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Published on 1 September 2007

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The pharmacist’s role in the quality assurance of medical gases


Brian Midcalf
BPharm FRPharmS

Assistant Director
Pharmaceutical Technology and Quality Assurance Course
School of Process, Environmental and Materials Engineering
University of Leeds


A medical gas pipeline system (MGPS) in a healthcare environment in the UK has had a history of incidents which have compromised patient welfare or safety and resulted in some deaths. Fortunately, these instances are very rare and controlled by the implementation of appropriate guidelines and the technical memoranda. However, a number of incidents have recently been reported in other European countries. Notably, the deaths of eight patients in Italy in April-May 2007 due to nitrous oxide administration provides recent evidence as to how such incidents can still occur: modification or installation of an MGPS can still compromise the patient. This article attempts to summarise the situation relating to the roles of pharmacists and their involvement with medical gas installations. In Europe medical gases are classed as drugs. It is essential that they are understood and dealt with in these terms, because administration of the wrong gas by the inhalation route could have such a rapid effect on the patient that recovery may not be possible.

It is recognised that many recommendations of technical memoranda current in the UK will differ from those of other countries, but many healthcare authorities use or adapt these same guidelines because they already exist and are tried and tested. This article is based on the system and standards used in the UK, but may be useful elsewhere.

History of involvement
In the early to mid 20th century, responsibility for medical gas quality distribution and use largely belonged to anaesthetists – the principal users of such gases. They would perform quality checks from time to time, but after a series of deaths due to crossconnections of medical gases it was established that a formal system for managing, delivering and controlling medical gases was necessary. This was to include a separate and independent level of checks implemented by a pharmacist

A “permit to work” was set up in order to control access to or interference with MGPSs. The final section of this relates to high-hazard work and involves an independent check for “identity” and “purity” to be performed by the pharmacist before the system is taken back into use. Inclusion of the pharmacist at this level of control was established in 1977. The rationale for this is still current: medical gases are medicines and medicines are controlled by pharmacists, so pharmacists should control these medicinal products too. Just because the items were invisible and odourless with boundaries indistinguishable from surrounding air and with packaging in the form of a length of copper pipe was no excuse not to become involved.

It became the task of the specialist technical pharmacist to develop roles in analysing medical gas, mainly to confirm that the correct gas was emanating from the correctly labelled terminal unit and that it was free from contamination. This formed an additional analytical role for the quality control pharmacist or his or her staff to take on. At the same time, there was a need to establish appropriate in-house training and a much better understanding of the MGPS and how it was controlled by the engineer.

Technical memoranda
In the UK, the installation, maintenance and modification of any MGPS is controlled by health technical memoranda (HTMs). For medical gases these have evolved from 1972 to the present day through HTM22 and HTM2022 to HTM02.(1) Successive HTMs have to an ever greater extent controlled the disciplines required to install or modify the installation of a medical gas system and indicate the checks and tests required to evaluate such an installation. For safety reasons it is unacceptable for anyone to alter an MGPS’s configuration without following these guidelines.

The HTMs established a hierarchy of control: the authorising engineer oversees and audits medical gas systems; the more local authorised person (AP) has sufficient technical knowledge, training and experience to understand the dangers and risks involved; and this individual in turn schedules the work involved with the competent person who is registered as able to work competently on an MGPS. There is also a link to the quality controller of medical gases (QCMGPS), who performs the pharmaceutical checks.

Pharmacist involvement
The pharmacist will usually work closely with the coordinating AP and attend the site once the installation has been completed and is ready for an independent check. The approach taken by the pharmacist in this role is one of problem sharing and collaborative involvement. Thus, it is necessary to understand the engineering principles involved with an MGPS, from its layout and control through to the use of isolation valves for different units and departments.

The fundamental role of the pharmacist is to assure the identity and quality of the gases. However, it is increasingly expected that pharmacists are conversant with the whole of the project, are familiar with or able to understand pipeline drawings, and are acquainted with potential problems of isolation, such as area-valve service units (AVSUs), noninterchangeable screw threads (NISTs) and correct fitting of terminal units (TUs; ie, gas-specific units to permit access to the gas at line pressure for the user). They should also be aware of contamination sources and be used to working in the user environment and, where necessary, should endorse and support the AP by confirming that the system is indeed complying with the current standards and is satisfactory for patient use.

