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Ovid: Oxford Handbook of Accident and Emergency Medicine

Editors: Wyatt, Jonathan P.; Illingworth, Robin N.; Clancy, Michael J.; Munro, Philip T.; Robertson, Colin E. Title: Oxford Handbook of Accident and Emergency Medicine, 2nd Edition Copyright ©2005 Oxford University Press > Table of Contents > Chapter 7 – Analgesia and anaesthesia Chapter 7 Analgesia and anaesthesia P.264
Pain relief Many patients who come to A&E departments are in pain. Knowledge of the site and characteristics of the pain is often important in diagnosing the problem. Relief of pain is an essential and urgent part of treatment. Pain and distress may prevent patients giving useful details of history and symptoms and may not allow them to co-operate with investigations or treatment. Methods of pain relief Relieving pain often requires analgesic drugs, but other types of treatment are sometimes more important. If an injury becomes more painful than expected consider the possibility of infection or vascular compromise. Severe pain despite immobilisation of a fracture suggests a vascular injury, compartment syndrome (p384) or a tight plaster (p410). Reflex sympathetic dystrophy (Sudeck’s atrophy) may also cause severe pain starting a few days after relatively minor trauma. Splintage Immobilisation of a fracture results in ↓pain and ↓requirement for analgesic drugs. Inhalation analgesia with Entonox® (p270) is often helpful while the splint or cast is being applied. Elevation Many limb injuries produce considerable swelling, which causes pain and stiffness. Elevate in order to ↓swelling, relieve the pain and allow mobilization as soon as possible. Cold Cool burns as soon as possible, usually in cold water, to relieve the pain and stop any continuing thermal injury. Chemical burns from hydrofluoric acid (p383) are often extremely painful and need prolonged cooling in iced water. Pain from recent sprains and muscle injuries may be ↓ by cooling with ice-packs (or a pack of frozen peas) applied for 10-15mins at a time, with a piece of towelling between the ice-pack and the skin. Heat Pain following sprains and strains of the neck, back and limbs is often caused by muscle spasm. It may be eased by heat from a hot bath, hot water bottle or heat lamp. Dressings Pain from minor burns and fingertip injuries often resolves after a suitable dressing is applied. Local anaesthesia LA provides excellent pain relief for fractured shaft of femur (p296) and for some finger and hand injuries (p286). Strongly consider administering LA prior to obtaining X-rays. Definitive treatment Reducing a pulled elbow or trephining a subungual haematoma usually gives immediate relief of pain, so no analgesia is needed. Psychological aspects of pain relief Anxiety and distress accompany pain and worsen patients’ suffering. Psycho-logical support is needed as well as physical relief from pain. Patients are helped by caring staff who explain what is happening and provide support and reassurance. The presence of family members or a close friend is often helpful. P.265
P.266
Analgesics: aspirin and paracetamol Many different analgesic drugs are available, but it is best to use only a few and become familiar with their actions, dosages, side effects and contraindications. Most hospitals have analgesic policies and limit the choice of drugs which may be used. Before prescribing any drug, check what treatment has been given. The patient may already be taking analgesia or have supplies at home. Many drugs interact with others: important drug interactions are listed in the BNF. Ask about drug allergies and record them. Before giving aspirin or NSAIDs ask and record about indigestion, peptic ulceration and asthma. Aspirin Aspirin is a good analgesic for headaches, musculoskeletal pain and dysmenorrhoea and has antipyretic and mild anti-inflammatory actions. It interacts with warfarin, some anticonvulsants and other drugs and may exacerbate asthma and cause gastric irritation. Do not use aspirin in children <12yrs or during breastfeeding. Adult dose PO is 300-900mg 4-6hrly (max 4g daily). Paracetamol Paracetamol (‘acetaminophen’ in USA) has similar analgesic and antipyretic actions to aspirin, but has no anti-inflammatory effects and causes less gastric irritation than aspirin. Adult dose is 0.5-1g 4-6hrly (max 4g daily). Child aged 3months-1yr: 60-120mg

  • 1-5yrs: 120-250mg
  • 6-12yrs: 250-500mg

Doses may be repeated 4-6hrly (max 4 doses in 24hrs). Overdosage can cause liver and renal damage (p184). Compound analgesics (paracetamol + opioid) Compound analgesic tablets containing paracetamol and low doses of opioids are widely used but have little benefit over paracetamol alone and cause more side effects, such as constipation and dizziness, particularly in elderly people. These compound preparations include: Co-codamol 8/500 (codeine phosphate 8mg, paracetamol 500mg) Co-dydramol (dihydrocodeine tartrate 10mg, paracetamol 500mg) Co-proxamol (dextropropoxyphene 32.5mg, paracetamol 325mg) Compound preparations of paracetamol and full doses of opioids, eg co-codamol 30/500 (codeine phosphate 30mg, paracetamol 500mg), are more potent than paracetamol alone, but may cause opioid side effects, including nausea, vomiting, constipation, dizziness, drowsiness and respiratory depression. Opioid dependency can occur with prolonged usage. Co-proxamol was withdrawn in the UK in 2005. P.267
Analgesics: NSAIDs Non-steroidal anti-inflammatory drugs NSAIDs are often used to treat musculoskeletal pain, with or without inflammation, although in many cases non-drug treatment (heat or cold, elevation) and paracetamol should be tried first. NSAIDs can cause gastric irritation, diarrhoea, GI bleeding and perforation, with ↑risk at higher drug dosage and in patients aged >60yrs and those with a history of peptic ulcer. NSAIDs may exacerbate asthma and can precipitate renal failure in patients with heart failure, cirrhosis or renal insufficiency. Interactions occur with diuretics, warfarin, lithium and other drugs (see BNF). When possible, advise that NSAIDs be taken after food to ↓risk of GI side effects. If NSAID treatment is essential in patients at high risk of GI problems consider prophylactic treatment with misoprostol (see BNF). Many NSAIDs are available and all can cause serious adverse effects, but ibuprofen, diclofenac and naproxen are relatively safe and cover most requirements. Ibuprofen has the lowest incidence of side effects, is the cheapest of these drugs and may be bought without prescription. Ibuprofen is useful in children as an analgesic and antipyretic, especially when paracetamol is insufficient. Ibuprofen dosage 1.2-1.8g daily in 3-4 divided doses (max 2.4g daily). Child (>7kg): 20mg/kg daily in 3-4 divided doses. Diclofenac (oral or rectal) 75-150mg daily in 2-3 divided doses. Naproxen 0.5-1g daily in 2 divided doses (max 1.25g daily). Acute gout: 750mg initially, then 250mg 8 hrly until pain resolves. Injectable NSAIDs Some NSAIDs may be given by injection for musculoskeletal pain (eg acute low back pain) or for renal or biliary colic. The contraindications and side effects are the same as for oral treatment. IM injections are painful and can cause sterile abscesses, so oral or rectal treatment is preferable. NSAIDs provide effective analgesia for renal colic, but the onset is slower than with IV opioids, which some prefer. A NSAID is particularly useful in suspected drug addicts who claim to have renal colic. Ketorolac may be given IM or slowly IV (initial dose 10mg over at least 15secs: see BNF). It is useful as an adjunct for MUAs. Diclofenac must be given by deep IM injection (not IV, which causes venous thrombosis). Dose: 75mg, repeated if necessary after 30mins (max 150mg in 24hrs). Topical NSAIDs NSAID gels or creams applied to painful areas provide some analgesia, but are less effective than oral treatment. Systemic absorption may occur and cause adverse effects as for oral NSAIDs. P.268
Analgesics: opioids Morphine Morphine is the standard analgesic for severe pain. As well as providing analgesia, it may ↑venous capacitance and so is used for pulmonary oedema due to LVF. Morphine frequently causes nausea and vomiting in adults—therefore give it with an antiemetic (cyclizine 50mg IV/IM or prochlorperazine 12.5mg IM). Antiemetics are not usually necessary in children aged <10yrs. Other side-effects of opioids include drowsiness and constipation. Pinpoint pupils can complicate neurological assessment. Respiratory depression and hypotension occur with large doses. The effects of opioids are reversed by naloxone (p182). In acute conditions, give morphine by slow IV injection, which provides rapid but controlled analgesia. The dose varies with the patient and the degree of pain. Titrate the dose depending on the response: 2mg may be adequate in a frail old lady, but sometimes 20mg is required in a young fit person with severe injuries. Dilute morphine with 0.9% saline to 1mg/mL and give it slowly IV (1-2mg/min in adults) in 1mg increments until pain is relieved. Label the syringe clearly. Give further analgesia if pain recurs. IV morphine dose in children is 100-200micrograms/kg, given in increments, repeated as necessary. Patient or nurse-controlled analgesia using a computerized syringe pump is very good for post-operative analgesia, but not appropriate in A&E. IM injections provide slower and less controlled effects than IV analgesia: avoid their use, especially in shocked patients. IM morphine could be used in small children needing strong analgesia but not IV fluids (eg while dressing superficial burns). However, oral or nasal analgesia is preferable. Morphine may be given orally as Oramorph® oral solution:

  • child aged 1-5yrs: max dose 5mg (2.5mL)
  • child aged 6-12yrs: max dose 5-10mg (2.5-5mL)

