Recurring concern

Unreliable alarm controls for oxygen therapy

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First reported 24 Nov 2014•Latest report 15 Jan 2026

Definition

What this concern includes

Includes failures in alarms dedicated to monitoring oxygen therapy, including missing or incorrectly configured upper or lower limits, failure to distinguish minor from critical oxygen-delivery problems, inadequate alarm prioritisation, and unreliable reactivation or escalation when an oxygen-related alarm occurs.

Not included

  • Excludes general patient-monitoring alarm failures where oxygen therapy is not the material safety concern.
  • Excludes failures to measure or monitor oxygen saturation where no oxygen-therapy alarm deficiency is identified.
  • Excludes oxygen prescribing, administration, supply or equipment failures that do not concern the alarm control itself.
  • Excludes failures to respond after an oxygen-therapy alarm has operated reliably and clearly.
Reports
4

Distinct published reports

Individual concerns
7

A report can raise multiple concerns

Date range
2014–2026

First to latest report issue date

Stated actions
8

Described in published responses

Reports over time

Reports over time

Reports about this concern issued each year.

* 2026 is projected from reports observed to 7 Sep 2026.

Most frequent recipients

Most frequent recipients

Reports about this concern sent to each recipient.

Betsi Cadwaladr University LHB1
Dolby Vivisol1
Invacare Limited1
Medicines and Healthcare products Regulatory Agency1
NHS England1
Salter Labs1
the Shrewsbury and Telford Hospital NHS Trust1

Concerns and responses across reports

Only concerns grouped under this recurring concern are included. Select any concern, action or position to view the source wording.

  1. Shropshire, Telford and Wrekin

    AI-generated summary

    Margaret Elizabeth GRIMSLEY · Prevention of Future Deaths report

    This summary was generated using AI from the published report. Please read the original report for the complete account.

    Report summary

    Margaret Elizabeth Grimsley was admitted to hospital after a fall at home and died there on 22 January 2025 following an infection during the last 24 to 48 hours of her life. Concerns included the apparent absence or use of an upper alarm setting on a bedside oxygen meter, inconsistencies in evidence about a response to her daughter, and uncertainty about whether an upper alarm could be set or was routinely used.

    Read the report on judiciary.uk

    Source evidence

    How this individual concern was interpreted

    PFD Monitor created a concise, searchable interpretation from the report wording shown below.

    PFD Monitor interpretation

    Failure to establish routine practice of setting upper alarms on bedside oxygen meters

    Wider context from the report

    “(3) It is not clear whether an upper alarm can be set and/or whether it is practice to do so. ”

    Source location

    Margaret Elizabeth GRIMSLEY · Prevention of Future Deaths report
    Page 2 · concerns

    Open source report

    Source evidence

    How this individual concern was interpreted

    PFD Monitor created a concise, searchable interpretation from the report wording shown below.

    PFD Monitor interpretation

    Uncertainty over whether bedside oxygen meters can be set with an upper alarm

    Wider context from the report

    “(3) It is not clear whether an upper alarm can be set and/or whether it is practice to do so. ”

    Source location

    Margaret Elizabeth GRIMSLEY · Prevention of Future Deaths report
    Page 2 · concerns

    Open source report

    Source evidence

    How this individual concern was interpreted

    PFD Monitor created a concise, searchable interpretation from the report wording shown below.

    PFD Monitor interpretation

    Failure to set an upper alarm on bedside oxygen meters

    Wider context from the report

    “(1) The apparent absence of or use of an upper alarm setting on a bedside oxygen meter. The evidence indicated that a lower scale alarm was set, but not an upper alarm which required manual observations and when a nurse or healthcare assistant was carrying out observations. The risk is that over-oxygenation could take place without medical attention being sought. ”

    Source location

    Margaret Elizabeth GRIMSLEY · Prevention of Future Deaths report
    Page 2 · concerns

    Open source report

    Source evidence

    How this respondent position was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Upper oxygen alarms are not used because lower alarms with regular monitoring better address the greater risk of low oxygen levels.

    Verbatim wording from the response

    “The upper alarm is not used as the greatest risk to the patient is low blood oxygen levels. Using the lower alarm in patients with severe lung disease to keep oxygen levels within the required tight range is extremely challenging, and will often require frequent adjustment by the nursing staff to keep the oxygen levels high enough. When considering the poor correlation between oxygen saturations and actual blood levels as well as the higher risk of low oxygen levels, the focus on the ward is the lower alarms with regular monitoring to minimise higher results.”

