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Anesthesia Electives

Anesthesia Electives. Lecture 1. Upper Airway. Nose and mouth Air is humidified Innvervations Trigeminal nerve Opthalmic division Anterior ethmoidal Maxillary division Sphenopalatine ganglion Mandibular division Lingual nerve Nasopalatine nerve. Upper Airway. Pharynx

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Anesthesia Electives

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  1. Anesthesia Electives Lecture 1

  2. Upper Airway • Nose and mouth • Air is humidified • Innvervations • Trigeminal nerve • Opthalmic division • Anterior ethmoidal • Maxillary division • Sphenopalatine ganglion • Mandibular division • Lingual nerve • Nasopalatine nerve

  3. Upper Airway • Pharynx • Glossopharyngeal nerve • Posterior third of tongue, soft palate, and oropharyx • Vagus nerve • Internal branches of superior laryngeal nerves = sensory innervation of hypopharynx • 3 parts • Nasopharynx [Soft palate] • Oropharynx [Epiglottis] • Hypopharynx

  4. Upper Airway • Larynx • Articulating cartilages • 3rd, 4th, 5th, and 6th cervical vertebrae • Separates trachea and esophagus • Vocal cords: formed by thyroarytenoid ligaments • Trachea • Starts: 6th cervical vertebrae • Ends: bifurcation (carina)of the 5th thoracic vertebrae • Supported by 16-20 horsehoe-shaped cartilages

  5. Upper Airway • Anterior structures • Skin  superficial  deep fascia • Thyroid isthmus • Lower neck strap muscles • Sternohyoid • Sternothyroid • Blood supply • Superior thyroid artery  superior laryngeal artery • Inferior thyroid artery  inferior larygneal artery • Venous drainage: Superior and inferior thyroid veins

  6. Upper Airway • Mallampati classification

  7. Upper Airway • Cormack and Lehane score

  8. Upper Airway • Atlanto-occipital extension • Extension of the head • Aligning the oral and pharyngeal axes

  9. Endotracheal Intubation • Indications • Provide to patent airway • Prevent inhalation of gastric contents • Need for frequent suctioning • Facilitate positive-pressure ventilation of the lungs • Operative position other than supine • Operative site near or involving the upper airways • Airway maintenance by mask difficult

  10. Endotracheal Intubation • Equipment • Endotracheal tube • Laryngoscope • Suction catheter • Anesthetic drugs • Equipment providing positive pressure ventilation

  11. Endotracheal Intubation

  12. Endotracheal Intubation

  13. Endotracheal Intubation

  14. Endotracheal Intubation • Endotracheal tube sizes • Internal diameter (ID) • Lengthwise markings

  15. Endotracheal Intubation • Cricoid pressure • “Sellick’s maneuver” • Exerting downward pressure on cricoid cartilage • Displace cricothyroid ring posteriorly; compress underlying esophagus against cervical vertebrae • Prevent spillage of contents into pharynx • Allows glottic area to be seen easier during intubation

  16. Extubation • Criteria • Adequate respiratory drive • Respiratory muscle strength • Cough reflex • Laryngeal function • Clearance of sedative / medications

  17. General Anesthesia • Act on CNS • Modifies electrical activity of neurons at molecular level • Ion channels dysruption • Essential components • Analgesia • Sedation • Depression of reflexes • Muscle relaxation

  18. General Anesthesia

  19. General Anesthesia • Theories • Lipid theory • Greater anesthetic solubility in oil = greater the potency • Protein theory • Greater ability to inhibit enzyme activity of protein = greater the potency • Binding theory • Anesthetics attach to hydrophobic area of the ion channel • 2 kinds • Inhalational • Intravenous

  20. Inhalational • E.g. • Halothane • Isoflurane • Desflurane • Sevoflurane • Gasses or vapors • Produces • Immobility • Analgesia • MAC (Minimum alveolar concentration required to suppress movement to a surgical incision in 50% patients)

  21. Inhalational • Central nervous system depression • Enhance inhibitory ion channels (hyperpolarization of the neuron) • Block excitatory ion channels • Depressed respiration and response to CO2 • Other effects • Depression of renal blood flow • Depression of urine output • Relaxation of skeletal muscles • Reduction in arterial pressure and PVR • Increase cerebral blood flow • Decreased cerebral metabolism

  22. Inhalational • Rate of entry into brain • Low solubility in blood = faster induction and recovery = fast increase in partial pressure • High solubility in blood= slower induction and recovery = slower increase in partial pressure

  23. Inhalational • Adverse effects • Depression of respiratory drive( CO2 dive) • Depressed cardiovascular drive • Fluoride-ion toxicity (methoxyflurane) • Decreases renal function • Fluoride will accumulate (nephrotoxicity) • Malignant hyperthermia

  24. Inhalational • Molecular structure • Halogenated hydrocarbons • Can induce cardiac arrhythmias • Fluorination: increases stability of molecule

  25. Intravenous • Intravenous • Injections • Combined with inhalational anesthestics • Purpose: • Maintain GA • Supplement • Sedation • Control BP • Brain protection

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