Anesthesia Workstation Basics

Anesthesia Workstations and Gas Delivery Systems

• Anesthesia workstations, like the Fabius and Apollo by Dräger Medical, facilitate safe gas delivery to patients.
• Fresh gas flow often exceeds patient consumption, requiring gas to exit the system to avoid increased airway pressure.
• Excess gas is expelled through the adjustable pressure-limiting (APL) valve or ventilator pressure relief valve, critical during spontaneous, manual, or mechanical ventilation.
• Scavenging systems capture waste gas, ensuring safety by directing it outside.

Evolution of Anesthesia Machines

• Anesthesia gas delivery systems have advanced through improved technology and safety standards since the Z79.8 was published in 1979.
• Each workstation component has designated functions, and understanding these aids in diagnosing potential failures.
• Digital flow indicators are replacing traditional glass tube flowmeters; electronic flow controllers are superseding manual gas flow valves.
• Comprehensive operator and service manuals provide essential information for each machine model.

Gas Flow Mechanics in Anesthesia Machines

• Anesthesia machines operate using compressed gases from cylinders and pipeline sources, primarily oxygen (O2) and nitrous oxide (N2O).
• Safety features prevent the delivery of hypoxic gas mixtures, including oxygen supply pressure failure alarms and gas flow proportioning systems.
• Gas pathways are categorized to ensure consistent flow, with essential components like the “fail-safe” valve that halts nitrous oxide flow if oxygen pressure drops below a specified threshold.

Safety Mechanisms

• Fail-safe valves sense oxygen flow pressure, ensuring nitrous oxide flow ceases when oxygen supply is compromised, reducing hypoxia risk.
• Oxygen supply pressure failure alarms alert users if pressure falls below a set point, enhancing operational reliability.
• Proportioning systems interlink oxygen and nitrous oxide flow, maintaining a safe gas mixture.

Mechanisms of Gas Control

• Mechanical flow controls allow user adjustments, but they are subject to potential failure; thus, pre-use checkout ensures safety.
• The oxygen ratio controller (ORC) and its sensitive counterpart, the S-ORC, are designed to proportion gases automatically based on oxygen flow adjustments.
• These systems are exclusive to oxygen and nitrous oxide interlinking, meaning other gases like air or helium do not influence their operation.

Oxygen Flush Valve Functionality

• The oxygen flush valve allows an immediate flow of oxygen from the common gas outlet at rates of 35–75 L/min, depending on system configuration.
• Its design minimizes accidental activation, ensuring safety during procedures.

Conclusion

• A thorough understanding of anesthesia machines and their safety features is indispensable for effective and safe anesthesia practice.

This quiz focuses on understanding the function and mechanics of anesthesia workstations, particularly the breathing systems used in modern devices like the Fabius, Apollo, and Perseus A500 from Dräger Medical. Learners will explore concepts related to fresh gas flow, pressure management, and the operation of circle breathing systems.