Intravenous Regional Anesthesia

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Chapter 32

Intravenous Regional Anesthesia*

Clinical use of intravenous regional anesthesia (IVRA) has been well established as a safe,1–3 quick, and effective alternative to general anesthesia in selected cases requiring surgical manipulation of the upper and lower extremities. Though historically relegated to the operating room, the procedure is readily applicable to outpatient use. Because of its reliability, safety, and ease of use, it is now commonly used in the emergency department (ED) and clinic. In the ED, the technique provides quick and complete anesthesia, muscle relaxation, and a bloodless operating field. The procedure is free from the troublesome side effects associated with other regional blocks, such as the axillary block. The procedure is easily mastered and has a very low failure rate; consistently good results can be expected. Although not a standard requirement of ED personnel, this technique can be safely used by trained ED clinicians, including physician’s assistants and nurse practitioners, and does not have to be administered by an anesthesiologist.3 The first practical use of analgesia associated with the intravenous (IV) injection of a local anesthetic agent was described by August Gustav Bier in 1908.4 Colbern has since proposed the eponym Bier block.5 Although the procedure has been in existence for many years, the need for special equipment and a safe anesthetic agent limited its use. However, the Bier block has now gained wide acceptance as a safe and effective procedure, and several papers extol its virtues.69 Even though complications do exist, no reported fatalities directly attributable to use of the Bier block with lidocaine have been reported. In this chapter the techniques and complications are discussed according to their application in the ED.

Indications and Contraindications

Indications for IVRA include any procedure on the arm or leg that requires operating anesthesia, muscle relaxation, or a bloodless field, such as reduction of fractures and dislocations, repair of major lacerations, removal of foreign bodies, débridement of burns, and drainage of infection (Fig. 32-1). IVRA is commonly used for extremity surgery, such as carpal tunnel surgery or tendon repair. The procedure may be carried out on any patient of any age who is able to cooperate with the clinician.

The only absolute contraindications are allergy to the anesthetic agent and, possibly, uncontrolled hypertension. Relative contraindications include severe Raynaud’s disease, Buerger’s disease, or a crushed or already hypoxic extremity in which further transient ischemia would be detrimental. Homozygous sickle cell disease is a theoretical contraindication, but few data exist on the treatment of patients with this condition. IVRA is best used for procedures requiring no more than 60 to 90 minutes of tourniquet time. Continuous cardiac or blood pressure monitoring is not standard and not required unless extenuating circumstances prognosticate potential cardiovascular problems. An uncooperative patient may delay the procedure rather than contraindicate it. The judicious use of standard ED sedation may facilitate the use of IVRA in an anxious or transiently uncooperative patient.

Equipment

The equipment required for IVRA consists of the following:

• 1% lidocaine (Xylocaine),* without epinephrine, to be diluted to a 0.5% solution (note: 1% lidocaine = 10 mg/mL; hence 1 mL of 1% lidocaine = 10 mg)

• Clonidine, a parenteral opioid such as fentanyl, or ketorolac if used as additives

• Sterile saline solution as a diluent

• 50-mL syringe/18-gauge needle

• Pneumatic tourniquet (single or double cuff) such as the Zimmer A.T.S. 2000 Automatic Tourniquet System (Fig. 32-2) (Note: Do not use a standard blood pressure cuff.)

• IV catheters (20 or 22 gauge) or a 21-gauge butterfly needle

• Elastic bandage/Webril padding

• 500 mL of 5% dextrose in water (D5W) and IV extension tubing (optional)

Procedure

The procedure should be explained to the patient in advance. Premedication with midazolam (Versed), diazepam (Valium), or an opioid (e.g., morphine, fentanyl) may be helpful but need not be used routinely. The only painful portions of the procedure are establishment of the infusion catheter and exsanguination. The procedure should not be done on patients who are persistently uncooperative, intoxicated, or obtunded or who have had a previous reaction to a local anesthetic.

