Transcript PPT
By. Dr. J.M. Nguta, PhD (Pharmacol/Toxicol Anaesthetics and Life "The wonderful dream that pain has been taken away from us has become reality. Pain, the highest consciousness of our earthly existence, the most distinct sensation of the imperfection of our body, must now bow before the power of the human mind, before the power of ether vapor."Johann Friedrich Dieffenbach (1795-1847), -German pioneer plastic surgeon Read more: http://explorable.com/history-ofanesthesia.html#ixzz29xcRzH8f Anaesthesia and life Not too many medical revelations could be termed as significant and elementary as the discovery and development of Anesthesia. It was a turning point for the world of medicine and surgery, as the physicians and surgeons could concentrate on the case at hand without either worrying about the safety of the patient in terms of enduring pain or the shrieks that shook the hospital buildings Read more: http://explorable.com/history-ofanesthesia.html#ixzz29xboXirg Anesthetics-What are they? Used to reduce sensory awareness and to suppress reflexes sufficiently to permit the conduct of surgery. Anesthetics are agents which eliminate body sensation Anesthetics/Anesthesia The term anesthesia is now broadly applied in the surgical field to a complex procedure by which the patient is prepared psychologically for the operation and then rendered insensible to all feelings in the operation area, oxygenation of the blood is maintained at optimum levels, pharmacological means are used to keep the field of surgery clear of blood and muscle tone is decreased so that manipulations may be carried out easily and quickly. Introduction/Why this topic If you search for anesthetics: Google search: 4, 570,000 Citations Pubmed: 277, 827 Citations Sciverse: 180, 413 Citations Introd. What are anesthetics? How are they classified? Why should we use them in Veterinary practice? How are they used with ancillary therapeutics? Examples of commonly used anesthetics General anesthetics What are Gas? (Loss of sensation; abolition of voluntary motor response; also induce sleep) Provision of: Analgesia; Amnesia; loss of consciousness; muscle relaxation; abolition of voluntary motor response) Classification of GAs How are they classified? Examples in various classes Commonly used anesthetics in various classes- Local anaesthetics Local anesthetics are drugs which reversibly block nerve conduction beyond the point of application, when applied locally in an appropriate concentration. Thus, local anesthesia is a drug induced reversible blockade of nerve impulses in a restricted region of the body. Classification of LAs Based on chemical structure: 1.Esters of benzoic or Amino benzoic acid (usually hydrolysed by pseudo cholinesterase) Examples: Benoxinate (Fluress); Butamben (Butesin) iii).Chloroprocaine (Nesacaine); v). Cocaine v).Cyclomethicaine (Surfacaine); vi). Dyclonine (Dyclone); vii).Ethyl aminobenzoate (Benzocaine); viii).Procaine (Novocaine); ix).Proparacaine (Aktaine) x).Tetracaine (Pontocaine Classification of LAs 2. Amides: Largely metabolised in the liver Examples: Bupivacaine (Marcaine); ii).Dibucaine (Nupercaine); iii).Etidocaine (Duranest); iv).Lidocaine (Xylocaine) v).Mepivacaine (carbocaine); vi).Prilocaine (Citanest) 3. Ether-e.g. Pramoxine (Prax). Classification of LAs Based on clinical usage: Topical e.g. benzocaine; butacaine Infiltration and block: e.g. procaine; lidocaine Spinal anesthetics: Procaine; lidocaine Epidural and caudal anesthetics: Lidocaine; prilocaine Absorption of LAs Role of adrenaline Role of Hyaluronidase Metabolism of LAs Esters of benzoic or Amino benzoic acid: mainly metabolised by plasma cholinesterase(Pseudo cholinesterase) Amides and Esters: Metabolised in the liver by: esterases; amidases and conjugation reactions Toxicity of LAS CNS toxicity Cardiovascular related toxicity Hypersensitivity reactions ( skin sensitization following local application) Brainy quote Nothing in this world can take the place of persistence. Talent will not; nothing is more common than unsuccessful people with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated failures. Persistence and determination alone are omnipotent.( Calvin Coolidge-1872-1933-U.S.President)