LOCAL/REGIONAL ANESTHESIA

1
LOCAL/REGIONAL ANESTHESIA

• SFC Shrader

2
Advantages/Disadvantages of Regional and Local
Anesthesia.
3
advantages

• patient remains conscious
• maintain his own airway
• aspiration of gastric contents unlikely
• smooth recovery requiring less skilled nursing
  care as compared to general anesthesia

4
advantages

• postoperative analgesia
• reduction in surgical stress
• earlier discharge for outpatients
• less expense

5
Disadvantages

• patient may prefer to be asleep
• practice and skill is required for the best
  results
• some blocks require up to 30 minutes or more to
  be fully effective
• analgesia may not always be totally
  effective-patient may require additional
  analgesics, IV sedation, or a light general
  anesthetic

6
Disadvantages

• toxicity may occur if the local anesthetic is
  given intravenously or if an overdose is injected
• some operations are unsuitable for local
  anesthetics, e.g., thoracotomies

7
Mechanism of Action of Local Anesthetics

• produce a blockade of nerve impulse by preventing
  increases in permeability of nerve membranes to
  Na ions, slowing the rate of depolarization
• interact directly with specific receptors on the
  sodium channel, inhibiting sodium influx
• do not alter the resting membrane resting
  potential or threshold potential

8
Selection of Local/Regional Anesthetics

• specific nerves to be blocked
• onset time or latency
• required duration of effect

9
Systemic Toxicity of Local Anesthetics

• Drugs-not a great difference in toxicity between
  equally potent local anesthetics-one of low
  toxicity when a large dose is required
• Site of injection-vascular sites lead to rapid
  absorption
• accidental I.V. injection is the most common
  cause of toxicity

10
Systemic Toxicity of Local Anesthetics

• Addition of Epinephrine-causes local
  vasoconstriction and slows absorption
• Follow recommended dose

11
Signs and Symptoms of Local/Regional Anesthesia
Toxicity

• CNS
• CV

12
Signs/symptoms of central nervous system (CNS)
toxicity-- CNS toxicity will be enhanced by
acidosis and hypoxia, both of which can occur
very rapidly if convulsions appear (when
breathing may stop and the excessive muscular
activity consumes oxygen stores)
13
S/S CNS Toxicity

• Unconsciousness
• Generalized convulsions
• Coma
• Apnea
• Numbness of the mouth and tongue, metal taste in
  the mouth

14
S/S CNS Toxicity

• Light-headedness
• Tinnitus
• Visual disturbance
• Muscle twitching
• Irrational behavior and speech

15
Cardiovascular toxicity

• slowing of the conduction in the myocardium
• myocardial depression
• peripheral vasodilatation
• usually seen after 2 to 4 times the convulsant
  dose has been injected

16
Prevention and Treatment of Local/Regional
Anesthesia Toxicity
17
prevention

• Always use the recommended dose
• Aspirate through the needle or catheter before
  injecting the local anesthetic. Intravascular
  injection can have catastrophic results.
• If a large quantity of a drug is required, use a
  drug of low toxicity and divide the dose into
  small increments, increasing the total injection
  time
• always inject slowly (lt10 ml/min) and communicate
  with the pt

18
treatment

• All necessary equipment to perform resuscitation,
  induction, and intubation should be on hand
  before injection of local/regional anesthetics
• Manage airway and give oxygen
• Stop convulsions if they continue for more than
  15 to 20 seconds
• Thiopental 100 mg to 150 mg IV
• or Diazepam 5 mg to 20 mg IV