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2. PERIPHERAL BLOCK TABLE 2-1 EQUIPMENT CLASSIFICATION OF REGIONAL TECHNIQUES AT WALTER REED ARMY MEDICAL INTRODUCTION CENTER

Basic Techniques Intermediate Techniques Advanced Techniques The safe and successful application of regional anesthesia in patients requires specialized train- Anesthesia providers who have completed Should be familiar to anesthesia providers Should be familiar to anesthesiologists with ing and equipment. In 2005, guidelines for regional an accredited anesthesia program should be who have completed a supervised advanced or fellowship training in regional anesthesia fellowship training were published in familiar with these techniques. program in regional anesthesia and anesthesia appropriate for a subspecialist the journal Regional Anesthesia and Medicine. have demonstrated proficiency in these consultant in regional anesthesia. The guidelines were a collaborative effort of a group techniques (usually 20–25 blocks of each of North American regional anesthesia fellowship type). program directors who met to establish a standard- • Superficial cervical plexus block • Deep cervical plexus block • Continuous peripheral nerve blocks: placement and management ized curriculum. An important part of this docu- • Axillary block • Interscalene block ment is the categorization of regional anesthetic • Ultrasound guided regional • Intravenous regional anesthesia • Supraclavicular block anesthesia procedures into basic, intermediate, and advanced (Bier block) techniques. The Walter Reed Army Medical Center • Infraclavicular block • Thoracolumbar paravertebral blocks (WRAMC) regional anesthesia fellowship program • Wrist block • Sciatic : posterior • Lumbar plexus block has adopted this categorization as well as the pub- • Digital nerve block approach • : anterior lished guidelines (Table 2-1). • block • Genitofemoral nerve block This manual will focus on intermediate and ad- approach vanced regional anesthesia techniques and acute • Saphenous nerve block • Popliteal block: all approaches • Obturator nerve block pain therapies, which may not be included in • Ankle block • block • Cervical epidural anesthesia routine anesthesia training. Some basic techniques • Spinal anesthesia • are covered as well (with the exception of neuraxial • Cervical paravertebral block anesthesia). The primary purpose of this manual is • Lumbar epidural anesthesia • Thoracic epidural anesthesia • Maxillary nerve block to serve as a guide for WRAMC resident and fellow • Combined spinal-epidural • Mandibular nerve block anesthesiologists during their regional anesthesia anesthesia and acute pain rotations. The facility, equipment, • Retrobulbar and peribulbar nerve • blocks and staffing used at WRAMC may not be entirely workable at other institutions; however, the editors are confident that other clinicians can benefit from this systematic approach to regional anesthesia REGIONAL ANESTHESIA AREA reduced anesthesia turnover times and improved and acute pain medicine. patient-anesthesiologist relationships. Finally, the Regardless of the practice environment (military Contemporary regional anesthesia increasingly regional anesthesia area greatly enhances resident care level III through IV), a designated area for the relies on sophisticated equipment, as providers education by providing an instructional environ- application of regional anesthesia techniques outside strive for accurate and safe methods of needle place- ment free from the pressures and distractions of a of the operating room will enhance block success. ment and anesthetic delivery. This chapter will busy operating room. This alternative location for nerve block placement review the equipment used at WRAMC as well as The regional block area should have standard will prevent unnecessary operating room delays, on the modern battlefield in the successful perfor- , oxygen, suction, airway, and emer- allow additional time for long-acting local anesthet- mance of regional anesthesia. Note: The equipment gency hemodynamic equipment. Certain military ics to “set up,” and allow the provider to assess the displayed in this chapter is for illustration purposes only practice environments will necessitate adjustments quality of the nerve block prior to . Other and should not be considered an endorsement of any or alternatives to this equipment list. Advanced advantages of a regional anesthesia area include product. cardiac life support capability and medications 5 2 PERIPHERAL NERVE BLOCK EQUIPMENT

