Considerations: Spinal & Epidural Anesthesia

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Considerations Spinal Epidural Anesthesia

• Joseph E Pellegrini, CRNA, PhD

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Spinal Column Anatomy

• Vertebra
• Vertebral Body
• Pedicles Anterior (2) Laminae Posterior (2)
• Transverse Process Junction of the Pedicles and
  Laminae
• Spinous Processes Joining of the Laminae
• Intervertebral Disks

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Advantages of Spinal/Epidural Anesthesia

• Avoids Hazards of General Anesthesia
• Patient is Alert earlier postoperative
• Lower incidence of Nausea/Vomiting
• Better Pain Control/Less Narcotics

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Spinal Anesthesia

• Indications
• Best reserved for operations below the level of
  the umbilicus
• R/LIH, GYN, Peroneal, Anal, LEs
• C-sections
• Preferable to Epidural GA
• Risk/Benefit Ratio
• Contraindications
• Refusal
• Infection
• Severe Neurological Disease
• Hypovolemia
• Coagulopathy
• LMWH use?

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LMWH Neuraxial Blockade

• Overall incidence of Spinal Hematoma
• Estimated lt 1/220,000 SAB
• Estimated lt 1/150,000 - CLE
• Benefit/Risk Ratio
• Recommendations

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LMWH Neuraxial Blockade
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Recommendations

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Spinal Anesthesia

• A single injection of a local anesthetic solution
  into the subarachnoid space usually at the lumbar
  level
• Intrathecal Narcotics
• Commonly at L3-L4
• Largest Interspace
• L5-S1

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Spinal Needle Considerations

• Small needles ? PDPH
• Large needles improve tactile sensations
• Pencil-point needles ? PDPH risk
• Further reduction with addition of ITN
• Side injection needles with large holes ? CSF but
  careful to have entire hole subarachnoid

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Most Important Factors Affecting Block Height -
SAB

• Baricity of anesthetic solution
• Position of the patient
• During injection
• Immediately after injection
• Drug Dosage (mg)
• Concentration times volume
• Addition of Opioids
• Site of Injection

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Additional Factors to Consider with SAB Height

• Patient Age
• Elderly patients gt 80 yrs
• Patient Height
• Intra-abdominal Pressure
• Pregnancy Obesity
• Drug Volume

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Factors Unrelated to SAB Height

• Added Vasoconstrictor
• Rate of Injection
• Except for Hypobaric
• Gender
• Females lt Males
• Pregnant versus Non-pregnant
• Weight
• Increased Weight
• Lesser concentration needed?

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Differential Block with SAB
Sympathetic

• Sympathetic Block
• 2-6 dermatomes higher than the sensory block
• Motor Block
• 2 dermatomes lower than sensory block

T5
Sensory
Motor
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Baricity of Local Anesthetics

• Isobaric Stays where you put it
• LA has the same density or specific gravity as
  CSF (1.003-1.008) Normal Saline
• Hypobaric Floats up Lighter than CSF
• LA has a density or specific gravity that is less
  than CSF (lt1.003) Sterile Water
• Hyperbaric Settles to Dependent aspect of the
  subarachnoid space Heavier than CSF
• LA has a density or specific gravity that is
  greater than CSF (gt1.008) - Dextrose

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Positioning the Patient

• Sitting
• With Legs hanging over side of bed
• Have the patient hug a pillow
• Put Feet up on a Stool (no wheels)
• Assistant MUST keep the patient from Swaying
• Curve her back like a C, Halloween Cat, Shrimp,
  Cannon ball
• Up in the Bed (quicker but not optimal)
• Baricity?
• Lateral Decubitus (Left or Right?)
• Needs to be Parallel to the Edge of the Bed
• Legs Flexed up to Abdomen
• Forehead Flexed down towards Knees
• Jack-knife Position
• Chosen for ano-rectal surgery
• CSF will not drip from hub of needle
• Use hypobaric solution
• Bupivacaine less run-off than lidocaine

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Preparation for SAB

• Identify Suitable Patients
• Equipment Required
• Single-shot or Catheter Placement
• Continuous spinal with epidural catheter
• Know your Spinal/Epidural Kit
• Determine Insertion Approach
• Midline
• Paramedian

