General anesthesia drugs and provide information about this

General anesthesia

1. General And Local Anaesthetics By : Simrandeep Kour Batch : 2021 - 2022 Roll No. : 01

2. GENERAL ANAESTHETICS : General Anaesthetics are drugs which produce reversible loss of all sensations and consciousness .

3. The Cardinal Features Of General Anaesthesia are : ------ Loss Of All Sensations Sleep ( Unconsciousness) Aboliti on Of Reflexes Muscle Relaxation

4. Stages Of General Anaesthesia : ------ 1) STAGE OF ANALGESIA : Heart Rate and Blood Pressure = Normal . Conscious Patient . Reflexes and Respiration = Normal . USES : Labour , Incisions and Minor Operations . 2) STAGE OF DELIRIUM : Uncontrolled Movements , Muscle Tone Increases , Jaws are tightly Closed , Breathing Is Jerky . BP and Heart Rate = Increases . Pupils Dilate USES : NIL .

5. 3) Surgical Anaesthesia : PLANE 1 : 🔵 Increased Depth Of Respiration. 🔵 Constricted Pupils. 🔵 Loss Of Eyelid and Conjunctival Reflexes . PLANE 2 : 🔵 Loss Of Laryngeal And Corneal Reflexes PLANE 3 : 🔵 Mainly Abdominal Respiration . 🔵 Pupils start dilating 🔵 Loss Of Light Reflex . PLANE 4 : 🔵 Irregular Breathing 🔵 Intercostal Paralysis 🔵 Shallow Abdominal Respiration 🔵 Dilated Pupil .

6. 4 ) Medullary Paralysis / Overdose : 🔵 Stage Of Cardio-respiratory Failure. 🔵 Pupil Widely Dilated . 🔵 Skeletal Muscle Tone And All Reflexes = Lost . 🔵 Hypotension And Bradycardia.

7. DIFFERENCE BETWEEN LOCAL AND GENERAL ANAESTHETICS : General Anesthetics : --- Site Of Action : CNS Area Of Body Involved : Whole Body . Consciousness : Lost Care of Vital Functions : Essential Major Surgery : Preferred Minor Surgery : Not Preferred . Local Anaesthetics : --- Site Of Action : Peripheral Nerves Area of Body Involved : Restricted Area . Consciousness : Unaltered Care Of Vital Functions : Usually Not Needed . Major Surgery : Cannot Be Used Minor Surgery : Preferred .

8. CLASSIFICATION OF GENERAL ANAESTHETICS : -- 1 ). INHALATIONAL AGENTS :-- ⬛ VOLATILE LIQUIDS :--- 🔺 ETHER 🔺 HALOTHANE 🔺 DESFLURANE 🔺 SAVOFLURANE ⬛ GAS :----- 🔺 EG :- NITROUS OXIDE .

9. 2) INTRAVENOUS AGENTS : --- (A) THIOPENTONE SODIUM , PROPOFOL . (B) BENZODIAZEPINES : -- 🔺 DIAZEPAM 🔺 LORAZEPAM 🔺 MIDAZOLAM .

10. 3) . AGENTS PRODUCING SPECIAL TYPE OF ANAESTHESIA ---- DISSOCIATIVE ANAESTHESIA ( VIA I.V. / I.M. ) : ----- EG : - KETAMINE .

11. INHALATIONAL ANAESTHETICS INHALATIONAL ANAESTHESIA REFERS TO THE DELIVERY OF GASES OR VAPOURS TO THE RESPIRATORY SYSTEM TO PRODUCE ANAESTHESIA VIA FACE MASK , LARYNGEAL MASK AIRWAY OR TRACHEAL TUBE CONNECTED TO AN ANAESTHETIC VAPORIZER AND AN ANAESTHETIC DELIVERY SYSTEM .

12. 1) . NITROUS OXIDE (N2O) : ---- 🔺Non - Inflammable 🔺 Colourless and Odourless Gas 🔺 Supplied Under Pressure In Steel Cylinders 🔺 Weak Anaesthetics Agent , i.e , produces light anesthesia . 🔺 Used for Dental and Obstetric Analgesia .

13. ADVANTAGES : - Strong Analgesic Action ( even in 20 % Concentration ) Onset Of Action is Quick and Smooth Recovery is Rapid . Non - toxic to liver , kidney and brain . Cheap and very commonly used . Cannot Produce Full Surgical Anaesthesia. Poor Muscle Relaxant. Prolonged Use May Lead to Bone Marrow Depression and Megaloblastic Anemia . DISADVANTAGES : -

14. 2) Ether : ---- 🔺Highly Volatile Liquid . 🔺 Irritant , Inflammable and Explosive

15. Advantages : - 🔺 Potent Anaesthetic 🔺 Good Analgesic agent . 🔺 Adequate Muscle Relaxation . 🔺 No Sensitisation Of Heart . 🔺 No Hepatotoxicity .

