Conduction of general anesthesia
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General anesthesia involves inducing a state of unconsciousness during surgery through the use of drugs. The goals are amnesia, hypnosis, analgesia, and immobility. Preparation includes evaluations of the patient's airway, medical conditions, medications, and labs. Monitoring is established and intravenous access and fluids are given. Induction involves preoxygenation before administering intravenous or inhalational drugs to induce unconsciousness and allow intubation. Maintenance of anesthesia involves increasing the depth of unconsciousness through volatile gases, IV drugs, or combinations while monitoring vital signs and homeostasis. Emergence and extubation involve ensuring the patient meets criteria like being awake, responsive, with full strength before discharge from recovery. Transport is the
Conduction of general anesthesia
- 1. Dr. Wesam Farid Mousa Ass. Prof. Consultant of Anesthesia and ICU Dammam University
- 2. Overview • What is general anesthesia? • Preoperative preparation • Induction: Deparutre • Maintenance: Flying • Emergence: Landing • Transport
- 3. What is general anesthesia • Primary goals Amnesia Hypnosis Analgesia Immobolity
- 4. • Secondary goals Medical condition Surgical procedures Surgical settings
- 5. Examples for secondary goals • Patients with CAD: Oxygen supply-demand balance • Neurosugery: ICP control, brain relaxation and CPP maintenance • Obstetrics: anesthetics and fetal depression, difficult airway • Day surgery vs Inpatient: which kind of analgesic you should choose to minimize postoperative pain and decrease PONV?
- 6. Preoperative preparation • Preoperative evaluations for: Airway examination Pt’s medical condition Medications Laboratory data Consultant notes Last oral intake
- 7. • Preoperative hydration and correction of intravascular volume as needed: Intravenous access Fluid or blood transfusion as needed • Prescribe preoperative medications as needed: e.g. Anxiety: Benzodiazepine: Midazolam Pain: Opioid or NSAI Increased gastric acidity: cimetidine, omeprazole
- 8. Monitoring Standard monitoring for GA Qualified anesthetist presence ECG NBP Pulse oximetry Capnography
- 10. Induction Let the pt go off to sleep Preoxygenation 8L~10L/min IV or Inhalational induction Airway management
- 11. Induction techniques • Intravenous: the most common method • Inhalation: for special pt (as pt with difficult airway, pediatric pt) • Intramuscular :rarely used, only used in uncooperative pts and young children
- 12. Maintenance Increasing depth of anesthesia stageⅠ Amnesia Loss of consciousness Stage Ⅱ Delirium Injurious responses to noxious stimuli Stage Ⅲ Surgical anesthesia Painful stimulation does not elicit somatic reflexes or deleterious autonomic responses Stage Ⅳ Overdosage Circulatory failure
- 13. Maintenance Anethesia • Volatile • Nitrous oxide-opioid relaxant technique • IV anesthesia • Combinations
- 14. • Maintain homeotasis Vital signs Acid-base balance Temperature Coagulation Volume status
- 15. Maintain Ventilation 1. Spontaneous or assisted ventilation 2. Controlled ventilation Tidal volume: 10-12ml/kg Respiratory rate: 8-10 breaths/min
- 16. Maintain Intravascular Volume 1. fluids Crystalloid sollutions: Colloid sollutions: 2. Blood & blood products
- 18. Extubation • Awake extubation Indications Risk of aspiration Difficult airways Tracheal or maxillofacial surgery
- 19. • Awake extubation Criteria Awake Hemodynamically stable Full muscle strength Able to follow simple verbal commands Breathing spontaneously with adequate ventilation
- 20. • Deep extubation Indications Severely asthmatic patients Middle-ear surgery Open-eye surgery Inguinal herniorrhaphy
- 21. • Deep extubation Criteria Sufficient anaesthetic depth to avoid response to airway stimulation Spontaneous breathing with adequate ventilation
- 22. Goals to be met before discharge from recovery: awake Responsive Full muscle strength Adequate pain control
- 23. Transport It is the responsibility of the Anaesthetist
- 24. Questions