1. Dr. Su Cheen Ng Consultant in Anaesthesia UCLH ANAESTHESIA DRUGS An Introduction to Anaesthesia 2016

2. TODAYS TALK Principles to drugs What we hope to achieve with anaesthesia Maintenance of anaesthesia Muscle relaxants Reversal agents for muscle relaxants Uppers and Downers Analgesia Antiemetic- anti nausea/vomiting

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

4. Objectives of Anaesthesia Loss of awareness / Amnesia If Warranted: Analgesia Suppression reflex /Reduce movement in response to stimuli Minimize autonomic responses to surgical stimuli Skeletal Muscle relaxation

5. TRIAD

6. What is Balanced Anesthesia? No single drug is capable of achieving all of the desired goals of anesthesia. SIDE EFFECTS TOXICITY “Balanced Anaesthesia” - A combination of agents, to limit the dose and toxicity of each drug

7. NOTE General anesthesia (GA) -uses intravenous and inhaled agents to allow adequate surgical access to the operative site. GA may not always be the best choice; depending on a patient’s clinical presentation!

8. THE GENERAL FLOW of GA  Intravenous induction- e.g. propofol, thiopentone  Short acting opiate - e.g. fentanyl  Muscle paralysis may be needed  Airway device  Set up of anaesthetic maintenance – inhaled or gasses (e.g. sevoflurane vapour in oxygen and air)  Others: Analgesia: IV, local anaesthesia, Anti- emetic

9. IV INDUCTION AGENT Used alone or with other drugs to: Achieve general anesthesia As components of balanced anesthesia To sedate patients Examples: Barbiturates : thiopentone Propofol Ketamine Etomidate

10. PROPOFOL -INDUCTION and MAINTENANCE of anaesthesia -Sedative, anaesthetic, amnesic, anticonvulsant, -Solvent :10% soyabean oil, 2.25% glycerol, 1.2% egg phosphatide -Rapid onset and short duration -Causes hypotension due to vasodilatation. -Pain on injection common especially small hand veins

11. MAINTANENCE of ANAESTHESIA Minimum alveolar concentration (MAC) = Measure of POTENCY 1 MAC= the concentration that results in immobility in 50% of patients when exposed to standardized skin incision Most Commonly : Inhalation Agents (OR IV agents) Ie: SEVOflurane, ISOflurane, DESflurane Inhaled and Exhaled gases AlveoliBlood CNS Path of Equilibrium of inhaled agents

12. In combination with: -Air -Oxygen

13. MUSCLE RELAXANTS Indication -Tracheal intubation -Surgical relaxation -Control of ventilation

14. Muscle Relaxants-Types Depolarizing muscle relaxant Suxamethonium Rapid sequence Intubation Side Effects -bradycardia -muscle ache -nausea -increase K+ level -suxamethonium apnoea Does NOT provide ANALGESIA or SEDATION/UNCONSCIOUNESS

15. Muscle Relaxants-Types Nondepolarizing muscle relaxants Short acting: Mivacurium Intermediate acting: Atracurium, Cisatracurium, Vecuronium, Rocuronium Long acting: Pancuronium Does NOT provide ANALGESIA or SEDATION/UNCONSCIOUNESS

16. Reversal of NDMB Neostigmine Increase Ach concentration SE: Slows HR, paristalsis Given with an anticholinergic Sugammadex -different doses based on indication: routine versus emergency

17. UPPERS AND DOWNERS INCREASE BP -α adreno-receptor agonists: Metaraminol, Phenylephrine -Mixed α and βadreno agonist:Ephedrine LOWER BP - more anaesthetic agent or opiate, - short acting β-blockers- labetalol,esmolol -GTN -α2agonist: clonidine

18. ANALGESIC Systemic (PO/IV/ PR/ SC)  Simple- Acetaminophen  NSAID – Diclofenac, Ibuprofen,coxibs  Opioids - Codeine, Morphine  Others – Ketamine, clonidine Regional – spinal / epidural / peripheral nerve blocks Local – infiltration of local anaesthesia

19. ANALGESIC LADDER NSAIDS= nonsteroidal anti-inflammatory drugs(ie: ibuprofen, coxibs, mefenamic acid)

20. ANTI -EMETIC  Postoperative nausea and vomiting (PONV- any nausea, retching, or vomiting occurring during the first 24–48 h after surgery  INCIDENCE: 30% in all post-surgical patients, up to 80% in high-risk patients

21. ANTI-EMETIC cyclizine

22. SUMMARY  TITRATION is key!! Can always give more – cannot take away  Caution in  Unwell  Elderly  Hypovolaemic  Lots of ways to anaesthetise- don’t worry  Ask for HELP

23. Pocket references

24. THANK YOU