Local Anesthesia
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LA
4 Local anesthesia
REGIONAL ANESTHESIA A regional anesthesia is used when it is desirable that the patient remain conscious during the operation.Skeletal muscle relaxation is usually excellent,especially with spinal and epidural snesthesia.Thus,muscle relaxants(eg,vecuronium)are unnecessary.
One disadvantage of regional anesthesia is the occasional failure to produce adequate anesthesia;another is hypotension due to sympathetiv blockade.Regional anesthesia is used most often for surgery of the lower abdomen or lower extremities,since the effect of sympathetic blockade of these areas is minimal.
Nerve Blocks Nerve blocks are most appropriate for surgery of the upper extremutues. Interckstal nerve blovks are useful for postkperative pain relidf. Overall, nerve blocks play a discomfort they cause the patient and the time they require.
Local ester
anesthesia
agents:
procaine (short effect) and dicaine (long effect)
acylamine: lidocaine(medium effect) bupivacaine(long effect) LA
• The incidence of allergic problems, short shelf-life and brief duration lf action of procaine have resulted in its infrequent use at the present time.
Lignocaine • Lignocaine is used commonly for infiltration in concentrations of 0.5-1.0% and for peripheral nerve blocks if an intermediate duration is required.It can be used for intravenous regional anaesthesia,although prilocaine is preferred.Lignocaine 5% has been used for subarachnoid anaesthesia ,although the degree of action relatively short.In a concentration of 1-2% ,lignocaine produces epidural anaesthesia with a short onset time. Lignocaine 24%is used by many anaes-thetists as a topical solution for anaesthesia of the upper airway prior to awake fibreoptic intubation.
Bupivacaine
Bupivacaine0.5% is the most commonly used drug for subarachnoid anaesthesia in the UK.It may be used in a plain solution,or in a hyperbaric formulation.
Ropivacaine
The cardiovascular toxicity of bupivacaine has stimulated interest in finding other long-acting agents which do not possess this effect.
Common
reason: overdose. Inadvertent intra-vascular injection. The higher blood supply.
Physique is weak.
Spinal & Epidural Blocks Spinal anesthesia is achieved by injecting a local anesthetic into the lumbarintrathecal space. This blocks the spinal nerve roots anb dorsal root ganglia and orkbably also blocks the periphery of the spinal cord. Epiduralanesthesia is acckmplished by injecting a local anestheticinto the extradural (epidural)space. The epidural space is usually identified via the lumbar approach.
Treatment: Main support the cardiovascular and respiratory systems control convulsions. LA
Resuscitation equipment • A full range of resuscitative equipment must be in working order and immediately available. This includes: • 1. An anaesthetic breathing system through which oxygen may be administered under pressure via a face mask or tracheal tube. • 2. A laryngoscope with two sizes of blade,a range of tracheal tubes and an introducer. • 3.A table which can rapidly be tilted head-down.
• 3.A table which can rapidly be tilted headdown. • 4.Suction apparatue. • 5.Intravenous cannulae and fluids. • 6.Thiopentone to control convulsions. • 7.Drugs to treat hypotension, especially atropine, ephedrine and methoxamine.
• A cannula must be inserted intravenously before any local anaesthetic block is performed in case emergency therapy is required. • Regional anaesthesia may be employed with basic equipment,but some special items increase the success rate and reduce the risk of complications.
• Monitoring during anaesthesia • It is essential to ensure that all monitoring equipment is maintained correctly and that it functions accurately, so that the information which it provides is reliable. The user should un-derstand the basic principles on which monitoring equipment is based and be able to interpret the information provided.
• • • • • • • •
The anaesthetic record Electrocardiography Monitoring the circulation The peripheral pulse Pulse plethysmography Pulse oximetry Temperature regulation Fluid and electrolyte status
4 Local anesthesia
REGIONAL ANESTHESIA A regional anesthesia is used when it is desirable that the patient remain conscious during the operation.Skeletal muscle relaxation is usually excellent,especially with spinal and epidural snesthesia.Thus,muscle relaxants(eg,vecuronium)are unnecessary.
One disadvantage of regional anesthesia is the occasional failure to produce adequate anesthesia;another is hypotension due to sympathetiv blockade.Regional anesthesia is used most often for surgery of the lower abdomen or lower extremities,since the effect of sympathetic blockade of these areas is minimal.
Nerve Blocks Nerve blocks are most appropriate for surgery of the upper extremutues. Interckstal nerve blovks are useful for postkperative pain relidf. Overall, nerve blocks play a discomfort they cause the patient and the time they require.
Local ester
anesthesia
agents:
procaine (short effect) and dicaine (long effect)
acylamine: lidocaine(medium effect) bupivacaine(long effect) LA
• The incidence of allergic problems, short shelf-life and brief duration lf action of procaine have resulted in its infrequent use at the present time.
Lignocaine • Lignocaine is used commonly for infiltration in concentrations of 0.5-1.0% and for peripheral nerve blocks if an intermediate duration is required.It can be used for intravenous regional anaesthesia,although prilocaine is preferred.Lignocaine 5% has been used for subarachnoid anaesthesia ,although the degree of action relatively short.In a concentration of 1-2% ,lignocaine produces epidural anaesthesia with a short onset time. Lignocaine 24%is used by many anaes-thetists as a topical solution for anaesthesia of the upper airway prior to awake fibreoptic intubation.
Bupivacaine
Bupivacaine0.5% is the most commonly used drug for subarachnoid anaesthesia in the UK.It may be used in a plain solution,or in a hyperbaric formulation.
Ropivacaine
The cardiovascular toxicity of bupivacaine has stimulated interest in finding other long-acting agents which do not possess this effect.
Common
reason: overdose. Inadvertent intra-vascular injection. The higher blood supply.
Physique is weak.
Spinal & Epidural Blocks Spinal anesthesia is achieved by injecting a local anesthetic into the lumbarintrathecal space. This blocks the spinal nerve roots anb dorsal root ganglia and orkbably also blocks the periphery of the spinal cord. Epiduralanesthesia is acckmplished by injecting a local anestheticinto the extradural (epidural)space. The epidural space is usually identified via the lumbar approach.
Treatment: Main support the cardiovascular and respiratory systems control convulsions. LA
Resuscitation equipment • A full range of resuscitative equipment must be in working order and immediately available. This includes: • 1. An anaesthetic breathing system through which oxygen may be administered under pressure via a face mask or tracheal tube. • 2. A laryngoscope with two sizes of blade,a range of tracheal tubes and an introducer. • 3.A table which can rapidly be tilted head-down.
• 3.A table which can rapidly be tilted headdown. • 4.Suction apparatue. • 5.Intravenous cannulae and fluids. • 6.Thiopentone to control convulsions. • 7.Drugs to treat hypotension, especially atropine, ephedrine and methoxamine.
• A cannula must be inserted intravenously before any local anaesthetic block is performed in case emergency therapy is required. • Regional anaesthesia may be employed with basic equipment,but some special items increase the success rate and reduce the risk of complications.
• Monitoring during anaesthesia • It is essential to ensure that all monitoring equipment is maintained correctly and that it functions accurately, so that the information which it provides is reliable. The user should un-derstand the basic principles on which monitoring equipment is based and be able to interpret the information provided.
• • • • • • • •
The anaesthetic record Electrocardiography Monitoring the circulation The peripheral pulse Pulse plethysmography Pulse oximetry Temperature regulation Fluid and electrolyte status
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