A seasoned anesthesiologist, Dr. Edwin Perez, MD, summarizes a lecture on regional anesthesia pharmacology and therapeutics, when to use them, the risk and benefits, and other important information about anesthesia.

1. Regional Anesthesia
Pharmacology and
Therapeutics
Edwin Perez, MD, BS, High School
Director-Acute Pain
Newark Beth Israel
(not the one in New York :(

2. Objectives
Types-Amides vs Esters
Spread of Local
Pharmacokinetics
Use of Vasoconstrictors
Toxicity

3. Objectives
key points about all blocks in general
when to use them
risks/benefits
ultrasound versus landmark/stim technique
LAST

4. Amides And Esters
All local Anesthetics (LA) have a hydrocarbon
chain connected to a lipophilic portion. This is
done by either an ester (-CO-) bond or amine (-
HNC-) bond.
amides are metabolized in liver
esters are metabolized in plasma by
pseudocholinesterase

5. Rule of iEsters AmIdes
procaine lIdocaine
chloroprocaine bupIvacaine
tetracaine mepIvacaine
cocaine ropIvacaine

6. Do you have any
allergies?
Extremely unlikely-1% of ADR are caused by
Local anesthetics
Most likely seeing systemic toxicity
esters are the culprit more than amides-think
PABA
when linked to amides usually due to
preservative-methylparaben

7. Max single-shot dose
Esters-
procaine-1000mg in 70kg male
chloroprocaine-800mg in 70kg male
1000mg in 70kg male w/epi
tetracaine-20mg in 70kg male
Amides
Lidocaine- 3 or 5mg/kg depending on epi
Bupivacaine/Ropivacaine 3mg/kg

8. Spread (rules are
different for peripheral)

9. Pharmacology 101:its
gotta get inside
LA bind to sodium channels on the inside of
the channel
They also obstruct the outside
maintains them in inactivated-closed state

10. Pharmacokinetics
pKa of local anesthetics makes them such
that only 0.5% is already in a nonionized form.
It must be nonionized to cross (abscess)
Intrinsic vasodilator-lidocaine
esters safer except in pseudocholinesterase
deficiency

11. Toxicity
1) #1 casue is accidental intravascular
placement
2) Then from absorption
intercostal>caudal>epidural> sciatic

12. CNS
Scale of effects
A) Analgesia
B) Lightheadedness, tinnitus, numb tongue
C) Seizures
D) Coma
E) Then cardiovascular depression

13. Cardiac
Hypotension
increased P-R and wide QRS
arrythmia
bupivacaine is fast in/slow out

14. Other effects
TRI
Cauda equina syndrome

15. Why Blocks
Significant improvement in analgesia
Significant improvement in patient
satisfaction
Sometimes decreased LOS
Decreased opioid requirements by 50% or
more

16. Blocks
Chronic vs Acute Pain Blocks (diag vs ther)
contraindications
peripheral blocks only work on periphery
block effect times
nerve sparing and the compartment syndrome
situation
adjuvant therapy (fem/sciatic controversy)
how long do blocks actually last

17. LAST
Rectus Sheath Block

18. Checklist for Treatment of Local Anesthetic
Systemic Toxicity
The Pharmacologic Treatment of Local Anesthetic Systemic Toxicity (LAST) is Different from
Other Cardiac Arrest Scenarios
❑ Get Help ❑ Initial Focus
❑ Airway management: ventilate with 100% oxygen ❑ Seizures uppression: benzodiazepines
are preferred; AVOID propofol
in patients having signs of cardiovascular instability ❑ Alert the nearest facility having
cardiopulmonary bypass capability
❑ Management of Cardiac Arrhythmias ❑ Basic and Advanced Cardiac Life Support
(ACLS) will require
adjustment of medications and perhaps prolonged effort
❑ AVOID vasopressin, calcium channel blockers, beta blockers, or local anesthetic
❑ REDUCE individual epinephrine doses to <1 mcg/kg ❑ Lipid Emulsion (20%)
Therapy (values in parenthesis are for 70kg patient)
❑ Bolus 1.5 mL/kg (lean body mass) intravenously over 1 minute (~100mL)
❑ Continuous infusion 0.25 mL/kg/min (~18 mL/min; adjust by roller clamp)
❑ Repeat bolus once or twice for persistent cardiovascular collapse
❑ Double the infusion rate to 0.5 mL/kg/min if blood pressure remains low
❑ Continue infusion for at least10 minutes after attaining circulatory stability
❑ Recommended upper limit: Approximately 10 mL/kg lipid emulsion over the first 30 minutes
❑ Post LAST events at www.lipidrescue.org and report use of lipid to www.lipidregistry.org

19. Bibliography
Dang, Charles;The value of adding sciatic block to continuous femoral
block for analgesia after total knee replacement;
Regional Anesthesia and Pain Medicine; Volume 30, Issue 2, March–
April 2005, Pages 128–133
Benzon, Honorio, Essentials of Pain Medicine and Regional
Anesthesia, 2005
Neal, Joseph;ASRA Practice Advisory on Local Anesthetic Systemic
Toxicity; Regional Anesthesia & Pain Medicine; March/April 2010; Vol
35 Issue 2; pp152-161
Stoelting, Robert; Basics of Anesthesia; 2000