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Anaesthesia

Anaesthesia. 13.30 - 14.30 Dr Rob Stephens Physiological and Pharmacological principles 14.30 - 15.30 Dr Andy Badacsonyi Anaesthesia in the 21st century 15.30 - 15.45 BREAK 15.45 - 16.45 Dr Brigitta Brandner Acute Pain Management. Physiology and …. Dr Rob Stephens

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Anaesthesia

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  1. Anaesthesia 13.30 - 14.30 Dr Rob Stephens Physiological and Pharmacological principles 14.30 - 15.30 Dr Andy Badacsonyi Anaesthesia in the 21st century 15.30 - 15.45 BREAK 15.45 - 16.45 Dr BrigittaBrandner Acute Pain Management

  2. Physiology and … Dr Rob Stephens Thanks to Drs James Holding and MaryamJadidi

  3. Contents • Introduction • Physiology • CVS, RS, NS, Other • Pharmacolgy • Anaesthetic/ Hypnotic Agents • Neuromuscular Paralysis & Reversal • Analgesia • Others, CVS, Gasses, Fluids

  4. Introduction • General word: • website, documents, coming to theatre

  5. Introduction • Anaesthesia is more than Physiology and Pharmacology! • Surgery vs Anaesthesia • Outside theatre

  6. CVS physiology O2 + C6H12O6 CO2 + H2O ATP • O2 delivery • =Amount ofO2to tissues per minute • =Cardiac Output xO2 content of blood x • Hbx Sa02 x constant HR x SV

  7. CVS physiology • MAP = CO x SVR Vaso-? constricted ? dilated HR x SV

  8. CVS physiology: Heart • Heart • pumps blood (02) from lungs to tissues • then back to heart / lungs (C02) • Work =02 needs  • rate • pre / afterload • contractility

  9. Anaesthesia and CVS

  10. CVS effects.. • Anxiety, illness, walking to theatre, pain • Induction of general anaesthesia • or onset of epidural/ spinal anaesthesia • Cardiovascular - active drugs • Intubation • Surgical stimulation / trauma • Haemorrhage • Extubation • ?Recovery or complication

  11. Cardiovascular changes • ‘artists impression’ version often filled in!

  12. Induction of anaesthesia Preoperative

  13. Surgical stimulation Incision

  14. Cardiovascular Bleeding Less oxygen in blood Less pressure at Atrial and Aortic stretch Sympathetic ++ response (+renal, adrenal) Blood pressure maintained … CO x SVR ↑ ↑ +veinotrope +vechronotropevasocontricts ↑HR x↑SV vasocontricts

  15. Respiratory Upper – Airway Lower- Trachea, lungs, muscles

  16. Respiratory- Airway Anaesthesia ‘Obtunds’ airway =“Airway obstruction’ = no airflow = no 02 = Badness

  17. Respiratory- Airway Keep Airway open: • Airway manoeuvres (chin lift etc) • Airway devices- above vs blow cords • Above Vocal Cords • eg , gudel, LMA • Below Vocal Cords - Into trachea = intubation, paralysis

  18. Guedel / Oro-Pharyngeal size 4 Adult male Adult female size 3 Guedel

  19. Laryngeal Mask Airway

  20. Respiratory- Airway

  21. Respiratory- Lower/ Lungs • Spontaneous vs Ventilated • Lungs smaller  depth • Drugs  respiratory rate • Small airways / Alveolar collapse • Can’t cough – secretions • = ‘pulmonary shunt (vs deadspace) • Hypoxaemia, persists postoperatively

  22. CT scan of Diaphragm duringawake spontaneous breathing

  23. CT scan of Diaphragm duringanaesthesia: Atelectasis

  24. Gastrointestinal General Anaesthesia relaxes gastro-oesophageal sphincter Fluid up oesophagus?into lungs starvation postoperative vomiting Other drugs (eg analgesia)

  25. Neurology • Many Effects • GA drug induced reversable unconsciousness • Many reflexes  (airway, gag, CN) • Awareness • +/- NMJ paralysis

  26. Physiology • 2(3) factors determining blood pressure • How does GA affect these? • 3 words about GA on resp system

  27. Contents Introduction – the classical triad Introduction – general principles Hypnotic Agents Neuromuscular Paralysis + Reversal Analgesia Cardiovascular Drugs – up and down Fluids and Gasses are drugs too!

  28. Pharmacology Introduction • Anaesthesia ‘classical triad’ • Hypnotic agent- unconsciousness • Gas or IV • Analgesia • Neuromuscular Paralysis • Induction, Maintenance, Emergence, Recovery • Basics of anaesthesia: diagrams, handout & lecture

  29. Introduction - Principles • Pharmacokinetics • What the body does to the drug • Absorption, distribution, metabolism, elimination • Pharmacodynamics • What the drug does to the body – ie it’s effects • CVS, RS, GI, NS, Other , Side effects

  30. TypicalAnaesthesia • Intravenous induction Propofol • Short acting opiate - e.g. fentanyl • Hypnotic ‘anaesthetic’ - e.g. propofol • Set up of anaesthetic maintenance - e.g. sevofluranevapour in oxygen and air • Specific muscle paralysis may be needed • Definitive analgesia • Anti-emetic • Others

  31. Hypnosis: Propofol

  32. Hypnosis: Propofol (and others) IV Redistributed out of CNS metabolised CVS - CO x SVR = MAP RS airway and lungs NS pain on injection

  33. Maintenance: Volatiles Oxygen Air Sevoflurane

  34. Maintenance • Sevoflurane(‘SEVO’) • Used for gaseous induction. • Desflurane • Isoflurane • Gases, inhaled, little metabolised, exhaled • CVS: CO x SVR = MAP • RS- irritant, bronchodilate NS • Given with Oxygen /Air /Nitrous Oxide CO x SVR = MAP

  35. MAC = minimum alveolar concentration

  36. Muscle Paralysis

  37. Neuromuscular blockers • Depolarising • Suxamethonium • Non-depolarising • Atracurium • Vecuronium • Rocuronium

  38. Neuromuscular blockers • Depolarising • Suxamethonium 2x Ach molecules • Activates receptor • Non-depolarising – competitive vs ACh • Atracurium • Vecuronium • Rocuronium

  39. Nicotinic ACh Receptor

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