Bier's Block

Procedure

• Explain procedure to the patient in advance
• General resuscitation equipment, including suction, anticonvulsant drugs, bag-valve-mask apparatus, and O₂, should be available
• Continuous cardiac and BP monitoring is not routine but may be used as an option depending on the clinician's assessment of the potential for cardiovascular events
• With manual pressure on brachial pulse and tourniquet in position but not inflated, elevate the arm for circa 3 min
• Inflate cuff
• The traditional dose of Lignocaine for the arm is 3 mg/kg. Inject it as a 0.5% solution (1% Lignocaine mixed with equal parts sterile saline in a 50-mL syringe). Hence, for a 70-kg patient, infuse 210 mg of Lignocaine (21 mL of 1% Lignocaine) mixed with 21 mL of saline for a total volume in the infusing syringe of 42 mL of 0.5% Lignocaine
• Studies have described a procedure termed the mini-dose Bier block in which 1.5 mg/kg of Lignocaine is used and reported a 95% success rate. This lower dose may decrease the incidence of central nervous system side effects and is more desirable in the ED setting
• A pneumatic tourniquet with cotton padding (to prevent ecchymosis) under the cuff is applied proximal to the pathology
• 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 anaesthetic proximal to or under the tourniquet
• With the extremity still elevated, the tourniquet is inflated to 250 mm Hg (or 100 mm Hg above systolic pressure) the arm is placed by the patient's side. 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. In the leg, a 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% Lignocaine solution into the infusion catheter at the calculated dose
• At this point, blotchy areas of erythema may appear on the skin. This is not an adverse reaction to the anaesthetic agent but merely the result of residual blood being displaced from the vascular compartment, and it heralds success of the procedure
• In 3 to 5 minutes, the patient will experience paraesthesia or warmth beginning in the fingertips and travelling proximally, with final anaesthesia occurring above the elbow, to the level of the tourniquet. Complete anaesthesia ensues in 10 to 20 minutes, followed by muscle relaxation
• Note that adequate analgesia may exist even if the patient can still sense touch and position and has some motor function. If the “mini-dose” technique (initial dose of 1.5 mg/kg of Lignocaine) does not provide adequate anaesthesia, infuse an additional 0.5 to 1 mg/kg of diluted Lignocaine at this time
• Wait a full 15 minutes before infusing additional Lignocaine. Alternatively, if analgesia is slow or inadequate, an extra 10 to 20 mL of saline solution may be injected to supplement the total volume of solution to enhance the effect
• Do not exceed a 3-mg/kg total dose of Lignocaine.
• A single deflation can be performed if the cuff has been inflated for longer than 30 min. It is reasonable to use a 20-minute cut-off if the mini-dose technique is used or a total of 200 mg or less of Lignocaine has been administered because this dose is equal to a commonly administered anti-arrhythmic IV bolus
• Sensation returns quickly when the tourniquet is removed, and in 5 to 10 minutes the extremity returns to its Pre-anaesthetic level of sensation and function. Many patients describe a transient intense tingling sensation after cuff deflation
• If the procedure takes longer than 20 or 30 minutes, many patients complain of pain from the tourniquet because it is not inflated over an anaesthetized area. Use of a double-cuff tourniquet may alleviate the problem of pain under the cuff. Most patients begin to feel significant discomfort after 30 minutes if only a single cuff is used. In the preferred double-cuff system, two separate tourniquets are placed side by side on the extremity. One is termed the proximal cuff and the other the distal cuff. The proximal cuff is inflated at the beginning of the procedure, and anaesthesia is obtained under the deflated distal cuff. When the patient begins to feel pain under the proximal cuff, the distal cuff is first inflated over an already anaesthetized area, and the pain-producing proximal cuff is then deflated. One must be certain to inflate the distal cuff before the proximal cuff is released
• After 45 to 60 minutes of observation, the patient may be discharged
• There are no standard or specific post-procedure instructions, but precautions similar to those given for conscious sedation are reasonable. Driving is best prohibited for 6 to 8 hours, and the patient should leave with a responsible adult. Delayed complications from Lignocaine have not been reported

Signs suggestive of toxicity

• Peri-oral paraesthesia (lips, tongue, nose)
• Hypotension
• Transient desaturation, cyanosis, dyspnoea: methaemoglobinaemia
• Dysrhythmia, dizziness
• Convulsion

Treatment of toxicity

More details on LA Toxicity page.

• Call for senior doctor
• Re-inflate cuff if it has been deflated
• 100 % oxygen
• Monitoring Sats, ETCO₂, ECG, BP
• Turn patient into lateral position
• Give Lorazepam if convulsion still ongoing
• Consider lipid emulsion