    Source location

    Response from Shewsbury and Telford Hospital Trust
    Page 2 · response
    Published 21 January 2026

    Open published response
  2. Inner North London

    AI-generated summary

    Chimezie DANIELS · Prevention of Future Deaths report

    This summary was generated using AI from the published report. Please read the original report for the complete account.

    Report summary

    Chimezie Daniels died from SARS CoV-2 infection, with pulmonary sarcoidosis also recorded as a cause. At inquest, concern was raised that CPAP machines may use the same alarm for a minor mask leak and a complete cessation of oxygen supply. Multiple simultaneous alarms in a busy medical ward made it more difficult to identify the cause of Mr Daniels’ low oxygen saturations.

    Read the report on judiciary.uk

    Source evidence

    How this individual concern was interpreted

    PFD Monitor created a concise, searchable interpretation from the report wording shown below.

    PFD Monitor interpretation

    Difficulty determining the cause of low oxygen saturations amid simultaneous CPAP alarms in medical wards

    Wider context from the report

    “At inquest, I heard that on most CPAP machines, the alarm that sounds for a very small leak from the mask is no different from the alarm that sounds for total cessation in oxygen supply. Clinicians told me that it would be much more helpful if very serious matters were denoted by an urgent alarm, and less serious matters in another way. When the alarm on Mr Daniels’ machine sounded, there were four other alarms sounding simultaneously for the four other patients in the bay where he was being nursed. This gave the determination of the cause of his low oxygen saturations an added complexity, particularly at a time in the pandemic when there was so much pressure on beds that CPAP patients were being nursed on medical wards rather than in the high dependency unit. I appreciate that there will not always be an intention to connect to an oxygen supply. Nevertheless, I am sure that further consideration can be given to the issue that the inquest touching Mr Daniels’ death has highlighted. ”

    Source location

    Chimezie DANIELS · Prevention of Future Deaths report
    Page 2 · concerns

    Open source report

    Source evidence

    How this individual concern was interpreted

    PFD Monitor created a concise, searchable interpretation from the report wording shown below.

    PFD Monitor interpretation

    Failure of CPAP alarms to distinguish minor mask leaks from total cessation of oxygen supply

    Wider context from the report

    “At inquest, I heard that on most CPAP machines, the alarm that sounds for a very small leak from the mask is no different from the alarm that sounds for total cessation in oxygen supply. Clinicians told me that it would be much more helpful if very serious matters were denoted by an urgent alarm, and less serious matters in another way. When the alarm on Mr Daniels’ machine sounded, there were four other alarms sounding simultaneously for the four other patients in the bay where he was being nursed. This gave the determination of the cause of his low oxygen saturations an added complexity, particularly at a time in the pandemic when there was so much pressure on beds that CPAP patients were being nursed on medical wards rather than in the high dependency unit. I appreciate that there will not always be an intention to connect to an oxygen supply. Nevertheless, I am sure that further consideration can be given to the issue that the inquest touching Mr Daniels’ death has highlighted. ”

    Source location

    Chimezie DANIELS · Prevention of Future Deaths report
    Page 2 · concerns

    Open source report

    Source evidence

    How this respondent action was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Review the designated medical-equipment alarm standard and its application to alarm severity and prioritisation.

    Verbatim wording from the response

    “1. We reviewed the designated standard available relating to alarms on medical equipment, ‘EN 60601-1-8:2007+A11:2017 Medical electrical equipment, Part 1-8: General requirements for basic safety and essential performance – Collateral Standard: General requirements, tests and guidance for alarm systems in medical electrical equipment and medical electrical systems’. This standard provides guidance to medical device manufacturers on requirements for alarm systems, including how the alarms should sound to allow users to prioritise action by level of risk involved. Philips have confirmed that they used the international (ISO) version of this standard during the design of their product. The text is the same in both standards.”

    Source location

    2021-0255-Response-from-MHRA_Published
    Page 5 · response
    Published 3 August 2021

    Open published response

    Source evidence

    How this respondent action was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Engage respiratory and anaesthesia professional bodies to explore training and healthcare-system measures addressing audible alarm prioritisation.

    Verbatim wording from the response

    “4. We are engaging with the Association of Respiratory Nurse Specialists to explore how the current training programme addresses the issue of audible alarm prioritisation, and whether there may be more actions for the health care system to take to mitigate the risk. We are also engaging with the Royal College of Anaesthetists and Association of Anaesthetists for their input into how this issue can be addressed.”