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Midline Insertion Approach

• Midline
• Most commonly used
• As needle passes thru the dura mater a pop is
  often appreciated
• CSF flows thru once stylet is used
• For small gauge needles (26-29 g) this may take
  5-10 seconds
• May take even longer in dehydrated or elderly
  patients
• If no CSF flow, needle can be obstructed by a
  nerve root (rotate 90 degrees)

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Paramedian (Lateral) Approach

• After identifying the proper interspace palpate
  the spinous process
• Insert needle 1 cm lateral and 1 cm inferior to
  this point and direct needle towards interspace
• May need to walk medially off of transverse
  process
• Ligamentum flavum is usually the first resistance
  indentified
• Bypasses supraspinous and intraspinous ligaments

Traditional
Taylor (L5-S1)
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Preparation continued

• GIVE INTRAVENOUS FLUID BOLUS OF 500 CC PRIOR TO
  SAB/EPIDURAL DOSE.
• If it is not a labor epidural/c-section, give
  versed, fentanyl and oxygen prior to neuraxial
  anesthesia.
• Local Anesthetics to the skin, deep tissues?
• Skin wheal should be performed at vertebral
  interspace (1-2 ml) and to adjacent sides (.5ml)
  with 1 Lidocaine

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MOST COMMON CAUSES OF INADEQUATE SPINAL ANESTHESIA

• Unable to locate CSF
• Inability to enter SA space
• If bone (os) encountered superficially
• redirect needle cephalad
• If bone (os) encountered deep
• redirect needle caudally
• Inability to aspirate CSF before injection
• Ensure that you have CSF in all 4 planes
• Surgery outlasting the drug selected
• Short, intermediate long term local anesthetics
• Can increase duration efficacy with opioids/LA
  admixture
• 5-10 mcg fentanyl or 1-2 mcg sufentanil

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Intrathecal Analgesia
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METHODS OF DETERMINING SPINAL LEVEL

• Definition of determining level analgesia
  versus anesthesia
• Alcohol skin wipe
• Pinch
• toothpick skin test
• Nerve stimulator
• Etc., etc., etc.
• Beware break no skin, use no needles

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STRATEGIES TO INCREASE THE LEVEL OF SPINAL
ANESTHSIA IN THE PERI-BLOCK FRAME

• Work fast after local anesthetic injected
• Assess early and frequently
• Augment position changes to maximize spread hyper
  / hypo baric solutions early
• Co-administration of IT Opioids
• ? Make patient cough several times
• More effective with lidocaine

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ACTIONS TO DEAL WITH INADEQUATE LEVEL

• Use previously discussed strategies
• Re-do spinal anesthetic
• Supplementation with local anesthetic per surgeon
• Analgesic intravenous supplements
• Dissociative intravenous supplements
• General Anesthesia

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Lidocaine Group 10 mg hyperbaric lidocaine via
SAB Fentanyl/Propofol Group 1 mcg/kg fentanyl
followed by 1 mg/kg bolus 90 mg/kg infusion
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A Comparison of Three anesthetic Techniques for
Outpatient Knee Arthroscopy General Anesthesia,
Spinal Anesthesia and Intraarticular Infiltration
of Local Anesthetic (2008)LT Riley Williams,
SRNA, LT Robert Haag, SRNA, LT Rodrigo Lopez,
SRNA, LT William Baker, SRNA, CDR Lisa Osborne,
CRNA, PhD and CAPT (ret) Joseph Pellegrini, CRNA,
PhD

• Spinal Anesthesia Group
• 10-12 mg Hyperbaric Bupivacaine
• Supplemental Anxiolysis fentanyl
• Intraarticular Group
• IA Injection 15 min before incision by anesthesia
  in holding
• Followed customized format
• 2-injection technique
• 20 ml Bupivacaine 0.5 with epinephrine
  (1200,000)
• Propofol Infusion
• 50-100 mg/kg/hr
• Fentanyl supplementation
• 50-100 mcg during injection with 2 mg midazolam
• General Anesthesia Group
• Standardized Induction
• Desflurane or Sevoflurane

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Epidural Anesthesia

• Placement of Local Anesthetic into epidural space

Dural Rent
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Epidural Anesthesia

• Indications
• Contraindications
• Same as SAB (
• ? Tattoos
• Epidural blocks can be placed 4 hrs after last
  dose of SQ Heparin, 12 hrs after last dose of
  LMWH
• NSAIDS (including ASA) not contraindicated
• Placement relatively safe with INR lt 1.5

