Epidural Anesthesia/Analgesia

Local anaesthetic solutions are deposited in the epidural space between the Dura mater and the periosteum lining the vertebral canal. The epidural space contains adipose tissue, lymphatics and blood vessels. The injected local anaesthetic solution produces analgesia by blocking conduction at the intradural spinal nerve roots.

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Wide application

Epidural block can be performed at the sacral(caudal), lumbar, thoracic or cervical levels.

Epidural techniques are widely used for operative anesthesia, obstetric analgesia, postoperative pain control, and chronic pain management.

Dose judgment could be single shot, intermittent bolus or continuous infusion or combined.

Epidural Anesthesia

Indication and Contraindication: the same of spinal anaesthesia.

Additional indication is the post operative Paine management using the epidural catheter technique.

Complications: the same of spinal anaesthesia, except the post dural puncture headache.

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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. puncture of

the Dura mater

Injection: epidural space (between Ligamentum

flavum and dura mater) i.e without puncture of

the dura mater

Identification of the subarachnoid space: When

CSF appears

Identification of the Epidural space: Using the

Loss of Resistance technique.

Dose: 2.5- 3.5 ml bupivacaine 0.5% heavy Dose: 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.

Differential block:By using relatively dilute concentrations of local anesthetic combined with an opiate, an epidural can block the smaller sympathetic and sensory fibers wile sparing the larger motor fibers.

Segmental block:Due to local anesthetic is not spread readily in CSF as spinal anesthesia, a well-defined band of anesthesia at certain nerve roots without those above and below blocked can be achieved with epidural techniques.

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Epidural Anesthesia continue

Technique:

Loss of resistance technique to identify the epidural space.

0.5% Bupivacaine (mainly) or lidocaine (2.0%) is usually used to produce epidural anaesthesia.

Technique

1)Position

2)Cleaning & Draping

3)Local Infiltration

4)Loss f Resistance Test

5)Catheter –in-situ

6)Fixing

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Advantages in conjugation with GA CV systems:

Blockade of cardiac sympathetic innervation (arise at T1-T4) with dilute local anesthetic postoperatively via a thoracic epidural catheter can reduce myocardial ischemia in patients with coronary artery disease.

Respiratory system

Thoracic or upper abdominal surgery is associated with 1.decreased diaphragmatic function postoperatively from decreased phrenic nerve activity2. decreased FRCthese can lead to atelectasis and hypoxia via V/Q mismatch

Some evidence suggests that postoperative thoracic epidural analgesia in high-risk patients can improve pulmonary outcome by decreasing the incidence of pneumonia and respiratory failure, improving oxygenation, and decreasing the duration of mechanical ventilatory support

Metabolic and endocrine system Surgical trauma produces increases in ACTH,

cortisol, epinephrine, norepinephrine and vasopressin and activate RAA system.

Neuraxial blockade can partially suppress (during major invasive surgery) or totally block (during lower extremity surgery) this stress response and then reduce perioperative arrhythmias and the incidence ischemia possibly. A T11 block can block adrenal pathways and blunt hyperglycemia.

Complication of neuraxial block Backache Headache Urinary retention Maternal fever Transient neurologic symptoms (TNS):

back pain radiating to the legs without sensory or motor deficits, occurring after the resolution of spinal block and resolving spontaneously within several days

High or total spinal anesthesia Subdural injection Cardiac arrest Systemic toxicity Cauda equina syndrome & other neurologic

deficits, transient or permanent Maningitis & arachnoiditis Epidural abscess Spinal & Epidural hematoma