Codeine is given orally for moderate pain (30-60mg 4 hrly, max 240mg daily) and has side effects similar to morphine. Codeine may also be given IM. Dihydrocodeine is similar to codeine. Diamorphine (heroin) has similar effects to morphine, but is more soluble and so can be dissolved in a very small volume of diluent. Nasal diamorphine provides effective analgesia in children (p273). Fentanyl is a short-acting opioid. Nalbuphine is not a controlled drug and has been used in prehospital care. It is a partial antagonist of opioids. If pain recurs after nalbuphine has been given, larger than usual doses of morphine may be needed to achieve analgesia. Pethidine provides rapid but short-lasting analgesia, but is less potent than morphine. It is sometimes used for renal or biliary colic in preference to morphine, which is said to cause smooth muscle spasm, although in practice this does not seem to be a problem. Pethidine is given slowly IV, titrated as necessary (usual adult dose ≈50mg IV), or less effectively IM (50-100mg). Give an antiemetic with it. P.269
P.270
Analgesics: Entonox® and ketamine Entonox Entonox is a mixture of 50% N2O and 50% O2. It is stored as a compressed gas in blue cylinders with a blue and white shoulder. It is unsuitable for use at <-6°C, since the gases separate and a hypoxic mixture could be given. Entonox diffuses more rapidly than nitrogen and so is contraindicated with the following: undrained pneumothorax (since it may produce a tension pneumothorax), after diving (↑risk of decompression sickness), facial injury, base of skull fracture, intestinal obstruction, ↓conscious level. Entonox is controlled by a demand valve and is inhaled through a mask or mouthpiece, often held by the patient. It provides rapid and effective analgesia and is widely used in prehospital care. In A&E, Entonox is useful for initial analgesia, for example while splinting limb injuries, and for many minor procedures such as reduction of a dislocated patella or finger. Tell the patient to breathe deeply through the mask or mouthpiece and warn him that he may feel drowsy or drunk, but that this will wear off within a few minutes. Ketamine Ketamine is a dissociative anaesthetic drug which may be given IM or IV by experts and which provides strong analgesia in sub-anaesthetic dosage. It is rarely used in hospital practice for adults, because it may cause severe hallucinations, but these are less of a problem in children. Ketamine is particularly useful in prehospital care and is the most appropriate drug in the rare cases when GA is needed outside hospital for extrication or emergency amputation. It is very useful for sedation of children for procedures such as suturing of minor wounds. Airway-protective reflexes are maintained better with ketamine than with other induction agents, but airway obstruction and aspiration of gastric contents are still potential hazards. Respiratory depression is uncommon at normal dosage, unless the drug is given too rapidly. Ketamine is a bronchodilator and may be used in asthmatics. It stimulates the cardiovascular system and causes tachycardia and hypertension, so avoid it in head-injured patients, in severely hypertensive patients and in chronic alcoholics. Hallucinations are less likely if a small dose of midazolam is given and the patient is not disturbed during recovery from anaesthesia. Ketamine is available in 3 strengths: 10, 50 and 100mg/mL. The IV dose is 1-2mg/kg over 60secs, which is effective after 2-7mins and provides surgical anaesthesia lasting 5-10mins. The IM dose for GA is 10mg/kg, which is effective after 4-15mins and gives surgical anaesthesia for 12-25mins. Further doses (10-20mg IV or 20-50mg IM) can be given if major limb movements occur or if ↑muscle tone prevents extrication of the patient. For sedation of children undergoing suturing or other minor procedures, ketamine may be given IM in a dose of 2-2.5mg/kg, with atropine 0.01mg/kg mixed in the same syringe. With this dose of ketamine, LA is needed for cleaning and suturing of wounds, but little physical restraint should be needed to allow the procedure to take place. Occasionally, a second dose of ketamine (1mg/kg IM) is required to achieve adequate sedation. Larger initial doses (such as 4 or 5 mg/kg) provide deeper sedation, but are more likely to cause side effects (eg vomiting or agitation) during recovery. With low doses of ketamine, agitation is unlikely and there is no advantage in adding midazolam. P.271
Analgesia for trauma Multiple injuries Entonox may be useful for analgesia during transport and initial resuscitation, but only allows administration of 50% O2 and should not be used if there is an undrained pneumothorax. As soon as practicable, use other forms of analgesia, usually IV morphine (p268) and/or nerve blocks (p284), together with splintage of fractures to ↓pain and ↓blood loss. Head injury Relief of pain is particularly important in head-injured patients, since pain and restlessness ↑ICP, which can exacerbate secondary brain injury. Headache due to a head injury can usually be treated with paracetamol, diclofenac or codeine phosphate (which may cause less central depression than stronger opioids such as morphine). If the headache is severe or increasing, arrange a CT scan to look for an intracranial haematoma. Try to avoid strong opioids, because of concern about sedation and respiratory depression, but if pain is severe give morphine in small IV increments. The effects can be reversed if necessary with naloxone. Femoral nerve block is particularly useful in a patient with a head injury and a fractured femur, since it ↓ or avoids the need for opioids. Small children with minor head injuries sometimes deny having headaches, but look and feel much better if given paracetamol (p266). Provide further doses if necessary over the following 12-24h. Chest injury Chest injuries are often extremely painful. Good analgesia is essential to relieve distress and ↓risk of complications such as pneumonia and respiratory failure. Avoid giving Entonox if a pneumothorax is a possibility, until this has been excluded or drained. Give high concentration O2 as soon as possible and check SaO2 and ABG. Give morphine in slow IV increments (p268) and monitor for respiratory problems. Intercostal nerve blocks (p295) provide good analgesia for fractured ribs, but may cause a pneumothorax and should only be used in patients being admitted. In severe chest injuries get anaesthetic or ITU help: thoracic epidural local anaesthesia can sometimes avoid the need for IPPV. Before a thoracic epidural is performed, check X-rays of the thoracic spine for fractures. P.272
Analgesia in specific situations Children Injured children are distressed by both fear and pain. Sensitive treatment, explanation and reassurance are important, but give analgesia whenever necessary. Oral analgesia is usually with paracetamol (p266), but if this is inadequate add ibuprofen (p267), dihydrocodeine elixir, or Oramorph. Ibuprofen dose: 20mg/kg daily in divided doses as ibuprofen suspension (Junifen, 100mg in 5mL) 1-2 yrs: 2.5mL; 3-7yrs: 5mL; 8-12yrs: 10mL, all 3-4 times daily. Dihydrocodeine elixir dose: 0.5-1mg/kg PO 4-6 hrly. Children in severe pain may benefit from PO morphine (as Oramorph oral solution—p268). Entonox (p270) gives rapid analgesia without the need for an injection. IV morphine is appropriate in severe injuries, but take particular care if there is a head injury, since sedation may occur. Femoral nerve block (p296) provides good analgesia for femoral fractures and is usually well tolerated. Digital nerve block with bupivacaine (p286) is useful for painful finger injuries (especially crush injuries). Provide this before X-ray: when the child returns from X-ray the finger may then be cleaned and dressed painlessly. IM morphine could be used to provide analgesia for small burns or fractured arms, but oral morphine or nasal diamorphine are preferable, since IM injections are painful and unpleasant. Nasal diamorphine is not licensed, but is playing an increasing role in the provision of pain relief in children (see below). Acute abdominal pain It is cruel and unnecessary to withhold analgesia from patients with acute abdominal pain. Adequate analgesia allows the patient to give a clearer history and often facilitates examination and diagnosis: tenderness and rigidity become more localised and masses more readily palpable. Good X-rays cannot be obtained if the patient is distressed and restless because of renal colic or a perforated ulcer. Morphine by slow IV injection (p268) is appropriate in severe pain, unless this is due to renal or biliary colic, in which an NSAID (p267) or pethidine (p268) may be preferred. Toothache Toothache or pain after dental extractions can often be eased by aspirin, an NSAID or paracetamol. Do not give opioids such as codeine or dihydrocodeine, which may make the pain worse. Drainage of a dental abscess may be required to relieve toothache. P.273
Nasal diamorphine for analgesia in children In the UK, diamorphine is licensed for use IV, IM, SC and PO. Nasal diamorphine is unlicensed, but clinical studies and experience have shown that this is an effective and acceptable method of analgesia for children with limb fractures or small burns who do not need immediate venous access. It should be given as soon as possible, prior to X-rays. Contraindications: age <1yr (or weight <10kg), nasal obstruction or injury, basal skull fracture, opioid sensitivity. Verbal consent for nasal diamorphine needs to be obtained from the child’s parents (and the child if appropriate), since this is an unlicensed route of administration of this drug. Follow local protocols. The advice below is based on the published studies. The dose of nasal diamorphine is 0.1mg/kg, given in a syringe in a volume of 0.2mL. The child is weighed. The appropriate concentration of solution for the weight of child is achieved by adding an appropriate volume of 0.9% saline to a 10mg ampoule of diamorphine (and then 0.2mL of this solution is administered):

Weight Volume of saline Dose of diamorphine (mg)(kg) (mL) in 0.2mL
10 2.0 1.0
15 1.3 1.5
20 1.0 2.0
25 0.8 2.5
30 0.7 2.9
35 0.6 3.3
40 0.5 4.0
50 0.4 5.0
60 0.3 6.7