16. Disadvantages : - 🔺Recovery Is Slow . 🔺 Increases Salivary and Bronchial Secretions , so more chances of Laryngospasm and Bronchospasm . 🔺 Post- Anaesthetics Nausea , Vomiting and retching are marked .

17. 3) HALOTHANE : ---- 🔺 Non - Inflammable. 🔺 Non - Explosive . 🔺 Rapid Action 🔺 Commonly Used Liquid Anaesthetic .

18. Advantages : - Onset and Recovery Is Smooth and Pleasant. Incidence Of Post-operative Nausea and Vomiting Is Low . Potent Bronchodilator ( Preferred in Asthmatics ) . Incidence Of Laryngospasm and Bronchospasm Is low . Poor Analgesic Poor Muscle Relaxant. Cardiac Arrhythmia / Respiratory Depression May occur . HYPOTENSION . Cerebral Vasodilator . Hepatitis may Occur . Disadvantages : -

19. 4) ISOFLURANE :--- 🔺Onset and Recovery Is Rapid 🔺 Unpleasant Due to Pungent Smell / Bronchial Irritation . 🔺 Hypotension 🔺 Vasodilator - Coronary Vasodilatation . 🔺 No Hepatic Or Renal Toxicity . 🔺 No Nausea and Vomiting 🔺 Bronchodilator . 🔺 Suitable For Neurosurgery - Doesn't Cause Seizures . 🔺 No Dilatation Of Pupil . 🔺 No loss Of Light Reflex .

20. 5 ) DESFLURANE :--- ⬛ Onset Of Action and Recovery are Rapid . ⬛ Bronchodilator / Irritant To Airways . ⬛ HYPOTENSION ( Vasodilatation ) . ⬛ Causes Tachycardia . ⬛ No Renal or Hepatic Toxicity . ⬛ Doesn't Cause Seizures . ⬛ Post anaesthetic Cognitive and Motor Impairment Is Shortlived - Patients Can be Discharged Few Hours after Surgery .

21. 6) SEVOFLURANE : --- 🔺 Ideal General Anaesthetic But Expensive . 🔺 Properties Intermediate Between ISOFLURANE and DESFLURANE . 🔺 Onset and Recovery Are Rapid . 🔺 Bronchodilator / Non - Irritant To Airways . 🔺 HYPOTENSION . 🔺 No Tachycardia 🔺 Weak Muscle Relaxant . 🔺 No Seizures . 🔺 No Sensitisation Of Heart .

22. INTRAVENOUS ANAESTHETICS : ---- Intravenous (IV) anesthetics are administered through the bloodstream to temporarily impair awareness or sensation .

23. 1 ) THIOPENTONE SODIUM : --- 🔺 Ultra - Short Acting ( 5-10 mins ) 🔺 Produces Unconsciousness in 15-20 seconds . 🔺 Used as a truth serum for narcoanalysis . 🔺 Potent Anticonvulsant . 🔺 Poor Analgesic 🔺 Weak muscle Relaxant . 🔺 Employed as the sole Anaesthetic for short operations that are not painful . 🔺 Shivering and Delirium May occur during recovery .

24. 2) PROPOFOL : --- ⬛ Unconsciousness occurs in 15-45 seconds. ⬛ Distribution Half life = 2-4 minutes . ⬛ Elimination half life = 45 minutes . ⬛ Antimetic and Anticonvulsant Action . ⬛ Safe in Pregnancy . ⬛ Helpful in Endotracheal Intubation . ⬛ Adverse Effects - Apnoea on Bolus Dose , Pain at the site of Injection . ⬛ Respiratory Depression and Hypotension may occur .

25. 3) BENZODIAZEPINES : --- These are slower acting agents used for induction and maintenance of anaesthesia for short procedures . Eg : - Cardiac Catheterization , Angiographies , Endoscopies , Closed Reduction Of Fractures . 🔺 Produces Sedation and Amnesia . 🔺 Produces Unconsciousness within 5-10 minutes Of I.V. Administry .

