Local Anesthesia and Additives

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Local Anesthesia and Additives

• R3 ???

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Intrathecal agent Transient Neurologic Symptoms

• Transient radicular irritation
• Freedman et al
• Factors associated with TNS
• Lidocaine use, outpatient status, lithotomy
  position

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Intrathecal Agent Transient Neurologic Symptoms

• Freedman et al
• Not associated with TNS
• Bupivacaine, age, sex, use of pencil-point needles

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What are the Alternatives to Intrathecal
Lidocaine ?

• Mepivacaine
• Addiction of epinephrine and opioids
• Meperidine
• Low-dose hypobaric lidocaine
• Ropivacaine

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Mepivacaine

• Reliable intrathecal anesthetics
• Ligouri and colleagues
• Intraoperative anesthesia
• 45mg dose knee arthroscopy
• 7.4 TNS incidence
• Intrathecal fentanyl
• 30mg mepivacaine knee arthroscopy

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Addiction of Epinephrine and Opoids

• Extend the duration of anesthesia
• Fentanyl, morphine sulfate
• Meperinde
• Alone, intrathecal anesthetic agent for
  postpartum sterilization procedure
• 60mg similar 70mg of hyperbaric 5 lidocaine
• 1.5mg/kg effective sensory anethesia for 2hr

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Newer Agents

• Levobupivacaine
• Clonidine
• Ketorolac
• Ketamine

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Levobupivacaine

• Less cardiotoxic than racemic bupivacaine
• Peripheral nerve blockade, lumbar epidural
  anesthesia
• Indistinguishable from racemic bupivacaine
• Postoperative epidural infusion
• Low incidence of dense motor blockade at 24hr

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Clonidine

• Increase the duration of anesthesia and analgesia
  for all regional anesthetic techniques
• Site of analgesia action
• Periphery, spinal level, brain stem
• Analgesia for patient with neuropathic pain
• Intraoperative epidural anesthesia
• Prolonged by 50 to 100 with the addition of
  150ug
• Bupibacaine SA 75-150ug clonidine prolong
  anesthesia, analgesia by 30 tourniquet pain
  reduce

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Clonidine

• Epidural analgesia with clonidine, local
  anesthtic, diamorphine
• Decreased incidence of phantom limb pain
• IV regional anesthesia
• With clonidine 150ug to lidocaine
• Decrease tourniquet pain , no significant change
  in hemodynamics
• Peripheral nerve block extended by 50 to 100

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Ketorolac

• Added to local anesthetic for various regional
  anestheic technique
• excellent analgesic adjuvant
• Significant difference in tourniquet pain and
  postoperative analgesic requirement in IV
  ketorolac and placebo
• Local antiinflammatory action at the site of
  mediator synthesis

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Ketamine

• Not new but rediscovered
• Cook
• Compared the addition of epinephrine, clonidine,
  ketamine to bupivacaine for postoperative caudal
  analgesia
• Duration of analgesia
• Ketamine (12.5hr), clonidine(5.8hr),
  epinephrine(3.2hr)
• Extended the duration of local anesthetics and to
  enhance the activity of epidural morphine
• Gantenbein and colleague
• Inhibit the bupivacaine metabolism

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Interesting Place for Local Anesthtics

• Catheter technique
• Increasingly popular to extend postoperative
  analgesia
• Prolonged anesthesia and postoperative analgesia
• Inhibit tachyphylaxis
• 0.125 to 0.25 bupivacaine and 0.2 ropivacaine
• Intraperitoneal lidocaine
• Primary anesthetic technique and for
  postoperative analgesia after mini-laparotomy and
  laparoscopy
• Reduction pain score, level of metabolic markers
  of stress
• Intra-articular injection of local anesthetics
  for knee surgery
• Analgesia, primary anesthetic technique anethesia
• Preoperative injection 20ml 2 lidocaine,
  bupivacaine

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Toxicity of Local Anesthetics

• Determinig toxicity of local anesthetics
• Lipid solubility and protein binding
• Dwell time or the amount of time that a local
  anesthetic occupies the cardiac sodium channel
• Bupivacaine
• 1.5s dwell time
• Fast-in, slow outprofile
• Lidocaine
• 0.15s dissociation time
• Rapidly in and out of cardiac sodium channel

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Toxicity of Local Anesthetics

• Levobupivacaine
• R isomer longer dwell time in cardiac sodium
  channel than S isomer (levobupivacaine)
• Less cardiotoxicity
• Ropivacaine
• Isomeric formulation of pure S ropivacaine
• Increased margin of cardiac safety