Operating Department Skills
Epidural anaesthesia
Usage:
Epidural anaesthesia has the advantage over spinal anaesthesia in it's ability to maintain continuous anaesthesia after placement of the epidural catheter, which makes it suitable for lengthy procedures. Epidural blocks can also be used for postoperative analgesia, using lower concentrations of local anaesthetic drugs, or in combination with other agents. With an Epidural block, a patient may still be able to walk - unlike with a Spinal block. Drugs used include Marcaine and opioids.

Description:
A Tuohy needle, size 16-17 (larger than spinal needle), is positioned outside of the dural membrane, in the fat filled epidural space, through which nerves pass, after leaving the spinal cord. The epidural space is identified by loss of resistance to a syringe, filled with saline or air. When the needle passes through elastic membranes of spinal ligaments, and into the epidural space, there is a "give".

Either a bolus dose of local is injected, or a plastic catheter is fed through the Tuohy needle, into the epidural space, in order to permit a continuous infusion technique.

A Lumbar block is performed more commonly than a Thoracic block, and the epidural space is widest (0.5 cm) at this level. If the Tuohy needle is inserted too deeply, and a tear made in the dura, the CSF leakage can give the patient a bad headache.

IndicationsPost-op, intra-op, and palliative pain; trauma; Obstetrics.
Contra-indicationsRaised intra-cranial pressure; spinal deformity; infection; obesity; allergic to opiates; neurologically diseased.
AdvantagesStable analgesia without peaks/troughs; increased patient mobility; fewer G.I. problems; better respiratory function; more patient satisfaction.
DisadvantagesMotor sensory weakness; catheter may dislodge; careful monitoring required.
Analgesics1. Fentanyl (fast action and absorption into epidural fat)
2. Bupivicaine (15-20 minutes before action; 6-12 hours duration.)
Emergency drugsAtropine, Ephedrine, Naloxone.
ProhibitionsAvoid Trendelenburg position.


Complications
CSF leakageFrontal headache, nausea. Treat with hydration, analgesia.
InfectionBackache, spasm, pyrexia, paralysis. Treat with analgesia and antibiotics.
Spinal haemotomaBack/leg pain, urinary retention.
Motor weaknessLeg tingling/numbness. Treat with positioning and decreasing infusion rate.
HypotensionStop infusion and give oxygen. Have Naloxone available.
Breathing difficultyStop infusion, sit patient up, give oxygen, check catheter patency.
BradycardiaStop epidural, give oxygen. Have available: Atropine, Naloxone, and Ephedrine.
Urinary retentionCatheterise, give fluids.
ItchingCool flannel, Ondansetron.


Venous access...

Equipment...

Method...
  1. Sit patient up with feet on stool
  2. Spray back with pink chlorex
  3. Open Epidural pack for Anaesthetist
  4. Squirt saline onto sterile tray
  5. Show Lidocaine label/date to Anaesthetist; drop onto tray
  6. Anaesthetist drapes back of patient
  7. Injects Lidocaine
  8. Inserts trocar into Epidural space
  9. Injects into trocar
  10. Inserts catheter through trocar
  11. Removes trocar
  12. Tape (mefix) Epidural catheter to skin
  13. Flexigrid over insertion site

Contraindications...
How an Epidural differs from a Spinal...

An Epidural may be given at a Cervical, Thoracic, or Lumbar site; a Spinal must be given below L2, to avoid piercing the spinal cord.

Onset of analgesia is 25-30 minutes for an Epidural, but 5 minutes for a Spinal.

The indwelling catheter of an Epidural allows topping-up of analgesia; a Spinal is a one shot injection.

The larger space with the Epidural requires a larger dose (10-20 ml); a Spinal dose is 1.5-3.5 ml.