Lecture Title : Regional Anaesthesia Techniques

1. Lecture Title : Regional Anaesthesia Techniques Lecturer name: DR. FATMA AL-DAMMAS ASSISTANT PROFESSOR DEPT OF ANAESTHESIA AND ICU COLLEGE OF MEDICINE KING SAUD UNIVERSITY Lecture Date:

2. Lecture Objectives.. Students at the end of the lecture will be able to: understand • What are the risks and benefits of regional (epidural/spinal) anesthesia/analgesia? • What are the contraindications to regional anesthesia? • How do you prevent hypotension following epidural/spinal anesthesia?

3. Spinal Anaesthesia • Describe the technique of spinal anesthesia. • At what level does the adult spinal cord end? • Name some of the surgical procedures that can be done with a spinal anesthetic. • What are the contraindications to spinal anesthesia? • What are the complications? • Describe the patient's perception as spinal anesthetic takes effect. • What are the expected cardiovascular changes associated with sensory level at T10? T1? • What are the characteristics of post-lumbar puncture headache? • How do the size and tip design of a spinal needle influence the incidence of post-puncture headache? • How do you treat post-lumbar puncture headache?

4. Epidural Anaesthesia Discuss the differences between spinal and epidural anesthesia. • What are the advantages and disadvantages of epidural compared to spinal anesthesia? • Study the size and tip of the epidural needle. • Name some of the surgical procedures that can be done with an epidural anesthetic. • Compare and contrast lumbar and thoracic epidural anesthesia. • What role does epidural has for post-operative pain control? • Local Anesthetics Pharmacology and toxicity (Lidocaine, Bupivacaine)

5. HISTORY • 1885 Corning - First attempt with epidural cocaine • 1891 Quincke - Describes the lumbar puncture technique • 1921 Pagis - First lumbar anesthesia for surgery • 1947 Lidocaine commercially available • 1949 Curbelo - First continuous lumbar analgesia with Touhy needle • 1963 Bupivicaine commercially available • 1979 Cousins - Epidural opioids provide analgesia • 1983 Yaksh - Different spinal receptor systems mediating pain • 1985 University of Kiel, Germany, Anesthesiology managed acute post-operative pain service Cousins & Bridenbaugh, 3rd Edition

6. Regional/Neuraxial Anesthesia A reversible loss of sensation in a specific area of the body. • Bier block • Axillary, Interscalene • Spinal, Epidural • Caudal • Foot block, metatarsal block • Paracervical

7. Regional anesthetic techniques categorized as follows • Epidural and spinal anesthesia • Peripheral nerve blockades • IV regional anesthesia

8. DEFINITIONS SPINAL ANESTHESIA INTRATHECAL=administration of medication into subarachnoid space

9. DEFINITIONS EPIDURAL ANESTHESIA EPIDURAL=administration of medication into epidural space

10. OVERVIEW OF THE SPINAL ANATOMY

11. SPINAL CORD Located and protected within vertebral column Extends from the foramen magnum to lower border 1st L1 (adult) S2 (kids) SC taper to a fibrous band - conus medullaris Nerve root continue beyond the conus- cauda equina Surrounded by the meninges,(dura,arachnoid &pia mater.)

13. anatomy The vertebrae are 33 number, divided by structural into five region: cervical 7, thoracic 12, lumber5, sacral 5, coccygeal3.

14. anatomy

15. EPIDURAL SPACE Potential space Between the dura mater,luigamentum flavum Made up of vasculature, nerves, fat and lymphatic Extends from foramen magnum to the sacrococcygeal ligament

16. Regional anesthesia • Spinal lower extremities, lower abdomen, pelvis • Epidural cervical thoracic lumber caudal

17. INDICATIONS The objective of epidural analgesia is to relieve pain. Major surgery Trauma (# ribs) Palliative care (intractable pain) Labour and Delivery abd surgery Pelvic surgery lower lime surgery

18. CONTRAINDICATIONS ABSOULET CONTRAINDICATION Patient refusal Known allergy to opioid or local anesthetic Infection/abscess near the proposed injection site Hematological disorder Increase ICP

19. CONTRAINDICATIONS RELATIVE CONTRAINDICATION Sepsis AntiCoagulant drugs Hypotension hypovolemia Spinal deformity Neurological disorder.