The patient need not be free of oral intake for a specific period before the procedure, but it is prudent to delay the procedure if the patient has just eaten a large meal. As a precaution, a suggested option is a large-bore catheter and an IV line with D5W in the unaffected extremity. General resuscitation equipment, including suction, anticonvulsant drugs, bag-valve-mask apparatus, and oxygen, should be available. Continuous cardiac and blood pressure monitoring is not routine but may be used as an option depending on the clinician’s assessment of the potential for cardiovascular events.

While the patient is being prepared, keep the lidocaine solution ready, but withhold it until the injured extremity is exsanguinated and the cuff is in place and inflated, as discussed later. The standard dose of lidocaine for the arm is 3 mg/kg. Inject it as a 0.5% solution (1% lidocaine mixed with equal parts sterile saline in a 50-mL syringe). Hence, for a 70-kg patient, infuse 210 mg of lidocaine (21 mL of 1% lidocaine) mixed with 21 mL of saline for a total volume in the infusing syringe of 42 mL of 0.5% lidocaine. Farrell and coworkers described a procedure termed the minidose Bier block in which 1.5 mg/kg of lidocaine is used and reported a 95% success rate.10 This lower dose may decrease the incidence of central nervous system side effects and is more desirable in the ED setting. Additional lidocaine may be infused if the initial dose is inadequate. Lidocaine with epinephrine should not be used. Plain lidocaine is also available as a 0.5% solution and can therefore be used directly to avoid diluting the stronger solution. Some prefer preservative-free lidocaine, but most clinicians use standard lidocaine with preservatives.

A pneumatic tourniquet with cotton padding (to prevent ecchymosis) under the cuff is applied proximal to the pathology. It is strongly advised that one not use a regular blood pressure cuff because these cuffs often leak or rupture and are not designed to withstand high pressure for any length of time. A specially designed portable double-cuff pneumatic system, such as that marketed by Zimmer Corporation, is ideal and preferred by the author.

Premix the anesthetic and saline solution in the syringe. Inflate the tourniquet and place a plastic catheter or a metal butterfly needle in a superficial vein as close to the pathologic site as possible, and securely tape it in place (Fig. 32-3, step 1). It is usually desirable to use a vein on the dorsum of the hand, but importantly, the injection site should be at least 10 cm distal to the tourniquet to avoid injection of anesthetic proximal to or under the tourniquet. Keep the hub on the catheter to avoid backbleeding, or attach the syringe to the butterfly tubing. This catheter will be the route of injection of the anesthetic agent. Anesthesia from a fingertip-to-elbow direction seems to occur irrespective of the site of infusion of the anesthetic, but selecting an injection location near the site of pathology may provide more rapid anesthesia at a lower dosage.

Deflate the tourniquet used to obtain IV access, and exsanguinate the extremity so that when the anesthetic agent is injected, it will fill the drained vascular system. Exsanguination may be accomplished by either of two methods. Simple elevation of the extremity for a few minutes may be adequate, but wrapping the extremity in a distal-to-proximal direction with an elastic or Esmarch bandage, while being careful to not dislodge the infusion needle, significantly enhances exsanguination (see Fig. 32-3, step 2). Wrapping may be painful, so this step can be eliminated if it causes too much anxiety for the patient. If the wrapping procedure is not done, the extremity should be elevated for at least 3 minutes. During the wrapping procedure, care must be taken to not dislodge or infiltrate the infusion catheter.

With the extremity still elevated or wrapped, the tourniquet is inflated to 250 mm Hg (or 100 mm Hg above systolic pressure), the arm is placed by the patient’s side, and the elastic exsanguination bandage is removed (see Fig. 32-3, steps 3 to 5). In a child the tourniquet is inflated to 50 mm Hg above systolic pressure. In elderly obese patients with calcified peripheral vessels, arterial occlusion may not be achieved safely.11 In the leg, cuff pressure of 300 mm Hg or approximately twice the systolic pressure measured in the arms is suggested.

With the tourniquet now inflated, slowly inject the 0.5% lidocaine solution into the infusion catheter at the calculated dose (see Fig. 32-3, step 6). Note that the solution is placed in the arm in which the circulation is blocked, not in the precautionary keep-open IV line on the unaffected side

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