0.2mL of this solution is drawn up into a syringe and administered drop by drop into one or both nostrils, whilst the child’s head is tilted back. The head should be turned to each side and then tilted forwards, each position being maintained for several secs. The time of administration should be recorded. Conscious levels and SaO2 should be assessed frequently. Resuscitation facilities and naloxone must be available in case respiratory depression were to occur, but this is unlikely. Nasal diamorphine provides rapid analgesia which lasts up to 4hrs. References Kendall JM, et al. Multicentre randomised controlled trial of nasal diamorphine for analgesic in children and teenagers with clinical fractures. BMJ 2001; 322: 261-5. South-west Medicines Information and Training, Bristol: Intranasal diamorphine for paediatric analgesia, October 2000. http://www.swmit.nhs.uk/pdf/diamort.pdf O’Sullivan I, Higginson I. Intranasal diamorphine in children, July 2003. http://www.ubht.nhs.uk/edhandbook/paediatrics P.274
Local anaesthesia (LA) Indications for LA in A&E: LA is indicated in any situation in which it will provide satisfactory analgesia or safe and adequate conditions for operations or procedures. These include the following:

  • Insertion of venous cannulae (0.1mL of 1% lidocaine SC 30secs prior to cannulation ↓pain of cannulation without affecting the success rate)
  • Cleaning, exploration and suturing of many wounds
  • Analgesia for some fractures, eg shaft of femur
  • Minor operations/procedures, eg manipulation of some fractures and dislocations, insertion of chest drain, peritoneal lavage, drainage of paronychia, removal of corneal FB.

Contraindications to LA:

  • Refusal or poor co-operation by the patient
  • Allergy to local anaesthetic Severe allergic reactions to LA are rare, but anaphylaxis can occur. If allergy to a LA is alleged, obtain full details of the circumstances and the drug involved and check with a senior before giving any LA. It may be possible to use a different drug. Some allergic reactions are caused by the preservative in multi-dose vials rather than the drug itself, so single dose ampoules may not cause a problem. Some alleged ‘allergies’ are actually toxic effects due to overdosage, or faints due to fear and pain.
  • Infection at the proposed injection site Injection into an inflamed area is painful and could spread infection. High tissue acidity from inflammation ↓effectiveness of LA drugs. Hyperaemia causes rapid removal of the drug and so a short duration of action and ↑risk of toxicity. LA nerve block at a site away from the infected area can provide good anaesthesia, eg digital nerve block for paronychia or nerve blocks at the ankle for an abscess on the sole of the foot.
  • Bleeding disorder Anticoagulant therapy and thrombocytopenia are contraindications for nerve blocks in which there is a risk of inadvertent arterial puncture.

Special cautions (↑risk of toxicity):

  • small children
  • elderly or debilitated
  • heart block
  • low cardiac output
  • epilepsy
  • myasthenia gravis
  • hepatic impairment
  • porphyria
  • anti-arrhythmic or ß-blocker therapy (↑risk of myocardial depression)
  • cimetidine therapy (inhibits metabolism of lidocaine)

P.275
Lidocaine (lignocaine) Lidocaine is the LA used most frequently for local infiltration and for nerve blocks. It is available in 0.5%, 1% and 2% solutions, both ‘plain’ (without epinephrine/adrenaline) or with epinephrine/adrenaline 1:200,000. For routine use the most suitable choice is 1% plain lidocaine. Duration of action Lidocaine acts rapidly and the effects last about 30-60mins (for plain lidocaine) to 90mins (for lidocaine with epinephrine/adrenaline). The duration of action varies with the dosage and the local circulation. For plain lidocaine the max dose is 200mg (20mL of 1% solution) in a healthy adult or 3mg/kg in a child. For lidocaine with epinephrine/adrenaline the max dose is 500mg (50mL of 1% solution) in a healthy adult or 7mg/kg in a child. These are the max total doses for one or more injections given together for local infiltration or nerve block (with care to avoid intravascular injection). ↓dose in debilitated or elderly patients, or if there is a particular risk of toxicity (p274). Lidocaine can also be used for anaesthesia of the skin (with prilocaine in EMLA cream, p280), urethra and cornea and also as a spray for anaesthetising mucous membranes in the mouth and throat. Bupivacaine Bupivacaine is particularly useful for nerve blocks since it has a long duration of action (3-8hrs), although its onset of anaesthesia is slower than lidocaine. It may also be used for local infiltration, but not for IV regional anaesthesia (Bier’s block, p282). Bupivacaine is available in concentrations from 0.25-0.75% without epinephrine/adrenaline and 0.25-0.5% with epinephrine/adrenaline. The most appropriate is usually 0.5% bupivacaine without epinephrine/adrenaline. The max dose of bupivacaine for a fit adult is 150mg (30mL of 0.5% or 60mL of 0.25%) and for a child 2 mg/kg. The max dose is the same with or without epinephrine/adrenaline. Prilocaine Prilocaine has a similar duration of action to lidocaine. It can be used for local infiltration or nerve blocks, but is particularly useful for Bier’s block (IV regional anaesthesia, p282). High doses (usually >600mg) may cause methaemoglobinaemia. The max dose of prilocaine for a healthy adult is 400mg (40mL of 1% solution) and for a child is 6mg/kg. Amethocaine Amethocaine is used for topical local anaesthesia of the cornea and skin (p280). P.276
Local anaesthetic toxicity Toxic effects These result from overdosage of LA or inadvertent intravascular injection. The first symptoms and signs are usually neurological, with numbness of the mouth and tongue, slurring of speech, lightheadedness, tinnitus, confusion and drowsiness. Muscle twitching, convulsions and coma can occur. Cardiovascular toxicity may initially result in tachycardia and hypertension, but later there is hypotension with a bradycardia and heart block. Ventricular arrhythmias and cardiac arrest occur occasionally, especially with bupivacaine. Early signs of toxicity These may be detected if the doctor maintains a conversation with the patient while injecting LA. Toxic effects may start immediately if an intravascular injection is given. However, peak blood levels usually occur ≈10-25mins after injection—so if a relatively large dose has been given, do not leave the patient alone while anaesthesia develops. Occasionally, patients initially agree to LA but become ‘hysterical’ or faint (even while lying flat) when an injection is given. In such circumstances it may be difficult to distinguish immediately between the effects of anxiety and those of drug toxicity. Treatment of LA toxicity

  • stop the procedure
  • call for help
  • clear and maintain the airway
  • give 100% O2
  • obtain IV access
  • monitor ECG
  • record pulse, BP, respiratory rate and conscious level
  • if convulsions occur ensure adequate oxygenation and give diazepam. Adult dose of diazepam is 5-10mg slowly IV (child: 0.1-0.2mg/kg).
  • treat hypotension by raising the foot of the trolley. If systolic BP remains <90mmHg in an adult, give IV fluids (eg colloid 500mL). In a child give 20mL/kg if systolic BP <70mmHg.
  • bradycardia usually resolves without treatment, but atropine and cardiac pacing could be used if bradycardia and severe hypotension persist. Treat cardiac arrest with standard techniques (p45).

P.277
Epinephrine/adrenaline in local anaesthesia Most LA causes vasodilatation, so epinephrine/adrenaline is sometimes added as a vasoconstrictor. This ↓blood loss, ↑duration of anaesthesia and ↓toxicity by delaying absorption of the LA. Lidocaine with epinephrine/ adrenaline is sometimes useful in scalp wounds, in which bleeding can be profuse but the bleeding point not visible. Bupivacaine with epinephrine/adrenaline is recommended for intercostal nerve block to ↓risk of toxicity from rapid absorption in a relatively vascular area. Lidocaine with epinephrine/adrenaline can be used in some situations (see below for contraindications) if a relatively large volume of LA is needed, since the max dose for a healthy adult is 500mg (50mL of 1% solution) compared to 200mg (20mL of 1%) for plain lidocaine. Other possibilities in such circumstances include 0.5% lidocaine, prilocaine (max dose: 40mL of 1% solution) or GA. The max concentration of epinephrine/adrenaline in LA is 1 in 200,000, except for dental anaesthesia in which 1 in 80,000 may be used. The max total dose of epinephrine/adrenaline in a healthy adult is 500micrograms. Contraindications and cautions Never use epinephrine/adrenaline for injections in fingers, toes, nose, ears or penis, nor in IV regional anaesthesia (Bier’s block, p282). Avoid epinephrine/adrenaline for injections in or near flap lacerations, since vasoconstriction could cause ischaemic necrosis. Avoid epinephrine/adrenaline in:

  • IHD
  • hypertension
  • peripheral vascular disease
  • thyrotoxicosis
  • phaeochromocytoma
  • patients on ß-blockers.

