Digital Nerve Block

imagesUsed to provide local anesthesia to the digits for repair, reduction, or drainage


   imagesLacerations


   imagesNail bed injuries


   imagesInfections (i.e., felons, paronychias)


   imagesAmputations


   imagesFractures or dislocations


CONTRAINDICATIONS



imagesAbsolute Contraindications


   imagesTransthecal technique contraindicated in cases of infection, including felon, tenosynovitis, and overlying cellulitis


   imagesAllergy to lidocaine, bupivacaine, or other selected anesthetic


imagesRelative Contraindications


   imagesComplex laceration or other injury involving multiple digits that can be more easily and adequately anesthetized with a nerve block at the wrist


RISKS/CONSENT ISSUES



imagesPain (site of needle insertion)


imagesBleeding (local at needle puncture site)


imagesInfection (theoretical risk of iatrogenic infection)


imagesPotential for damage to neurovascular bundle


imagesParesthesias


imagesPossible need for additional anesthetic or alternate procedures if the initial nerve block fails



imagesGeneral Basic Steps


   imagesAseptic technique


   imagesChoose approach and deliver anesthetic


   imagesMassage area for 25 to 30 seconds


   imagesTest for adequate analgesia


LANDMARKS



imagesThe common digital nerves divide into two pairs of nerves corresponding to the dorsal and volar sides of the digits


imagesPalmar Nerve


   imagesLocated at the 4- and 8 o’clock positions when looking at a cross section of the digit


   imagesSupplies the volar surface of the digit and the dorsal surface distal to the distal interphalangeal (DIP) joint for the middle three fingers


   imagesBlocking only the palmar nerves will provide adequate anesthesia on fingertip injuries distal to the DIP for the three middle fingers


imagesDigital Nerve


   imagesLocated at the dorsal 2- and 10 o’clock positions when looking at a cross section of the digit


   imagesSupplies the nail beds of the thumb, fifth digit, and dorsal aspects of all three middle fingers up to the DIP


imagesFor the thumb and fifth digit, all four nerves must be blocked for fingertip and nail bed anesthesia (FIGURE 52.1)



images


FIGURE 52.1 Dorsal technique for palmar and dorsal digital nerve block. A: Nerve distribution in hand. B: Traditional digital nerve block. C: Dorsal three-sided ring block. D: Volar three-sided ring block. (Lewis L, Stephan M. Local and regional anesthesia. In: Henretig FM, King C, eds. Textbook of Pediatric Emergency Procedures. Philadelphia, PA: Williams & Wilkins; 1997:481, with permission.)


TECHNIQUE: SEVEN APPROACHES



imagesPatient Preparation


   imagesDocument neurovascular examination before anesthesia


   imagesPlace patient’s affected hand/foot comfortably on bedside procedure table with volar surface down (for metacarpal nerve block, traditional ring block, wing block) or volar surface up (for subcutaneous block, transthecal approach or thumb block)


   imagesPrepare the digit and web space by using standard aseptic technique


imagesEquipment


   imagesLidocaine or procaine 1% to 2% (or 0.25% bupivacaine for longer, complicated procedures), 2 to 3 mL


   imagesAn 18-gauge needle for drawing up the anesthetic


   imagesA 25- to 30-gauge needle for the nerve block


   imagesA 5-mL syringe


   imagesPovidone–iodine or chlorhexidine solution


   imagesSterile drapes and sterile gauze


   imagesGloves


imagesTraditional Digital Block (Web-space Block or Metacarpal Nerve Block)


   imagesAnesthetizes all digits except great toe


   imagesPrepare skin over dorsal surface of web space between metacarpal/metatarsal heads


   imagesAspirate and inject subcutaneous wheal between metacarpal/metatarsal bones on dorsum of hand/foot 1 to 2 cm proximal to web space


   imagesSlowly advance needle through the wheal toward lateral volar surface of metacarpal/metatarsal head until slight tenting of the volar surface is appreciated


   imagesAspirate and then inject 2 mL of anesthetic


   imagesRepeat the process on the opposite side of the finger/toe


imagesTraditional Three-sided Ring Block


   imagesAnesthetizes all digits including the dorsal, medial, and lateral nerve branches of great toe


