Donald H. Lambert

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Dannemiller San Antonio - June 12, 2007
Spinal - Epidural - Combined Spinal Epidural

• Donald H. Lambert
• Boston, Massachusetts

http//dann2007.debunk-it.org http//www.debunk-it
.org
2
Dannemiller - Chicago - May 10, 2007
Spinal - Epidural - Combined Spinal Epidural

• Donald H. Lambert
• Boston, Massachusetts

http//dann2007.debunk-it.org http//www.debunk-it
.org
3
Spinal Anesthesia

• Advantages v. Disadvantages
• Pharmacology of spinal agents
• Addition of a vasoconstrictor
• Baricity
• Dosing
• Complications

4
Advantages of Spinal Anesthesia

• Technically easy
• Objective end-point
• Rapid onset
• Profound sensory and motor block
• Low potential for systemic toxicity

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Disadvantages of Spinal Anesthesia

• Limited duration
• Limited sensory-motor separation
• Hypotension
• Potential neuro-toxicity
• Headache

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Spinal Anesthesia

• Advantages v. Disadvantages
• Pharmacology of spinal agents
• Addition of a vasoconstrictor
• Baricity
• Dosing
• Complications

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Spinal Anesthesia Agents
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• The dosing in this study was 10 mg, 15 mg, and 20
  mg of bupivacaine
• The lowest dose limited spread

• The lowest dose also resulted in more
  failures than the higher doses.

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Spinal Anesthesia

• Advantages v. Disadvantages
• Pharmacology of spinal agents
• Addition of a vasoconstrictor
• Baricity
• Dosing
• Complications

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Tetracaine
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Lidocaine
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Bupivacaine
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Lido
Bupiv
Tetra
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Spinal Anesthesia

• Advantages v. Disadvantages
• Pharmacology of spinal agents
• Addition of a vasoconstrictor
• Baricity
• Dosing
• Complications

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1 ml 5 lido with dextrose immediately after
injection
1 ml 5 lido with dextrose during injection
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• The effect of baricity on the distribution of
  bupivacaine in spinal model

Hyperbaric

• In spite of the crudeness of this model, the
  levels of anesthesia predicted by the model are
  remarkably similar to the levels of anesthesia
  observed in patients

Isobaric
Hypobaric
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Hyperbaric
Isobaric
Hypobaric
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Spinal Anesthesia

• Advantages v. Disadvantages
• Pharmacology of spinal agents
• Addition of a vasoconstrictor
• Baricity
• Dosing
• Complications

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Spinal Anesthesia

• Dosing will affect
• Spread
• Duration
• Quality of Anesthesia
• That is, the need for supplemental IV medication

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Spinal Anesthesia

• I have been doing spinal anesthesia for 25 years
• I spent the first 10 years trying to control the
  level of spinal anesthesia
• I have failed
• I have given up trying
• If you know how to control the level of spinal
  anesthesia please tell me how it is done

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Dosing Guidelines

• Based on the spinal canal model (and many years
  in the trench)
• Hyperbaric solutions extend into the thoracic
  region
• Isobaric solution remain in the lumbar region
• I give hyperbaric solutions for operations above
  the L1 dermatome and isobaric solutions for those
  below

Hyperbaric
Isobaric
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CHOOSING A LOCAL ANESTHETIC FOR SPINAL
ANESTHESIABASE DECISION ON THE EXPECTED
DURATION OF THE OPERATION
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CHOOSING A LOCAL ANESTHETIC FOR SPINAL
ANESTHESIAGIVE ENOUGH TO PROVIDE ADEQUATE
ANESTHESIA
? CHLOROPRACAINE, ? ROPIVACAINE
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Isobaric Spinal Anesthesia

• Epidural Bupivacaine
• It says right on the bottle
• Not for Spinal Anesthesia
• What is the value or wisdom behind using that
  agent?
• It works great and I have used it since the
  1980s.
• I know of no reports of complications associated
  with using it.
• Litigation for the off-labeled use of a drug has
  not appeared in the ASA closed claims database.
• Who would know?
• Unless you wrote on your anesthesia record, I
  used the bupivacaine that is not for spinal
  anesthesia.