The BNF states that LA with epinephrine/adrenaline appears to be safe in patients on tricyclic antidepressants. Storage Keep ampoules and vials of LA with epinephrine/adrenaline in a locked cupboard separate from those without epinephrine/adrenaline, so that they are only available by special request and are not used inadvertently or inappropriately. P.278
General principles of local anaesthesia Obtain a brief medical history and record drug treatment and allergies. Think about possible contraindications and cautions for LA (p277). Obtain expert advice if you have any query. Consent for LA Explain to the patient what is planned. Verbal consent is adequate for most LA procedures in A&E. Written consent is needed:

  • if there is a significant risk of a toxic reaction or complication, including procedures needing large doses of LA
  • IV regional anesthesia (Bier’s block—p282)
  • intercostal nerve block (risk of pneumothorax)

Safety Ensure that resuscitation equipment and drugs for possible toxic reactions are readily available. Monitoring and IV access are not needed for routine simple LA, but are essential if there is a risk of complications or toxicity. Calculate the max dose of LA that could be used (p275) and think how much might be needed. Check the drug label carefully before drawing up any LA, especially if epinephrine/adrenaline is contraindicated. Giving LA

  • Lie the patient down in a comfortable position with the site of injection accessible and supported. Some patients faint if local is injected while they are sitting up.
  • Warm the LA to body temperature prior to use.
  • Wash your hands, use gloves and clean the skin.
  • Use a thin needle if possible. Before inserting the needle warn the patient and hold the relevant part firmly to prevent movement.
  • Aspirate and check for blood in the syringe before injecting any LA. If the needle moves, aspirate again.
  • Inject LA slowly to ↓pain. Do not use force if there is resistance to injection.
  • Maintain a conversation with the patient, to allay anxieties and also to detect any early signs of toxicity (p276).

Further details of techniques and precautions are listed on other pages:

  • Topical anaesthesia: p280.
  • Local infiltration and field blocks: p281.
  • Haematoma block for fractures: p281.
  • Bier’s block (IV regional anaesthesia): p282.
  • Nerve blocks: pp284-99.

Recording the LA Write clearly in the notes to record the time and site of injection and the type and quantity of LA given. P.279
LA in children The general principles are the same as for adults. LA is very useful in children, but requires experienced staff. Many children tolerate LA without any problem, but in some sedation with midazolam (p300) or ketamine (p301) can be helpful. Weigh the child if possible and calculate the max dose of LA carefully (p275). A simple estimate of the max dose of 1% plain lidocaine in an average size child is 1mL per year of age (ie 3mL for a 3yr old). If a larger volume may be needed, consider using 0.5% solution or lidocaine with epinephrine/adrenaline (p277), or possibly a GA instead. Prepare everything before bringing the child into the room: rattling equipment and drawing up LA within sight of a patient cause unnecessary anxiety. Most parents prefer to stay with their child during the procedure and this is often helpful. Position the child and parent comfortably. Explain simply and honestly what is going to happen. Have adequate help to keep the child still. Use a small needle if possible and inject slowly to ↓pain from the injection. P.280
Topical anaesthesia LA applied directly to mucous membranes of the mouth, throat or urethra will diffuse through and block sensory nerve endings. Development of anaesthesia may take several mins and the duration is relatively short because of the good blood supply. Overdosage is dangerously easy because most topical preparations contain high concentrations of lidocaine (2% in lidocaine gel, 5% in ointment and 4% or 10% in lidocaine spray). Lidocaine gel has been used to allow cleaning of gravel burns, but this is not advisable: absorption of lidocaine can easily cause toxicity and the degree of anaesthesia is rarely satisfactory. Scrubbing is often necessary to remove embedded gravel, so proper anaesthesia is essential. Field block may be adequate for a small area, but GA is often necessary for cleaning large or multiple gravel burns, in order to avoid tattooing (p389). Topical anaesthesia EMLA cream ‘Eutectic Mixture of Local Anaesthetics’ cream contains lidocaine 2.5% and prilocaine 2.5% and is used for topical anaesthesia of the skin. EMLA is of limited value in A&E because it must only be applied to intact skin (not wounds) and the onset of anaesthesia is slow, usually ≈1h. EMLA must not be used in children aged <1yr and caution is needed in patients with anaemia or methaemoglobinaemia. EMLA can usefully ↓pain of an injection or cannulation (eg for aspiration of a hip effusion, venography or GA). Apply a thick layer of EMLA cream to the skin and cover it with an occlusive dressing, which must be left undisturbed for 1h. Amethocaine gel (Ametop) This is similar to EMLA, but acts more quickly and causes vasodilatation, which aids venous cannulation. It must not be used in wounds because of the risk of rapid absorption and toxicity. Topical agents such as TAC (tetracaine, adrenaline and cocaine) or LET (lidocaine, epinephrine and tetracaine) are sometimes used to provide anaesthesia for wound repair. These preparations can provide effective anaesthesia, but toxic effects may occur from excessive absorption (especially of cocaine) and they are not licenced in the UK. Ethyl chloride Ethyl chloride is a clear fluid which boils at 12.5°C. Spraying the liquid on the skin causes rapid cooling and freezing of the surface. In the past ethyl chloride was used for incision of paronychias and small abscesses, but it rarely provides adequate anaesthesia and cannot be recommended. Ethyl chloride is highly inflammable and is a GA, so it must be handled with care if it is used at all. P.281
Local anaesthetic administration Local infiltration anaesthesia Local infiltration is the technique used most often in A&E. The LA injected subcutaneously in the immediate area of the wound acts within 1-2mins. Anaesthesia lasts ≈30-60mins with plain lidocaine or ≈90mins with lidocaine and epinephrine/adrenaline (see p277 for contraindications). In clean wounds the pain of injection can often be ↓ by inserting the needle through the cut surface of the wound. Do not do this in dirty or old wounds, because of the risk of spreading infection. Less pain is produced by injecting slowly through a thin needle, injecting in a fan-shaped area from a single injection site and by inserting the needle in an area already numbed by an earlier injection. Rapid injection of LA, especially in scalp wounds, can cause spraying of solution from the tip of the needle or from separation of the needle from the syringe. Slow injection and the use of goggles should ↓risk of infection. Field block This involves infiltration of LA subcutaneously around the operative field. Sometimes it is only necessary to block one side of the area, depending on the direction of the nerve supply. Field block can be useful for ragged and dirty wounds and for cleaning gravel abrasions. Check the max safe dose before starting a field block. If relatively large volumes of anaesthetic might be needed, consider 0.5% lidocaine or lidocaine with epinephrine/adrenaline (p277). Haematoma block A Colles’ fracture (p426) can be manipulated after infiltration of LA into the fracture haematoma and around the ulnar styloid. This often provides less effective anaesthesia than Bier’s block (p282). It converts a closed fracture into an open one and so there is a theoretical risk of infection, but in practice this is rare. Contraindications and warnings

  • fractures >24h old (since organization of the haematoma would prevent spread of the LA).
  • infection of the skin over the fracture.
  • methaemoglobinaemia (avoid prilocaine)

Drug and dosage 15mL of 1% plain prilocaine. Lidocaine can be used, but there is a lower margin of safety. Never use solutions containing epinephrine/ adrenaline. Technique Full asepsis is essential. Use a 20mL syringe and a 0.6 × 25mm needle. Insert the needle into the fracture haematoma and aspirate blood to confirm this. Inject very slowly to ↓pain and the risk of high blood levels and toxicity. Anaesthesia develops in 5mins and lasts for 30-60mins. Sometimes anaesthesia is inadequate for proper manipulation and so an alternative anaesthetic is needed. P.282
Bier’s block Bier’s block (IV regional anaesthesia) is often used to provide anaesthesia for reduction of Colles’ fractures or for minor surgery below the elbow. Bier’s block uses a large dose of LA and so there is a risk of a toxic reaction, although this is minimised by proper technique. Ensure that the patient has fasted for 4h before the procedure. Pre-operative assessment is necessary, including recording of BP. Obtain written consent for the operation. Bier’s block should only be performed by doctors who are competent to deal with severe toxic reactions. At least two trained medical staff must be present throughout the procedure. Contraindications

  • severe hypertension or obesity
  • severe peripheral vascular disease
  • Raynaud’s syndrome
  • sickle cell disease or trait
  • methaemoglobinaemia
  • children aged <7yrs
  • unco-operative or confused patient
  • procedures needed in both arms
  • surgery which may last >30mins
  • surgery which may need the tourniquet to be released

Proceed with caution in epileptic patients because of the risk of a fit from LA toxicity. Drug and dose The drug of choice is 0.5% plain prilocaine from a single dose vial without preservative. Never use solutions with epinephrine/adrenaline. Do not use lidocaine or bupivacaine, which are more likely than prilocaine to cause toxic effects. The dose of 0.5% plain prilocaine for most adults is 40mL. Use 30mL for elderly, frail or debilitated patients. Bier’s block is rarely used in children, but appropriate doses are: 14-17yrs: 30mL; 11-13yrs: 20mL; 7-10yrs: 15mL. If 0.5% prilocaine is not available, use 20mL of 1% (for an adult) and dilute it with 0.9% saline up to 40mL. Equipment Special tourniquet apparatus is essential, with a 15cm wide cuff for adults. Check the tourniquet apparatus and cuff regularly. Ordinary BP cuffs and sphygmomanometers are not reliable enough and should not be used for Bier’s blocks. Check that resuscitation equipment and drugs are available immediately. Ensure that the patient is on a tipping trolley. Monitor the ECG, BP and SaO2 throughout. P.283
Technique for Bier’s block

  • Insert a small IV cannula in the dorsum of the hand on the side ofoperation (ready for injection of prilocaine) and another IV cannula in the opposite arm (for emergency use if needed).
  • Check the radial pulse. Place the tourniquet high on the arm over padding, but do not inflate it yet.
  • Elevate the arm for 3mins while pressing over the brachial artery, to try to exsanguinate the limb. (Do not use an Esmarch bandage for this purpose, because of pain).
  • While the arm is elevated inflate the tourniquet to 300mmHg, or at least 100mmHg above the systolic BP. Lower the arm on to a pillow and check that the tourniquet is not leaking.
  • Record the tourniquet time. A trained person must observe thetourniquet pressure constantly during the procedure.
  • Slowly inject the correct volume of 0.5% plain prilocaine into theisolated limb, which will become mottled. If the operation is on the hand, squeeze the forearm during injection to direct LA peripherally. Test for anaesthesia after 5mins. If anaesthesia is inadequate inject 10-15mL 0.9% saline to flush the prilocaine into the arm. Occasionally, no adequate anaesthesia is achieved and GA is needed instead.
  • Complete the manipulation or operation. Before applying a POP backslab remove the cannula from the injured arm.
  • The tourniquet cuff must remain inflated for at least 20mins, even if surgery is completed before then. Deflate the tourniquet slowly and record the time. Maintain a conversation with the patient and watch carefully for any sign of toxicity. If any toxic effects occur reinflate the tourniquet and give any necessary treatment (p276). After release of the tourniquet the arm becomes warm and flushed. Sensation returns after a few mins.
  • Observe the patient carefully for at least 30mins after a Bier’s block in case of delayed toxicity. Check the circulation of the limb before the patient is discharged home. Reactive swelling can occur: elevate the limb in a sling and give POP instructions.

