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Procedural Skills (SLO6)
Question 133 of 141
A 76 year old woman presents to the Emergency Department after falling at home. She has sustained a dorsally angulated fracture of her dominant right radius. You plan to reduce the fracture using a Bier's block for regional anaesthesia. What dose of prilocaine should be used?
Answer:
Drug and dose:- 0.5% or 1% prilocaine without preservative
- No preparation with adrenaline
- Prilocaine 3 mg/Kg (there are no reported problems at this dose)
- If 0.5% prilocaine unavailable, use half volume of 1% plain prilocaine and the same volume of normal saline (e.g. instead of 40 ml 0.5% plain prilocaine, use 20 ml 1% plain prilocaine and dilute with 20 ml normal saline)
- During a period of prilocaine shortage in the UK, the following regime was found to be an acceptable alternative; 0.5% plain lidocaine at a dose of 3 mg/kg up to a maximum of 200 mg (40 ml)
Bier's Block
Procedural Skills (SLO6)
Last Updated: 17th March 2023
Indication
Reduction of wrist fractures, most commonly Colles' fracture
Contraindications
- Allergy to local anaesthetic
- Children – consider whether appropriate on individual basis
- Hypertension >200 mmHg
- Infection in the limb
- Lymphoedema
- Methaemoglobinaemia
- Morbid obesity (as the cuff is unreliable on obese arms)
- Peripheral vascular disease
- Procedures needed in both arms
- Raynaud’s phenomenon
- Scleroderma
- Sickle cell disease or trait
- Paget's disease
- Uncooperative or confused patient
Drug and dose
- 0.5% or 1% prilocaine without preservative
- No preparation with adrenaline
- Prilocaine 3 mg/kg (there are no reported problems at this dose)
- If 0.5% prilocaine unavailable, use half volume of 1% plain prilocaine and the same volume of normal saline (e.g. instead of 40 ml 0.5% plain prilocaine, use 20 ml 1% plain prilocaine and dilute with 20 ml normal saline)
- During a period of prilocaine shortage in the UK, the following regime was found to be an acceptable alternative; 0.5% plain lidocaine at a dose of 3 mg/kg up to a maximum of 200 mg (40 ml)
Pre-procedure checks
- Obtain consent
- Obtain patient's weight in kilograms
- Fasting not required
- Transfer patient to resus or an appropriately sited well lit area with resuscitative equipment
- Ensure ECG, BP and pulse oximetry monitoring in situ throughout procedure
- Check air cylinder at least 1/4th full if electronic machine not used; electronic machines must be kept on charge when being stored between procedures
- Check cuff for leaks
- Calculate drug dosage and prepare drug to be used
- Be aware of the location of stocked emergency drugs
- Obtain IV access on normal side 22G (in case of complications which require systemic drug administration)
- Obtain IV access, distal to the cuff, with small bore cannula (22G) on the side to be anaesthetised (a proximal vein can be used but injection should be slow and wait 13 mins for effect)
- Ensure radiographer is informed about the requirement of a post reduction film
Procedure
- Place double cuff tourniquet on upper arm and not on forearm as adequate arterial compression cannot be obtained; padding must always be applied prior to cuff placement and applying a well fitted double cuff will be a 2 person procedure
- If a plaster has already been applied then apply tourniquet before removing the plaster
- Elevate the injured arm to exsanguinate the limb
- Inflate the proximal cuff to 100 mmHg above the systolic BP (up to a maximum of 300 mmHg); if rotation of cuff is considered then the machine should have a fail-safe selected preventing decompression of proximal cuff prior to inflation of distal cuff
- Record the time of inflation
- Check for the absence of a radial pulse
- Inject 0.5% plain prilocaine, prepared according to patient weight, slowly and record the time of injection
- Remove the cannula and apply pressure as the venepuncture site is prone to bleeding (thus use of 22G)
- Warn the patient about the cold/hot sensation and mottled appearance of the arm
- Check for anaesthesia, the patient may sense movement but not pain after 10 minutes which is when the manipulation should be done and the plaster applied by 2nd member of staff
- Lower the arm on to a pillow and obtain a check x-ray
- Tourniquet dials must be under observation at all times
- The cuff must be inflated for a minimum of 20 minutes and a maximum of 45 minutes.
- If rotation of cuff is required because of pain at cuff site or a prolonged procedure (2nd manipulation), this should done after the manipulation and plaster is applied; the distal cuff will then be inflated over an anaesthetised area and be more comfortable for the patient
- If satisfied with the post reduction position of fracture, deflate the cuff observing the patient and monitor
- If fail safe selection applied the distal cuff will need to be inflated first prior to deflations
- Record the time of deflation
- Check limb circulation prior to discharge and arrange patient follow up and analgesia as appropriate
Complications
- Systemic toxicity
- Note: none have been recorded using Prilocaine at 3 mg/kg dose for intravenous regional anaesthesia
- Intralipid should be easily available in all departments using local anaesthetics
- Methaemoglobinaemia
- A problem specific to prilocaine, usually in doses >16 mg/kg
If any features of minor prilocaine toxicity are noted during the procedure or after tourniquet release:
- Note the cuff pressure and inflate the cuff to 100 mmHg above the pre-operatively recorded blood pressure
- Measure the current systolic BP and ensure cuff pressure is maintained 50 mmHg above this
- Commence oxygen and IV fluids
- Prepare to treat serious features mentioned above
- Intralipid is helpful in local anaesthetic toxicity
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
