1. DR. MOHD NAZAM ANSARI

3. Partial or complete loss of sensation with or with out loss of consciousness as a result of disease, injury, or administration of an anesthetic agent, usually by injection or inhalation.

4.  A. GENERAL-  A drug that brings about a reversible loss of consciousness  Total loss of consciousness and sensation, sleep (unconsciousness), and muscle relaxation;  IV, Inhalation, Rectal  B. LOCAL-  Reduce all painful sensation in one region of the body without inducing unconsciousness.

5.  Volatile Liquids  Ether  Halothane ( Fluothane)  Enflurane (Ethrane)  Isoflurane (Forane)  Sevoflurane (Ultrane)  Desflurane ( Suprane)  Gases  Nitrous oxide  Cyclopropane  Ethylene

6.  Inducing Agent (~11 sec)  Thiopentone sodium  Propofol  Etomidate  Slower Acting Drugs  Benzodiazepines  Diazepam (5-10 min)  Lorazepam  Dissociative anesthesia  Ketamine  Neurolept analgesia  Fentanyl + Droperidol

7.  Rectal (Pediatrics)-  Anectine, Pentothal Na 5-10%  Spinal anesthesia-  Procaine (Novocaine),  Tetracaine(Pontocaine),  Lidocaine(Xylocaine),  Mepivacaine (Carbocaine),  Bupivacaine( Marcaine)  Muscle relaxants-  Anectine (Succinyl choline),  Pavulon (Pancuronium)

8. DescriptionGeneral AnestheticsLocal Anesthetics 1. Site of actionCentral Nervous SystemPeripheral Nerves 2.Area of body involvedWhole bodyRestricted area 3. ConciousnessLostUnaltered 4. Major surgeryPreferredCan not be used 5. Minor surgery Can not be usedPreferred 6. Poor health patientRiskySafer 7. Care of vital functionEssentialUsually not needed

9. Preanesthetic medication: It is the use of drugs prior to anesthesia to make it more safe and pleasant.  To relieve anxiety – benzodiazepines.  To prevent allergic reactions – antihistaminics.  To prevent nausea and vomiting – antiemetics.  To provide analgesia – opioids.  To prevent bradycardia and secretion – atropine.

10.  Based on the fact the anesthetic action is correlated with the oil/gas coefficients.  Higher the solubility of general anesthetics in oil greater is the anesthetics action.

12. Molecular mechanism of the GA :  GABA –A : Potentiation by Halothane, Propofol, Etomidate  NMDA receptors : inhibited by Ketamine

13.  Ligand-gated ion channels  Chloride channels gated by the inhibitory GABA A receptor  GABA A receptor mediates the effects of gamma-amino butyric acid (GABA), the major inhibitory neurotransmitter in the brain  GABA A receptor found throughout the CNS  Most abundant, fast inhibitory, ligand-gated ion channel in the mammalian brain  Located in the post-synaptic membrane

14.  GABA A receptor is a 4-transmembrane (4-TM) ion channel  5 subunits arranged around a central pore: 2 alpha, 2 beta, 1 gamma  Each subunit has N-terminal extracellular chain which contains the ligand-binding site

16.  Receptor sits in the membrane of its neuron at the synapse  GABA, endogenous compound, causes GABA to open  Receptor capable of binding 2 GABA molecules, between an alpha and beta subunit  Binding of GABA causes a conformational change in receptor  Opens central pore  Chloride ions pass down electrochemical gradient  Net inhibitory effect, reducing activity of the neuron

17.  Irregular descending depression of CNS  STAGE 1 (ANALGESIA/ONSET/INDUCTION):  Extends from the administration of anesthesia to the time of loss of consciousness.  Pain is progressively abolished during this stage.  Patient remains conscious, can hear and see, and feels a dream like state.  Reflexes and respiration remain normal.  Some minor and major operation can be carried out.

18.  STAGE 2 (EXCITEMENT/DELIRIUM):  Extends from the time of loss of consciousness to beginning of regular respiration  Characterized by struggling, delirium, irregular respiration, and breatholding are commonly seen.  Muscle tone increases, jaws are tightly closed, vomiting, involuntary micturation or defecation may occur.  Heart rate and BP may rise.  Pupils are dilated.  No operation.

19.  STAGE 3 (Surgical Anesthesia):  Extends from the regular respiration to the loss of most of the reflexes.  Muscle tone decreases, BP falls, HR increases, constricted pupils, and regular respirations.  Surgical procedure is started.  STAGE 4 (Impending Death/ Stage of Danger):  Cessation of breathing, to failure of circulation and death.  Pupil is widely dilated.  It is due to anesthesia overdose.