Perioperative
Regional Anesthesia
A practical approach
November 7, 2015
Gareth Nakasone, MD
Types of Regional Anesthesia

Neuraxial



Spinal
Epidural
Peripheral Nerve Blocks



Plexus Blocks
Selective Peripheral
Nerve Blocks (PNB)
Bier Block
Duration of Action

Neuraxial



Spinal: 60-400 minutes
Epidural: 45-240 minutes
Peripheral Nerve Blocks



Plexus Blocks:
1.5–18+ hours
Peripheral Nerve Blocks: 230+ hours
Bier Block:
15-90 minutes
Why Use PNB’s?






Superb analgesia
Long Duration of Action
Decreased Intraop Anesthesia Needs
Decreased Incidence of PONV
Excellent Risk Profile
Pt can be discharged with block intact
Medicines Used for PNBs





Chloroprocaine
Mepivacaine
Lidocaine
Ropivacaine
Bupivacaine
Shorter Acting
↓
↓
↓
Longer Acting
Medicines Used for PNBs

Chloroprocaine

Shortest acting of the
common anesthetics


Very safe


Duration measured in
minutes (30-120) rather
than hours
Toxic levels rarely occur,
even with large doses
Typically used for short
procedures where longlasting analgesia is not
required
Medicines Used for PNBs

Lidocaine

Short-Intermediate acting




Lasts 2-8 hours
Epinephrine significantly
increases duration
Low-Moderate risk of
toxicity
Very commonly used

Most people feel
comfortable with it
Medicines Used for PNBs

Mepivacaine (Polocaine)


Faster onset than
Lidocaine
Slightly longer duration of
action than Lidocaine (28+ hours)

Causes less vasodilation, so
less absorption
Medicines Used for PNBs

Ropivacaine (Naropin)

Very similar to
Bupivacaine, but better
risk profile


Much less cardiotoxic, and
easier to metabolize
Provides sensory>motor
blockade
Medicines Used for PNBs

Bupivacaine (Marcaine)




Most commonly 0.25-0.5%
Gives the longest lasting,
most dense block
Highest risk of cardiovascular
complications
Cheap and commonly used
Medicines Used for PNBs

Epinephrine



Significantly prolongs
block effect
Provides earlier indication
of systemic toxicity
Sodium Bicarbonate

Increases pH of
anesthetics

Speeds onset of block
Types of Peripheral Nerve Blocks

Upper Body

Brachial Plexus
Interscalene
 Supraclavicular
 Infraclavicular
 Axillary


Bier Block
Types of Peripheral Nerve Blocks

Lower Body

Upper and Front of Leg
Lumbar Plexus
 Femoral Nerve Block


Lower and Back of Leg
Sacral Plexus
 Sciatic Nerve Block
 Popliteal Nerve Block

Brachial Plexus Blocks
Types of Peripheral Nerve Blocks

Brachial Plexus Blocks
The closer to the neck, the higher on the arm
 All of these blocks hit the same nerves, but to
different extent
 The medial portion of the upper arm is not covered
(intercostobrachial nerve)
 Complications are rare, and usually occur early after
injection

Bier Block






Arm is exsanguinated
Tourniquet inflated
Lidocaine 0.5% infused
via small IV in hand
Lasts 15-90 minutes
Resolves very quickly
Complications dealt with
prior to PACU
Lumbar Plexus/Femoral N Block
Types of Peripheral Nerve Blocks

Lumbar Plexus and
Femoral Nerve Block



Basically the same block,
done at two different sites
Lumbar Plexus also
covers Lateral Femoral
Cutaneous n. and
Obturator n.
Covers only front half of
upper leg and a strip of
skin from the medial knee
to the medial ankle
Sacral Plexus &
Sciatic Nerve Block
Sciatic Nerve/Sacral Plexus Block

Covers the posterior portion of
the upper leg and (almost) the
entire lower leg



Except that strip of skin on the
inside of the lower leg mentioned
earlier
This is a very long lasting block,
up to 30+ hours
A Popliteal Block is simply a
Sciatic N. block done at the knee
Risks of Nerve Blocks

Infection


Bruising


Late complication, rarely seen
when aseptic technique is used
Quite common, usually small
and self-limited
Hematoma

