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بسم الله الرحمن الرحيم

بسم الله الرحمن الرحيم. بسم الله الرحمن الرحيم. Neuroaxial Anesthesia: An overview. Dr. Mahmoud Othman MD, Professor Of Anesthesia and SICU, Depart. of Anesthesia and SICU, Mansoura Faculty Of Medicine. The Advantages of Neuroaxial Anaesthesia: 1.Cost. . 2.Patient satisfaction.

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بسم الله الرحمن الرحيم

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  1. بسم الله الرحمن الرحيم بسم الله الرحمن الرحيم

  2. Neuroaxial Anesthesia:An overview. Dr. Mahmoud Othman MD, Professor Of Anesthesia and SICU, Depart. of Anesthesia and SICU, Mansoura Faculty Of Medicine

  3. The Advantages of Neuroaxial Anaesthesia: 1.Cost.. 2.Patient satisfaction. 3.Respiratory disease. 4.Patent airway. 5.Diabetic patients. 6.Muscle relaxation. 7.Bleeding. 8.Splanchnic blood flow. 9.Visceral tone. 10.Coagulation.

  4. * Physiology: ……….. • -Sensory Block . ……………………………. …. … • -Motor block……………………………………………… • -Autonomic Block……………………………….………. • * Anatomy: …….. …………….. • * Pharmacology: ….. ……….. ……………

  5. Today: PNS & spinal cord Tomorrow: CNS

  6. Nervous system Central nervous system (CNS): brain & spinal cord Peripheral nervous system (PNS): nerves outside brain and s.c. Somatic NS: nerves going from sense organs to CNS & from CNS to muscles & glands Autonomic NS: controls heart, blood vesseles,intestines, other organs Sympathetic NS: for vigerous activity (fight or flight) Parasympathetic NS: vegetative, nonemergency responses

  7. Peripheral NS • Somatic NS : • Sense organs  CNS  muscles and glands • Something touches leg  message to brain  message from brain to arm muscle  brush thing off leg Sensory stimulation Motor response

  8. Physiology http://www.carleton.ca/ics/courses/cgsc5001/img/06/neuron.jpg http://home.earthlink.net/~dayvdanls/REFLEXARC.GIF

  9. Bell-Magendie law: • The entering dorsal roots carry sensory information to the brain • & • the exiting ventral roots carry motor information to the muscles and glands • In other words: Dorsal=sensory • Ventral=motor http://www.unm.edu/~jimmy/spinal_neurons.jpg

  10. Dorsal root (sensory in) rostral Ventral root (motor out)

  11. The Spinal Cord The Spinal Cord Figure 4.7, p82 http://www.bcs.rochester.edu/~dlee/bcs245/spinal_cord.jpg Know above terms (for left figure) + terms circled in red for right figure!! To be clear, DRG: collections of cell bodies of sensory neurons; cell bodies of motor neurons are within SC

  12. Peripheral NS • Autonomic NS : • Sympathetic NS: axons activate organs for “fight or flight” • (Thoraco-lumber outflow) : T1 to L2 • Sympathetic ganglia are closely linked and act “in sympathy” with each other Short pregang. Long postgang.

  13. Facilitates energy expenditure Behaviors? Physiology? Fibers (short pre, long post, NT?)

  14. Peripheral NS • Autonomic NS : • Parasympathetic NS: facilitate vegetative, nonemergency functions • Para means “beside” or “related to”; opposite action of sympathetic NS • (Cranio- sacral outflow) :Cr1-12 & S2-4 • consists of cranial nerves and nerves of sacral SC long pregang. short postgang.

