARATION

Before the performance of any peripheral nerve block, as in any anesthetic procedure, several things must take place. First, a review of the patient’s history and physical examination findings, including vital signs, height and weight, medications, and functional capacity, is crucial before the placement in order to elicit any potential complications or contraindications of performing this procedure. (For specific complications regarding each individual block, refer to the section discussing the individual block.) It is also important to discuss with the surgeon the procedure, including the location and length of the procedure, as well as postoperative pain control options, in order to choose a proper peripheral blockade site and technique and the desired local anesthetic volume and concentration.

It is helpful to gather all of the materials needed for the block to facilitate efficiency. These include the following:

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  Local anesthetic for skin infiltration

  
  
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  Syringes and needles

  
  
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  Local anesthetic choices

  
  
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  Ultrasound machine and probe or nerve stimulator

  
  
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  Chlorhexidine/Betadine skin preparation

  
  
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  Intravenous (IV) line placement before block

  
  
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  Availability of intralipid in the event of local anesthetic systemic toxicity⁴

  
  
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  Gloves and appropriate sterile attire

  
  
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  Sedation (e.g., midazolam IV) before the block to ease patient anxiety

  
  
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  Marking of the correct side and site

MONITORING DURING BLOCK

Monitoring of a patient during regional anesthesia should proceed in accordance with American Society of Anesthesiology’s guidelines.⁵ The basic principles used in monitoring for general anesthesia should be assessed during performance of regional anesthetics. Oxygen and resuscitation equipment should be readily available in the event of any adverse reaction or complication of the block occurs.

INTERSCALENE NERVE BLOCK

Surgical Indications

This block is used for any procedure from the shoulder through the upper arm. Coverage of the inferior trunk is not reliable with this block, so it is generally not the preferred nerve block for coverage for procedures below the elbow.

Anatomic Coverage

Blockade at the interscalene groove targets the brachial plexus at the trunks, blocking the superior trunk composed of C5 and C6 nerve roots, the middle trunk composed of the nerve root from C7, and the inferior trunk composed of the C8 and T1 nerve root. The suprascapular nerve arises from fibers from the superior trunk and exits the brachial plexus to travel posteriorly through the suprascapular notch traveling between the supraspinatus and infraspinatus muscles. The superficial cervical plexus arises from the ventral rami of C2 to C4 and provides sensation to the skin overlying the shoulder and clavicle.

Technique

A landmark-guided approach traditionally describes needle insertion at the level of the cricoid cartilage, or C6, locating the groove between the anterior and middle scalene muscles at the posterior border of the clavicular head of the sternocleidomastoid muscle.⁶

An ultrasound-guided approach favors the location of a vascular structure, either tracing the nerve bundle in a superior direction from the supraclavicular location or locating the carotid or internal jugular vein and moving the probe laterally to locate the plexus as it runs between the anterior and middle scalene muscles (Fig. 52-1).

There is much debate in the regional anesthesia community regarding optimal needle placement for this block. Many experts in the field advocate for keeping needle placement as far away from the neural structures as possible while still obtaining adequate spread of local anesthetic to minimize the risk of needle–nerve trauma.⁷ Extra-sheath injection (local anesthetic spread between the anterior and middle scalene muscles) compared with intra-sheath injection (needle placement between the trunks) results in comparable block onset and quality of sensorimotor block, although intra-sheath injection results in a modestly prolonged duration of blockade.⁸

Choice of Local Anesthetic and Volume

An interscalene nerve block is typically used for postoperative analgesia, so longer-acting anesthetics, such as ropivacaine and bupivacaine, are usually favored. Minimizing the volume of local anesthetic results in a lower incidence of phrenic nerve paralysis (13% to 45% as opposed to 100% in traditional nerve stimulator techniques), so most practitioners use a volume of between 5 and 10 mL of 0.75% ropivacaine or bupivacaine 0.5%.^9–11

Contraindications

The traditional nerve stimulator technique has been found to result in a 100% incidence of ipsilateral phrenic nerve paralysis,¹² so an advantage of ultrasound-guided blockade is the ability to reduce the incidence to 13% to 45% by using a lower volume of local anesthetic.^13–15 Unilateral hemidiaphragmatic paresis decreases the forced vital capacity and forced expiratory volume by approximately 20%, so significant underlying pulmonary pathology is considered a contraindication to interscalene blockade.^16,17 Additionally, patients with contralateral phrenic nerve paralysis should not have this type of nerve block because complete diaphragmatic paralysis would result in respiratory failure and a need for intubation and ventilator support until resolution of blockade. The interscalene nerve block is also associated with a remote incidence of recurrent laryngeal nerve block, so the presence of a contralateral laryngeal nerve block would make this blockade contraindicated.¹⁸

Complications

Possible complications include infection, hematoma, nerve injury, pneumothorax, total spinal, Horner’s syndrome (blockade of the stellate ganglion resulting in ptosis, miosis, and anhydrosis), recurrent laryngeal nerve paralysis, and diaphragmatic paralysis.

SUPRACLAVICULAR NERVE BLOCK

Surgical Indications

This block is used for any upper extremity procedure from the shoulder to the hand.