P.284
Local anaesthetic nerve blocks LA nerve blocks are very useful in A&E for many minor operations and to provide analgesia. Several nerve blocks are described on pp286-299. Many other nerve blocks and regional blocks are possible, but are not normally appropriate in A&E. Some should only be performed by doctors with anaesthetic training, or in a few cases dental training. Equipment for nerve blocks Ordinary injection needles can be used for most local blocks in A&E. Anaesthetists sometimes use special pencil-point or short bevel needles when blocking large nerve trunks and plexuses. They may also use peripheral nerve stimulators to locate nerves. General procedure for nerve blocks

  • Follow the general principles of LA (p274).
  • Review the relevant anatomy for the block. Determine the site of injection by feeling for local structures such as arteries or tendons.
  • When performing a nerve block hold the needle with the bevel in the line of the nerve (rather than across it), to ↓ the risk of cutting nerve fibres.
  • Ask the patient about tingling in the area supplied by the nerve. Do not try to elicit paraesthesiae. If paraesthesiae occur withdraw the needle 2-3mm before injecting.
  • Wait for the nerve block to work, but do not leave the patient alone during this time. Tell the nurse when to call you back, in case you are busy with other patients. Estimate when a nerve block should be effective and do not test sensation before then. Small nerves may be blocked in 5mins, but large nerves may take up to 40mins.

Failed nerve block If a nerve block does not work, consider waiting longer or giving another injection. Before giving any more LA, review the relevant anatomy and check that the maximum safe dose of the drug will not be exceeded. Entonox can be helpful as a supplement to LA for some short procedures, such as reduction of dislocations. Alternatively, sedation (p300) may be useful in some cases. However, it is occasionally necessary to abandon LA and arrange GA instead. P.285
P.286
Digital nerve block Digital nerve block is used frequently for simple operations on the fingers and toes. (The term ‘ring block’ is often used, but is incorrect since it implies that LA is injected in a ring around the finger, which is unnecessary and might cause ischaemia due to vascular compression). A dorsal and a palmar digital nerve run along each side of the finger and thumb. Similarly, there are dorsal and plantar nerves in the toes. Drug and dosage 1% plain lidocaine is usually the most suitable drug. Bupivacaine (0.5% plain) is useful if prolonged anaesthesia or analgesia are needed. Never use epinephrine/adrenaline or any other vasoconstrictor. In an adult use 1-2mL on each side of the finger, thumb or great toe. Use smaller volumes in the other toes or in children. Technique

  • Use a 0.6 × 25mm (23G) needle (0.5 × 16mm, 25G needle, in smallchildren).
  • Insert the needle from the dorsum on the lateral side of the base of the digit, angled slightly inwards towards the midline of the digit, until the needle can be felt under the skin on the flexor aspect.
  • Aspirate to check the needle is not in a blood vessel.
  • Slowly inject 0.5-1mL and then continue injecting as the needle iswithdrawn.
  • Repeat on the medial side of the digit.
  • If anaesthesia is needed for the nail bed of the great toe give anadditional injection of LA subcutaneously across the dorsum of the base of the proximal phalanx, to block the dorsal digital nerves and their branches. This is also required for anaesthesia of the dorsum of the digit proximal to the middle phalanx. This ‘additional’ injection may render the injection on the medial side of the digit less painful, so if possible, give it before the medial side injection.

Anaesthesia develops after ≈5mins. The autonomic nerve fibres are blocked as well as sensory nerve fibres, so when the block is working the skin feels dry and warm. Occasionally, anaesthesia remains inadequate and another injection is needed. The max volume which can be used at the base of a finger, thumb or great toe is 5mL. Use less in the other toes or in children. Digital nerve block at metacarpal level Digital nerves can be blocked where they run in the interspaces between the metacarpals. Insert a thin needle in the palm through the distal palmar crease, between the flexor tendons of adjacent fingers. Injection of 3-4mL of 1% plain lidocaine will block the adjacent sides of these two fingers. Anaesthesia develops after 5-10mins. Alternatively, a dorsal approach can be used: this is often preferred because it is less painful, but there is a ↑risk of inadvertent venepuncture and the digital nerves are further from the dorsal surface, so a deep injection is needed. P.287

Figure. Digital nerve block

P.288
Nerve blocks at the wrist 1 The median nerve supplies sensation to the radial half of the palm, the thumb, index and middle finger and the radial side of the ring finger. The ulnar nerve supplies the ulnar side of the hand, the little finger and the ulnar side of the ring finger. The radial nerve supplies the dorsum of the radial side of the hand. The different nerve distributions overlap. In some people, the radial side of the ring finger and the ulnar side of the middle finger are supplied by the ulnar rather than median nerve. LA block of one or more nerves at the wrist provides good anaesthesia for minor surgery on the hand and fingers. Median nerve block At the wrist the median nerve lies under the flexor retinaculum on the anterior aspect of the wrist, under or immediately radial to the tendon of palmaris longus and 5-10mm medial to the tendon of flexor carpi radialis. Just proximal to the flexor retinaculum, the median nerve gives off the palmar cutaneous branch which travels superficially to supply the skin of the thenar eminence and the central palm. Carpal tunnel syndrome is a contraindication to median nerve block. Technique

  • Use a 0.6mm (23G) needle and ≈5-10mL of 1% lidocaine.
  • Ask the patient to flex the wrist slightly and bend the thumb to touch the little finger, in order to identify palmaris longus.
  • Insert the needle vertically at the proximal wrist skin crease, between palmaris longus and flexor carpi radialis, angled slightly towardspalmaris longus, to a depth of 1cm. If paraesthesiae occur withdraw the needle by 2-3mm.
  • Inject ≈5mL of LA slowly.
  • If necessary, block the palmar cutaneous branch by injecting another 1-2mL SC while withdrawing the needle.
  • A small but significant proportion of individuals do not have palmaris longus—in this case, identify flexor carpi radialis and insert the needle on its ulnar side.

Ulnar nerve block In the distal forearm the ulnar nerve divides into a palmar branch (which travels with the ulnar artery to supply the hypothenar eminence and palm) and a dorsal branch (which passes under flexor carpi ulnaris to supply the ulnar side of the dorsum of the hand). Technique

  • Use a 0.6mm (23G) needle and 5-10mL of 1% lidocaine. Avoidepinephrine/adrenaline in peripheral vascular disease.
  • Check the radial pulse before blocking the ulnar nerve.
  • Feel the ulnar artery and flexor carpi ulnaris tendon and insert the needle between them at the level of the ulnar styloid process.
  • Aspirate and look for blood in the syringe. Withdraw the needle 2-3mm if paraesthesiae occur.
  • Inject 5mL of LA.
  • Block the dorsal branch of the ulnar nerve by SC infiltration of 3-5mL of LA from flexor carpi ulnaris around the ulnar border of the wrist.

P.289

Figure. Nerve blocks at the wrist

P.290
Nerve blocks at the wrist 2 Radial nerve block In the distal part of the forearm the radial nerve passes under the tendon of brachioradialis and lies subcutaneously on the dorsum of the radial side of the wrist, where it separates into several branches and supplies the radial side of the dorsum of the hand. Technique

  • Use a 0.6mm (23G) needle and 5mL of 1% lidocaine, with or without epinephrine/adrenaline.
  • Infiltrate LA subcutaneously around the radial side and dorsum of the wrist from the tendon of flexor carpi radialis to the radio-ulnar joint. Beware of inadvertent IV injection.