  15. Facilitates energy conservation Behaviors? Physiology? Fibers (long pre, short post, NT?)

  16. Neurotransmitters Few exceptions: sweat glands stimulated by Ach. http://members.aol.com/Bio50/LecNotes/LNPics/ln26a.gif Why does that matter?? Drugs!! OTC cold meds block parasymp or increase symp activity b/c flow of sinus fluids is parasympathetic. Side effect: inh salivation & digestion and inc HR

  17. Spinal anesthesia

  18. Spinal nerves Cauda equina http://dentistry.ouhsc.edu/intranet-web/Courses/DH3342/images/spin_nerves.JPG

  19. Myelin Sheath :

  20. Types of Nerve Fibers:

  21. Physiology of neuroaxial blockage 1. zone of differential block : level block (sympathetic > sensory > moter ) 2. nervous system Sodium channel block :nerve root ,spinal cord 3. cardiovascular system Autonomic denervation vasodilatationdecrease venous returndecrease CO hypotension Decrease HR 4. respiratory system 5. GI systemparasympathetic increase bowel move rupture of distened bowel 6. Liver and kidney .

  22. Vertebral Columen Curves:

  23. Lumber Vertebrae Anatomy

  24. Spinal Cord Terminal

  25. The spinal cord usually ends at the level of L1 in adults and L3 in children. Dural puncture above these levels is associated with a slight risk of damaging the spinal cord and is best avoided. An important landmark to remember is that a line joining the top of the iliac crests is at L4 to L4/5

  26. Local Anesthestic : A substance which reversibly inhibits nerve conduction when applied directly to tissues at non-toxic concentrations

  27. Local Anesthetics- History • 1860 - cocaine isolated from erythroxylum coca • Koller - 1884 uses cocaine for topical anesthesia • Halsted - 1885 performs peripheral nerve block with local • Bier - 1899 first spinal anesthetic

  28. Local anesthetics - Mechanism Limit influx of sodium, thereby limiting propagation of the action potential.

  29. Mechanism of action • Local anesthetics block generation, propagation, and oscillations of electrical impulses in electrically excitable tissue. • Mainly by acting on Sodium channels.

  30. Local Anesthetics - Classes Esters Esters

  31. PHARMACOLOGY AND PHARMACODYNAMICS • Clinically used local anesthetics consist of lipid-soluble, substituted benzene ring linked to amine group via alkyl chain containing either an amide or esterlinkage. • Type of linkage separates local anesthetics into either aminoamides (metabolized in liver) or aminoesters (metabolized in liver or by plasma cholinesterase).

  32. Local anesthetics - Classes (Rule of “i’s”) Esters Cocaine Chloroprocaine Procaine Tetracaine Am”i”des Bupivacaine Lidocaine Ropivacaine Etidocaine Mepivacaine

  33. Cinchocaine (Nupercaine, Dibucaine, Procaine, Sovcaine). 0.5% hyperbaric (heavy) solution is similar to bupivacaine. Amethocaine (Tetracaine, Pantocaine, Pontocaine, Decicain, Butethanol, Anethaine, Dikain). A 1% solution can be prepared with dextrose, saline or water for injection. Mepivacaine (Scandicaine, Carbocaine, Meaverin). A 4% hyperbaric (heavy) solution is similar to lignocaine.

  34. Bupivacaine (Marcaine). 0.5% hyperbaric (heavy) bupivacaine is the best agent to use if it is available. 0.5% plain bupivacaineis also popular. Bupivacaine lasts longer than most other spinal anaesthetics: usually 2-3 hours. Lignocaine (Lidocaine/Xylocaine). Best results are obtained with 5% hyperbaric (heavy) lignocaine which lasts 45-90 minutes.

  35. Local Anaesthetics for Spinal Anaesthesia. Local anaesthetic agents are either heavier (hyperbaric), lighter (hypobaric), or have the same specific gravity (isobaric) as the CSF. Hyperbaric solutions tend to spread below thelevel of the injection, while isobaric solutions are not influenced in this way. It is easier to predict the spread of spinal anaesthesia when using a hyperbaric agent. Hypobaric agents are not generally available.

