Neuraxial AnesthesiaNeuraxial anesthesia is a type of regional

anesthesia that involves injection of anesthetic medication in the fatty tissue that surround the nerve roots as they exist the spine (also known as an epidural) or into the cerebrospinal fluid which surrounds the spinal cord (also known as a spinal).   This numbs the patient from the abdomen to the toes and often eliminates the need for general anesthesia.

HISTORY1885 - J. Leonard Corning – first spinal anesthetic was administered accidentally The needle was made of gold1898 - August Bier - first planned spinal anesthesia for

surgery In 1921, Spanish military surgeon Fidel Pagés (1886–

1923) developed the modern technique of lumbar epidural anesthesia

Robert Andrew Hingson (1913–1996), working at the United States Marine Hospital in New York, developed the technique of continuous caudal anesthesia.

Advantages over Regional Anaesthesia over GA

Safe, reliable technique in patients at risk of apnoea, bradycardia, desaturation, cardiac or respiratory complications after GA

Good alternative for day care surgeries

Minimal risk of postoperative respiratory depression

Limited stress response to surgery

Cost effective

VERTEBRA

33 Vertebrae◦ 7 Cervical◦ 12 Thoracic◦ 5 Lumbar◦ 5 Sacral◦ 4 Coccygeal

Spinal CordSpinal Cord

Adult Begins: Foramen Magnum Ends: L1

Newborn Begins: Foramen Magnum Ends: L3

Terminal End: Conus MedullarisFilum Terminale: Anchors in sacral regionCauda Equina: Nerve group of lower dural

sac

Sagittal Section Through Lumber Vertebrae

Supraspinous Ligament

(Outer most layer)

Intraspinous Ligament

(Middle layer)Ligamentum

Flavum(Inner most

layer)

CONTRAINDICATIONSAbsolutePatient RefusalInfection At The Site Of InjectionCoagulopathy And Other Bleeding DisordersSevere HypovolemiaIncreased Intracranial PressureSevere Aortic StenosisSevere Mitral Stenosis

CONTRAINDICATIONSRelativeSepsisUncoperative PatientPreexisting Neurological DeficitsSevere Spinal Deformity

ControversialPrior Surgery At The Site Of InjectionComplicated SurgeryProlonged OperationMajor Blood Loss

SURFACE ANATOMY

PATIENT POSITIONINGSITTING POSITION

PATIENT POSITIONINGLATERAL DECUBITUS

Midline ApproachSkinSubcutaneous tissueSupraspinous ligamentInterspinous ligamentLigamentum flavumEpidural spaceDura materArachnoid mater

Paramedian or Lateral ApproachSame as midline excluding supraspinous &

interspinous ligaments

Anatomic Approach

Spinal Needle Types

Quincke Whitacre Sprotee

Selection of equipmentsSelection of block needles and

catheters:Block procedure

Recommended device

Spinal anaesthesia

Spinal needle (24-25 gauge; 30, 50 or 100 mm long, Quincke bevel, stylet)

Caudal anaesthesia

Short (25-30 mm) and short beveled (45-degree) needle with stylet

Epidural anaesthesia

Tuohy needle (22, 20, and 19/18 gauge); LOR syringe and medium epidural catheter

PNB Insulated 21-23 gauge short beveled needles

FACTORS AFFECTING LEVEL BARICITY OF DRUGPOSITION OF PATIENTDOSESITEAGECURVATURE OF SPINEPATIENT HEIGHTPREGNANCY

Spinal Anesthesia Levels

DRUGSBUPIVACAINE HEAVYDOSE<5 KG -- 0.5MG/KG BODY WT5-15 KG -- 0.4MG/KG BODY WT>15 KG -- 0.3MG/KG BODY WT

Complications of Spinal AnaesthesiaHypotensionBradycardiaCardiac ArrestTotal Spinal AnesthesiaNeurological Complecations – Cauda Equina

SyndromePost Dural Puncture HeadacheInfection

BackacheInflammatory reaction due to tissue traumaMay result in back spasmsShort lived, analgesics, iceMay last a few weeksBack ache may be a sign of serious

complications such as epidural/spinal hematoma, abscess

Careful evaluation to determine if a common/benign complication or something more serious

Postdural Puncture HeadacheCaused by disrupting the integrity of the duraCan occur due to: spinal anesthesia, “wet” tap with

epidural, epidural catheter migration, tip of the epidural needle “indenting” the dura enough to cause a leak.

Headache occurs due to leakage of CSF through the dura

Decrease in intracranial pressure occurs due to the leak

Upright position in the patient leads to traction on the dura, tentorium, and blood vessels resulting in pain.

