C lecture general anesthesia
- 1. GENERAL ANAESTH ESIA Dr Nisar Ahmed Arain Assistant professor Anesthesiology/Critical Care/ER
- 2. CONTENTS -Introduction -History -Levels of sedation -Goals of sedation -Sequence of depression of CNS -Mechanism of action of GA -Pre- anesthetic evaluation -Pre-operative preparation
- 3. INTRODUCTION Many advancements in pharmacology has been a great help to the perfect conduction of anesthesia. When the surgery is completed patient is- -Comfortable -cooperative and -hemodynamically stable This also provides the patient with following benefits. -Sedation -anxiolysis and -analgesia The goal has been to establish an environment in which equipment and techniques are safe and surgeon is less worried about the stability of the patient pre and post operatively.
- 4. They did it for a better tomorrow HISTORY (Just to see)
- 5. -Anesthetic Equipments -Pharmacology of anaesthetics -Muscle relaxants -Stages of anaesthesia -Post operative care -Complications of GA. -Conclusion CONTENT’s of the Lecture
- 7. Minimal Sedation LEVELS OF SEDATION At minimal level of sedation, patient is ------Breathing himself and maintains his airway without any assistance. ------He responds normally to tactile stimulation and to ------Responds to verbal command His cardiovascular remain normal and are unaffected (Anxiolysis )
- 8. Moderate Sedation LEVELS OF SEDATION -A drug induced sedation of a patient reflects that he would respond to -Purposeful verbal commands either alone or accompanied by -Light tactile stimulation, this will work well and no intervention would be required to maintain a patent airway. - His cardiovascular function will comfortably be maintained. conscious sedation
- 9. -A drug-induced depression of a conscious patient during which he cannot be easily aroused, but respond to purposefully repeated painful stimulations. -The patient’s ability to independently maintain ventilator function may be impaired, and the patient may require assistance in maintaining airway control cardiovascular function will be maintained during deep sedation LEVELS OF SEDATION Deep Sedation
- 10. General Anesthesia LEVELS OF SEDATION -A drug-induced loss of consciousness during which patient is not arousable even by painful stimulation. The ability to maintain ventilatory function is impaired. Patients often require assistance in maintaining a patent airway, and a positive pressure ventilation may be required because of a depressed spontaneous ventilation or drug-induced depression of neuromuscular function. Cardiovascular function may be impaired.
- 11. Minimal Sedation (anxiolysis) Moderate Sedation/ Analgesia Deep Sedation/ Analgesia General Anesthesia Responsiveness Normal response to speech Purposeful response to speech or touch Purposeful response to repeated or painful stimulation No response, even to pain Airway Unaffected Remains open May need help to maintain airway Often needs help to maintain airway Ventilation Unaffected Adequate May not be adequate Often require ventilatory support Cardiovascular Function Unaffected Usually maintained Usually maintained May be impaired LEVELS OF SEDATION
- 12. SEQUENCE OF DEPRESSION IN CENTRAL NERVOUS SYSTEM CEREBRAL CORTEX CEREBELLUM SPINAL CORD MEDULLARY CENTERS
- 13. The basic process of taking - A detailed history and -Performing a systematic clinical examination remains the foundation on which preoperative assessment relies, backed up ordering appropriate investigations is additional help where ever required. PRE-ANAESTHETIC EVALUATION
- 14. 1-Medical history questionnaire 2-Physical examination and 3-Lab investigations PRE-ANAESTHETIC EVALUATION and REQUIREMENT
- 15. Medical history Questionnaire 1- Current problems 2- Other known problems 3- Treatment/medicines for the problems: dose duration and effectiveness 4-Current drugs use: reason, dose, duration effectiveness and side effect 5- History of drug allergies 6- History ofuse of tobacco—smoking or smokeless tobacco or alcohol consumption, frequency quantity and duration 7- Prior anesthetic exposure: type and any adverse effects 8- General health and review of organ systems
- 16. Physical Examination 1. Vital Signs 2. Airway 3. Heart 4. Lungs 5. Extremities 6. Neurologic examination
- 17. Airway Evaluation 1-Mallampati Classification 2-Thyromental Distance 3-Sternomental Distance 4-Maximum vertical opening (MVO)
- 23. Maximum vertical opening (MVO) of the mouth
- 24. 2----Potentially difficult airway. Limited neck extension. Limited mouth opening. Receding mandible. Mallampati class III or IV Short thyromental distance Airway Evaluation Categories of difficult airway
