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Lecture Title : General Anesthesia

Lecture Title : General Anesthesia. Lecturer name: Lecture Date:. Lecture Objectives.. Students at the end of the lecture will be able to:. Define general Anaesthesia

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Lecture Title : General Anesthesia

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  1. Lecture Title : General Anesthesia Lecturer name: Lecture Date:

  2. Lecture Objectives..Students at the end of the lecture will be able to: • Define general Anaesthesia • Learn about several agents used on induction of general anaesthesia including intravenous agents, inhalation agents, neuromuscular blocking agents and reversal agents. • Understand basic advantages and disadvantages of these agents. • Complications commonly encountered during general anaesthesia

  3. General anesthetics have been performed since 1846 when Morton demonstrated the first anesthetic (using ether) in Boston, USA. Local anesthetics arrived later, the first being scientifically described in1884.

  4. General anesthesia is described as a reversible state of unconsciousness with inability to respond to a standardized surgical stimulus. In modern anesthetic practice this involves the triad of: unconsciousness, analgesia, muscle relaxation.

  5. Anesthetic plan • A good anesthetic begins with a good plan. • There is no rigid format for planning anesthesia. • Each plan is adapted to each case. • The fundamental goal of anesthetic management is • to provide safety, • comfort and convenience, first for the patient and second for those caring for the patient.

  6. Anesthetic plan • After a good plan, a good preparation is required for a good anesthetic. •  Before every anesthetic, every anesthesiologist should go through a checklist of necessary items including, • anesthesia machine, • ventilator, • oxygen and nitrous supply check, • suction device, • monitors and anesthesia cart.

  7. Anesthetic plan • Before bringing the patient to the operating room, • the proper verification of patient's identity, • the planned procedure and • the site of the procedure should be carried out by the anesthesiologist. • All the preparations should be completed before the patient enters the room including the placement of a working peripheral intravenous line.

  8. Anesthetic plan • The primary goals of general anesthesia are • to maintain the health and safety of the patient while providing amnesia, hypnosis (lack of awareness), analgesia, and optimal surgical conditions (e.g., immobility). • Preoperative planning involves • the integration of pre-, • intra-, and • postoperative care. • Flexibility is an essential • multiple approaches to • induction, • maintenance, and • emergence should be considered.

  9. Anesthetic plan • Preoperative planning involves the integration of • pre-, • intra-, and • postoperative care. • Flexibility is an essential • Multiple approaches to • induction, • maintenance, and • emergence should be considered.

  10. Anesthetic plan • The plan should include the following: • A premedication. • Need standard ASA monitors. However, if the patient may experience large hemodynamic fluctuations, invasive monitoring should be considered (e.g., central venous pressure for volume monitoring, arterial line for potential hemodynamic instability). • A review of anesthetic options; general anesthesia, regional anesthesia, and combinations thereof should be reviewed and options appropriate for the patient listed in the final assessment. • Plan for postoperative pain control.

  11. NPO status • NPO, Nil Per Os, means nothing by mouth • Solid food: 8 hrs before induction • Liquid: 4 hrs before induction • Clear water: 2 hrs before induction • Pediatrics: stop breast milk feeding 4 hrs before induction

  12. Premedication • Guidelines for prophylaxis for pulmonary aspiration • Histamine (H2) antagonists • Cimetidine (Tagamet), ranitidine (Zantac), significantly reduce the volume and the acidity of gastric secretions. • Metoclopramide (Reglan) enhances gastric emptying • Midazolam (Versed) provides excellent amnesia and sedation. • Lorazepam (Ativan) may also be used but can cause more prolonged amnesia and postoperative sedation. It should not be given intramuscularly. • Opioids are not usually given as premedication unless the patient has significant pain

  13. THE MONITORS Standard ASAmonitoring :- • Oxygenation (oxygen analyzer, pulse oximetry) • Ventilation (capnography, minute ventilation), respiratory rate (under regional anesthesia) • Circulation (electrocardiogram [ECG], arterial blood pressure, perfusion assessment), • Temperature.

