What is the name of the system that ensures only the correct gas can be attached to the correct yoke on the anaesthetic machine?

• A. Pin index safety system
• B. Color coding
• C. Pressure locking
• D. Gas compatibility

Answer: (A)

The key idea here is a mechanical safety system that prevents the wrong gas cylinder from being connected to the anaesthetic machine. The pin index safety system uses two pins on the machine’s cylinder yoke and two corresponding holes on the cylinder valve. Each gas has a unique pin-hole pattern, so only the correct gas cylinder can engage properly with the yoke. This physical keying stops accidental connections and ensures the patient receives the intended gas mix, which is crucial for safe anesthesia delivery. Color coding is helpful as a quick reference but can be misleading if colors fade or are misread, so it isn’t the primary safeguard. The other terms don’t describe this physical interlock that guarantees correct gas attachment.