Usually results from
inadvertent vascular puncture

Treat with direct pressure
Risks of Nerve Blocks

Secondary injury to blocked
area

Pressure injury



Patient can’t feel pressure
points
Place a pillow between
extremity and gurney
Unintentional self-inflicted
injury


Motor returns before sensory
Warn outpatients not to cook,
chop, or touch hot objects
until “tomorrow”
Risks of Nerve Blocks

Spinal/Epidural injection





Occurs most commonly
with interscalene block
Occurs very soon after
block placement
Very rare
Treatment is supportive,
intubation and vasopressors
may be needed
Remember the ABCs
Risks of Nerve Blocks

Pneumothorax




Seen most frequently with
Supraclavicular blocks (~5%)
and rarely with other brachial
plexus blocks
Usually small and require no
treatment
Chest X-rays are not usually
ordered
An elevated hemidiaphragm is
normal after interscalene blocks
Risks of Nerve Blocks

Seizure


Results from intravascular
injection or (rarely) systemic
uptake
Seizures may indicate cardiac
arrest is coming


STAT page the anesthesiologist
Treatment:


Remember the ABC’s
Get help
Risks of Nerve Blocks

Seizure treatment, cont.

Drugs to help stop the seizure:

Benzodiazepines


Thiopental


50-75 mg
Propofol


Versed 2-5 mg
50-150 mg
Again, prepare for
hypotension/cardiac arrest
Risks of Nerve Blocks

Cardiovascular Collapse




Most commonly seen when
Bupivacaine is injected
intravascularly
Occurs only rarely
Usually seen immediately during
placement of the block
Can be very long-lasting and very
hard to treat
Risks of Nerve Blocks

Treatment of Cardiovascular Collapse

Airway Management






Hypoxia, Hypercapnia, and Acidosis make it more difficult to treat
CPR, CPR, CPR
Follow basic ACLS protocols, and consider:
Amiodarone is the drug of choice for arrythmias (150-300 mg
IV push)
Vasopressin for hypotension (40u IV push)
Try to avoid epinepherine as a first-line drug


But it may be needed later in the code
It can potentiate arrythmias from local anesthetics
Epinephrine Controversy
 September 2009
 Hiller et al, Anesthesiology and an editorial by
Cave and Martyn.
 This paper shows by dose-response that a single dose
of epinephrine above a certain threshold (~10mcg/kg)
given along with lipid infusion profoundly inhibits
successful recovery from bupivacaine overdose
(20mg/kg) compared with lipid alone.
 The potential clinical implication is that higher dose
epinephrine is potentially harmful to patients with
drug-induced cardiac arrest.
Risks of Nerve Blocks

Treatment of Cardiovascular Collapse

Intralipid (20% lipid emulsion) may be helpful
1 mL/kg bolus (May be repeated twice)
 Infusion of 0.25 mL/kg/min for 10 min


Cardiopulmonary Bypass may be indicated in
refractory cases

(Wow, that’s scary…)
Helping with Block Placement

PNBs may be placed in
pre-op and occasionally
in PACU

Don’t Panic!

Assisting should be very
easy
Nerve Block Set-Up

Anesthesiologist will set up
most equipment

Sterile technique is used on
the field, but the stimulator
and syringes are not sterile
Block Placement




Remember, this is easy
Use continuous negative
aspiration
Do not inject until
requested
Turn stimulator slowly
down from 1.0 mA to
0.3 mA when requested
Block Placement






Inject 1cc (test dose)
Aspirate
Inject 3-5 cc slowly
Aspirate
Repeat Injection &
Aspiration until done
Expect your hands to be
a little tired
Key Points:




Nerve Blocks are generally safe and well
tolerated
Complications are rare, but need to be treated
immediately if detected
Common sense prevails –just treat the extremity
like it’s numb, cuz it is!
Don’t be afraid to ask questions –most folks
who place blocks like to talk about them
Barriers to Regional Anesthesia

Absolute contraindications
Patient refusal
 Infection at site of injection
 Allergy


Relative contraindications
Coagulopathy
 Indeterminate neurologic disease
 Unknown duration of surgery

Questions?