An anesthesia machine has three main roles:
✅ Delivers oxygen to the patient.
✅ Mixes and delivers anesthetic gases (e.g., sevoflurane, desflurane, isoflurane).
✅ Ventilates the patient when they are under anesthesia.
🩺 Key Components of the Anesthesia Machine
1️⃣ Gas Delivery System
- 🧪 Oxygen (O₂) Supply: Comes from wall supply or cylinders attached to the machine.
- 💨 Medical Air & Nitrous Oxide (N₂O): Mixed with O₂ for gas delivery.
- ⚠️ Fail-Safe Mechanism: Prevents delivery of hypoxic gas mixtures by ensuring O₂ is always present.
2️⃣ Vaporizer (Where the Anesthetic Gas Comes From)
- Converts liquid anesthetic agents (e.g., sevoflurane, desflurane, isoflurane) into gas.
- Allows precise control of anesthetic concentration delivered to the patient.
- Each anesthetic gas has its own specific vaporizer to prevent mixing errors.
3️⃣ Breathing Circuit (Delivers Gas to the Patient)
- Connects the machine to the endotracheal tube (ETT) or face mask.
- Includes one-way valves, filters, and reservoirs to control airflow.
- Two main types:
✅ Circle System (Rebreathing System) → Used in most general anesthesia cases.
✅ Mapleson System (Non-rebreathing) → Used in pediatrics or short procedures.
4️⃣ Ventilator System (Controls Breathing)
- Ensures the patient receives adequate ventilation under anesthesia.
- Can be set to volume-controlled, pressure-controlled, or spontaneous modes.
- Adjusts tidal volume, respiratory rate, and inspiratory pressure.
5️⃣ Scavenging System (Prevents OR Pollution)
- Collects and removes waste anesthetic gases to protect healthcare workers.
- Ensures excess gases don’t accumulate in the OR air.
📊 Monitoring & Safety Features in Anesthesia Machines
Anesthesia machines are equipped with built-in safety features to prevent errors:
✅ O₂ Analyzer – Ensures proper oxygen levels are delivered.
✅ Pressure Sensors & Flowmeters – Monitor gas flow and prevent delivery failures.
✅ Ventilator Alarms – Alert for issues like disconnections or low tidal volumes.
✅ Carbon Dioxide Absorber (CO₂ Scrubber) – Removes excess CO₂ in the breathing circuit.
🔬 Advanced Features in Modern Anesthesia Machines
- Electronic Vaporizers → More precise anesthetic gas delivery.
- Integrated Patient Monitoring → Displays vitals, end-tidal CO₂, and gas concentrations.
- Closed-Loop Anesthesia Delivery → Adjusts anesthetic depth automatically.
📚 References
1️⃣ Miller RD. Miller’s Anesthesia. 9th ed. Philadelphia, PA: Elsevier; 2020.
2️⃣ Morgan GE, Mikhail MS, Murray MJ. Morgan & Mikhail’s Clinical Anesthesiology. 6th ed. New York, NY: McGraw Hill; 2018.
3️⃣ Steiner J. Anesthesia Made Easy: The Survival Guide to Make Your First Anesthesia Rotation a Success. 2nd ed. Independently Published; 2019.