Radial nerve block involves an infiltration technique and often has a more rapid onset and shorter duration of action than median nerve and ulnar nerve blocks. In combined blocks, experts may use lidocaine with epinephrine/adrenaline in order to prolong the anaesthetic and ↓ the risk of lidocaine toxicity. Other blocks Nerve blocks at the elbow The median, ulnar and radial nerves can be blocked at the level of the elbow, but this is rarely necessary. The onset of anaesthesia is slower than with blocks at the wrist. Brachial plexus blocks These should only be used by doctors with anaesthetic training. Brachial plexus blocks can provide good anaesthesia for operations on the arm but the onset of anaesthesia is often slow (30-45mins) and there is a risk of LA toxicity because of the large dose required. The axillary approach can be used in outpatients. If the supraclavicular approach is used, admission to hospital is necessary, because of the risk of a pneumothorax. P.291

Figure. Radial nerve block at the wrist

P.292
Nerve blocks of forehead and ear Nerve blocks of the forehead Many wounds of the forehead and frontal region of the scalp can be explored and repaired conveniently under LA block of the supraorbital and supratrochlear nerves. The supraorbital nerve divides into medial and lateral branches and leaves the orbit through two holes or notches in the superior orbital margin, ≈2.5 cm from the midline. The branches of the supraorbital nerve supply sensation to most of the forehead and the frontal region of the scalp. The supratrochlear nerve emerges from the upper medial corner of the orbit and supplies sensation to the medial part of the forehead. Technique

  • Use 5-10mL of 1% lidocaine, with or without epinephrine/adrenaline.
  • Insert the needle in the midline between the eyebrows and direct itlaterally.
  • Inject LA subcutaneously from the point of insertion along the upper margin of the eyebrow.
  • If the wound extends into the lateral part of the forehead SCinfiltration of LA may be needed lateral to the eyebrow to block the zygomaticotemporal and auriculotemporal nerves.

Possible complications

  • Injury to the eye can occur if the patient moves during the injection.
  • It is possible to block the supraorbital nerve at the supraorbital foramen, but this is not advisable since inadvertent injection into the orbit may cause temporary blindness if the LA reaches the optic nerve.

Nerve blocks of the ear The auricle (pinna) of the ear is supplied by branches of the greater auricular nerve (from inferiorly), lesser occipital nerve (posteriorly) and the auriculotemporal nerve (anteriorly/superiorly). These nerves can be blocked by SC infiltration of up to 10mL of 1% plain lidocaine) in the appropriate area, or in a ring around the ear. To block the greater auricular nerve infiltrate 1cm below the ear lobe from the posterior border of the sternomastoid muscle to the angle of the mandible. Block the lesser occipital nerve by infiltration just behind the ear. When blocking the auriculotemporal nerve by infiltration just anterior to the external auditory meatus, aspirate carefully to avoid inadvertent injection into the superficial temporal artery. P.293

Figure. Nerve blocks: forehead and ear

P.294
Dental anaesthesia Intraoral injections of local anaesthetic are used frequently for dental procedures, but can also be useful for cleaning and repair of wounds of the lips, cheeks and chin. Instruction by a dentist or oral surgeon is required. Give dental anaesthetics with dental syringes and cartridges of LA. An appropriate drug for most purposes is lidocaine 2% with epinephrine/ adrenaline 1 in 80,000. Some dental syringes do not allow aspiration prior to injection. Disposable dental syringes are preferable to reusable syringes, to ↓risk of needlestick injury from resheathing of needles. Infraorbital nerve block The infraorbital nerve supplies the skin and mucous membrane of the cheek and upper lip and also the lower eyelid and the side of the nose. The nerve emerges from the infraorbital foramen, which is 0.5cm below the infraorbital margin and vertically below the pupil when the eyes are looking forwards. The nerve can be blocked at the infraorbital foramen by injection through the skin, but the intraoral approach is preferable, because it is less unpleasant for the patient. Insert the needle into the buccogingival fold between the first and second premolars and direct it up towards the infraorbital foramen. Mental nerve block The mental nerve supplies sensation to the lower lip and the chin. It emerges from the mental foramen, which is palpable on the mandible on a line between the first and second premolar teeth. The nerve can be blocked at the mental foramen with 1-2mL of LA, using either an intraoral or an extraoral approach. Avoid injecting into the mental canal, since this may damage the nerve. If the wound to be repaired extends across the midline bilateral mental nerve blocks will be needed. The nerves to a single lower incisor may be blocked by submucous infiltration of LA in the buccal sulcus adjacent to the tooth. P.295
Intercostal nerve block Intercostal nerve blocks can give useful analgesia for patients with ribfractures who are admitted to hospital, but it is not a routine procedure and requires training and experience. These blocks must not be used in outpatients and should not be performed bilaterally because of the risk of pneumothorax. Patients with obesity or severe obstructive airways disease have ↑risk of complications. Alternative procedures used in ITU are interpleural analgesia and thoracic epidurals, but these are not appropriate in A&E. P.296
Femoral nerve block Femoral nerve block is a simple technique and provides good analgesia within a few mins for pain from a fractured shaft of femur. It may be used in children as well as in adults. Perform femoral block on the clinical diagnosis of a fractured shaft of femur, before X-ray or the application of a traction splint. Femoral nerve block can be used with a block of the lateral cutaneous nerve of the thigh for anaesthetizing a skin donor site. Anatomy The femoral nerve passes under the inguinal ligament, where it lies lateral to the femoral artery. The femoral nerve supplies the hip and knee joints, the skin of the medial and anterior aspects of the thigh and the quadriceps, sartorius and pectineus muscles in the anterior compartment of the thigh. Technique

  • In an adult use 10mL of 1% lidocaine or 10mL of 0.5% bupivacaine (child 0.2mL/kg of plain bupivicaine). Check the max dose carefully, especially in children or if bilateral femoral nerve blocks are needed.
  • Use a 0.8 × 40 mm (21G) needle in adults and a 0.6 × 25 mm (23G) needle in children.
  • Blocking the right femoral nerve is best performed from the patient’s left side (and vice versa).
  • Feel the femoral artery just below the inguinal ligament.
  • Clean the skin.
  • Insert the needle perpendicular to the skin and 1cm lateral to the artery to a depth of ≈3cm. If paraesthesiae occur withdraw the needle by 2-3mm.
  • Aspirate and check for blood.
  • Inject LA while moving the needle up and down and fanning outlaterally to ≈3cm from the artery. (The distances quoted refer to adults).
  • If the femoral artery is punctured compress it for 5-10mins. If no bleeding is apparent, continue with the femoral nerve block.

P.297

Figure. Femoral nerve block

P.298
Nerve blocks at the ankle Indications

  • cleaning, exploration and suturing of wounds of the foot
  • removal of FB. Drainage of small abscesses on the sole of the foot
  • analgesia for crush injuries of the forefoot
  • LA blocks at the ankle are particularly useful for anaesthetising the sole of the foot, where local infiltration is very painful and unsatisfactory

Anatomy Sensation in the ankle and foot is supplied by 5 main nerves:

  • saphenous nerve (medial side of ankle)
  • superficial peroneal nerve (front of ankle and dorsum of foot)
  • deep peroneal nerve (lateral side of great toe and medial side of 2nd toe)
  • sural nerve (heel and lateral side of hind foot)
  • tibial nerve (which forms the medial and lateral plantar nerves, supplying the anterior half of the sole)

There are individual variations and significant overlap between the areas supplied by different nerves, especially on the sole of the foot. It is often necessary to block more than one nerve. For each of these blocks use a 0.6mm (23G) needle and 5mL of 1% lidocaine (with or without epinephrine/adrenaline) or 0.5% bupivacaine. Check the max dose (p275), especially for multiple blocks. Do not use epinephrine/adrenaline in patients with peripheral vascular disease. Saphenous nerve Infiltrate LA subcutaneously around the great saphenous vein, anterior to and just above the medial malleolus. Aspirate carefully because of the risk of IV injection. Superficial peroneal nerve Infiltrate LA subcutaneously above the ankle joint from the anterior border of the tibia to the lateral malleolus. Deep peroneal nerve Insert the needle above the ankle joint between the tendons of tibialis anterior and extensor hallucis longus. Inject 5mL of LA. Sural nerve Lie the patient prone. Insert the needle lateral to the Achilles tendon and infiltrate subcutaneously to the lateral malleolus. Tibial nerve Lie the patient prone. Palpate the posterior tibial artery. Insert the needle medial to the Achilles tendon and level with the upper border of the medial malleolus, so the needle tip is just lateral to the artery. Withdraw slightly if paraesthesiae occur. Aspirate. Inject 5-10mL. P.299