Permit to work
Working on an MGPS is only acceptable if a permit to work is in place and completed properly by the appropriate personnel; details of this are provided in HTM 02-01 (2006).(1)

Checking role
The QCMGPS will perform identity and purity tests on sample TUs depending on the work that has been undertaken. Such assessment must be carried out on site and determines the level of testing required. For a new installation, each TU needs to be checked for correct gas identity and freedom from contamination. There is insufficient space in this article to go into details of the relevant techniques; suffice it to say here that tests are usually performed with gas analysers using infrared, fuel-cell or paramagnetic principles together with moisture measurement and gas pressure at the terminal, while particulate contamination is assessed using a membrane filter in a high-pressure holder.

Technical competence
Assessments of competence needs for the independent specialist could be visualised by the nontechnical manager as following a standard procedure with defined boundaries of responsibility to perform the “simple” identity and purity check. The AP or QCMGPS will recognise a different role of shared responsibility in a working situation possibly following a reduction in the number of experienced engineers. Perceived boundaries between disciplines need to be crossed in a shared-partnership arrangement to ensure that all checks have been completed and that all aspects of the MGPS are as they should be and safe for use by patients and staff.

It has been clear to us that the QCMGPS needs to acquire an understanding of the whole MGPS as well as current project work under completion and ready for testing. This competence is a combination of experience and training.

Training needs and registration
A specialist working group exists to advise on matters relating to medical gas testing. The group is part of the NHS Quality Assurance Committee, itself a specialist committee of quality assurance pharmacists working within the NHS in collaboration with the Department of Health. The working group, comprising practicing medical gas testers, advises the main committee. It maintains a register of technical pharmacy staff who perform this testing role and who have appropriate experience and competence. They will also monitor the requirement of HTM 02 that staff admitted to the register maintain continued competence by attending an “update course”, probably every five years.

The group has commissioned a “Pharmaceutical Medical Gas Testing” course, to be administered by the University of Leeds under the Pharmaceutical Technology and Quality Assurance (PTQA) scheme. Current arrangements are to run the main course and update sessions annually or every 18 months. Participants on the main course will be able to undertake the full three-month, work-based module, for which a certificate of competence will be awarded, attend the week’s residential section as basic training or take part in a two-day update as part of their CPD requirement. We believe the full course to be unique and the first of its kind. Delegates are welcome from any European country and further information, as well as the course content, can be obtained from the website or course director (see Resources). The full course includes information on analytical testing, teaching on the HTM, engineering aspects of plant, policies, what can go wrong, and practical sessions.

Conclusion and recommendations
An MGPS can be a complex and convoluted installation, especially if there have been a number of modifications during its lifetime. The installation may involve a range of personnel, with medical gas installers often working alongside other contractors under supervision conditions that may not always be ideal. The mechanical installation is checked by the AP and must comply with his or her standards, usually in compliance with the HTM. The QCMGPS retains an independent role and is expected to confirm that the installation complies with the required standard. There is only one state in which an MGPS can be, and that is “right” – with no defects or misconnections. If there is room for doubt, more checks and tests will be necessary.

It is vital that any mistake is discovered. Adopting a “no-blame culture” has been found to be a more useful approach than trying to blame any particular individual involved for any error or misunderstanding. Together, all team members will work to resolve any issues and act earnestly to ensure everything is in order before completion. A sound and sympathetic management approach, with managers as part of the team, works well in these situations.

I hope that this brief overview serves to assure the reader that there is a definite and valued role for te technical pharmacy staff member acting as QCMGPS. As the final link in a chain involving a range of disciplines, such individuals often represent the final opportunity to pick up any defect or error. If such are missed, patients could be seriously compromised. An experienced and understanding view of this specialist activity is a valued asset.

1. NHS Estates. Health technical memorandum. Part A: design, installation, validation, verification. HTM 02-01: 2006. London: HMSO; 2006.
2. NHS Estates. Health technical memorandum. Part B: operational management. HTM 02-01: 2006. London: HMSO; 2006.
3. NHS Estates. Health Technical Memorandum. Piped medical gases, medical compressed air and medical vacuum installations. HTM 22/HN (76) 175. London: HMSO; 1972, 1978.
4. NHS Estates. Health Technical Memorandum. Piped medical gases, medical compressed air and medical vacuum installations. HTM 2022. London: HMSO; 1994.

PTQA medical gas testing course

PTQA course director


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