26. A) DIAZEPAM : -- ⬛Onset of Action Is Slow . ⬛ Apnoea and Hypotension may Occur on Rapid Administration . ⬛ Slower Acting But More Potent and Less Irritant . ⬛ Can be given I.M. Route . ⬛ Amnesia is greater . ⬛ Recovery of Conscious may be delayed . B ) LORAZEPAM : --

27. C) MIDAZOLAM : -- 🔺 Short Acting . 🔺 Rapid Onset Of action . 🔺 Greater Amnesia . 🔺 Lesser Postoperative Sedation . 🔺 Non - Irritant To Veins ( No Thrombophlebitis ) . 🔺 No Respiratory And Cardiovascular Depression .

28. DISSOCIATIVE ANAESTHESIA : --- This is a type of Anaesthesia in which patient feels dissociated from the surroundings as well as from own body . Other Characteristics are : ---------- ⬛ Analgesia ( Maximum among general anesthetics ) . ⬛ Amnesia ⬛ Sedation ⬛ Light Hypnotic Effect ⬛ Patient Is Immobile .

29. 1) KETAMINE : --- ⬛ Commonly Used By I.V. Route & sometimes by I.M. Route . ⬛ Can also be used by Oral and Rectal Route . ⬛ Can produce its effect for 15 minutes . ⬛ Recommended for : Surgery of Head and Neck region , dressing of a severe burn , Cardiac Catheterization and Angiography . ⬛ Also called as Club Drug / Rape Drug .

30. Advantages : -- No Hypertension and Vomiting . Little Impairment of Reflexes ( Pharyngeal & Laryngeal ) Respiration is not Depressed . Potent Bronchodilator . Good For Hypovolemic Patients. Can Be Used for Assisted Vaginal Delivery and for Caesarean Section . Disadvantages : -- Slower onset of Action . Doesn't Produce Muscle Relaxation . Increases BP , Heart Rate and Cardiac Output . Hallucinations , Emergence Delirium and Involuntary Movements may Occur . Contraindicated in Hypertension , Myocardial Ischemia ( Angina ) , Eclampsia or Pre-eclampsia etc .

31. LOCAL ANAESTHETICS Local Anaesthetics are the drugs which upon topical application or local injection cause reversible loss of sensory perception ( Especially of pain ) in a restricted area of the body .

32. CLASSIFICATION : --- INJECTABLE : ------ LOW POTENCY , SHORT DURATION : Procaine , Chloroprocaine INTERMEDIATE POTENCY AND DURATION : Lignocaine , Prilocaine HIGH POTENCY , LONG DURATION : Tetracaine , Bupivacaine , Ropivacaine , Dibucaine SURFACE ANAESTHETICS : ----- SOLUBLE : Cocaine , Lignocaine , Tetracaine , Benoxinate . INSOLUBLE : Benzocaine , Oxethazaine , Butylaminobenzoate .

33. LOCAL ACTIONS : --- No / minimal Local Irritant Action . Blocks Sensory Nerve Endings , Nerve Trunks , Neuromuscular Junction , Receptors, Synapses Causes Anesthesia of Skin and Paralysis of Voluntary Muscle Supplied By the Mixed Nerve . Susceptibility Of Different Fibres is Different : Sensory > Motor Fibres . Nonmyelinated > Myelinated Fibres . Small Fibres > Large Fibres . Autonomic Fibres > Somatic Fibres .

34. SYSTEMIC EFFECTS : --- 1) Central Nervous System : -- LAs Causes Stimulation ( Restlessness , Tremors , Convulsions ) followed by Depression . Cocaine causes : Euphoria - Excitement - Mental Confusion - Restlessness - Tremor - Twitching - Convulsions - Unconsciousness - Respiratory Depression - Death . Both Procaine and Lignocaine Causes Drowsiness , Sedation and Loss Of Consciousness . 2) Cardiovascular System : -- LAs are Cardiac Depressants . Lignocaine and Procainamide are used as Antidysrhythmic agents . High SYSTEMIC Concentration may Cause Ventricular Tachycardia and Fibrillation .

35. 3) Smooth Muscles : --- LAs causes Reduced Contraction of Bowel and Relaxation of Vascular and Bronchial Smooth Muscles . 4) Sympathetic Nervous System : -- Paralysis may Occur whether used as Spinal Anaesthesia , Epidural Anaesthesia etc .

36. INDIVIDUAL AGENTS : ------

37. 1) LIGNOCAINE : --- 🔺 Most Widely Used Local Anaesthetic . 🔺 Good for both Injection and Surface Application . 🔺The Local Anaesthesia produced. is faster , more intense , long lasting and more extensive than Procaine .

