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General Anesthesia
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- 2. QUESTIONS ASKED PREVIOUSLY •100 marks : Hospital dentistry
- 3. DEFINITION A medically induced coma,witha loss of protective reflexes , resulting from the administration of one or more general anesthetic agents.
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- 5. GENERAL ANAESTHESIA Unconsciousness Analgesia Amnesia Skeletal Musclerelaxation Loss of motor reflexes
- 6. ADVANTAGES Patient cooperation not essential for success. Patientdoes not respond to pain Amnesia present Is the only successful technique in some patients. Rapid onset Titration possible
- 7. DISADVANTAGES Patient is unconscious Protectivereflexes &Vital signs depressed Advanced training required Anesthesia team required Special equipment, recovery room required More post anesthetic complications
- 8. INDICATIONS Certain physical, mentalor medically compromised condition. Patients that do not respond to local anesthetics or are allergic to it. Trauma patients Fearful , uncooperative anxious patient whose behaviour is not expected to improve.
- 9. CONTRAINDICATIONS Lack of adequatetraining by doctor,personnel Lack of adequate equipment , facility ASA IV And certain ASA III medically compromised patients
- 10. OTHER PATIENTS MAYNOT BE CANDIDATES(RELATIVE) Significantly decreased cardiac/pulmonary reserve
- 11. REASONS FOR GA Medically compromisedor Handicap 39.14% Uncooperative Or Lacking cooperative behaviour 23.48% Others 37.4% Tharian and Tandon(1995)
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- 13. MALLAMPATTI TEST Patient upright Maximaljaw opening Tongue protrusion without phonation
- 14. PREMEDICATION Systemic background • SABE–Antibiotic prophylaxis • Abscess –Antibiotic therapy Normal child objectives • Block unwanted reflexes • Prevent excessive secretions • Allay anxiety • Facilitate induction of anesthesia .
- 15. PREANESTHETIC MEDICATION • Itis 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 acidity – Proton Pump Inhibitor • To prevent bradycardia and secretion – Atropine
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- 17. EQUIPMENT S=Scope T=Tube A=Airway T=Tape to fixtube I=Introducer stilet C= Connecto mask apparatus S=Suction
- 18. CIRCUITS: •No rebreathing •No reservoir Open •Reservoir •Norebreathing Semi-open •Reservoir •Partial rebreathing Semi-closed •Reservoir •Complete rebreathing Closed
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- 26. INDUCTION • Patient progressesfrom analgesia without amnesia to analgesia with amnesia. • i.v thiopental, produces unconsciousness within 25 seconds after injection. • Inhalation induction: For children without iv access, non pungent agents, such as halothane or sevoflurane, are used to induce GA. • Agents include propofol,ketamine
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- 30. EYE MANAGEMENT • Lagopthalmos(incompl eteeye closure) • Corneal drying • Bells phenomenon lost
- 31. MAINTENANCE • Volatile anestheticsadministered because these agents offer good minute-to-minute control over the depth of anesthesia. • Opioids such as fentanyl are often used for pain along with inhalation agents, because the latter are not good analgesics. • Usually: N2O + volatile agent (halothane, isoflurane) • Less often : N2O + iv Opioid analgesic (fentanyl, morphine, pethidine + N.M blocking agents
- 32. TARGET CONTROLLED INFUSION(TCI) • Glasgow,Scotland •1990s • Advantages
- 33. RECOVERY • The timefrom discontinuation of administration of the anesthesia until consciousness and protective physiologic reflexes are regained. • It depends on how fast the anesthetic drug diffuses from the brain. • May be accompanied by acute mental confusion, aphasia, shivering
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- 35. TYPES OF ANESTHETICS •For maintainen ce For induction and short procedures
- 36. INHALATIONAL ANESTHETICS Advantage ofcontrolling the depth of anesthesia Metabolism is very minimal Excreted on exhalation Nonhalogenated Nitrous oxide Halogenated Halothane Enflurane Desflurane Sevoflurane Isoflurane Methoxyflurane
- 37. HALOTHANE • Potent anesthetic •Poor analgesic, poor muscle relaxant • Induction is pleasant • It sensitizes the heart to catecholamines. • It dilates bronchus (preferred in asthmatics) • A/E : Halothane hepatitis and malignant hyperthermia
- 38. NITROUS OXIDE • Safestinhalational anesthetic • Noninflammable, nonirritating • Low potency anesthetic, poor muscle relaxant but a good analgesic. • No toxic effect on the heart, liver and kidney • A/E: Diffusional hypoxia, megaloblastic anemia
