Dr. S. Parthasarathy MD., DA., DNB, MD (Acu), Dip. Diab. DCA, Dip. Software statistics PhD (physio) Mahatma Gandhi medical college and research institute, puducherry – India Epidural anaesthesia part 1.

Are they same ?? Peridural Extradural Epidural

History Corning in 1885 Uptake of drugs in spinal cord by injections can produce anaesthesia 100 years ??

History Heile – 1913, Paramedian approach tried Pages 1921 Feel

Dogliotti & Gutierrez – 1939 Described fundamentals action and results for the first time In 1945 Tuohy introduced the needle which is still most commonly used for epidural anaesthesia Cleland - obstetrics 1949 – nm blockers offset the role of EA

Now - prime uses Surgical anaesthesia, labour analgesia, post op pain relief and Chronic pain relief Epidural blood patch

How many vertebrae ?? There are 24 individual vertebrae: 7 cervical, 12 thoracic and 5 lumbar. The five (fused) sacral vertebrae and the coccyx (made up of 3–5 rudimentary vertebrae) not always classed as being a part of the vertebral column.

Boundaries of epidural space ?? Above : Foramen magnum – periosteal and spinal layers of dura fuse Below : the sacrococcygeal membrane

Epidural space

Boundaries Anterior : Posterior longitudinal ligament, vertebral bodies, intervertebral disc Posterior Laminae and ligamentum flavum Laterally : pedicles and interverbral foramina

Boundaries AP

Anatomy

Cut section

Distance from dura to lig. Flavum Lumbar 2 : 5 – 6 mm Midthoracic : 3 – 5 mm Cervical : 1.5 – 2 mm

Contents fat, vessels and nerve roots Fat : Important pharmacological space : Depot for drugs Obese – more capacious epidural space

Vessels Arteries : intersegmental arteries from Laterally mainly Veins : Segmental connections Valveless, sluggish More anterior

Vascular network

Different epidural spaces Cervical : Fusion of the spinal and periosteal layers of dura mater at the foramen magnum to lower margin of C7 Thoracic : Lower margin of C7 to upper margin of L1 Lumbar : Upper margin of L1 to upper margin of S1 Sacral : Upper margin of S1 to sacrococcygeal membrane

Contents Dural sac ends at approximately S2. Contains the spinal cord (to the lower border of L1) and cauda equina Spinal nerves In pairs. Lymphatics are present around the region of the nerve root and function to remove foreign material. Connective tissue- Variable dorso median folds, median fold.

Nerve supply The spinal canal and its contents have their own innervation. The anterior dura is heavily innervated fortunately for spinal, epidural anaesthesia, the posterior dura is sparsely supplied The periosteum is pain sensitive but the ligamentum flavum is not

Methods of entry Interlaminar The ‘usual’ method. Loss of resistance methods. Transforaminal Directs solution to the anterior epidural space. Radiological guidance mandatory. Specialist use only Transsacral Direct vision Spinal endoscopy Paravertebral Frequent epidural blockade

Location A 4 mm wide space to be located 4 – 8 cm depth No obvious end point

Location of space

Other positions Epidural anesthesia and analgesia is most often performed in the lumbar region. Thoracic epidural blocks are technically more difficult to accomplish than lumbar blocks because of greater angulation and marked overlapping of the spinous processes at the vertebral level

Other positions the potential risk of spinal cord injury with inadvertent dural puncture Cervical blocks are usually performed with the patient sitting, with the neck flexed, using the midline approach. Clinically, they are used primarily for management of pain Caudal epidural

Spinous process

Angulation of puncture

Why is epidural pressure negative ?? Dural tenting and coning Negative intra thoracic pressure Recumbent position

Denting

Position

Approaches Cervical, Thoracic, Lumbar, Caudal

Techniques Median paramedian ↓ ↘ ↙ ↓ Loss of Hanging drop resistance 1. air filled 2. fluid filled 3. both

Midline and paramedian – skin entry – 10 – 15 deg.

Midline As the epidural needle enters the midline of the back over the bony spinous processes, it passes through (1) skin, (2) subcutaneous fat, (3) supraspinous ligament, (4) interspinous ligament, (5) ligamentum flavum, and (6) epidural space

Paramedian anesthetized skin subcutaneous tissues, paraspinous muscle, lamina of the inferior vertebra The needle tip is walked medially until the base of the spinous process is encountered, The needle tip is then marched superiorly until it “walks off” of the lamina, encounter resistance as it meets the ligamentum flavum.

Bromage grip

Hanging drop technique Hanging drop method

False hanging drop Initial aspiration feeble Persistent neg. pressure – nil Cardiac pulsations absent Catheter – passage – no

Air, fluid and Bubble

Other adjuncts Peripheral nerve stimulator Ultrasound

Ultrasound proved useful

supplements Radiological screening is helpful for difficult epidural entry. Spinal endoscopy adds another dimension to epidural catheterization

Lumbar and thoracic

Equipments Needle Accessories Catheter

Touhy and huber tip crawford, bromage – outdated

LEE needle

Macintosh balloon

Odom s indicator

Others U tube manometer Zorraquin s bulb Zelenka bulb Auditory devices

Adjuvants 5 ml syringe Glass – sticky ?? Air filled - jerky Fluid filled – smooth slow, controlled

Space Sudden loss of resistance No further movement Never advance without syringe control

Now that space entered Aspiration Test dose Water injection Rapid saline (Duran sign)

Aspiration 2 ml syringe Repeat after 2 ml air injection Aspirate again

Test dose 3 – 5 ml of ligno + adrenaline Advantages – intrathecal, intravascular,catheter easy,vigilance for beginners Disadvantages – 5 ml for old age !! Time ?? After test dose, puncture possible Catheter insertion – useless

Drip back test ml given at a rate of 10 ml / minute Fluid drips back What is it ??

Why drip back ?? CSF Too rapid injection Injection gone into tissue planes Temperature test Glucose oxidase test

Accidental dural puncture Abandon the procedure Convert into SA Try again in the same space Try again in different space Continuous spinal anaesthesia Epidural blood patch

Catheter Vinyl Nylon PVC PTFE

5 ml initially Test dose Threading easy Start the block Sacral sparing – NO

Space ok – catheter now Slow 10 cm – some resistance, rotate No excess force 3 – 4 cm ok Aspiration and test dose again !! Insert from below up – WHY ?

Catheterisation

Drugs and comp[lications Part 2 Next time

Thank you all