   imagesGive two injections of lidocaine, one on each side of the digit


   imagesLocate dorsal–lateral aspect of proximal phalanx at the web space, just distal to metacarpal/phalangeal (MCP) or metatarsal/phalangeal (MTP) joint


   imagesAdvance needle perpendicular to digit until bone is struck, aspirate and slowly inject 0.5 mL of lidocaine to anesthetize the dorsal nerve


   imagesWithdraw needle slightly, then redirect and advance toward volar surface and slowly inject 1 mL of lidocaine


   imagesWithdraw needle partially and redirect it medially over dorsal aspect of digit, aspirate and slowly inject lidocaine while withdrawing needle to anesthetize medial and dorsal aspect of digit


   imagesWithdraw the needle


   imagesRepeat procedure on medial side of digit at site of anesthetized skin


   imagesMassage area of infiltrated skin for 15 to 30 seconds to ensure diffusion of the anesthetic


   imagesWait for 5 to 10 minutes to test for efficacy


imagesFour-sided Ring Block


   imagesAdvantages: Anesthetizes volar side of digits


   imagesDisadvantages: May result in ischemic complications


   imagesPerform traditional three-sided ring block


   imagesLocate anesthetized volar–lateral aspect of proximal phalanx at the web space, just distal to MCP or MTP joint


   imagesAdvance needle medially, aspirate and slowly inject 0.5 mL of lidocaine to anesthetize the volar side while withdrawing needle


imagesSubcutaneous Block


   imagesPrepare skin over volar surface at proximal skin crease


   imagesPinch skin distal to proximal skin crease


   imagesInsert needle at midpoint of crease, aspirate and inject subcutaneous 1 to 2 mL wheal


   imagesMassage injected area for 15 to 30 seconds to improve diffusion process


imagesTransthecal Approach


   imagesAdvantages: Single injection and low risk of neurovascular bundle injury


   imagesDisadvantage: More painful to inject through volar surface


   imagesAnesthetic is infused directly into the flexor tendon sheath at the proximal digital crease on volar surface


   imagesFill 5-mL syringe with lidocaine


   imagesInsert 25-gauge needle at a 90-degree angle at the midpoint of the proximal digital crease and advance until bone is struck


   imagesWithdraw needle approximately 2 to 3 mm (should be in flexor tendon sheath) and redirect at a 45-degree angle to the long axis of the digit


   imagesAspirate and inject 1.5 to 3 mL lidocaine while palpating tendon sheath with other hand; continue until resistance is felt


   imagesAfter removing the needle, apply pressure over the tendon proximally to facilitate distal spread


   imagesWait for 2 to 3 minutes to test for efficacy of anesthesia


   imagesMost effective for middle three fingers (FIGURE 52.2)


imagesThumb Block


   imagesAll four digital nerves must be blocked for complete anesthesia of the thumb


   imagesLocate the flexor pollicis longus on the volar aspect of the thumb at the level of the proximal thumb flexor crease


   imagesThe nerves lie immediately adjacent to this tendon


   imagesAspirate and inject 1 to 2 mL of lidocaine along both sides of the tendon (FIGURE 52.3)


imagesWing Block


   imagesAnesthetizes distal digit and nail bed


   imagesPrepare the distal digit by using standard aseptic technique


   imagesInsert 30-gauge needle perpendicular to the long axis of digit at a 45-degree angle at a point 3 mm proximal to the imaginary intersection of the lateral and proximal nail folds


   imagesAspirate and inject anesthetic across the dorsum of digit parallel to proximal nail fold


   imagesPartially withdraw needle and redirect along lateral nail fold


   imagesAspirate and inject anesthetic along the lateral nail fold


   imagesRepeat procedure on opposite side of digit if bilateral anesthesia is required (FIGURE 52.4)



images


FIGURE 52.2 Digital nerve block: Transthecal approach. The needle is directed into the proximal digital crease at a 45-degree angle to the long axis of the digit into the flexor tendon sheath where the lidocaine is deposited slowly.

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Aug 9, 2016 | Posted by in EMERGENCY MEDICINE | Comments Off on Digital Nerve Block

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