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Spinal Anesthesia

• Advantages v. Disadvantages
• Pharmacology of spinal agents
• Addition of a vasoconstrictor
• Baricity
• Dosing
• Complications

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Spinal Anesthesia

• Complications
• Cardiac arrest
• Hypotension
• Headache
• Nerve injury

30
Unexpected cardiac arrest during spinal
anesthesia a closed claims analysis of
predisposing factors
Caplan, R A et al. Unexpected cardiac arrest
during spinal anesthesia a closed claims
analysis of predisposing factors. Anesthesiology
1988685-11 Caplan, R A et al. Injuries
Associated with Regional Anesthesia in the 1980s
and 1990s A Closed Claims Analysis.
Anesthesiology. 2004101143-152
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Unexpected cardiac arrest during spinal
anesthesia a closed claims analysis of
predisposing factors
Caplan, R A et al. Unexpected cardiac arrest
during spinal anesthesia a closed claims
analysis of predisposing factors. Anesthesiology
1988685-11
32
Unexpected cardiac arrest during spinal
anesthesia a closed claims analysis of
predisposing factors

• Factors Predisposing to Asystole
• High level
• Loss of Cardiac Sympathetic Stimulation
• Unopposed Vagal Tone
• Decreased Venous Return
• Empty Left Ventricle
• Activation of Intracardiac Reflexes
• ? So-called Bezold-Jarisch Reflex or the
  so-called Vaso-vagal Syncope

Caplan, R A et al. Anesthesiology 1988685-11
and Mackey, D C, et al. Anesthesiology
198970866-868
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Cardiac arrest during spinal anesthesia

• How can this be prevented and/or treated?
• Maintain venous return at all cost
• Use epinephrine at the first sign of cardiac
  arrest

Keats, A. S. Anesthesia mortality--a new
mechanism.Anesthesiology 1988682-4.
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Spinal Anesthesia Complications

• Hypotension (happens!)

But, if you want to know the truth it happens
also when I do general anesthesia!!
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The Two Components of Spinal Headache

• There must have been a lumbar puncture
• The headache is related to posture
• Worst when standing or sitting
• Gone or improved with recumbency

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Effect of Age on the Incidence of Spinal Headache
This and AARP discounts are two of the few
advantages to aging!
Vandam and Dripps, JAMA 1956161586-591
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How Safe are Spinals?

• TNS/TRI

• Most frequent with lidocaine (10-34 incidence)
• More frequent with lithotomy position and knee
  arthroscopy
• VAS pain score averages 6 out of 10
• Many rate the pain worse than their incision
• Can last up to three days
• Least frequent with bupivacaine

47
Spinal Anesthesia

• Is there a reasonable alternative to lidocaine?
• What are the possibilities?
• Procaine
• ? Chloroprocaine (non-neurotoxic in isolated
  nerve)
• recent data in rats indicates neural toxicity
  with i.t. infusion
• Prilocaine (low incidence of TRI, but neurotoxic
  in rat)
• Mepivacaine (same incidence of TRI as with
  lidocaine)
• Low dose bupivacaine
• ? Ropivacaine

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Spinal Anesthesia

• Advantages v. Disadvantages
• Pharmacology of spinal agents
• Addition of a vasoconstrictor
• Baricity
• Dosing
• Complications

49
EPIDURAL ANESTHESIA

• Advantages v. Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

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EPIDURAL ANESTHESIA

• Advantages
• Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

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Advantages of Epidural Anesthesia

• UNLIMITED DURATION
• POSSIBLE SENSORY / MOTOR SEPARATION
• LESS HYPOTENSION
• LOWER POTENTIAL FOR NEURO-TOXICITY
• NO HEADACHE

52
EPIDURAL ANESTHESIA

• Advantages
• Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

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Disadvantages of Epidural Anesthesia

• TECHNICALLY DIFFICULT
• LESS OBJECTIVE ENDPOINT
• HIGHER FAILURE RATE
• MISSED SEGMENTS MORE COMMON
• POTENTIAL FOR DURAL PUNCTURE
• CATHETHER COMPLICATION

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EPIDURAL ANESTHESIA

• Advantages
• Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

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CSF
Dura
Epidural space
Ligamentum flavum
Interspinous lig
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EPIDURAL ANESTHESIA

• Advantages
• Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

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EPIDURAL ANESTHESIA AGENTS
DRUG CONC. DOSE VOLUME DURATION () (mg) (ml) (m
in) CHLOROPROC. 2 - 3 300 - 900 15 - 30 30 -
90 LIDOCAINE 1 - 2 150 - 500 15 - 30 60 -
180 MEPIVACAINE 1 - 2 150 - 500 15 - 30 60 -
180 PRILOCAINE 1 - 3 150 - 600 15 - 30 60 -
180 ROPIVACAINE 0.5 - 1.0 75 - 300 15 - 30 180
- 300 BUPIVACAINE 0.25 - 0.75 37.5 - 225 15 -
30 180 - 300 LEVOBUPIV. 0.25 - 0.75 37.5 - 225 15
- 30 180 - 300 ETIDOCAINE 1 - 1.5 150 - 300 15 -
30 180 - 300
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EPIDURAL ANESTHESIA