- 26. Patient’s counselling or psychologicalpreparation ----Premedication ----Preoperative instructions - Fasting instructions - current or pre-existing drug therapy. PRE OPERATIVE PREPARATION INCLUDE S
- 27. For relief of apprehension or anxiety For sedation For analgesia For amnesia of preoperative events For prevention of nausea and vomiting For vagolytic actions For facilitation of anaesthetic induction For prophylaxis against allergies. PRE OPERATIVE PREPARATION PREMEDICATIONS
- 38. PHARMACOLOGY OF ANASTHETICS INTRAVENOUS 1-BARBITURATES -Thiopental 2- BENZODIAZEPINES -Diazepam -Midazolam 3-OPOIDS -Fentanyl 4-DISSOSIATIVE - Ketamine 5-MISCELLANEOUS -Etomidate -Propofol INHALATIONAL GASES -Nitrous oxide VOLATILE LIQUIDS -Ether -Halothane - Isoflurane - Desflurane -Sevoflurane
- 39. It is Non flammable,non explosive. -Pleasant smell, non irritating. -Induction with 2-4 % -Maintenance with 1-2%. -BP falls in proportion to the inhaled vapour concentration -Depression of respiratory center in high concentrations. -Initially respiratory rate increases and depth of respiration decreases. -Malignant Hyperthermia can occur in susceptible individuals INHALA TIONAL ANESTHETICS HALOTHANE(Fluothan e)
- 40. -Introduced into practice in 1984 -Cheap and widely used -Non carcinogenic, nonflammable -Less soluble than halothane. -It can cause coronary artery vasodilatation -Depresses respiratory drive patient -Myocardial depression is less than halothane INHALA TIONAL ANESTHETICS ISOFLURANE(Fora ne)
- 41. --it is non flameable derivative of Isoflorane --It has a lowest oil-gas coefficient (18.7) -Very fast action (on and off) makes it a great choice for outpatient anesthesia. --Induction by using 6 to 10 % desflurane in air or in oxygen, or by using 5 to 8 % desflurane in 65 % nitrous oxide --Maintenance with 5 to 7 % desflurane INHALA TIONAL ANESTHETICS DESFLURA NE -- Volatile anesthetic
- 42. --Nonflammable --Its properties are intermediate between isoflurane and desflurane. --Induction and emergence from anesthesia are fast. --Absence of pungency makes it pleasant and administrable through face mask. --It does not sensitize the heart to arrhythmias or cause coronary artery steal syndrome. INHALA TIONAL ANESTHETICS SEVOFLURA NE
- 43. -Used as an induction agent. -It’s a poor analgesic and muscle relaxant. -It suppresses excitatory neurotransmission and enhance inhibitory neurotransmission -Its pH>10 and it is water soluble. -It is unstable when kept longer and preferably -Should be freshly prepared. -It has very rapid onset of action "30-60"sec. -It is contraindicated in porphyria and status asthematicus cases. INTRAVENOUS ANESTHETICS THIOPENT AL
- 44. Produce sedation and amnesia -Potentiate GABA inhibitory receptors. -Onset of action is 30-60 secs. -Duration of action 50-80mins. -Dose- Premedication 2-to-10mg -Induction- 0.1-0.3mg/kg IV. INTRAVENOUS ANESTHETICS BENZODIAZIPIN ES
- 45. Short acting Opioid.(30-50mins) -Very potent anlgesic. -Minimal cardiac effects -No myocardial depression -Marked respiratory depression -Tone of chest muscles may increase after rapid fentanyl injection muscle relaxant is required. INTRAVENOUS ANESTHETICS FENTAN YL
- 46. KETAMINE -Dissociative amnesia -Profound amnesia/analgesia consciousness and despite maintaining protective reflexes. -Dose--- Analgesia(0.1-0.5mg/kg IV) -Mixed with propofol infusion 1mg ketamine per 10mg propofol INTRAVENOUS ANESTHETICS
- 47. -Excitation of inhibitory neurotransmitters(GABA) -Oily liquid employed as a 1% emulsion for IV induction -Available in 20 ml vials -Very rapid onset and of short duration of action -Induction dose: 1-2.5mg/kg -Sedation dose: 0.2mg/kg -Decreases systemic vascular resistance. INTRAVENOUS ANESTHETICS PROPOF OL
- 48. -Direct CNS depressant Lipid soluble. -Pain on injection. -Dose- 0.2-0.3mg/kg -Minimal cardiac and respiratory effects. -Anti epileptic -Post operative nausea and vomiting are common side effects. INTRAVENOUS ANESTHETICS ETOMIDATE
- 49. MUSCLE RELAXANTS DEPOLARIZIN G NONDEPOLARIZING -Succinylcholine -Decamethonium 1-Long acting -Pancuronium -tubocurarine 2-Intermediate acting -vecuronium 3-Short acting -mivacurium
- 50. INDUCTION -Initially nitrous oxide 70% in oxygen is used -Anesthesia is deepened by the gradual increments of volatile anesthetic agent i.e. Sevoflurane -Maintenance concentrations of isoflurane (1-2 %) or sevoflurane(2-3%). -If spontaneous ventilation is to be maintained through out the procedure, the mask is applied firmly as consciousness is lost and airway is supported manually -Pre- oxygenation may be started with 100% oxygen using face mask. At the rate of 8L- 10L/min
- 51. MAINTAINANCE -Inhalational agents -Propofol infusion -Oxygen + N2O -Relaxants –Vecuronium, Atracurium -Pancuronium. -Intubation -Analgesia –opioids -Sedation –midazolam etc.