should be readily available as well as Intralipid • Stimulating needles should be insulated Centimeter markings on the needle shaft are (KabiVitrum Inc, Alameda, Calif). Recent data have along the shaft, with only the tip exposed for particularly important now that ultrasound tech- shown Intralipid to be an effective therapy for stimulation. nology can provide accurate measurements of skin related to toxicity (see • A comfortable grip should be attached to to nerve distances (Figure 2-1). A typical back table Table 3-2 for Intralipid dosing). the proximal end of the needle. set-up for a peripheral nerve anesthetic is illustrat- • The wire attaching the needle to the stimula- ed in Figure 2-2. Figure 2-3 provides the preferred PATIENT CONSENT FOR tor should be soldered to the needle’s shaft and method for all local anesthetic injections. REGIONAL ANESTHESIA have an appropriate connector for the nerve stimulator. As with any medical procedure, proper consent • Long, clear extension tubing must also be inte- for the nerve block and documentation of the gral to the needle shaft to facilitate of procedure (detailing any difficulties) is essential. local anesthetic and allow for early detection of Counseling should include information on risks of blood through frequent, gentle aspirations. regional anesthesia, including intravascular injec- • Stimulating needles are typically beveled at tion, local anesthetic toxicity, and potential for nerve 45° rather than at 17°, as are more traditional injury. Patients receiving regional anesthesia to needles, to enhance the tactile sensation of the extremities should be reminded to avoid using the needle passing through tissue planes and to blocked extremity for at least 24 hours. In addition, reduce the possibility of neural trauma. patients should be warned that protective reflexes • Finally, markings on the needle shaft in centime- and proprioception for the blocked extremity may ters are extremely helpful in determining needle be diminished or absent for 24 hours. depth from the skin. Particular attention must be paid to site verifica- tion prior to the nerve block procedure. Sidedness should be confirmed orally with the patient as well as with the operative consent. The provider should Figure 2-2. Set-up for peripheral nerve block initial the extremity to be blocked. If another anes- A: ruler and marking pen for measuring and marking landmarks and injection points thesia provider manages the patient in the operating B: alcohol swabs and 25-gauge syringe of 1% lidocaine to room, the provider who places the regional block anesthetize the skin for needle puncture must ensure that the accepting anesthesia provider C: chlorhexidine gluconate (Hibiclens, Regent Medical Ltd, Norcross, Ga) antimicrobial skin cleaner is thoroughly briefed on the details of the block D: syringes for (at WRAMC, having 5 mg and procedure. 250 mg fentanyl available for sedation is standard) E: local anesthetic F: peripheral nerve stimulator EQUIPMENT G: stimulating needle H: sterile gloves Needles. A variety of quality regional anesthesia stimulating needles are available on the market today. Qualities of a good regional anesthesia needle include the following:

Figure 2-1. Representative single injection, 90-mm, insulated peripheral nerve block needle (StimuQuik, Arrow International Inc, Reading, Pa; used with permission)

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Peripheral Nerve Block Stimulators. Peripheral The initial 10 mL of local anesthetic injection should contain nerve stimulation has revolutionized the practice epinephrine 1:400,000 as a marker for intravascular injection unless clinically contraindicated (eg, high sensitivity to of regional anesthesia by providing objective evi- epinephrine, severe cardiac disease). dence of needle proximity to targeted . In the majority of peripheral nerve blocks, stimula- tion of nerves at a current of 0.5 mA or less sug- Raj Test gests accurate needle placement for injection of 1. Gently aspirate on the 20-mL local anesthetic local anesthetic. Chapter 4, Nerve Stimulation and When the needle is correctly placed near the target nerve syringe and look for blood return in the clear as confirmed with , nerve stimulation, and/or connecting tubing. Aspiration of blood suggests an Ultrasound Theory, discusses nerve stimulation in ultrasound, an initial Raj test is performed. intravascular needle placement; the needle should detail. A variety of peripheral nerve stimulators be removed if this occurs. Gentle aspiration is are available on the market. A good peripheral important to avoid the possibility of erroneously aspirating blood vessel wall and missing the nerve stimulator has the following characteristics: appearance of blood. 2. Following a negative aspiration for blood, inject 1 mL • a light, compact, battery-operated design with Slowly inject 3–5 mL of local anesthetic. Observe the of local anesthetic . Excessive resistance to adjustable current from 0 to 5 mA in 0.01 mA injection and/or severe patient discomfort suggest patient’s monitors for indications of local anesthetic toxicity increments at 2 Hz impulse frequency; (see Chapter 3). Slow injection of local anesthetic is poor needle positioning in or around the nerve; if this crucial to allow the provider time to recognize develop- occurs, terminate the injection and reposition the • a bright and easily read digital display; ing local anesthetic toxicity before it progresses to needle. When using stimulation, the initial 1 mL of • both a visual and audible signal of an open or , cardiovascular collapse, and death. local anesthetic should terminate the muscle twitching of the target nerve. This occurs because closed circuit between the stimulator, needle, the stimulating current is dispersed by the saline and patient; and containing the anesthetic. Failure to extinguish twitching with a Raj test should alert the provider26 to • an impulse duration adjustable between 0.1 the possibility of an intraneural injection. The needle millisecond (ms) and 1 ms. Gently aspirate for blood after each 3–5 mL increment of should be repositioned in this case. local anesthetic is injected. If blood is suddenly noted during one of the incremental aspirations, the injection should be 3. Gently aspirate for blood a second time. If this series Continuous Peripheral Nerve Block . terminated and the patient closely observed for signs of local of maneuvers does not result in aspiration of blood anesthetic toxicity. or in severe patient discomfort, the local anesthetic Chapter 24, Continuous Peripheral Nerve Block, injection can continue. provides details on WRAMC procedures for placing and securing continuous peripheral nerve block (CPNB) catheters. The majority of catheters placed The slow, incremental injection of local anesthetic with at WRAMC and in the field are nonstimulating frequent gentle aspiration for blood is continued until the catheters (Figure 24-1) because of how long the desired amount of local anesthetic is delivered. catheters remain in situ—1 to 2 weeks on average— and currently available stimulating systems Figure 2-3. Procedure for injection of all local anesthetics recommend removal after 72 hours (however, new catheter technology may soon change this limita- tion). In the management of combat wounded, hun- dreds of nonstimulating CPNB catheters have been placed to manage pain for weeks, some as long as a month, without complication related to the catheter. Desirable characteristics of a long-term CPNB cath- eter are listed in Table 2-2. The Contiplex Tuohy (B