Postdural Puncture Headache- SymptomsOnset is generally within 12-72 hoursHeadache associated with upright position (i.e.

sitting or standing). Relief found with a supine position

Headache may be bilateral, frontal, retroorbital and/or occipital with or without radiation to the neck

Described as “throbbing” or constantMay be associated with nausea and/or

photophobiaTraction on the 6th cranial nerve can result in

diplopia and tinnitus

Postdural Puncture Headache- Conservative Treatment

Hydration- theoretically helps to encourage the production of CSF.

Analgesics- will decrease the severity of symptoms and include acetaminophen and NSAIDS

Caffeine- Helps to decrease symptoms by vasoconstriction of the cerebral vessels.

A dose of 300 mg of oral caffeine has been shown to decrease the intensity of PDPH

Epidural blood patch.

Epidural SpaceSpace that surrounds

the spinal meningesPotential spaceLigamentum FlavumBinds epidural space

posteriorlyWidest at Level L2 (5-

6mm)Narrowest at Level C5

(1-1.5mm)

Epidural AnatomySafest point of

entry is midline lumbar

Spread of epidural anesthesia parallels spinal anesthesia◦Nerve rootlets◦Nerve roots◦Spinal cord

Epidural Anesthesia

Order of BlockadeB fibersC & A delta fibers

Pain Temperature Proprioception

A gamma fibersA beta fibersA alpha fibers

Epidural AnesthesiaTest Dose: 1.5% Lido with Epi 1:200,000

◦Tachycardia (increase >30bpm over resting HR)

◦High blood pressure ◦Light headedness◦Metallic taste in mouth◦Facial numbness◦Note: if beta blocked will only see increase in

BP not HRBolus Dose: Preferred Local of Choice

◦10 milliliters for labor pain◦20-30 milliliters for C-section

Epidural AnesthesiaDistances from Skin to Epidural Space

Average adult: 4-6cmObese adult: up to 8cmThin adult: 3cm

Assessment of Sensory BlockadeAlcohol swab

Most sensitive initial indicator to assess loss of temperaturePin prick

Most accurate assessment of overall sensory block

Epidural AnesthesiaComplications

Penetration of a blood vesselHypotension (nausea &

vomiting)Intravascular catheterizationBack painWet tapInfection

Differences between Spinal and Epidural Anesthesia Spinal anaesthesia Extradural Anaesthesia

Level: below L1/L2, where the spinal cord

ends

Level: at any level of the vertebral column.

Injection: subarachnoid space i.e punture

of the dura mater

Injection: epidural space (between

Ligamentum flavum and dura mater) i.e

without punture of the dura mater

Identification of the subarachnoid space:

When CSF appears

Identification of the Peridural space: Using

the Loss of Resistance technique.

Dosis: 2.5- 3.5 ml bupivacaine 0.5% heavy Doses: 15- 20 ml bupivacaine 0.5%

Onset of action: rapid (2-5 min) Onset of action: slow (15-20 min)

Density of block: more dense Density of block: less dense

Hypotension: rapid Hypotension: slow

Headache: is a probably complication Headache: is not a probable. 32

Caudal AnaesthesiaBlock of the sacral and lumbar

nerve roots. This technique is popular in pediatric patients.

The S5 processes are remnants and form the cornua, which provide the main landmarks for indentifying the sacral hiatus. The hiatus is covered by the sacro-coccygeal membrane.

The canal contains areolar connective tissue, fat, sacral nerves, lymphatics, the filum terminale and a rich venous plexus.

Caudal anaesthesiaIndications of caudal anaesthesia:Surgical procedures below the umbilicusAs an adjuvant to GASole anaesthetic technique in fully awake ex-premature

infants younger than 60 wk of post conceptual age

Contraindications to caudal anaesthesia:Major malformations of sacrum (myelomeningocele,

open spina bifida)MeningitisIntracranial hypertension

Caudal DosesPediatric population0.5 ml/kg, 0.25% bupivacaine

(sacro-lumbar block)1 ml/kg, 0.25% bupivacaine (upper abdominal block)1.2 ml/kg,0.25% bupivacaine (mid-thoracic block)(Doses described by Armitage).

Adults: 20-30 ml 0.25-0.5% bupivacaine. Average volume of the sacral canal is 30-35 ml.

Caudal AnesthesiaAnatomy

Sacrum Triangular bone 5 fused sacral vertebrae

Needle InsertionSacrococcygeal

membraneNo subcutaneous bulge

or crepitous at site of injection after 2-3ml

Caudal AnesthesiaPost Operative Problems

Pain at injection site is most commonSlight risk of neurological complicationsRisk of infection

Complications and side effects of neuraxial methods

THE END

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