• Advantages
• Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

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X1.5
X1
X1
X1.5
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Truisms on Dose

• The more you put in
• The quicker it comes on
• The better the block
• The longer it lasts
• The more you put in
• The more likely are you to cause toxicity

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EPIDURAL ANESTHESIA

• Advantages
• Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

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EPIDURAL ANESTHESIA

• Advantages
• Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

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• The are many potential sites where epidural local
  anesthetics can act.
• The highest concentrations of local anesthetic
  are found in the CSF and nerve roots.

• The lowest concentrations are found in the dorsal
  root ganglia and the substance of the spinal cord.

• All sites likely contribute to the mechanism of
  epidural anesthesia, but the most likely
  conclusion is that the epidural anesthesia comes
  about by an intrathecal action.

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EPIDURAL ANESTHESIA

• Advantages
• Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

72
Effect of Epinephrine on Peak Venous Plasma Level
with Epidural Anesthesia

• The more vasodilating agents - mepivacaine and
  lidocaine show the greatest epinephrine effect.

• The lack of effect with prilocaine may be due to
  its good diffusion.

• The lack of effect with etidocaine and
  bupivacaine is due to their avid binding to
  lipids.

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EPIDURAL ANESTHESIA

• Advantages
• Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

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Cardiovascular Toxicity
HYPERTENSION - TACHYCARDIA OWING TO CNS
EXCITATION NEGATIVE INOTROPY DECREASED CARDIAC
OUTPUT MILD - MODERATE HYPOTENSION PERIPHERAL
VASODILATATION PROFOUND HYPOTENSION SINUS
BRADYCARDIA CONDUCTION DEFECTS
VENTRICULAR ARRYTHMIAS CARDIOVASCULAR
COLLAPSE
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LEVEL T5 T1 T2-3 T5 T5 T5 Lido (ug/ml) lt4 lt4 gt4 lt4
lt4 lt4 Epinephrine 0 0 0
0 Hypovolemia 0 0 0 0
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The Two Components of Spinal Headache

• There must have been a lumbar puncture
• The headache is related to posture
• Worst when standing or sitting
• Gone or improved with recumbency

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Accidental puncture during labor epidural

• About a 1 chance or less
• About 60 will develop a headache
• About 70 will require a blood patch

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Guidelines for Regional Anesthesia in the
Anticoagulated Patient

• See Consensus Statement at the ASRA Web site

http//www.asra.com/items_of_interest/consensus_st
atements/
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EPIDURAL ANESTHESIA

• Advantages
• Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

84
Test Dose

• Used to prevent intravascular injection of local
  anesthetic and detect a spinal injection
• Epinephrine in 1.5 lidocaine most frequently
  advocated and most extensively studied
• 15 ug of epinephrine produces a tachycardia
  within 20 seconds
• Reliability diminished by beta blockade, aging,
  general or combined general-epidural anesthesia
• Lidocaine will give signs of spinal anesthesia

Mulroy, MF RAPM 27556-5612002
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Test Dose

• When epinephrine is not practical
• Use moderate doses of local anesthetic while
  monitoring for CNS effects
• 100 mg of lidocaine or chloroprocaine
• 25 mg of bupivacaine
• Requires non pre-medicated patient
• Medication with midazolam will interfere

Mulroy, MF RAPM 27556-5612002
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Local Anesthetic ToxicityRate of Injection

• Slow rates of injection are less likely to result
  in systemic toxicity
• Intermittent injections, at slow rates will
  lessen further the likelihood of systemic
  toxicity
• These two steps, in my opinion, are better than a
  test dose of local anesthetic with epinephrine as
  tracer

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EPIDURAL ANESTHESIA

• Advantages
• Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

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Comparing spinal to epidural

• Spinal easier to do
• No chance systemic toxicity
• Increased risk of neural toxicity
• Duration too short
• Low incidence of spinal headache

• Epidural more difficult
• Systemic toxicity possible
• Less chance neural toxicity except with certain
  agents and accidental spinal injection
• Unlimited duration
• Incidence of spinal headache about the same as
  spinal

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EPIDURAL ANESTHESIA

• Advantages
• Disadvantages
• Technique
• Pharmacology of Specific Agents
• Effect of Dose
• Mechanism of Action
• Addition of a Vasoconstrictor
• Complications
• Test Dose
• Comparison with Spinal

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Good luck with your exam!

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