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 (<10 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