Figure. Nerve blocks at the ankle

P.300
Sedation Sedation is often used in A&E to help patients tolerate distressing procedures, such as reduction of dislocations, but carries the same risks and complications as GA. When appropriate, sedation may be used with an analgesic or LA, but do not use sedation as a substitute for adequate analgesia or anaesthesia. Sedative drugs may be given PO, IM, IV or by inhalation. Oral sedation may be helpful in children. Inhalational sedation and analgesia with nitrous oxide (Entonox, p270) is rapidly reversible, relatively risk-free and can be used when appropriate in adults and some children. IV sedation of children is particularly hazardous because of the narrow margin between sedation and anaesthesia, so it should not be performed in A&E, except by staff with paediatric anaesthetic training. Risk assessment The main risks of sedation are depression of respiration, ↓cardiac output and inhalation of gastric contents. Patients at particular risk of respiratory or cardiac complications include the elderly, the obese and those with pre-existing heart or lung disease. Patients with renal or hepatic conditions may require ↓drug dosage. Ideally, patients should be fasted before IV sedation. Before giving sedation ask about and record pre-existing medical conditions, drug therapy, allergies and the time of the last food and drink. Record the pulse and BP. If there is any uncertainty postpone the procedure or get expert help. Equipment Place the patient on a trolley which can be tilted head-down. Ensure suction, resuscitation equipment and drugs are immediately available. Staff Sedation should only be given by doctors trained in resuscitation. A second person (doctor or nurse) must be present throughout to assist. Some sedatives cause amnesia and transient confusion—the presence of a chaperone may avoid difficulties if there is any allegation of impropriety. Drugs for IV sedation All sedative drugs will produce anaesthesia if given in excessive dosage. Use the minimum amount that will give adequate sedation and allow the procedure to be completed satisfactorily. Midazolam is the most suitable benzodiazepine drug, since it is short acting. Midazolam has a plasma half-life of about 2h in young adults (longer in elderly or obese) and the metabolites are relatively inactive. It is available in 2 concentrations: 10mg in 2mL and 10mg in 5mL, of which the latter is preferable. In fit adults the initial dose of midazolam is 2mg IV over 30secs. If sedation is inadequate after 2mins, give incremental doses of 0.5-1mg (0.25-0.5mL of the 10mg/5mL solution). When fully sedated the patient will be drowsy with slurred speech, but will obey commands. The usual dose range is 2.5-7.5mg. Elderly patients are more susceptible to benzodiazepines and require smaller doses. Give 1mg as an initial dose. The total dose needed is usually ≈1-2mg. Diazepam is not suitable for IV sedation of outpatients, since it has a prolonged action and an active metabolite with a plasma half-life of ≈3-5days. Opioids such as morphine (p268) may be used IV combined with midazolam, but there may be a synergistic effect with ↑risk of respiratory depression. Give the opioid first in ↓dosage, followed by careful titration of midazolam. Other drugs The anaesthetic drug propofol can provide sedation for short painful procedures with rapid recovery, but it should only be used by staff with anaesthetic training. Ketamine may be given IV or IM, but also requires special training. P.301
Monitoring during IV sedation Ensure patients given IV sedation receive O2, pulse oximetry monitoring and have a venous cannula. Monitor ECG. Antagonists The specific antagonists flumazenil (for benzodiazepines) and naloxone (for opioids) must be available immediately, but should be needed very rarely. If respiratory depression occurs, standard techniques to maintain the airway and breathing are more important than giving antagonists. Flumazenil and naloxone have shorter durations of action than the drugs they antagonize, so careful observation is essential if either drug is used. Recovery and discharge after sedation1 If IV sedation is used, monitor the patient carefully until recovery is complete. Monitoring and resuscitation equipment and drugs must be available. Minimum criteria for discharging a patient are:

  • stable vital signs
  • ability to walk without support
  • toleration of oral fluids and minimal nausea
  • adequate analgesia
  • adequate supervision at home by a responsible adult

Instruct the patient (verbally and in writing) not to drive, operate machinery, make any important decision or drink alcohol for 24h. Arrange appropriate follow-up. Ensure the adult accompanying the patient knows who to contact if there is any problem. Sedation in children Many children (and their parents and staff) are distressed by procedures such as suturing of minor wounds under LA. Sedation is helpful to prevent distress and allows procedures to take place with minimal physical restraint. Sedation may be given by oral or nasal routes, IM or IV. Paediatric IV sedation requires anaesthetic experience because of the narrow therapeutic margin between sedation and anaesthesia. Ketamine given IM in a dose of 2-2.5mg/kg is currently the method of choice for paediatric sedation in A&E by doctors with appropriate training. This dose of ketamine does not provide anaesthesia and so local anaesthesia is required for cleaning and suturing of wounds. Oral midazolam is unlicenced but has been advocated by some specialists. Oral sedation with promethazine or trimethazine is not advisable, since it is often ineffective. Footnote 1 Roy Coll Surg Engl 1993 Guidelines for Sedation by Non-anaesthetists. P.302
General anaesthesia in A&E GA may be needed in A&E for many different conditions:

  • minor surgery (eg drainage of abscesses, manipulation of fractures)
  • cardioversion
  • airway problems (eg facial trauma, burns, epiglottitis)
  • respiratory failure (eg asthma, chronic obstructive airways disease, pulmonary oedema, chest injuries)
  • to protect the airway and control ventilation after head injuries and to keep the patient immobile for a CT scan
  • to protect the airway and maintain ventilation in status epilepticus unresponsive to standard drug therapy
  • immediate major surgery (eg ruptured ectopic pregnancy, aortic aneurysm, thoracotomy or laparotomy for trauma): in extreme emergencies it may be necessary to anaesthetize the patient before transfer to the operating theatre, or to operate in A&E

GA in A&E tends to be stressful for the anaesthetist and potentially hazardous for the patient, who is often unprepared for anaesthesia with a full stomach and particular risk of aspiration. GA should only be given by doctors with anaesthetic training, but other staff should know what is required so they can help when necessary. Pre-operative assessment This is essential for safe anaesthesia. If time allows, assess the patient before contacting the anaesthetist to arrange the anaesthetic. However, if emergency anaesthesia is needed, call the anaesthetist immediately so that he/she can come and assess the patient and get senior help if necessary. A checklist of questions to ask before GA is shown below. Fitness for GA The American Society of Anaesthesiologists (ASA) classification of pre-operative fitness is widely used by anaesthetists:

  • Healthy patient with no systemic disease.
  • Patient with a mild to moderate systemic disease process which does not limit the patient’s activity in any way (eg mild diabetes, treated hypertension, heavy smoker).
  • Patient with a severe systemic disturbance from any cause which limits activity (eg IHD with ↓exercise tolerance, severe COPD).
  • Patient with a severe systemic disease which is a constant threat to life, (eg severe chronic bronchitis, advanced liver disease).
  • Moribund patient who is unlikely to survive 24h with or without treatment.

The risk of complications from GA correlates well with ASA group. Only patients in ASA groups 1 and 2 should be given an elective anaesthetic by a junior anaesthetist in A&E. Children aged <7yrs should not usually have an elective GA in A&E. Pre-operative investigations No investigation except ‘dipstick’ urinalysis is needed, unless pre-operative assessment reveals a problem. Measure Hb in any patient who appears anaemic. Check the Sickledex test for sickle cell disease in any patient of Afro-Caribbean, Cypriot or Indian origin. Measure U&E in patients on diuretics and blood glucose in diabetics. ECG and CXR are not needed, unless clinically indicated. Perform a pregnancy test if pregnancy is possible. P.303
Checklist for pre-operative assessment in A&E:

Age Airway problem?
Weight Dentures/crowns/loose teeth?
Time of last drink Chest disease?
Time of last food Smoker?
Drugs Cardiac disease?
Drugs given in A&E Blood pressure
Time of last analgesia GI problem?
Allergies Other illness?
Sickle cell risk? Possibility of pregnancy?
Infection risk? Previous GA? (problems?)
Family history of GA problems? Consent form signed?
Is the patient expected to go home after recovery from anaesthetic?
Is there a responsible adult who can look after the patient at home?

Preparation for GA Ideally, the patient should have nothing to drink for 4h and no food for 6h before anaesthesia. Explain why this is necessary. Fasting does not guarantee an empty stomach. Trauma, pregnancy and opioids delay gastric emptying. If the patient is in pain, give analgesia and an antiemetic after discussion with the anaesthetist. Discuss any other drug treatment that is required. Patients with a hiatus hernia or gastro-oesophageal reflux need antacid prophylaxis (eg ranitidine 50mg IV and an antacid). Explain the proposed operation and anaesthetic to the patient (and relatives if appropriate) and ensure valid consent is obtained. The patient must be clearly labelled with a wrist-band. Remove contact lenses, false teeth and dental plates. Recovery and discharge after anaesthesia When the operation has finished, place the patient in the recovery position and ensure continuous observation by trained staff until recovery is complete. The anaesthetist should stay with the patient until consciousness is regained and the airway is controlled. Monitoring and resuscitation equipment and drugs must be available. The minimum criteria for discharging a patient are the same as following sedation (p301). Importantly, tell the patient (verbally and in writing) not to drive, operate machinery, make any important decision or drink alcohol for 24h. Arrange appropriate follow-up and make sure that the adult accompanying the patient knows who to contact if there is a problem. P.304
Emergency anaesthesia Emergency anaesthesia and intubation are often needed in A&E to protect the airway and provide adequate ventilation in a patient with a head injury or multiple trauma. There is a serious risk of aspiration of gastric contents into the lungs, so protect the airway as soon as possible with a cuffed ET tube (uncuffed in small children). In a patient with a gag reflex any attempt to intubate without anaesthesia may cause vomiting and aspiration. Anaesthesia before intubation is essential in head-injured patients to minimize the ↑ in ICP. Rapid sequence intubation (RSI) RSI involves administration of a sedative or induction agent virtually simultaneously with a neuromuscular blocking agent to allow rapid tracheal intubation. RSI should only be performed by those who have received specific training and experience in the techniques and drugs used and the recognition and management of possible problems. However, it is helpful if A&E staff who have not had such training understand the principles of RSI, so that they can assist as needed.