    Source location

    2021-0255-Response-from-MHRA_Published
    Page 5 · response
    Published 3 August 2021

    Open published response

    Source evidence

    How this respondent action was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Engage with the Faculty for Intensive Care Medicine to include disconnection-alarm guidance addressing alarm indications and response urgency.

    Verbatim wording from the response

    “• The national patient safety team continues to work with the Faculty for Intensive Care Medicine to develop guidance on the setting up of breathing circuits and we will engage with them to include guidance on disconnection alarms to ensure staff are aware of what each alarm may be indicating and the relative urgency to respond to an alarm.”

    Source location

    2021-0255-Response-from-NHS-England-and-NHS-Improvement_Published
    Page 2 · response
    Published 3 August 2021

    Open published response

    Source evidence

    How this respondent action was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Search the MHRA adverse-incident and corrective-action database for comparable ventilator alarm events.

    Verbatim wording from the response

    “A search of the MHRA database of reported adverse incidents and corrective actions relating to all types of ventilators over the past 5 years has not identified any similar reports where an inability to identify the device fault from the audible alarm tone has been reported.”

    Source location

    2021-0255-Response-from-MHRA_Published
    Page 5 · response
    Published 3 August 2021

    Open published response

    Source evidence

    How this respondent position was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    The available evidence does not indicate a wider safety concern involving inability to identify ventilator faults from audible alarm tones.

    Verbatim wording from the response

    “Information supplied by Philips Respironics states they are aware of 11 reports worldwide of events involving alarms which were not acknowledged or addressed during the last 3 years. Of these, 8 involved alarms which were not acknowledged by the caregiver, one concerned a device which alarmed but was not acted upon as the family were on another floor, one involved a patient who went into cardiac arrest before the caregiver acknowledged the alarm, and one involved a patient who desaturated before the caregiver acknowledged the alarm. None of these occurred in the UK and none involved failure of the device.”

    Source location

    2021-0255-Response-from-MHRA_Published
    Page 5 · response
    Published 3 August 2021

    Open published response

    Source evidence

    How this respondent position was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Existing internationally recognised alarm standards, user training and manufacturer guidance sufficiently mitigate residual risks, so wholesale audible alarm redesign is not justified.

    Verbatim wording from the response

    “1. We reviewed the designated standard available relating to alarms on medical equipment, ‘EN 60601-1-8:2007+A11:2017 Medical electrical equipment, Part 1-8: General requirements for basic safety and essential performance – Collateral Standard: General requirements, tests and guidance for alarm systems in medical electrical equipment and medical electrical systems’. This standard provides guidance to medical device manufacturers on requirements for alarm systems, including how the alarms should sound to allow users to prioritise action by level of risk involved. Philips have confirmed that they used the international (ISO) version of this standard during the design of their product. The text is the same in both standards.”

    Source location

    2021-0255-Response-from-MHRA_Published
    Page 5 · response
    Published 3 August 2021

    Open published response

    Source evidence

    How this respondent position was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Changes to CPAP alarm design fall within the Medicines and Healthcare products Regulatory Agency’s remit.

    Verbatim wording from the response

    “The main area of concern that you raised within the Preventing Future Deaths report relates to the alarm sound and whether there should be a different sound for ‘serious matters’. This will require a change in the design of the associated medical devices which would fall into the remit of the Medicines and Healthcare products Regulatory Agency (MHRA).”

    Source location

    2021-0255-Response-from-NHS-England-and-NHS-Improvement_Published
    Page 2 · response
    Published 3 August 2021

    Open published response
  3. North Wales (East and Central)

    AI-generated summary

    Kay Michelle Sheard · Prevention of Future Deaths report

    This summary was generated using AI from the published report. Please read the original report for the complete account.

    Report summary

    Kay Michelle Sheard underwent an outpatient procedure under sedation for removal of gall stones from the bile duct and subsequently suffered cardiorespiratory failure. The report raised concern that pulse oximeter alarm settings were routinely fixed at 85% without taking account of the individual patient’s normal oxygen saturation or the extent of a drop from that baseline.

    Read the report on judiciary.uk

    Source evidence

    How this individual concern was interpreted

    PFD Monitor created a concise, searchable interpretation from the report wording shown below.

