24 Mar 2020

The MHRA has published its guidance for manufacturers wishing to assist the UK by turning their capabilities to the urgent manufacture of ventilators during the Coronavirus outbreak. The guidance includes information on the minimum specification for clinically acceptable ventilators to be used in UK hospitals during the COVID-19 outbreak. These clinical requirements are based on the consensus of opinion on what is ‘minimally acceptable’ performance by anaesthesia and intensive care medicine professionals and medical device regulators. The full guidance is available here.

The MHRA makes the point that lower specifications are likely to render no clinical benefit and may cause increased harm. The specification is for ventilators providing short-term stabilisation i.e a few hours, although if absolutely necessary for a patient then their use can be extended to 1 day. Ideally, the ventilator should also be capable of delivering more advanced support over several days, but this is not an absolute requirement.

The Specification covers the following areas:

  • Ventilation – covering the requirement for at least 1 and optionally 2 modes of operation (mandatory for those unable to breathe for themselves and optional support for those patients breathing to some extent themselves), Inspiratory airway pressure, Positive End Expiratory Pressure and Tidal Volume.
  • Gas and Elec supply requirements, including gas supply to the patient
  • Infection control - All parts coming into contact with the patient’s breath must be disposable or decontaminatable between patients. All external parts must be manually cleanable using a surface wipe or approved cleaning fluid;
  • Alarm system - The ventilator must alarm at for example gas or electricity supply failure, or the machine being switched off while in mandatory ventilation mode
  • Monitoring – it must continuously display current ventilation settings and achieved rates, with optional features including CO2 monitoring.

Standards and testing

The MHRA has set out those standards which are the most relevant but stresses that these are not formal legal requirements but should be considered as helpful advisory standards. It is planning to define those which could be ‘safely’ relaxed for this situation. The standards set out include:

  • BS EN 794-3:1998 +A2:2009: Particular requirements for emergency and transport ventilators
  • ISO 10651-3:1997: Lung ventilators for medical use – emergency and transport
  • BS ISO 80601-2-84:2018: Medical electrical equipment. Part 2 to 84. Particular requirements for basic safety and essential performance of emergency and transport ventilators – especially the parts on ‘patient gas pathway’ safety (very similar to IEC 60601)
  • BS ISO 19223:2019: Lung ventilators and related equipment. Vocabulary and semantics.

The MHRA specifically states that it is accepted that full demonstration of compliance to ISO 80601-2-12:2020 is unrealistic in the time-scales required for development, but that compliance with the essential safety standards must be demonstrated for patient safety. However, usability testing at both prototype and final production stages will be required, using the short formative usability testing to ISO 62366, which can be done in one day.

Approval and CE marking

Ventilators are not required to be CE marked – they will be MHRA approved via the "Exceptional use of non-CE marked medical devices” procedure. However, once the emergency situation has passed, they cannot be used for routine care unless they have been CE marked in accordance with the Medical Device Regulations. Ventilators must display a prominent and indelible label making this clear.

Other requirements

The specification also requires the ventilator to be:

  • It must have 100% duty cycle for up to 14 days, although it can be longer. The expected life must be specified
  • as robust as possible, so that it can survive being dropped from bed to floor
  • intuitive to use for qualified medical personnel, who may not be specialists in ventilator use:
    • of transparent design, supply chain, manufacture and testing processes of sufficient quality to enable the MHRA to deem appropriate for use in exceptional circumstances
    • easily moveable within hospital premises, and ideally small and light so that it can be mounted on a bed.
  • made from materials and parts readily available in the UK supply chain

Lastly, the MHRA outlines a number of unknown factors which must be considered, and emphasises the need to further consider battery back-up systems, which are supplied with every current hospital ventilator. It acknowledges that to include this requirement in the specification would be burdensome in terms of trying to source sufficient numbers of batteries, but has currently stopped short of stating that this is not required, only going so far as to say that technical advice from an electronic engineer with military or similar background is required on this point, to make sure that the guidance on this is "right first time."

Manufacturers who wish to start manufacturing emergency ventilators should read the guidance, acquire the relevant standards and also carefully consider whether it has the resources and personnel available now to ensure that efforts are not wasted in meeting the specification.