Introduction to Anesthesia

Clinical Refresher

1. INTRODUCTION TO ANESTHESIA Gradian Health Systems Simulation-Based Product Training Version 2.0

2. Agenda 2 Introduction to Anesthesia Definition Types Phases of GA Components of B alanced A nesthesia Main E ffects of GA Benefits of GA Anesthesia Machines Operating Principles Function Vaporizers and Anesthetic Agents Differences in Anesthesia Machines UAM Training I Lecture Content | Introduction to Anesthesia

3. I. Introduction to Anesthesia 3 UAM Training I Lecture Content | Introduction to Anesthesia

4. Introduction to Anesthesia 4 Definition of Anesthesia “Anesthesia” means loss of sensation In the practice of medicine, anesthesia is a state of temporary, induced loss of sensation or awareness that takes place prior to surgery Anesthesia is given to: Prevent pain Ease and expedite surgery Reduce patient complications during surgery UAM Training I Lecture Content | Introduction to Anesthesia

5. Introduction Anesthesia: Types 5 Local Topical application or infiltration with local anesthetic agent (subcutaneously or IM) intended to numb a small localized area of the body. (e.g., lignocaine, bupivacaine ) Regional Use of local anesthetic drugs to block painful sensations in a larger region of the body; can be administered in several ways (peripheral nerve blocks and neuraxial blocks) including: Spinal anesthesia Epidural analgesia Peripheral nerve blocks General Drug-induced complete loss of consciousness. This can be induced using IV or inhalational drugs. Maintenance is achieved with a combination of IV and inhalational agents or TIVA alone. It is often administered using an anesthesia machine UAM Training I Lecture Content | Introduction to Anesthesia

6. Introduction to Anesthesia 6 Phases of A nesthesia Induction Maintenance Recovery UAM Training I Lecture Content | Introduction to Anesthesia

7. Introduction to Anesthesia 7 Components of Balance Anesthesia Hypnosis (sleep induction and amnesia) e.g., IV: ketamine, thiopentone and propofol e.g., Inhalational: halothane, sevoflurane Analgesia (loss of pain sensation) e.g., Opioids: pethidine, morphine, fentanyl, tramadol e.g., Non-opioids: NSAIDs, paracetamol Muscle relaxation (loss of reflexes) e.g., Depolarizing: suxamethonium e.g., Non- depolarizing: pancuronium , vecuronium, atracurium UAM Training I Lecture Content | Introduction to Anesthesia

8. Introduction Anesthesia 8 Main Effects of General Anesthesia Respiratory depression Action: secure the airway; provide assisted ventilation (when needed) Cardiovascular effects (hypotension, hypertension) Action: titration of the drug; provision of supportive care Standard monitoring is mandatory ! UAM Training I Lecture Content | Introduction to Anesthesia

9. Introduction to Anesthesia 9 Benefits of Balanced General Anesthesia Amnesia Muscle relaxation (facilitates surgical access) Analgesia (enhanced patient comfort) Synergistic effect of drugs Reduced doses of individual drugs and minimizes the side effects Smoother recovery/emergence UAM Training I Lecture Content | Introduction to Anesthesia

10. II. Anesthesia Machines 10 UAM Training I Lecture Content | Introduction to Anesthesia

11. Anesthesia Machines 11 Operating Principles Anesthesia machines dispense the gases that are necessary to induce sleep and prevent pain during surgical procedures or other potentially painful operations Basic delivery system consists of: Source of oxygen (O 2 ) and air, or oxygen diluted with air Precision vaporizer Patient breathing circuit Scavenging device During delivery of gaseous anesthesia to the patient, O 2 , air, and sometimes nitrous oxide flow through the vaporizer and picks up the anesthetic vapors The O 2 -anesthetic mix then flows through the breathing circuit and into the patient's lungs It is sometimes necessary to use assisted ventilation , which can be accomplished by use of manual bellows or an automatic ventilator UAM Training I Lecture Content | Introduction to Anesthesia

12. Anesthesia Machines 12 5 Primary Functions Deliver oxygen Accurately mix anesthetic gases and vapors Reduce anesthesia-related risks to patients and staff Enable patient ventilation Monitor patient vital signs during surgery ( if patient monitoring equipment is available ) UAM Training I Lecture Content | Introduction to Anesthesia

13. Anesthesia Machines 13 Vaporizer Functions Vaporizer holds liquid volatile anesthetic agent Adds the set agent % concentration to the fresh gas flow  delivered to the patient via the breathing circuit UAM Training I Lecture Content | Introduction to Anesthesia

14. Anesthesia Machines 14 Anesthetic Agents N 2 O (0-75%), MAC 100% ( analgesic/anesthetic supplement ) Enflurane (0-5%), MAC 1.7% Halothane (0-5%), MAC 0.7% Isoflurane (0-5%), MAC 1.2% Sevoflurane (0-8%), MAC 2.0% Desflurane (0-18%), MAC 6.0% The UAM supports the delivery of halothane, isoflurane, or sevoflurane, but each agent requires its own vaporizer . UAM Training I Lecture Content | Introduction to Anesthesia

15. Anesthesia Machines 15 Differences in Anesthesia Machines Gas Circulation Circle (closed) system – extracts exhaled CO 2 , recycles gas Open system – vents all gases through a scavenging system Gas Flow Continuous flow – uses high pressure gas to vaporize agent Draw over – low resistance, low pressure Level of Sophistication Manual – everything is done by the care provider Semi-automatic – between manual and automatic Fully automatic – everything is done by the machine UAM Training I Lecture Content | Introduction to Anesthesia

16. Anesthesia Machines: Circle System 16 UAM Simulation-based Training I Lecture Content | Introduction to Anesthesia Fresh gas enters the circle from the common gas outlet of the machine and flows through the inspiratory limb one-way valve Gas then flows through the inspiratory breathing tube and then through the Y-piece to the patient’s lungs The patient’s expired gas flows through the expiratory breathing tube to the expiratory limb one-way valve It then passes through the reservoir bag, with excess gas vented out through the pop-off (APL) valve to the scavenging system And then arrives at the absorbent canister where CO 2 is removed before flowing back towards the patient 1 2 3 4 5

17. Anesthesia Machines: Open System 17 UAM Simulation-based Training I Lecture Content | Introduction to Anesthesia 1 Fresh gas enters the circle from the common gas outlet of the machine and flows through the inspiratory limb one-way valve 2 It then passes through the reservoir bag 3 Flows through the inspiratory breathing tube and through the Y-piece to the patient’s lungs The patient’s expired gas flows through the expiratory breathing tube to the expiratory limb one-way valve 4 5 Exhaust gas vented out through the scavenging system