38. USES : --- ⬛ For Cardiac Arrhythmias . ⬛ Used For Bronchoscopy ⬛ Resistant Cases Of Status Epilepticus . ADVERSE EFFECTS : --- ⬛ Drowsiness ⬛ Tinnitus ⬛ Dysguesia ⬛ Dizziness ⬛ Twitching ⬛ Convulsions ⬛ Hypotension ⬛ Cardiac Arrhythmias ⬛ Respiratory Depression .

39. 2) BUPIVACAINE : --- 🔺 Potent and Longer Acting than Lignocaine . 🔺 Preferred when Prolonged Anaesthesia is Needed . 🔺 Example During Labour or for postoperative pain relief . 🔺More Cardiotoxic ( Causing Ventricular Tachycardia or Cardiac Depression ) . 🔺 Highest Local Irritancy Among Local Anaesthetics . 🔺Mainly Used In Spinal and Epidural Anaesthesia , infiltration anesthesia and in Nerve Block .

40. 3) PRILOCAINE : --- ⬛ Similar To Lignocaine. ⬛ Suitable For I.V. Regional Block ⬛ Lower CNS Toxicity due to larger volume of Distribution . ⬛ May Cause Methaemoglobinaemia .

41. 4) PROCAINE : --- 🔺 First Synthetic Local Anaesthetic ( 1905 ) . 🔺 Equally effective as Cocaine but less toxic . 🔺 Not Used As Surface Anaesthetic due to poor absorption from mucous membrane . 🔺 Toxicity is Low . 🔺 Delayed Onset . 🔺 Short Action . 🔺 Low Potency . 🔺 Used with Penicillin - G to prolong the action .

42. 5) TETRACAINE ( AMETHOCAINE ) : --- ⬛ More Potent , more toxic and longer acting than Procaine . ⬛ Mainly Used For Topical Anaesthesia , e.g. , Eye , Nose and Throat . ⬛ It Is Preferred For Spinal Anaesthesia, if Prolonged Action Is Required .

43. 6 ) ROPIVACAINE : --- ⬛ Less Potent but Less Cardiotoxic Than Bupivacaine . ⬛ Suitable For Both Regional and Epidural Anaesthesia . ⬛ Continuous Epidural Ropivacaine is being used For Relief Of Post-operative and Labour Pain . ⬛ Also Employed For Nerve Blocks .

44. 7) ARTICAINE : --- 🔺 Penetration In Bone Is More Than Other LAs . 🔺 Rapid Onset ( 6 minutes ) . 🔺 Duration of Action is About 1 hour . 🔺 Suitable For Short Procedures . 🔺It Is Not Used For Nerve Block due to Risk Of Nerve Damage .

45. 8) DIBUCAINE ( CINCHOCAINE ) : --- 🔺 Most Potent , Most Toxicity and Longest Acting Local Anaesthetic ( 3 to 8 Hours ) . 🔺 It Is Used As a Surface Anaesthetic For Skin and Delicate Mucous Membranes ( Anal Canal ) . 🔺 Occasionally Used For Spinal Anaesthesia of Long Duration .

46. 9 ) OXETHAZAINE : --- ⬛ Produces Local Action On Gastric Mucosa with Low pH . ⬛ Useful For Producing Anaesthesia Of Gastric Mucosa and used Usually with Antacids In Gastric Oesophagitis , Heart Burn During Pregnancy .

47. 10 ) BENZOCAINE : --- ⬛ Poorly Soluble . ⬛ Remain At Site Of Application For Long Duration . ⬛ Not Toxic owing to Extremely Slow and Poor Absorption From Skin and Mucous Membranes . ⬛ Used For Application To Wounds , Ulcers , Used As Lozenges , For Stomatitis , Sore Throat and As Suppository For Anorectal Application .

48. 11 ) BENOXINATE : --- 🔺It Is Good Surface Anaesthetic for the eye . 🔺 Rapid Onset and Negligible Irritancy . 🔺 A 0.4 % Solution Rapidly produces Corneal Anaesthesia Sufficient For Tonometry without causing Mydriasis or Corneal Damage .

49. 12) COCAINE : ---- ⬛ It is a Natural Alkaloid from leaves of Erythroxylon coca . ⬛ Cocaine is a good Surface Anaesthetic and is rapidly absorbed from Buccal Mucous Membrane . ⬛ Cocaine should never be Injected . Cocaine produces prominent CNS Stimulation with Marked Effect on Mood And Behaviour . ⬛ It Induces a Sense Of Wellbeing, Delays Fatigue and Increases Power Of Endurance . ⬛ It was First Used For Ocular Anaesthesia in 1884 . ⬛ Cocaine causes Tachycardia , Rise in B.P. , Nausea and Vomiting , Pyrexia , Vasoconstriction . ⬛ The only Indication For Cocaine is in Ocular Anaesthesia . ⬛ However , it Causes Constriction Of Conjunctival Vessels, Clouding And Rarely Sloughing Of Cornea .