  • Check all drugs and equipment, including suction, bag and masks, laryngoscope (and spare with large blade), tracheal tubes and introducers, syringe and valve or clamp for ET tube cuff, connectors. Check that the trolley can be tilted head-down easily.
  • Check monitoring equipment (ECG, BP, SaO2, end-tidal CO2 monitor).
  • Explain the procedure to the patient if possible.
  • Assess the risks and any conditions which might cause problems with intubation (eg trauma to the face or neck, ↓mouth opening, receding chin).
  • Establish monitoring (ECG and pulse oximetry) and secure IV access.
  • Protect the cervical spine in all trauma patients: an assistant should provide in-line immobilisation during intubation. In other patients, use a pillow and position the head and neck to aid intubation.
  • If possible, pre-oxygenate for 3mins with 100% O2 via a tight-fitting mask, with the patient breathing spontaneously. If breathing isinadequate, ventilate for 2mins with a bag and mask and 100% O2, with an assistant applying cricoid pressure by pressing firmly downwards with a thumb and index finger on the cricoid cartilage, while supporting the patient’s neck with the other hand.
  • Give an induction agent (eg thiopentone or etomidate) quickly to provide rapid anaesthesia. As the induction agent is given an assistant must occlude the oesophagus by applying cricoid pressure, which must be maintained continuously until the airway is secure.
  • Follow the induction agent immediately by a muscle relaxant (usually suxamethonium).
  • Keep the face mask tightly applied until the anaesthetic and relaxant are effective. Then intubate and inflate the cuff quickly.
  • Try to confirm tracheal placement of the tube: ideally it will have been seen to have passed through the cords, but this may not be possible in an emergency intubation. Check air entry in both sides of the chest. Check end-tidal CO2 (but be aware that this may be misleading if oesophageal intubation occurs in a patient who has recently consumed antacids or fizzy drinks). If CO2 is not detected, oesophageal intubation has occurred.
  • Cricoid pressure can be released when the ET tube is correctlypositioned, the cuff has been inflated and ventilation is satisfactory.
  • Secure the tracheal tube.
  • Continue observation and monitoring.

P.305
P.306
Difficult intubation Difficulties with intubation may result from problems with the equipment, the patient, the circumstances of intubation and from lack of experience or skill. Equipment Proper working equipment must be available where intubation may be needed: pillow, suction, laryngoscope (and spare) with interchangeable blades, ET tubes of different diameters (cut to suitable lengths, but with uncut tubes available), syringe and clamp for cuff, connectors, flexible stylet, gum-elastic bougie, lubricating jelly, Magill’s forceps, tape for securing ET tube. A face mask and ventilating bag and oral/nasal airways must be immediately available. Cricothyroidotomy equipment must be accessible. Laryngeal masks and fibre-optic laryngoscopes are useful in skilled hands, but are not routinely kept in A&E. The patient Patients may be difficult to intubate because of facial deformity or swelling, protruding teeth, ↓mouth opening from trismus or trauma, ↓neck movement or instability of the cervical spine, epiglottitis or laryngeal problems, tracheal narrowing or deviation, blood, vomit or FB in the airway. Circumstances and skills Intubation is much easier in the controlled environment of an operating theatre than in an emergency in A&E or in pre-hospital care. Skilled help is vital: in-line immobilisation of the neck, cricoid pressure and assistance with equipment and cuff inflation are needed. Practice intubating manikins regularly. Practical points Before attempting intubation, oxygenate by bag and mask ventilation (unless spontaneous breathing is adequate). Take a deep breath as you start intubation: if the patient is not intubated successfully when you have to breathe again, remove the ET tube and laryngoscope and ventilate with O2 for 1-2mins using a bag and mask before making another attempt. Consider adjusting the patient’s position, using a different size of laryngoscope blade or ET tube or a stylet or bougie. Cricoid pressure can help by pushing the larynx backwards into view. Blind nasal intubation is sometimes useful, but requires special expertise. Oesophageal intubation Fatal if unrecognised. The best way of confirming tracheal intubation is to see the ET tube pass between the vocal cords. Inadvertent oesophageal intubation can produce misleadingly normal chest movements and breath sounds. End-tidal CO2 measurement helps to confirm tracheal intubation, but end-tidal CO2 can be misleadingly ↑ in patients who have taken antacids or fizzy drinks. If in doubt, remove the ET tube and ventilate with bag and mask. P.307
Failed intubation drill Persistent unsuccessful attempts at intubation cause hypoxia and ↑risk of aspiration and damage to teeth and other structures. If 3 attempts at intubation are unsuccessful, follow a failed intubation drill:

  • Inform all staff that intubation attempts have ceased and get senior help.
  • Ventilate the patient on 100% O2 using bag and mask and an oral or nasal airway, while an assistant maintains cricoid pressure.
  • If ventilation is impossible, turn the patient onto the left side and tilt the trolley head down, while maintaining cricoid pressure. If ventilation is still impossible release cricoid pressure slowly and attempt to ventilate again. A laryngeal mask airway may help, but requires expertise. Cricothyroidotomy (p318) is rarely needed, but must be performed if necessary.
  • In non-emergency cases, the patient can be allowed to wake up, but this is not an option in a life-threatening emergency. Discuss the problem with a senior anaesthetist.
  • Warn the patient and GP if the difficulty with intubation is liable to recur.

Laryngospasm Laryngospasm occurs when the laryngeal muscles contract and occlude the airway, preventing ventilation and causing hypoxia. Causes

  • stimulation of the patient during light anaesthesia
  • irritation of the airway by secretions, vomit, blood or an oropharyngeal airway
  • irritant anaesthetic vapours
  • extubation of a lightly anaesthetized patient

Treatment

  • give 100% O2
  • clear the airway of secretions, using gentle suction
  • gently ventilate the patient using a bag and mask. Over-inflation is liable to fill the stomach and cause regurgitation.
  • monitor the ECG for bradycardia or arrhythmias

In severe laryngospasm an experienced anaesthetist may considerdeepening anaesthesia or giving suxamethonium to allow intubation or ventilation with a bag and mask. In a hypoxic patient, suxamethonium may cause bradycardia requiring treatment with atropine. P.308
General anaesthetic drugs GA should only be given after anaesthetic training. IV anaesthetic induction agents are used for induction of anaesthesia, as the sole drug for short procedures (eg cardioversion), for treatment of status epilepticus unresponsive to other anticonvulsants (p145), for total IV anaesthesia and for sedation of a ventilated patient. They are contra-indicated if there is upper airway obstruction or severe hypovolaemia. Thiopentone, etomidate and many other drugs are unsafe in acute porphyria (see BNF). Thiopentone is the most widely used IV anaesthetic agent and is a barbiturate. Overdosage causes hypotension and respiratory depression. Care is needed with injections because extravasation causes irritation and arterial injection is particularly dangerous. Thiopentone solution is unstable and has to be prepared from powder to form a 2.5% solution (25mg/mL). The induction dose in a fit adult is up to 4mg/kg (child: 2-7mg/kg). Methohexitone is similar to thiopentone, but is contra-indicated in epileptics. It is prepared as a 1% solution (10mg/mL). The induction dose is ≈1-1.5mg/kg. Etomidate causes less hypotension than other induction agents and recovery is rapid. However, the injection is painful and uncontrolled muscle movements may occur. Induction dose is up to 0.3mg/kg. Propofol is particularly useful in day-case surgery because recovery is rapid. The injection may be painful. Bradycardia can occur. Induction dose is 2-2.5mg/kg. Ketamine (p301) is used mainly in prehospital care, but might be useful for rapid sequence intubation in acute asthma. Induction dose is 1-1.5mg/kg. Muscle relaxants Suxamethonium is a short-acting depolarising muscle relaxant which is often used to allow intubation, especially in rapid sequence induction of anaesthesia (p304). In a dose of 600micrograms-1mg/kg it causes muscle fasciculation followed rapidly by flaccid paralysis. It is contra-indicated in hyperkalaemia and burns, paraplegia or crush injuries, where dangerous hyperkalaemia may develop if suxamethonium is used 5-120 days after injury. Suxamethonium causes ↑ICP and ↑intraocular pressure. Usual duration of action is 5mins, but prolonged paralysis occurs in patients with abnormal pseudo-cholinesterase enzymes. Atracurium and vecuronium are non-depolarizing muscle relaxants which act for ≈20-30mins. They cause fewer adverse effects than older relaxants (eg pancuronium). Paralysis from these drugs can be reversed with neostigmine, which is given with atropine or glycopyrronium to prevent bradycardia. Inhalational anaesthetics can be used for: analgesia (especially Entonox), induction of anaesthesia (particularly in upper airway obstruction, when IV induction of anaesthesia is contra-indicated), maintenance of anaesthesia. Nitrous oxide (N2O) is widely used for analgesia as Entonox, a 50:50 mixture with O2 (p270). It is also used frequently in GA in a concentration of 50-70% in O2, in combination with other inhaled or IV anaesthetics. N2O is contra- indicated in certain circumstances (eg undrained pneumothorax)—see p270. Halothane, enflurane, isoflurane and sevoflurane are inhalational anaesthetic agents which are given using specially calibrated vaporisers in O2 or a mixture of N2O and O2. Halothane is effective, but is less widely used than previously because of the risk of hepatotoxicity, especially after repeated use. Halothane sensitizes the heart to catecholamines: do not use epinephrine/adrenaline in patients breathing halothane. Halothane and these other inhalational anaesthetic agents can precipitate malignant hyperpyrexia (p261) in susceptible patients.

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