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Braun Melsungen AG, Melsungen, Germany) CPNB TABLE 2-2 TABLE 2-3 nonstimulating catheter system used at WRAMC DESIRABLE CHARACTERISTICS of A LONG- DESIRABLE CHARACTERISTICS of A has had years of successful long-term use in combat TERM CONTINUOUS PERIPHERAL NERVE MILITARY PAIN casualties and remains the recommended CPNB BLOCK CATHETER system for the field. • Easily identifiable by shape and color Ultrasound. Some regional anesthesia provid- • Easily placed through a standard 18-gauge Tuohy needle • Used only for pain service infusions ers consider recent developments in ultrasound • Composed of inert, noninflammatory material technology to be the next ”revolution” (after pe- • Lightweight and compact • Centimeter markings to estimate depth/catheter ripheral nerve stimulation) in regional anesthesia. • Reprogrammable for basal rate, bolus amount, lockout migration Improvements in ultrasound technology allow for interval, and infusion volume • Colored tip to confirm complete removal from patient high image resolution with smaller, portable, and • Battery operated with long battery life less expensive ultrasound machines (Figure 2-4). • Flexible, multiorifice tip Elements of a superior ultrasound machine for re- • Program lock-out to prevent program tampering • Hyperechoic on ultrasound gional anesthesia are high image quality, compact • Simple and intuitive operation • Radiopaque • Medication free-flow protection • Secure injection port Figure 2-4. Contemporary laptop ultrasound machine (Logiq Book • Latex free XP, GE Healthcare, Buckinghamshire, United Kingdom; used with • Capable of stimulation permission) • Visual and audible alarms • Nonadherent with weeks of internal use • Stable infusion rate at extremes of temperature and • High resistance to breaking or kinking pressure • Low resistance to infusion • Inexpensive • Bacteriostatic • Durable for long service life without needing maintenance • System to secure the catheter to the patient’s skin • Certified for use in US military aircraft

and rugged design, simple and intuitive controls, easy image storage and retrieval, and ease of porta- of CPNB and other techniques bility. Ultrasound for peripheral nerve blocks is dis- during casualty evacuation depends on this technol- cussed in Chapter 4. ogy. Infusion pumps for the austere military envi- ronment should have the attributes listed in Table Infusion Pumps. Recent improvements in 2-3. The pain infusion pump currently used during acute pain management on the battlefield would casualty evacuation for patient-controlled analgesia have been impossible without improvements in (PCA), epidural catheters, and CPNB is the AmbIT microprocessor-driven infusion technology. The use PCA pump (Sorenson Medical Inc, West Jordan, Utah [Figure 2-5]).

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Figure 2-5. Casualty evacuation acute pain management pump (AmbIT PCA pump [Sorenson Medical Inc, West Jordan, Utah; used with permission]) in current use, with operating instruction quick reference card

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