Downloaded 261 times
Uploaded byAbril Santos
General Anesthetics
General anesthetics are drugs that induce reversible loss of consciousness and sensations during surgery. They work by depressing the central nervous system in stages, starting with cortical centers and ending with the medulla. There are two main types - inhalational gases administered through masks or intravenous drugs given through injections. A balanced anesthesia approach uses multiple drugs to induce unconsciousness, amnesia, analgesia, and muscle relaxation. Precise drug combinations and dosages are tailored for each patient and procedure type. The goal is to smoothly induce and rapidly recover from anesthesia with minimized risks and side effects.
More Related Content
Similar to General Anesthetics
More from Abril Santos
General Anesthetics
- 1. General Anesthetics ByAbril Santos Universidad Popular Autónoma del Estado de Puebla International Intership Program
- 2. introduction General anesthetics(GAs) are drugs which: • Reversible loss of all sensations and consciousness. • Loss of memory and awareness with insensitivity to painful stimuli, during a surgical procedure.
- 3. General Anesthesia Needfor unconsciousness ‘Amnesia-hypnosis’ Need for analgesia ‘Loss of sensory and autonomic reflexes’ Need for muscle relaxation
- 4. • 1846 –Oliver Wendell Sr. “Anesthesia” meaning: Insensibility during surgery produced by inhalation of ether. • William T. G. Morton (dentist) was the first to publicly demonstrate the use of ether during surgery. • 1860 – Albert Niemann Cocaineas.
- 5. Types of Anesthesia • General anesthesia • Local and regional anesthesia • Local Infiltration • Topical block • Surface anesthesia • Nerve Block • Spinal or subarachnoid anesthesia • Peridural anesthesia
- 6. Balanced Anesthesia Describesthe multidrug approach to managing the patient needs. Beneficial effects Adverse Qualities
- 7. Intraoperative, an idealanaesthetic drug: 1. Would induce anesthesia smoothly, rapidly 2. Permit rapid recovery as soon as administration ceased. *So a ‘balanced anesthesia’ is achieved by a combination of I.V and inhaled anesthesia and Pre-anaesthetic medications
- 8. General Anesthesia Inhalational Gas Nitrous oxide Zenon Volatile liquids Ether Halothane Enflurane Isoflurane Desflurane Sevoflurane Methoxyflurane Intravenous Slower acting Dissociative anesthesia Ketamine Opiod analgesia Fentanyl Benzodiazepines Diazepam Lorazepam Midazolam Inducing agents Thiopentone sod. Methohexitone sod. Propofol Etomidate Droperidol
- 9. Stages of anesthesia Guedel (1920) described four stages with ether anesthesia, dividing the III stage into 4 planes. The order of depression in the CNS is: 1. Cortical centers 2. Basal ganglia 3. Spinal cord 4. Medulla
- 10. Surgical Period andGA protocol Use pre-anesthetic medication ↓ Induce by I.V thiopental or suitable alternative ↓ Use muscle relaxant ↓ Intubate ↓ Use, usually a mixture of N2O and a halogenated hydrocarbon→maintain and monitor. ↓ Withdraw the drugs → recover
- 11. Pre-operative Period •Meet the patient personally. • Choose the right technique by the preferences, case and patient. Use the ASA and GOLDMAN scale for anaesthetic risk.
- 12. ASA score Useto measure risk for anaesthetic procedures.
- 13.
- 14. Pre-anaesthetic Medications Serveto • Calm the patient, relieve pain • Protect against undesirable effects of the subsequently administered anesthetics or the surgical procedure. • Facilitate smooth induction of anesthesia • Lowered the dose of anaesthetic required
- 15. PreanestheticMedicine: • Benzodiazepines;midazolam or diazepam: Anxiolysis & Amnesia. • Barbiturates; pentobarbital: sedation • Diphenhydramine: prevention of allergic reactions: antihistamines • H2 receptor blocker- ranitidine: reduce gastric acidity.
- 16. Intraoperative Period •Induction: Onset of anesthetic to the surgical anesthesia (I.V thiopental or inhalated halothane or sevoflurane) • Maintenance: Volatile anesthetics = good minute-to-minute control over the depth. (halothane, isoflurane or fentanyl, morphine, pethidine + N.M blocking agents) • Recovery: From discontinuation of anesthesia until • Consciousness • Protective physiologic reflexes Regained.
- 17. Post-operative Period •N.M blocking agents and Opioids worn off or reversed by antagonists. • Regained consciousness and protective reflex restored • Relief of pain: NSAIDs • Postoperative vomiting: metoclopramide, prochlorperazine
- 18. Properties of IntravenousAnesthetics. Drug Induction and recovery Main unwanted effects Notes Thiopental Fast onset (accumulation occurs, giving slow recovery) hangover Cardiovascular and respiratory depression Used as induction agent declining. ↓ CBF and O2 consumption Injection pain Etomidate Fast onset, fairly fast recovery Excitatory effects during induction adrenocortical suppression Less cvs and resp depression than with thiopental, injection site pain Propofol Fast onset, very fast recovery Cvs and resp depression Pain at injection site. Most common induction agent. Rapidly metabolized; possible to use as continuous infusion. Injection pain. Antiemetic Ketamine Slow onset, after-effects common during recovery Psychotomimetic effects following recovery, postop nausea, vomiting， salivation Produces good analgesia and amnesia. No injection site pain Midazolam Slower onset than other agents Minimal CV and resp effects. Little resp or cvs depression. No pain. Good amnesia.
- 19. Non-barbiturate induction drugseffects on BP and HR Drug Systemic BP Heart rate Propofol ↓ ↓ Etomidate No change or slight ↓ No change Ketamine ↑ ↑
- 21.
- 24. Order of sensory function block 1. Pain 2. Cold 3. Warmth 4. Touch 5. Deep pressure 6. Motor *Recovery in reverse order.
- 25. Vasoconstrictors decrease therate of vascular absorption which allows more anesthetic to reach the nerve membrane and improves the depth Vasoconstrictor of anesthesia.
- 26. In Conclusion: •Type of surgical procedure • Duration of surgical procedure • Type of anesthesia • PATIENT • Risk vs Benefit • ALWAYS monitor
- 27. References • AmericanSociety of Anesthesiologists (2011). Guidelines for patient care in anesthesiology. Available online: http://www.asahq.org/For- Members/Standards-Guidelines-and-Statements.aspx. • Dorian RS (2010). Anesthesia of the surgical patient. In FC Brunicardi et al., eds., Schwartz’s Principles of Surgery, 9th ed., pp. 1731–1752. New York: McGraw-Hill. • Brown DL (2010). Spinal, epidural and caudal anesthesia. In RD Miller et al., eds., Miller's Anesthesia, 7th ed., pp. 1611–1638. Philadelphia: Churchill Livingstone. • Handbook of Local Anesthesia 6th ed. Stanley F. Malamed, DDS iii Handbook of Local Anesthesia, 6th Edition
- 28.
Editor's Notes
- #5 used Cocaineas the first local anaesthetic which was isolated from coca leaves.
- #17 Induction: Period of time from the onset of administration of the anesthetic to the development of effective surgical anesthesia in the patient. Maintenance: Administration of volatile anesthetics, because these agents offer good minute-to-minute control over the depth of anesthesia. Recovery: The time from discontinuation of administration of the anesthesia until consciousness and protective physiologic reflexes are regained.
- #18 N.M blocking agents and Opioids induced respiratory depression have either worn off or have been adequately reversed by antagonists.
- #21 Interrupts pain impulses in a specific region of the body without a loss of patient consciousness.