Class gen and local anaesth
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Class gen and local anaesth






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Class gen and local anaesth Presentation Transcript

  • 2. General anaesthetics are the drugs which produce reversible loss of sensation and conciousness. Cardinal Features Loss of sensation Sleep and Amnesias Immobility and muscle relaxation Abolition of somatic and autonomic reflexes Minimal Alveolar Concentration :- Is the alveolar concentration of an inhaled anesthetic that prevents movement in 50 % of patients in response to standardized stimulus ( surgical incision ).
  • 3. Awake Amnesia sedation Hypnosis Coma Death
  • 4.  Stage of analgesia  Stage of delirium  Surgical anaesthesia  Plane1- Rolling eye balls  Plane2- Loss of corneal and laryngeal reflexes  Plane3- Loss of light reflex  Plane4- Intercostal paralysis  Medullary paralysis
  • 5. INHALATIONAL ANAESTHETICS  Nitrous oxide, cyclopropane,xenon VOLATILE LIQUIDS  Isoflurane, Sevoflurane  Desflurane, Halothane  (Ether), Enflurane INTRAVENOUS ANAESTHETICS INDUCING AGENTS Thiopentone sod. Methohexitone sod., Propofol, Etomidate
  • 6. SLOWER ACTING DRUGS Benzodiazepines Diazepam Lorazepam Midazolam Dissociative anaesthesia Ketamine Neurolept analgesia Fentanyl
  • 7.  Short-acting agent used for the induction , maintenance of GA and sedation in adult patients and pediatric patients older than 3 years of age. It is highly protein bound in vivo and is metabolised by conjugation in the liver. Side-effects is pain on injection hypotension and transient apnea following induction 7
  • 8. •widely used •Potent analgesic •Produce a light anesthesia •Do not depress the respiration/vasomotor center •Used ad adjunct to supplement other inhalationals
  • 9. • Non-flammable • 20% metabolism by P450 • induction of hepatic microsomal enzymes • Myocardial depressant (SA node), sensitization of myocardium to catecholamines - arrhythmia
  • 10.  Transient hepatic damage  Liver necrosis  In repeated exposure  Immunosensititation  Malignant hyperthermia (MH) is a pharmacogenetic hypermetabolic state of skeletal muscle induced in susceptible individuals by inhalational anesthetics and/or succinylcholine (and maybe by stress or exercise).
  • 11. Rapid, smooth induction and maintenance • 2-10% metabolized in liver • Introduced as replacement for halothane ISOFLURANE smooth and rapid induction and recovery very little metabolism (0.2%) no reports of hepatotoxicity or renotoxicity most widely employed
  • 12.  rapid onset (20 sec), short-acting  Effect terminated not by metabolism but by redistribution  repeated administration or prolonged infusion approached equilibrium at redistribution sites  Build-up in adipose tissue = very long emergence from anesthesia Side effects  Hypotension  apnoea  airway obstruction
  • 13.  NMDA Receptor Antagonist  usually stimulate rather than depress the circulatory system.  Analgesic  dissociative anesthesia  Cataleptic appearance, eyes open, reflexes intact, purposeless but coordinated movements
  • 14.  Use specific drugs for each component 1. Sensory ▪ N20, opioids, ketamine for analgesia 2. Cognitive ▪ Produce amnesia, and preferably unconsciousness ▪ inhaled agent ▪ IV hypnotic (propofol, midazolam, diazepam, thiopental) 3. Motor ▪ Muscle relaxants
  • 15.  Sedatives / Anxiolytics ▪ Benzodiazepines,Barbiturates ▪ Butyrophenones,Phenothiazines ▪ Chloral hydrate & Paraldehyde  Opioid Analgesics ▪ Morphine ▪ Pethidine ▪ Buprenorphine
  • 16. Anticholinergic Drugs Atropine SO4 Scopolamine (Hyoscine) Synthetic Anticholinergics – Glycopyrrolate Antiemetics Phenothiazins (Promethazine and Trimeprazine) Cyclizine Trimethobenzamide Benzquinamide Metoclopramide
  • 17. Local anaesthetics as distinguished from general anaesthetics as they abolish the pain and other sensations in localized areas without affecting the degree of consciousness of the patient
  • 18.  Drugs that cause reversible loss of sensory perception specially of pain in a restricted area of the body, when applied topically or local injection.  LA if applied to a mixed nerve—sensory and motor impulses are interrupted—resulting in muscular paralysis and loss of autonomic control.
  • 19.  Reversibly block the impulse conduction  Transient loss of sensation  Local anaesthesia blockade  C,B > Aδ > Aα,ß,γ
  • 22.  Vasoconstrictor is a substance used to keep the anesthetic solution in place at a longer period and prolongs the action of the drug  Vasoconstrictor delays the absorption which slows down the absorption into the bloodstream  Vasoconstrictor used ---the natural hormone called epinephrine (adrenaline).