  14. General Anesthesia • Monitor • Preoxygenation • Induction ( including RSI & cricoid pressure) • Muscle relaxants • Mask ventilation • Intubation & ETT position comfirmation • Maintenance • Emergence

  15. Airway exam Mallampati classification Class I: uvula, faucial pillars, soft palate visible Class II: faucial pillars, soft pillars visible Class III: soft and hard palate visible Class IV: hard palate visible

  16. Sniffing position

  17. Mask and airway tools

  18. Mask ventilation and intubation

  19. Oral and nasal airway

  20. Intubation

  21. Intubation

  22. Laryngeal view

  23. Laryngeal view scoring system

  24. Difficult airway

  25. Fiberoptic scope intubation

  26. Trachea view Carina view

  27. Glidescope

  28. Fast track LMA

  29. LMA

  30. Induction agents • Opioids – fentanyl • Propofol, Thiopental and Etomidate • Muscle relaxants: Depolarizing Nondepolarizing

  31. Induction • IV induction • Inhalation induction

  32. General Anesthesia • Reversible loss of consciousness • Analgesia • Amnesia • Some degree of muscle relaxation

  33. Intraoperative management • Maintenance Inhalation agents: N2O, Sevo, Deso, Iso Total IV agents: Propofol Opioids: Fentanyl, Morphine Muscle relaxants Balance anesthesia

  34. Intraoperative management • Monitoring • Position – supine, lateral, prone, sitting, Litho • Fluid management - Crystalloid vs colloid - NPO fluid replacement: 1st 10kg weight- 4ml/kg/hr, 2nd 10kg weight-2ml/kg/hr and 1ml/kg/hr thereafter - Intraoperative fluid replacement: minor procedures 1-3ml/kg/hr, major procedures 4- 6ml/kg/hr, major abdominal procedures 7-10/kg/ml

  35. Intraoperative managementEmergence • Turn off the agent (inhalation or IV agents) • Reverse the muscle relaxants • Return to spontaneous ventilation with adequate ventilation and oxygenation • Suction upper airway • Wait for pts to wake up and follow command • Hemodynamically stable

  36. Postoperative management • Post-anesthesia care unit (PACU) - Oxygen supplement - Pain control - Nausea and vomiting - Hypertension and hypotension - Agitation • Surgical intensive care unit (SICU) - Mechanical ventilation - Hemodynamic monitoring

  37. General AnesthesiaComplications and Management • Respiratory complication - Aspiration – airway obstruction and pneumonia - Bronchospasm - Atelectasis - Hypoventilation • Cardiovascular complication - Hypertension and hypotension - Arrhythmia - Myocardial ischemia and infarction - Cardiac arrest

  38. General AnesthesiaComplication and Management • Neurological complication - Slow wake-up - Stroke • Malignant hyperthermia

  39. Case ReportArterial oxygen desaturation following PCNL 大林慈濟醫院麻醉科 陳炳碩

  40. The Patient • Patient : 73 y/o Female • BW 68 kg, BH 145 cm (BMI 32) • Chief complaint : • Right flank pain (stabbing, frequent attacks) • General malaise and fatigue

  41. The Patient • Past history : Hypertension under regular control • Senile dementia (mild) • Preoperative diagnosis : Right renal stone (3.2 cm) • Operation planned : Right PCNL(percutaneous nephrolithotomy)

  42. EKG : Normal sinus rhythm • CXR : Borderline cardiomegaly & tortuous aorta • Lab data : Hb 10.5 / Hct 33.2 • BUN 24 / Creatinine 1.1 • GOT 14 • PT, aPTT WNL Pre-anesthetic Assessment

  43. Preop

  44. General anesthesia with endotracheal intubation • Standard monitoring apparatus for ETGA • Induction : Fentanyl ug/kg • propofol 2mg/kg • Succinylcholine 80 mg • Atracurium 25 mg • Endotracheal tube (ID 7.0-mm) @ 19cm • Maintenance: Isoflurane 2~3% in O2 0.5 L/min • Position: prone • Blood loss : 300 mL → PRBC 2U Anesthetic Technique

  45. Stable hemodynamics • Abnormal findings 30 minutes after surgery started • Increased airway pressure 35~40 mmHg • SpO2 dropped to 90~95% • Bilateral breathing sounds were still audible then • Management : Solu-cortef 100 mg IV stat • Aminophylline 250 mg IV drip • Bricanyl 5 mg inhalation Intra-operative Events

  46. ABG data Intra-operative Events

  47. The patient’s condition was kept up until the end of surgery • SpO2 90~92% after the patient was placed in the supine position • again with diminished breathing sound over right lower lung • The patient was transferred to SICU for further care (*) • Chest X-ray was followed in SICU Post-operative Course

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