  36. ADDITIVES TO LOCAL ANESTHETICS (1)Epinephrine : • Epinephrine added to local anesthetic may » prolong block » increase intensity of block » decrease systemic absorption • Epinephrine analgesia may act via interaction with 2-adrenergic receptors in spinal cord and brain

  37. Addatives to spinal anesthesia (Cont.) • (2)Analgesics:… A-Opioids : .. .. . ….. As : 1- Fentanyl 2-Colinidine B-Non-opioids: ………… As : 1- Tramadol 2- Midazolam 3-Neostigmine.

  38. Advantages : • - cost. ………………………………….. • -Patient Satsifaction………………… • -Respiratory Diseases. ……………… • -Diabetic Patients…………………… • - Muscle Relaxation…………………. • -Surgical Bleeding………………… • -Visceral Tone. ……………………….. • -Coagulation(DVT, PE)………………….

  39. Indications for Neuroaxial Anaesthesia: A- Spinal anaesthesia is best reserved foroperations below the umbilicus e.g. hernia repairs, gynaecological and urological operations and any operation on the perineum or genitalia. B- Spinal anesthesia applied for All operations on the legs(orthopedic-Vascular) but an amputation,though painless, may be an unpleasant experience for an awake patient.

  40. C - Older patients and those with systemic disease such as chronic respiratory disease, hepatic, renal and endocrine disorders such as diabetes. D- It is suitable for managing patients with traumaif they have been adequately resuscitated and are not hypovolaemic. E- In obstetrics, it is ideal for manual removal of a retained placenta (again, provided there is no hypovolaemia). Also spinal anesthesia is best choice for casearan section and instrumental dlivery There are definite advantages for both mother and baby in comparison to general anesthesia .

  41. Preoperative Visit: • Indications of spinal anesthesia : • -General surgery ………. • -Orthopedic surgery……………………………. • -Gynacological surgery………………………… • -Obestatric surgery………………………………. • -Urological surgery……………………. ……… • -Vascular surgery………………………………. • Medical Examination: • Laboratory Investigations: • Intravenous Preloading:

  42. Contraindictions Of Neuroaxial Anesthesia: • .Inadaquat Resuscitation Facilities. … • Hypovolaemia………………………… • .Patient Refusal……………………… • .septicaemia…………………… .. • .Local infection………………… • . Neurological Diseases . . … • -Coagulation Defects…………………………. • .Infants and childern(expert anesthetist)…

  43. Absolute contraindications: 1.sepsis 2.bacteremia 3.skin infection at injection site 4.severe hypovolemia 5.coagulopathy 6.increase intracranial pressure 7.lack of consent

  44. Relative contraindications: 1.peripheral neuropathy . 2.uncooperative patients 3.psychosis or emotional instability . 4.Mini dose heparin . 5.aspirin or anticoagulant drug . 6.demyelating CNS . 7.certain cardiac lesions (valve stenosis) . 8.prolonged surgery. 9.surgery of uncertain duration 10……. infants and young childern (experience) . .

  45. Pre-operative Visit. Patients should be told about their anaesthetic during the pre-operative visit. It is important to explain that although spinal anaesthesia abolishes pain, they may be aware of some sensation in the relevant area, but it will not be uncomfortable and is quite normal. They must be reassuredthat, if they feel painthey will be given a general anaesthetic.

  46. Premedication is not always necessary, but if a patient is apprehensive, a benzodiazepine such as 5-10 mg of diazepam may be given orally 1 hour before the operation. Other sedative or narcotic agents may also be used. Anticholinergics such as atropine or scopolamine (hyoscine) are unnecessary

  47. Preparation for Lumbar Puncture.: 1 . spinal needle. 2 . Introducer 3 . 5ml syringe for the spinal anaesthetic solution. 4 . 2 ml syringe for local anaesthetic to be used for skin infiltration. 5 . selection of needles for drawing up the local anaesthetic solutions and for infiltrating the skin. 6 . gallipot with a suitable antiseptic for cleaning the skin, eg chlorhexidine, iodine, or methyl alcohol. 7 . Sterile gauze swabs for skin cleansing.

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