Anatomic Coverage

Blockade at the supraclavicular location blocks the divisions of the brachial plexus. The suprascapular nerve and supraclavicular nerve have already left the plexus by this location, so they must be blocked separately if coverage is desired for the top of the shoulder.

Technique

An ultrasound-guided technique favors the location of the subclavian artery and corresponding reliable location of the plexus at approximately the 2 o’clock position. When performed correctly, the supraclavicular block is considered the “spinal block of the upper extremity” because it anesthetizes the entire upper extremity. The technique, described as “eight ball corner pocket” in which the needle is advanced under from a lateral to medial approach to deposit local anesthetic between the subclavian artery, first rib, and divisions of the brachial plexus, is described as providing a fast-onset full blockade with as little as 15 mL of local anesthetic¹⁹ (Fig. 52-2). Obviously, close ultrasound tracking of the needle tip is essential to stay above the first rib and avoid contacting pleura, with the consequence of pneumothorax.²⁰ Fifteen to 20 mL of local anesthetic is an adequate volume to block the plexus in this location.

Contraindications

This block has similar contraindications to those for the interscalene nerve block. Some practitioners advocate for the supraclavicular block because of a lower incidence of phrenic nerve palsy caused by a more distal injection point. The supraclavicular block performed via traditional nerve stimulation techniques is reported to cause a 50% incidence of hemidiaphragmatic paralysis²¹ compared with a 0% incidence in the ultrasound-guided group using identical volumes of 20 mL of 0.75% ropivacaine.²² Although this decreased incidence is reassuring, this block would still be considered contraindicated in patients who would be unable to tolerate hemidiaphragmatic paralysis and the resulting 20% decrement in pulmonary function.

Complications

Possible complications include infection, hematoma, nerve injury, pneumothorax, total spinal, Horner’s syndrome (blockade of the stellate ganglion resulting in ptosis, miosis, and anhydrosis), recurrent laryngeal nerve paralysis, and diaphragmatic paralysis.

INFRACLAVICULAR NERVE BLOCK

This block is done for elbow, forearm, and hand procedures. The infraclavicular block has been shown in some studies to provide enhanced blood flow in arteriovenous fistula procedures.²³ Infraclavicular blockade has a similar area of anesthesia as axillary blockade but can be performed with fewer needle passes; hence, it is the block of choice for some providers for hand surgery.²⁴ It tends to have a faster onset than the supraclavicular block.²⁵ In patients at either weight extreme, either very obese or cachectic, it can be difficult to visualize or plan a safe needle trajectory, so for these patients, an alternative block may be a better option. Abduction of the arm may pull the artery into a more superficial location, easing the performance of this block.²⁶

Anatomic Coverage

The infraclavicular nerve block blocks the brachial plexus at the level of the cords. The musculocutaneous nerve is closely applied to the lateral cord in this location, so it is blocked with an infraclavicular block.

Technique

The ultrasound probe is placed in a sagittal orientation in the deltopectoral groove to cut the subclavian artery and cords in cross-section (Fig. 52-3). It is prudent to stay as lateral as possible to avoid puncture of the pleura with the block needle. It is crucial to use color Doppler for blockade in this location to visualize and avoid potential anomalous vasculature. Much debate has occurred regarding a single injection versus a triple injection technique around all three cords, but the single injection technique of 20 to 30 mL of local anesthetic posterior to the artery has been shown to be an effective technique with an optimal procedural time.²⁷

Contraindications

This block is considered a deeper block in a noncompressible area, so caution is advised in performing this block in a coagulopathic patient. Although a lateral approach is advised to avoid pleural puncture, bullous emphysematous disease is a relative contraindication.

Complications

Possible complications include infection, hematoma, nerve injury, and pneumothorax, especially when performed from a more medial approach.

AXILLARY NERVE BLOCK

Surgical Indications

This block is used for surgery at the elbow and below, including the hand.

Anatomic Coverage

Axillary blockade provides coverage of the brachial plexus at the terminal branches. The musculocutaneous nerve has already left the plexus and travels in the body of the coracobrachialis muscle, so it must be localized separately to anesthetize the lateral, cutaneous aspect of the forearm. The intercostobrachial nerve providing sensation to the medial aspect of the upper arm travels separately from the thoracic region, so separate blockade would be necessary in any brachial plexus block.

Technique

The orienting structure is the axillary artery. The patient is positioned with the arm abducted and the hand resting 90 degrees from the elbow or behind the head while lying supine. The axillary artery is then palpated in the axilla, and the area is prepped in standard fashion using aseptic technique. The artery can then be visualized in short axis by placing the ultrasound probe parallel to the pectoralis major muscle in the anterior axillary fold (Fig. 52-4A). When the axillary artery and vein are identified in this probe orientation, the nerves of the brachial plexus may be visualized. Using this probe orientation, the median nerve is often first visualized superoanterior to the artery, with the radial nerve located inferolateral to the artery and the ulnar nerve located more inferior to the artery. The musculocutaneous nerve is located within the coracobrachialis muscles and is more superior to the artery; it appears very hyperechoic and bright relative to the surrounding muscle (Fig. 52-4B).