    PFD Monitor interpretation

    Failure to set pulse oximeter alarm levels to reflect individual patients’ baseline oxygen saturations

    Wider context from the report

    “During the procedure the Deceased’s oxygen saturations were being monitored by a pulse oximeter for which I was advised that the alarm settings are routinely set at 85%. However all evidence indicated that it was the actual level of reading which would be significant for a patient but rather the amount by which saturations had dropped from the patient’s normal base level. Notwithstanding this, the evidence indicated that this would not be taken into account when fixing an alarm setting level and I am therefore concerned that there exists a potential risk to patients which could be reduced or eliminated by ensuring that the alarm level correctly reflects the individual patient’s condition. ”

    Source location

    Kay Michelle Sheard · Prevention of Future Deaths report
    Page 1 · concerns

    Open source report

    Source evidence

    How this respondent action was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Check pulse oximeter alarm settings across approximately 1,200 devices.

    Verbatim wording from the response

    “Since receiving the report BCU has done a significant amount of work in reviewing device holdings, checking device settings, and scoping the Action Plan for an inventory of approximately 1200 devices of varying complexity across the Health Board.”

    Source location

    Kay-Sheard-Response
    Page 1 · response
    Published 21 December 2015

    Open published response

    Source evidence

    How this respondent action was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Scope an action plan addressing pulse oximeter alarm-level safety.

    Verbatim wording from the response

    “Since receiving the report BCU has done a significant amount of work in reviewing device holdings, checking device settings, and scoping the Action Plan for an inventory of approximately 1200 devices of varying complexity across the Health Board.”

    Source location

    Kay-Sheard-Response
    Page 1 · response
    Published 21 December 2015

    Open published response

    Source evidence

    How this respondent action was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Raise pulse oximeter alarm-setting issues at Welsh and UK level through the MHRA.

    Verbatim wording from the response

    “A number of national and international bodies have produced guidelines on pulse oximetry. The Health Board has a significant amount of work to do on this issue, noting that pulse oximetry is used so widely, by so many different staff, in different clinical situations. However, our inquiries indicate that this issue also extends beyond the Health Board to the manufacturers, who install default alarm levels in their products, and the extent to which they support and facilitate user adjustment of alarm levels. Accordingly there are likely to be issues to be considered beyond BCU Health Board, and we will raise these both at Wales level, and at UK level through the MHRA (Medicines and Healthcare products Regulatory Agency).”

    Source location

    Kay-Sheard-Response
    Page 1 · response
    Published 21 December 2015

    Open published response

    Source evidence

    How this respondent position was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Some pulse oximetry alarm-setting issues concern manufacturers and should be addressed through Wales- and UK-level channels, including the MHRA.

    Verbatim wording from the response

    “A number of national and international bodies have produced guidelines on pulse oximetry. The Health Board has a significant amount of work to do on this issue, noting that pulse oximetry is used so widely, by so many different staff, in different clinical situations. However, our inquiries indicate that this issue also extends beyond the Health Board to the manufacturers, who install default alarm levels in their products, and the extent to which they support and facilitate user adjustment of alarm levels. Accordingly there are likely to be issues to be considered beyond BCU Health Board, and we will raise these both at Wales level, and at UK level through the MHRA (Medicines and Healthcare products Regulatory Agency).”

    Source location

    Kay-Sheard-Response
    Page 1 · response
    Published 21 December 2015

    Open published response
  4. Surrey

    AI-generated summary

    Gaenor Moore · Prevention of Future Deaths report

    This summary was generated using AI from the published report. Please read the original report for the complete account.

    Report summary

    Gaenor Moore, who had chronic obstructive pulmonary disease and required an oxygen concentrator with humidifier, became breathless, deteriorated and died at her residential care home after the humidifier cap was not properly engaged, preventing oxygen flow to her nasal cannula. Concerns included the absence of a visual or audible alarm to indicate loss of oxygen flow and training and literature that did not explain the implications of failing to properly engage the humidifier cap.

    Read the report on judiciary.uk

    Source evidence

    How this individual concern was interpreted

    PFD Monitor created a concise, searchable interpretation from the report wording shown below.

    PFD Monitor interpretation

    Absence of a visual or audible alarm indicating loss of oxygen flow to the nasal cannula

    Wider context from the report

    “• The lack of oxygen flow to the nasal cannula as a result of the screw cap to the humidifier not being properly engaged. • Absence of a visual or audible alarm on concentrator machine (product number INV-IRC5PO2AWN) to indicate the loss of oxygen flow to the nasal cannula when the screw cap to the humidifier (manufactured by Salter Labs) was tightened and cross threaded. • Accompanying training and literature did not reference the implications to oxygen flow in the event of failing to properly engage the screw cap to the humidifier. ”

    Source location

    Gaenor Moore · Prevention of Future Deaths report
    Page 2 · concerns

    Open source report

    Source evidence

    How this respondent action was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Assess whether an alarm can detect oxygen-flow loss caused by an improperly engaged humidifier cap.