- 39. PARENTERAL ADMINISTRATION • Usedfor induction of anesthesia. • Rapid onset of action • Recovery is mainly by redistribution. • Also reduce the amount of inhalation anesthetic for maintenance. • Drugs are Thiopental, Midazolam, Propofol, Etomidate & Ketamine
- 40. THIOPENTAL(PENTOTHAL) • It isan ultra short acting barbiturate • Consciousness regained within 10-20 mins by redistribution to skeletal muscle. • Doesn’t increase ICT. • It can be used for rapid control of seizures. • A/E – Laryngospasm, Pain, Necrosis, Gangrene on extravasation & inadvertant arterial injection
- 41. PROPOFOL • Most commonlyused IV anesthetic • Unconsciousness in 45 seconds and lasts 15 minutes • Anti-emetic • Non-irritant to airways • Suited for day care surgery (residual impairment is less marked) • A/E- Pain during injection, Fall in BP
- 42. KETAMINE • Dissociative anesthesia •Produce - profound analgesia, immobility, amnesia with light sleep. • Heart rate and BP are elevated due to sympathetic stimulation • Respiration is not depressed and reflexes are not abolished. • Emergence delirium, hallucinations and involuntary movements occurs during recovery • Dangerous for hypertensive and IHD patients
- 43. TYPES OF GENERALANESTHESIA Outpatient iv barbiturates or propofol (less than 30 mins) Conventional OT anesthesia(30 mins-4 hours) Inpatient
- 44. OUTPATIENT GENERAL ANESTHESIA Also calledultralight general anesthesia Less than 30 minute procedure iv barbiturates and propofol used Complications hypoxia, hypercarbia seen unless oxygen supplemented. Local anesthesia important, helps block painful stimuli thus lesser barbiturate dose required also in postoperative pain control 1:4,000000 deaths (Lytle,Driscoll,Herbert,Batting)
- 45. CONVENTIONAL OPERATING ROOM TYPEGENERAL ANESTHESIA Utilised for procedures ranging from 30minutes - 4 hours or less. Usually limited to ASA I,II and select III patients. Mortality rate 1:539000 as per Coplans and Curson
- 46. INPATIENT GENERAL ANESTHESIA Patient admitted1 day prior to procedure for work up Remains atleast 1 day postoperatively to recover or for physical status to stabilize Mortality rate 1:63000
- 47. TEAM COMPRISES OF Anesthetist Pedodontist Dentalsurgery assistant Anesthesia technicians
- 48. PRE PROCEDURE Observing &recording child’s behavior , history Informing parents and obtaining a verbal consent. Asking for anesthetists clearance regarding fitness . Parents instructed to report 1 day prior to surgery for admission.
- 49. ON THE DAYPRIOR TO SURGERY Child reports for admission. Preanesthetic check up (PAC). Preoperative orders.
- 50. NIL BY MOUTH •Lantham(1999): The goal of preoperative fasting is to decrease gastric acid volume and minimise the pneumonitis that may result in the event that a patient aspirates gastric contents. • NPO after midnight 6-8 hours preop (solids) and 2-3 hours perop (liquids).
- 51. ON DAY OFPROCEDURE Child is draped, surgical area prepared by assistant using betadine.
- 52. 4 handed dentistryfollowed. Treatment is carried out from oral prophylaxis, endodontics , restorative, crown placement, PFS, Impressions for space maintainers, extractions. Operating dentist to inform anesthetist 30 mins prior to completion. Adequate control of haemorrhage done . Throat pack removed Patient extubated, shifted to recovery room.
- 53. ON DAY 3 •Check up done • Patient discharged with a discharge card. • Follow up scheduled.
- 54. SPECIAL CONDITIONS • Diabetes& NBM consideration. • ADHD difficult preoperative period, medications like methyl phenidate and clonidine may have interaction. • Down’s syndrome: Macroglossia and airway management. • Congestive heart disease: Minimise oxygen consumption and demand on cardiovascular system during induction.
- 55. OTHER CONDITIONS • Intracranialvascular malformations : Prevent dangerous hypertension prior to and during anesthesia. • Cerebral palsy: Stoetling and Dundorf (1993) Patients have propensity for gastroesophageal reflux & poor laryngeal & pharyngeal reflexes. Hypothermia is also a problem. • Dentinogenesis imperfecta: Loose teeth a concern in intubation, hyperthermia may also be present.
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- 57. EMERGENCY DRUGS • Vasopressors •Corticosteroids • Bronchodilators • Succinylcholine • iv fluids • Drugs for arterial dilation
- 58. REFERENCES • 1.Marwah N.Textbook of pediatric dentistry.3rd edn. • 2.Tandon S. Textbook of Pedodontics. 2nd edn. Paras medical publishers 2009 • 3.Malamed S. Sedation :A guide to patient management.4th edn.Mosby 58