  • 23.  Blockage of membrane depolarisation in all excitable tissues, usually intended on peripheral nerve  Membrane stabilizer  They prevent the  Initiation and propa-  Gation of the nerve  Impulse by reducing  the passage of Na
  • 24.  Effects of LA: injection as acid (hydrochloric salt)= ionized form  at physiological pH dissociation to free base (lipid soluble) passage through cell membrane to interior of axon re-ionisation enter and blockage of Na+-channel and thereby preventing influx of Na+ no generation of AP conduction blockade  They block nerve conduction by reducing the permeability of Na ions during depolarisation
  • 25.  Should not benot be coadministered for nerve block in areas such as fingers and toes that are supplied with end-arteries because it may cause ischemia or necrosis  It should be used cautiously in patients in labour and in patients with thyrotoxicosis or cardiovascular disease.
  • 26.  Usually at range 7.6 – 8.9  Decrease in pH shifts equilibrium toward the ionized form, delaying the onset action.  Lower pH, solution more acidic, gives slower onset of action  Presence of Pus and inflammation will retard the action of LA. ( probably low acidic pH)
  • 27.  Most widely used Amide linked LA and most versatile ana.  Has variety of applications like Local, nerve block, spinal, epidural, IVRA.  When used locally action starts within 3 mts and causes vasodilatation.  Overdose causes muscle twitchings, convulsions, cardiac arrhythmias, fall in BP, coma, respiratory arrest.  Most popular ant arrhythmic drug
  • 28. • Standard agent for infiltrations, regional blocks or topical • Short onset time, intermediate duration of action • Class Ib antiarrhythmic properties • Medium toxicity • Maximal recommended dose: 3 mg/kg, 6 mg/kg with vasconstrictor
  • 29.  A potent long acting ---Amide linked LA available in India, most widely used allover.  Not used for IVRA but all others like local, spinal epidural blocks.  Action lasts for 2 to 3 hours. Strength for epidural is 0.25 to 0.5 % solution.  Has high lipid solubility, distributes more in tissues than in blood
  • 30.  It is similar to Bupivacaine  One of the metabolites are toxic and can cause Methamoglobinemia  Used for Nerve Blocks and IVRA.
  • 31.  Causes more sensory block, than motor block the advantage taken in during Caesarean Section. (Walking Epidural)  Bupivacaine is more prone to prolong QTc interval and induce ventricular tachycardia or Cardiac depression----( Membrane Stabilization action ) ( toxic doses and accidental entry into vessel)- should not be used for IVRA.  Longest acting LA available in India now.
  • 32. 1. Surface anesthesia 2. Infiltration anesthesia 3. Conduction block a. Field block b. Nerve Block 4. Spinal anesthesia 5. Epidural anesthesia 6. I V R A (Bier’s Block)
  • 33.  Amethocaine ---eye, throat, urethra, rectum and skin.  Benzocaine and Lidocaine hydrochloride—same ---except for eye.  Procaine is unsuitable as a surface ana. Because of its poor penetrating power  Lignocaine --4 % topical solution, 2 % Jelly 2 % vials for injections
  • 34.  Eutectic : Lowering of melting point of two solids when they are mixed.  combination of Lidocaine and Prilocaine.  For Pediatric purpose. It can penetrate intact skin.  I v .cannula inserting.  Split skin graft harvesting  Other superficial procedures.
  • 35.  Mech. of action : Nerve endings as exposed to the drug there by action.  Procaine, Lignocaine 2 % are used either with or without Adrenaline 1 : 2,00,000  C/I : blocking where end arteries are involved either for Penis, or for Digits, C A D patients.
  • 36.  Drug is injected close to the nerve or big nerve trunks eg. Brachial Block, Sciatic, Femoral Nerve, Radial, Ulnar Nerves.
  • 37.  LA is injected into the subarachnoid space. Injection is made heavy by adding dextrose or light by adding saline.  When the anesthetic in injected outside the dura, the technique is known as Epidural anesthesia.  Lignocaine, Bupivacaine the two agents most commonly used regularly in anesthesia practice.
  • 39.  Intravenous regional anesthesia  Agent of choice------ Lignocaine (Xylocaine )  20 to 40 ml of 0.5 % Lidocaine is used  Used for only for Upper Limb orthopedic surgeries and others on Up. Limb.
  • 40.  We have seen all Local actions of LA s  Systemic action when given IV : Bupivacaine is relatively more cardiotoxic , produces ventricular tachycardia or fibrillation.  Lidocaine has little effect on contractility and conductivity, used as antiarrhythmic.  The prominent cardiac action of Xylocaine is suppression of automaticity in ectopic foci.
  • 41.  Depression of function of CNS and CVS when high plasma concentrations are reached  CNS toxicity : usually before cardiovacular effects First signs of excitation due to initial blockade of inhibitory pathways mild: circumoral tingling, metallic taste, tinnitus, visual disturbance, slurred speech moderate: altered consicous state, convulsions Later sings of generalized CNS depression with potentially fatal toxicity: coma,respiratory arrest
  • 42.  1.Bradycardia, 2.Hypotension 3.Headache  4.Cauda Equina syndrome 5.Septic meningitis EPIDURAL ANESTHESIA :  Here the drug is injected outside the dura. Drug spread is restricted to a specific region causes fewer complications.
  • 43.  Allergic reactions: common with ESTERS like Procaine, caused by para-aminobenzoic acid (also found to cause arachnoiditis), less common with AMIDES, then mostly through preservatives  Drug interactions: i.e. Anticholinesterases, other competing drugs hydrolyzed by Plasma CE  Attention with heavy sedation with anticonvulsants: may mask early signs of toxicity  Methaemoglobinaemia: after large doses Prilocaine