Failure of a “foolproof” pin-index medical pipeline system

BACKGROUND: The pin-index medical gas pipeline system, which complies with Japan Industrial Standard (JIS), is considered to be “foolproof” and is widely used in Japan to avoid medical gas misconnections. CASE PRESENTATION: The wall-mounted gas outlet used in our hospital (NSV outlet, CENTRAL UNI, Co., Ltd., Tokyo, Japan) contains multiple sockets, which connect to hoses with gas-specific pins. Each socket is covered with a gas-specific plastic pin guide, which is considered to make the system foolproof; i.e., to prevent misconnections. However, while checking an anesthesia machine in accordance with the guidelines developed by the Japanese Society of Anesthesiologists, an anesthesiologist found that one of the gas-specific plastic pin guides covering the wall-mounted gas outlets had disappeared; and hence, the gas outlet system was no longer foolproof. A subsequent verification test performed by engineers of the system’s manufacturer revealed that the plastic pin guides could be dislodged by applying 29.4 N of vertical force. CONCLUSIONS: It is important to check that gas outlet systems are functioning in a gas-specific manner when they are used for clinical purposes.