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Epidural Placement

• Typically use Loss of Resistance Technique
• Routinely placed in Lumbar region
• Use the needle for skin infiltration to identify
  midline structures
• Insert the needle in a slightly cephalad
  direction
• Dorsum of non-injecting hand rests on patients
  back
• Thumb and index finger grasp hub of needle
• Seat needle into intraspinous ligament and
  advance in slightly cephalad direction with
  continuous pressure on plunger of syringe and
  when the needle exits ligamentum flavum feel
  sudden loss of resistance
• The distance from skin to epidural space is 4-6
  cm in 90 of the population
• Never change the direction of the needle tip
  after it passes through the ligamentum flavum
• Do not advance the needle
• Air versus Normal Saline
• Missed dermatomes
• Presence of parasthesias?

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Epidural Placement

• Thread catheter 3-5 cm
• Check position
• Presence of parasthesias?
• Remove needle while keeping positive pressure on
  catheter (thread concurrently)
• Check position
• Secure catheter
• Check position
• Test dose
• Aspirate for Blood or CSF
• Off midline insertion usually results in higher
  blood vessel puncture
• A change of 20 or greater in HR after test dose
  indicates intravascular injection (replace
  catheter)
• A dense motor block within 5 minutes after test
  dose indicates spinal block (if positive either
  replace catheter or convert to continuous spinal
  technique)
• Only give test dose after contraction is over in
  pregnant women
• If patient on beta blocker a change in systolic
  pressure gt 20 mm Hg indicates intravascular
  injection
• 1.5 Lidocaine with epinephrine vs 2 Lidocaine

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Problem Solving with Epidural Placement
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Local Anesthetics for Epidural Blockade
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Epidural Dosing

• Volume is the key factor in determining height of
  blockade
• Typical loading dose is 10-20 ml given in 5 ml
  increments
• Wait about 2-3 minutes between increments
• Use of epinephrine and bicarbonate will speed up
  onset on anesthesia
• If block incomplete after bolus replace catheter
  rather than wasting time giving larger dose or
  re-positioning catheter
• Inject one-quarter to one-third of initial dose
  about 15 minutes after initial bolus to enhance
  sensory blockade
• Cookbook guideline
• To determine volume you can use the 5-foot rule
• Example For an individual who is 5 feet in
  height you administer 1 ml of local anesthetic
  solution for each segment requiring blockade and
  increase the volume by 0.1 ml for every 2 inches
  above 5 feet.
• Example For someone 510 in height and you
  enter at L3-L4 Interspace and want a to block up
  to T-6.
• 8 ml for L3-S5 and 7 ml for L2-T6 15 ml (base
  amount)
• Additional amount is 0.1 ml times 5 (10 inches/2)
  0.5 times 15 segments 7.5 (supplemental
  amount)
• Overall add the 15 ml plus the 7.5 ml to get a
  dose of 22.5 ml
• Need a total of 22.5 ml to achieve a T-6 level on
  a 70 person

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Epidural Additives

• Opioids
• Morphine, Fentanyl, Sufentanil, Depo-Dur
• Depo-Dur Considerations
• Clonidine
• Hemodynamic Considerations
• Sodium Bicarbonate
• Speeds onset Prolongs duration

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Combined-Spinal Epidural (CSE) Technique

• CSE technique
• Allows for immediate relief of pain (from SAB)
  subsequent administration of medications via CLE
  for prolonged anesthesia
• Advantages
• Reported to decrease failure rates of CLE
  (confirmation of epidural placement)
• Clinical uses
• General Surgery
• Laboring analgesia Cesarean Section
• High risk patients
• Slower onset of sympathetic blockade
• Careful positioning during SAB with subsequent
  titration of CLE
• Administration of intrathecal opioids with small
  amount of bupivacaine (2.5-5 mg) decreases
  epidural dosing requirements and decreases degree
  of sympathectomy

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CSE Technique
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CSE Technique

• CSE offers the advantages of both spinal and
  epidural anesthesia
• CSE provides rapid onset and careful titration
• Can use doses as low as 40 mg lidocaine or 7.5 mg
  bupivacaine
• Additional Opioids
• Sufentanil
• Fentanyl
• Morphine
• Potential disadvantages
• PDPHA
• Catheter migration into SA space
• Test Dose
• Transient parasthesias
• Ideal length of spinal needle beyond epidural
  needle is 12-13 mm
• Longer spinal needles associated with higher
  incidence

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Joseph.pellegrini_at_med.navy.mil