50. USES AND TECHNIQUES OF LOCAL ANAESTHESIA .

51. 1) SURFACE / TOPICAL ANAESTHESIA : ---- 🔺 The Drug is applied locally on intact skin , abraded skin and Mucous Membrane in the form of Cream , Ointments , Sprays etc . 🔺 Anaesthesia is only Superficial . 🔺 Doesn't Affect the Submucosal Structures . 🔺 Systemic Toxicity May occur due to rapid absorption into Systemic circulation . 2) INFILTRATION ANAESTHESIA : ---- 🔺 Injection Of LA directly into tissues . 🔺 Used For Short Procedures,e.g, excisions . 🔺 It blocks Sensory nerve endings while motor function is not affected . 🔺 Onset Of Action is almost immediate and duration is shorter than that after nerve block . 🔺More chances of Systemic Toxicity .

52. 3) CONDUCTION BLOCK : --- (A) FIELD BLOCK : -- ⬛ The LA is injected into subcutaneous tissue . ⬛ All the nerves in that area / Field are blocked . ⬛ Reduced Amount - Increased Anaesthetised Area - Prolonged Duration . ⬛ Such Technique is used for stitching on Scalp , Surgery on Forearms , Legs , Appendicectomy etc .

53. b ) Nerve Block : -- ⬛ Drug Is Injected Around Individual Nerves or Nerve Plexus . ⬛ Anaesthesia produced is more than Field Block and Infiltration Anaesthesia . ⬛ Muscles Supplied by Injected Nerve / Plexus are Paralyzed . ⬛ The Commonly Used Nerve Blocks are Lingual , Trigeminal , Facial , Intercostal , Brachial Plexus , Phrenic , Sciatic , Femoral etc . ⬛ Used For Tooth Extraction , Operations On Eyes , Limbs , Abdominal Wall , Fracture Setting , Trauma to Ribs , Neuralgias etc .

54. 4 ) Spinal Anaesthesia : --- 🔺The LA is Injected in the Subarachnoid Space between L2 - L3 or L3 - L4 . 🔺 Lower Abdomen and Hind Limbs are Anaesthetised and Paralysed. 🔺 The Factors important for Spinal Anaesthesia are Amount Of Drug , Volume of Drug , Speed of Injection and Position of Patient. 🔺It is Suitable for operations on the Lower limbs , Pelvis , Lower Abdomen , Prostate , Fracture Setting , Obstetric Procedures , Caesarean Section etc . 🔺 Addition of Adrenaline increases the duration and intensity of Spinal Anaesthesia by about 1/ 3rd .

55. ⬛ COMPLICATIONS OF SPINAL ANAESTHESIA : --- 🔺 Hypotension . 🔺 Headache . 🔺 Infection. 🔺 Hematoma . 🔺 Respiratory Paralysis . 🔺 Cauda Equina Syndrome . 🔺 Nausea and Vomiting . 🔺 Septic Meningitis .

56. CONTRAINDICATIONS OF SPINAL ANAESTHESIA : -- 🔺 Vertebral Abnormalities ( Scoliosis , Kyphosis , Lordosis ) . 🔺 Sepsis At Injection Site . 🔺 Hypotension . 🔺 Hypovolemia . 🔺 Uncooperative and Mentally - Ill patients . 🔺 Infants and Children .

57. 5 ) EPIDURAL ANAESTHESIA : --- ⬛ LA is administered into Epidural Space through which nerve roots travel . ⬛ It Can Be Administered through a needle or Epidural Catheter .

58. 🔺 Epidural Anaesthesia can be divided into 3 categories depending on the Site of Infection : - (A) THORACIC : -- 🔺 Injection is made in the midthoracic region . 🔺 Analgesia involving the middle and lower thoracic Dermatomes is produced . 🔺 Used Generally for Pain Relief following thoracic / Abdominal Surgery . (B) LUMBAR : -- 🔺 Produces Anaesthesia of Lower Abdomen , Pelvis and Hind Limbs . ( C ) CAUDAL : -- 🔺 Injection is given in the Sacral Canal Through the Sacral Hiatus . 🔺 Produces Anaesthesia Of Pelvic and Perineal Region . 🔺 Used mostly for Vaginal Delivery , Anorectal and Genitourinary Operations .

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