A reply

Abstract

As a supplier of medical gas cylinders, BOC are concerned about the inherent risk associated with the wrong cylinder being used where cylinders are supplied with non-gas specific connections. BS 381 is the basic standard that prescribes the different valve outlets that should be used for industrial, medical and research grade gas cylinders in the UK. This standard has been in place for over 50 years and utilises the 5/8 inch BSP (F) bull-nose connection for many gases. These include oxygen, air, argon, nitrogen, helium and their mixtures in both medical and industrial service. As identified in this incident, there is a risk that the end user can mistakenly attach the wrong cylinder to the patient supply system, causing the wrong gas to be administered to the patient. Whereas the incident was very serious and could have had serious consequences for the patient, had the regulator been attached to a helium or argon cylinder (both used in medical applications) the consequences would have been much more serious. In the 1980s it was recognised that there was a risk that medical air and medical oxygen cylinders could be used incorrectly on cylinder manifolds and the valves used on these cylinders were changed to a pin index type. The pin index outlets, detailed in ISO 407, provide both a gas-specific and service-specific outlet for medical gas cylinders. At this time BOC requested that other cylinders should also be converted to pin index valve outlets but this request was rejected because of the cost of converting all of the regulators in the hospital service. It was reported that the risk was less with the F and G size cylinders as they were used for the administration of gas local to the patient where it was possible for the responsible person to identify the correct gas by the cylinder colour coding and the label. Although there are many thousands of these cylinders in service, there have been a number of reports of ‘near misses’ with the wrong cylinders being connected. To try and mitigate this potential risk of supplying the wrong gas to the patient, BOC has taken steps to assist the end users in selecting the correct package. The introduction of new cylinders fitted with an integrated cylinder valve (that have a built-in pressure regulator) has meant that a standard terminal outlet connection can be fitted to the valve outlet. The terminal outlet has a product specific connection, preventing the wrong equipment being connected to the cylinder. With the changes in the regulations for colour coding cylinders, the new types of cylinders now being supplied have the name of the gas clearly visible on the cylinder body. The new collar label has meant that both the product name and the user instructions are now more legible to allow the person administering the gas to check the contents more easily. Unfortunately it is not possible to convert all cylinders to the new type of valve overnight and the reported incident identifies the need to train all personnel appropriately to ensure that the correct cylinder is being used. In addition, it is very important to manage cylinder stores correctly to segregate the different gases (and to not mix the medical and non-medical cylinders). This will assist in the correct cylinder being selected by the porter for supply to the ward or operating theatre. It is also important to minimise the number of cylinders being stored in those areas where the gas is used, to make it more difficult for the wrong cylinder to be selected. These issues should be identified by the routine risk assessments of the hospital and be addressed by the appropriate corrective actions detailed to address the potential risks. This is a subject that concerns all of the medical gas cylinder suppliers in the UK. The British Compressed Gas Association (BCGA) have talked to the MHRA about how this issue could be addressed. It would be helpful if similar incidents could be reported to me to enable a consolidated view of the potential risk to be presented to the authorities in support of proposals concerning the change to gas- and service-specific medical gas cylinder valve outlets.