The document provides an introduction to anesthesia, including its definition, types (local, regional, general), phases (induction, maintenance, recovery), components of balanced anesthesia, effects, and benefits. It also discusses anesthesia machines, their operating principles, functions, vaporizers, agents used, and differences between closed and open systems. The key functions of anesthesia machines are to deliver oxygen, mix gases and vapors accurately, reduce risks, enable ventilation, and monitor vital signs.

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

2. Agenda
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I. Introduction to Anesthesia
a. Definition
b. Types
c. Phases of GA
d. Components of Balanced Anesthesia
e. Main Effects of GA
f. Benefits of GA
II. Anesthesia Machines
a. Operating Principles
b. Function
c. Vaporizers and Anesthetic Agents
d. Differences in Anesthesia Machines
UAM Training I Lecture Content | Introduction to Anesthesia

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

4. Introduction to Anesthesia
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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:
o Prevent pain
o Ease and expedite surgery
o Reduce patient complications during surgery
UAM Training I Lecture Content | Introduction to Anesthesia

5. Introduction Anesthesia: Types
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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
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Phases of Anesthesia
• Induction
• Maintenance
• Recovery
UAM Training I Lecture Content | Introduction to Anesthesia

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

11. Anesthesia Machines
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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 (O2) and air, or oxygen diluted with air
Precision vaporizer
Patient breathing circuit
Scavenging device
• During delivery of gaseous anesthesia to the patient, O2 , air, and sometimes
nitrous oxide flow through the vaporizer and picks up the anesthetic vapors
• The O2-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
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5 Primary Functions
1. Deliver oxygen
2. Accurately mix anesthetic gases and vapors
3. Reduce anesthesia-related risks to patients and staff
4. Enable patient ventilation
5. Monitor patient vital signs during surgery
(if patient monitoring equipment is available)
UAM Training I Lecture Content | Introduction to Anesthesia

13. Anesthesia Machines
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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
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Anesthetic Agents
• N2O (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
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Differences in Anesthesia Machines
Gas Circulation
• Circle (closed) system – extracts exhaled CO2, 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
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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
CO2 is removed before
flowing back towards the
patient
1
2
3
4
5

17. Anesthesia Machines: Open System
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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