- 52. REVERSAL from anesthesia -Check equipment -Check drugs -Turn off agents -Give 100% oxygen -Suction -Reverse relaxant -Usually a combination of neostigmine glycopyrrolate in the ratio of 5:1, or neostigmine and atropine in the ratio of 5:2 is given. -Wait for adequate breathing -Wait until patient wakes up -Extubate and give 100% oxygen by mask
- 53. POST OPERATIVE CARE -Patient is shifted to recovery for Post- op care -N.P.O in normal cases for 4-6 hrs. -Vital sign monitoring should be done. -Iv fluids and blood products if required may be given postoperatively. -Analgesia- iv/im Ns aids or opioids if required -may be supplemented -Antiemetic's may be given if required -"Antibiotics“ if required -Continue medications for medical disorders If patient is taking already.
- 54. ----ACTIVITY 2=Move all extremities voluntarily or on command 1= Move two extremities 0= Unable to move extremities -----RESPIRATION 2 = Breathes deeply and coughs freely, shallow /limited breathing 1 = Requires assistance 0 = Apnic -----CIRCULATION 2 = BP+20mm Hg of preanesthetic level 1 = BP+20-50 mm Hg of preanesthetic level 0 = BP+50 mm Hg of preanesthetic level POST ANESTHESIA RECOVERY SCORE
- 55. POST ANESTHESIA RECOVERY SCORE --CONCIOUSNESS --2= Fully awake --1= Arousable on calling --0= Not responding --OXYGEN SATURATION --2 = > 92% on room air or more --1 = supplemental oxygen required --To maintain SpO2 >90% --0 = SpO2< 92% with oxygen supplementation
- 56. Pre operative Period During maintenance of GA - Related to anesthetic drug used - Anesthetic technique - Equipment failure - Medical condition - Surgical pathology Post operative period -Related to anesthetic drug used - Anesthetic technique - Intubation technique - Pain - Infection - Medical condition COMPLICATIONS OF GENERAL ANAESTHESIA
- 57. ----COUGHING -Occurs during light plane of anesthesia -Causes- Irritation of respiratory passages due to artificial airways,blood, regurgitated gastric contents. ----Management - Deepening of anesthesia -Giving muscle relaxant -Keep working suction machine ready COMPLICATIONS OF GENERALANAESTHESIA
- 58. 1-Reflex stimulation under light anesthesia 2-Tracheal / surgical stimulation. 3-Endotracheal tubes- kinking overdistended inserted too far 4-Anaphylactic reaction 5-Aspiration 6-Pnemothorax. COMPLICATIONS OF GENERALANAESTHESIA WHEEZIN G Cause s
- 59. COMPLICATIONS OF GENERALANAESTHESIA MALIGNANT HYPERTHERMIA -Hypermetabolic syndrome occurs in genetically susceptible patients when exposed to anesthetic triggering agents. -Triggering agents-Halothane, Isoflurane, Desflurane,Sevoflurane,Succinylcholine. -The syndrome is thought to be due to reduction of reuptake of calcium ions by sarcoplasmic reticulum leading to sustained muscle contraction. This results in signs of hypermetabolism like tachycardia,
- 60. -Discontinue all anesthetic agents. -Administer Dantrolene 2.5mg/kg IV. and repeat to a total of 10 mg/kg. -Hyperkalemia to be corrected by Insulin and glucose --Cold sponging -Monitor urinary output COMPLICATIONS OF GENERALANAESTHESIA MALIGNANT HYPERTHERMIA Treatmen t
- 61. -It is caused by irritative stimulus of the upper airway during light plane of anesthesia. -The common noxious stimuli to elicit reflex are throat secretions, vomitus and inhalation of pungent volatile anesthetic agents. -The reflex closure of vocal cords causing Partial or total Glottic Obstruction --Hypoxia, Hypercarbia, and Acidosis are the worst complications COMPLICATIONS OF GENERAL ANAESTHESIA LARYNGOSPAS M
- 62. -Female gender -Obesity -Pregnancy -Abdominal distention -Premedication's opiods, NSAID’s -Anesthetics- ether, nitrous oxide. -Presence of pain, hypoxia, hypotension, -hypoglycemia in post op period COMPLICATIONS OF GENERALANAESTHESIA POST OPERATIVE NAUSEA AND VOMITING Cause s
- 63. -Of Underlying cause -Lateral position -Anti emetics, Promethazine, Metoclopramide -12.5-25mg IM/IV and Antihistamines -Ranitidine(Antacids) 50 mg IV -Sodium citrate 30-60 ml orally COMPLICATIONS OF GENERAL ANAESTHESIA POST OPERATIVE NAUSEA AND VOMITING Treatment
- 64. CONCLUSION IMP--Pre-operative anesthetic assessment, decreases complications rates and mortality. The pre- operative visit may relieve anxiety and answers questions about both the anesthetic and surgical processes Effective communication and a team approach are vital in the pre-operative period.
- 65. THANK YOU