20. Patient assume a sitting or side-lying position with the back arched toward the physician.Help to spread the vertebrae apart

21. Height of sensory blockLumbar-T4Thoracic-T2

22. INSERTION OF EPIDURAL CATHETER Positioning of patient The site is dependent upon the area of pain Fixing the catheter Incision Level Thoracic T4-T6 Upper abdo T6-T8 Lower abdo T8-T10 Pelvic T8-T10 Lower extremity L1-L4

30. EPIDURAL CATHETERS Ideal Placement (adult) 10-12 cm at the skin Epidural catheters have markings that indicate their length. = there is a mark at the tip of the catheter = the 1st single mark up the catheter is 5cm = double mark up the catheter is 10 cm = triple mark on the catheter is 15 cm = four mark together indicate 20cm A change in depth of the catheter indicates migration either into or out of the epidural space.

31. CATHETER MIGRATION Catheter migration into a blood vessel in the epidural space or subarachnoid space rapid onset LOC Decrease loss of sensory or motor loss (marcain) Toxicity Profound hypotension

32. CATHETER MIGRATION Out of the epidural space ineffective analgesia no analgesia drugs deposited into soft tissue.

33. Advantages/Disadvantages of Regional and Local Anesthesia.

34. advantages • patient remains conscious • maintain his own airway • aspiration of gastric contents unlikely • smooth recovery requiring less skilled nursing care as compared to general anesthesia

35. advantages • postoperative analgesia • reduction in surgical stress • earlier discharge for outpatients • less expense

36. Disadvantages: • patient may prefer to be asleep • practice and skill is required for the best results. • some blocks require up to 30 minutes or more to be fully effective • analgesia may not always be totally effective-patient may require additional analgesics, IV sedation, or a light general anesthetic

37. Disadvantages: • toxicity may occur if the local anesthetic is given intravenously or if an overdose is injected • some operations are unsuitable for local anesthetics, e.g., thoracotomies

38. DRUGS One of the most important factors influencing drug absorption and bioavailability is the drug SOLUBILITY The more lipid soluble rapid onset & shorter duration

39. MEDICATION COMMONLY USED OPIOIDS-Fentanyl +Morphine (affect the pain transmission at the opioid receptors) L.A.-Bupivacaine(marcaine) (inhibits the pain impulse transmission in the nerves with which it comes in contact)

40. LOCAL ANESTHETICS AMIDES MAX / DOSE • BUPIVACAINE 2 MG/KG • LIDOCAINE 7 MG/KG • ROPIVACAINE 4 MG/KG • MEPIVACAINE 7 MG/KG • PRILOCAINE 6MG/KG

41. LOCAL ANESTHETICS ESTERS MAX /DOSE CHLOROPROCAINE 20 MG/KG COCAINE 3 MG/KG NOVOCAINE 12 MG/KG TETRACAINE 3 MG/KG

42. Metabolism • Amides • Primarily hepatic • Plasma conc may accumulate with repeated doses • Toxicity is dose related, and may be delayed by minutes or even hours from time of dose. • Esters • Ester hydrolysis in the plasma by pseudocholinesterase • Almost no potential for accumulation • Toxicity is either from direct IV injection • tetracaine, cocaine or persistent effects of exposure • benzocaine, cocaine

43. Clinical Pharmacology Patients with genetically abnormal pseudocholinesterase are at increased risk for toxic side effects, as metabolism is slower.

44. Clinical Pharmacology CSF lacks esterase enzymes, so the termination of action of intrathecally injected ester local anesthetics, eg, tetracaine, depends on their absorption into the bloodstream.

45. METHODS OF ADMINISTRATION BOLUS (FENTANYL, DURAMORPH) CONTINUOUS INFUSION(MARCAINE+FENTANYL) All drugs administered epidural should be preservative free. All epidural opioids should be diluted with normal saline prior to intermittent bolus administration.

46. Mechanism of Action Bupivacaine (marcaine) - local anaesthetic works as an analgesic (subanesthetic dose) - inhibiting impulse transmission in the nerve fibers - sensory nerves are blocked first before the motor fibers - sensory fibers carrying the pain is blocked before those carrying heat cold touch and pressure.

47. Progression of local anesthesia • Loss of: 1. Pain 2. Cold 3. Warmth 4. Touch 5. Deep pressure 6. Motor function

48. EPIDURAL LOCAL ANESTHETIC(MARCAINE) Onset 10-15 minutes Duration- 4 hrs+ after a bolus or after infusion is stopped Marcaine(0.0625%-0.125%-0.25%) Extend of spread influenced by volume and position of patient

49. OPIOIDS Mechanism of action-distribution Vascular uptake by blood vessels in the epidural space Diffusion through dura into CSF to spinal cord to the site of action. Uptake by the fat in the epidural space.

50. Morphine (Duramorph/Astramorph) Hydrophilic(water soluble) Slow to diffuse across the dura on to the spinal cord Can cause late respiratory depression Monitor respiratory status for 12 hrs after the last dose of duramorph Duration 6 hrs+ Broad spread