    Verbatim wording from the response

    “Invacare has however still given consideration to whether it is possible to have either a visual or audible alarm on the concentrator machine that detects the loss of oxygen flow when the humidifier cap is not properly engaged. The company has concluded that as a responsible organisation it has properly assessed the risks to the intended user and has appropriate alarms in place to counter these. Further, it has concluded that an alarm to indicate loss at the humidifier point would be technically complex such that it would introduce unacceptable risks and inconvenience to the end user without any benefits to counter or justify them. Examples of these are:”

    Source location

    2014-0512-Response-by-Invacare
    Page 3 · response
    Published 24 November 2014

    Open published response

    Source evidence

    How this respondent position was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    The humidifier’s existing safety valve and leak-test instructions provide warnings for blockages and leaks, including cross-threading-related leaks.

    Verbatim wording from the response

    “2. Absence of a visual or audible alarm on concentrator machine (product number INV-IRCSPO2AWN) to indicate the loss of oxygen flow to the nasal cannula when the screw cap to the humidifier (manufactured by Salter Labs) was tightened and cross threaded.”

    Source location

    2014-0512-Response-by-Salter-Labs
    Page 3 · response
    Published 24 November 2014

    Open published response

    Source evidence

    How this respondent position was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    The concentrator manufacturer is responsible for addressing the absence of a visual or audible alarm for lost oxygen flow.

    Verbatim wording from the response

    “2. Absence of a visual or audible alarm on concentrator machine (product number INV-IRCSPO2AWN) to indicate the loss of oxygen flow to the nasal cannula when the screw cap to the humidifier (manufactured by Salter Labs) was tightened and cross threaded.”

    Source location

    2014-0512-Response-by-Salter-Labs
    Page 3 · response
    Published 24 November 2014

    Open published response

    Source evidence

    How this respondent position was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Equipment manufacture and design concerns fall outside the company’s functions, so it cannot respond to them.

    Verbatim wording from the response

    “As stated above, the Company cannot respond on points relating to the manufacture or design of the Equipment. Concerns about these issues should properly be addressed by the manufacturer of the oxygen concentrator and/or humidifier (Invacare (UK) Limited and Salter Labs respectively).”

    Source location

    2014-0512-Response-by-Dolby-Vivsol
    Page 2 · response
    Published 24 November 2014

    Open published response

    Source evidence

    How this respondent position was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Equipment manufacture and design concerns should be addressed by the relevant manufacturers, Invacare and Salter Labs.

    Verbatim wording from the response

    “As stated above, the Company cannot respond on points relating to the manufacture or design of the Equipment. Concerns about these issues should properly be addressed by the manufacturer of the oxygen concentrator and/or humidifier (Invacare (UK) Limited and Salter Labs respectively).”

    Source location

    2014-0512-Response-by-Dolby-Vivsol
    Page 2 · response
    Published 24 November 2014

    Open published response

    Source evidence

    How this respondent position was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    Existing alarms detect relevant concentrator faults, comply with applicable standards, and are considered sufficient without additional alarms.

    Verbatim wording from the response

    “The alarms presently on Invacare’s concentrator unit are in place to properly detect the output of oxygen from the unit itself and issues such as power failures, degradation of oxygen quality, blockages in the tubes and overheating of the appliance.”

    Source location

    2014-0512-Response-by-Invacare
    Page 3 · response
    Published 24 November 2014

    Open published response

    Source evidence

    How this respondent position was interpreted

    PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

    PFD Monitor interpretation

    An alarm detecting oxygen loss at the humidifier would be technically complex and introduce unacceptable risks and inconvenience without sufficient benefit.

    Verbatim wording from the response

    “Invacare has however still given consideration to whether it is possible to have either a visual or audible alarm on the concentrator machine that detects the loss of oxygen flow when the humidifier cap is not properly engaged. The company has concluded that as a responsible organisation it has properly assessed the risks to the intended user and has appropriate alarms in place to counter these. Further, it has concluded that an alarm to indicate loss at the humidifier point would be technically complex such that it would introduce unacceptable risks and inconvenience to the end user without any benefits to counter or justify them. Examples of these are:”

    Source location

    2014-0512-Response-by-Invacare
    Page 3 · response
    Published 24 November 2014

    Open published response
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Data last updated 7 September 2026