epidural anaesthesia presentation

1. Epidural anesthesia
Presenter: Brenda Richard
Supervisor: Dr Lugano

2. Overview
• Introduction
• Applied anatomy
• Technique
• Indications & contraindications
• Complications

3. Spinal Anatomy
 33 Vertebrae
◦ 7 Cervical
◦ 12 Thoracic
◦ 5 Lumbar
◦ 5 Sacral
◦ 4 Coccygeal
 High Points: C5 & L5
 Low Points: T5 & S2

4. Sagittal Section
• Supraspinous Ligament
• Outer most layer
• Interspinous Ligament
• Middle layer
• Ligamentum Flavum
• Inner most layer

5. Spinal Cord
• Spinal Cord
• Adult
• Begins: Foramen Magnum
• Ends: L1
• Newborn
• Begins: Foramen Magnum
• Ends: L3
• Terminal End: Conus Medullaris
• Filum Terminale: Anchors in sacral region
• Cauda Equina: Nerve group of lower dural sac

6. Epidural Space
• Potential Space that surrounds the spinal meninges
• Ligamentum Flavum
• Binds epidural space posteriorly
• Widest at Level L2 (5-6mm)
• Narrowest at Level C5 (1-1.5mm)

7. Spinal Meninges
 Dura Mater
◦ Outer most layer
◦ Fibrous
 Arachnoid
◦ Middle layer
◦ Non-vascular
 Pia
◦ Inner most layer
◦ Highly vascular
 Sub Arachnoid Space
◦ Lies between the arachnoid
and pia

8. Technique
• It is given in sitting or lateral position
• The epidural space is most commonly located by loss of resistance
technique. Another technique is hanging drop technique (rarely used
in current practice)
• Once the needle is confirmed in epidural space, a test dose of 2-3mls
of lignocaine 1-2% with adrenaline 5mcg/ml is given. If in 5mins there
are no signs of either spinal block or intravascular injection, further
dose can be injected 15-20mls.
• An epidural catheter is then passed through the needle(3-4cm of the
catheter should be in epidural space)

9. Standard Epidural needle is typically 17 to 18 gauge, 3-3.5inches long
and has a blunt bevel with a gentle curve of 15 to 30degrees. Tuohy
needle is the most commonly used
Placing a catheter into epidural space allows for continuous infusion or
intermittent bolus technique which is useful for intraoperative epidural
anesthesia and postoperative analgesia
Distances from Skin to Epidural Space
• Average adult: 4-6cm
• Obese adult: up to 8cm
• Thin adult: 3cm

10. Indications
All surgeries which can e performed under spinal anesthesia can be
performed under epidural block.
However in clinical practice epidural block in mainly used in
• Postoperative pain management
• Chronic pain management
Others include
• Upper abdominal surgery
• Thoracic surgery
• Neck surgery

11. contraindications
• Raised intracranial pressure
• Patient refusal
• Severe hypovolemia and hypotension
• Coagulopathy

12. Physiologic effects of epidural block
1. Cardiovascular system
Blockade of Sympathetic Preganglionic Neurons
• Send signals to both arteries and veins
• Predominant action is venodilation
• Reduces:
• Venous return
• Stroke volume
• Cardiac output
• Blood pressure
T1-T4 Blockade
• Causes unopposed vagal stimulation
• Bradycardia
• Associated with decrease venous return & cardioaccelerator fibers blockade
• Decreased venous return to right atrium causes decreased stretch receptor
response

13. 2. Respiratory system
• Healthy Patients
• Appropriate epidural blockade has little effect on ventilation
• High Spinal
• Decrease functional residual capacity (FRC)
• Paralysis of abdominal muscles
• Intercostal muscle paralysis interferes with coughing and
clearing secretions
• Apnea is due to hypoperfusion of respiratory center

14. Factors affecting the spread(level) of block
• Volume of the drug
• Age
• Length of vertebral column
• Patient position

15. Complications
• Failed epidural anesthesia
• High or total spinal anesthesia
• Nerve injury
• Postdural puncture headache
• Back pain
• Infection

16. References
• Morgan & Mikhail’s clinical anesthesiology 6th edition
• A short textbook of anesthesia Ajay Yadav 6th edition
• UpTodate