100% Nitrous Oxide in the Oxygen Line: How Could This Happen in a Modern Anesthesia Machine?

Area of Science:

• Anesthesiology
• Medical Device Safety
• Gas Delivery Systems

Background:

• Inadvertent gas crossover in anesthesia delivery systems is a critical safety concern.
• Modern anesthesia machines incorporate safety features like the Diameter Index Safety System (DISS) to prevent such errors.
• Despite safety measures, incorrect assembly during maintenance can compromise system integrity.

Purpose of the Study:

• To report a rare case of unintended nitrous oxide (N2O) delivery instead of oxygen (O2).
• To identify the cause of the gas crossover incident.
• To propose improvements to prevent future occurrences.

Main Methods:

• Case report describing an incident on a Dräger Apollo anesthesia system.
• Analysis of the Diameter Index Safety System (DISS) component assembly during preventative maintenance.
• Review of the anesthesia machine's gas manifold and connection protocols.

Main Results:

• Ventilation with 100% N2O instead of 100% O2 was possible.
• The incident resulted from incorrect assembly of DISS components, bypassing the failsafe mechanism.
• The specific failure mode involved the defeat of the DISS failsafe during maintenance.

Conclusions:

• Incorrect assembly of DISS components can lead to critical gas delivery errors.
• Enhanced labeling (prominent, color-coded) of DISS components is recommended.
• Modifying the internal construction of the gas manifold to incorporate DISS could further prevent misconnections.