Critical IllnessEXAKTNCT05481515
Exploring Pulse OXimeter Accuracy Across SKin Tones
An observational study of Critical Illness and Hypoxemia, run by Intensive Care National Audit & Research Centre at 1 site in United Kingdom.
Trial summary
This study within a trial (SWAT) will be a sub-study of the UK-ROX trial (ISRCTN13384956), which is currently running in intensive care units across the UK. UK-ROX is large-scale randomised controlled trial evaluating conservative oxygen therapy (a target SpO2 of 88-92%) versus usual oxygen therapy in mechanically… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Critical Illness, Hypoxemia
- What is being tested?
- Pulse oximetry and Spectrophotometry
- Type of treatment
- Medical device
- How many people
- 903 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 24 Jun 2022to 31 Oct 2024
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult patients admitted to an ICU who require mechanical ventilation and supplemental oxygen.
Who may be able to join
- Adult (aged ≥18 years)
- Receiving invasive mechanical ventilation in the ICU following an unplanned ICU admission OR invasive mechanical ventilation started in the ICU (i.e. the patient was intubated in the ICU).
- Receiving supplemental oxygen (> 21% oxygen) at the time of enrolment
Who cannot join
- The clinician considers that one study treatment arm is either indicated or contraindicated.
- In order in increase the number of patients eligible for this observational diagnostic accuracy study, we will have also received ethical approval to enrol mechanically ventilated adult patients who have been screened for, but not enrolled into, the UK-ROX trial. These may include patients who missed the 12 hour recruitment window for the main trial and patients in whom the clinical team decided that one study treatment arm is either indicated or contraindicated.
Trial locations and contacts
1 site in 1 country.
United Kingdom1 site
Intensive Care National Audit and Research Centre
London, London, WC1V 6AZ
About this study
Official title: A Study Within a Trial to Determine the Effect of Skin Tone on the Diagnostic Accuracy of Pulse Oximeters
This study within a trial (SWAT) will be a sub-study of the UK-ROX trial (ISRCTN13384956), which is currently running in intensive care units across the UK. UK-ROX is large-scale randomised controlled trial evaluating conservative oxygen therapy (a target SpO2 of 88-92%) versus usual oxygen therapy in mechanically ventilated adult patients admitted to ICUs in the UK. The purpose of this observational sub-study is to compare pulse oximeter-derived peripheral oxygen saturation (SpO2) values to co-oximeter-derived arterial oxygen saturation (SaO2) measurements from arterial blood gas (ABG) samples, for a range of fingertip pulse oximeters in an ethnically diverse group of adult patients admitted to UK intensive care units (ICUs). Approximately 900 patients will be recruited over 12 month period from 24 sites to provide an anticipated 10,800 paired SpO2 and SaO2 measurements. Patient skin tone will be objectively measured using a handheld spectrophotometer. Data from the sub-study will be used to determine the accuracy of the tested pulse oximeters across a range of skin tones and arterial oxygenation levels.
Read the detailed description
Research question: What is the diagnostic accuracy of different pulse oximeters at peripheral oxygen saturation levels (SpO2) relevant to their use by patients at home and how does this vary in people with darker skin pigmentation?
Primary objective: To compare pulse oximeter-derived SpO2 values to co-oximeter-derived arterial oxygen saturation (SaO2) measurements from arterial blood gas (ABG) samples, for a range of fingertip pulse oximeters in an ethnically diverse group of adult patients with a broad spectrum of skin tones admitted to UK intensive care units (ICUs).
Design: This study within a trial (SWAT) that will form an observational sub-study of the NIHR HTA funded UK-ROX trial (https://fundingawards.nihr.ac.uk/award/NIHR130508), which is currently running in ICUs across the UK. Twenty four ICUs enrolling patients into the UK-ROX trial trial will be randomly allocated two brands of pulse oximeter to evaluate. Over a period of 24 hours for each participant, SpO2 values from the test pulse oximeters will be compared to simultaneous SaO2 values from ABG samples analysed on a standard ICU ABG co-oximeter machine. Patient skin tone will be objectively measured using a handheld spectrophotometer. The difference between SpO2 and SaO2 will be compared across skin tones and across a range of arterial oxygenation levels.
Setting: The UK-ROX trial is large-scale, multi-centre, data-enabled, registry embedded randomised controlled trial (RCT) evaluating conservative oxygen therapy (a target SpO2 of 88-92%) versus usual oxygen therapy in mechanically ventilated adult patients admitted to ICUs in the United Kingdom.
Target population: 900 mechanically ventilated adults screened for enrolment into the UK-ROX trial.
Primary outcome: The accuracy of SpO2 measurement in the evaluated pulse oximeters, validated against co-oximeter-derived SaO2 ABG sample analysis.
- Conditions
- Critical Illness, Hypoxemia
- Being tested
- Pulse oximetry, Spectrophotometry
- Medical subject headings
- Critical Illness, Hypoxia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Pulse oximetryDevice
Pulse oximeters will be evaluated against routine arterial blood gas measurements
SpectrophotometryDevice
Spectrophotometry will be used to measure skin tone
| Study group | Role | What they receive |
|---|---|---|
| Critically ill adults | Adult patients admitted to an intensive care unit who require mechanical ventilation and supplemental oxygen Receives: Device: Pulse oximetry; Device: Spectrophotometry |
What is being measured
The primary outcome is the main question the study is designed to answer.
Accuracy of SpO2 measurements
Accuracy of SpO2 measurement, validated against co-oximeter derived SaO2 arterial blood gas analysis (calculated as SpO2 minus paired SaO2)
Measured: Over 24 hour observation window
Secondary outcomes (2)
Detection of hypoxaemia
Diagnostic accuracy (area under the receiver operating characteristic curve and sensitivity and specificity at relevant cut-points) for SpO2 as a predictor of SaO2 ≤ 92%.
Measured: Over 24 hour observation window
Detection of occult hypoxaemia
The presence of an SaO2 < 88% among participants with a paired SpO2 reading of >92%
Measured: Over 24 hour observation window
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted1 Aug 2022
- Study start24 Jun 2022
- Primary completion15 Aug 2024
- Study completion31 Oct 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Critical IllnessStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 903 participants (actual)
Sponsor and investigators
- Lead sponsor
- Intensive Care National Audit & Research Centre
- Sponsor type
- University, hospital or other
- Collaborators
- Lewisham Council, Centre Ethnic Health Research
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05481515
- Sponsor's protocol ID
- EXAKT Sub-Study
- Acronym
- EXAKT
- Status last verified
- Mar 2025
- First submitted
- 22 Jul 2022
- Last updated
- 12 Mar 2025
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: If requested, we aim to make the IPD data available to other investigators. This will include anonymised data related to the accuracy of the tested pulse oximeters.
Publications
Martin DS, Doidge JC, Gould D, Shahid T, Cowden A, Charles WN, Francis Johnson A, Garrett R, Mbema C, Olusanya O, Healy E, Rowan K, Mouncey P, Harrison DA; EXAKT Study Investigators. The impact of skin tone on performance of pulse oximeters used by NHS England COVID Oximetry @home scheme: measurement and diagnostic accuracy study. BMJ. 2026 Jan 14;392:e085535. doi: 10.1136/bmj-2025-085535.
PubMed 41534914
Study at a glance
From the registry record, last updated by the sponsor on 12 Mar 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Study Within a Trial to Determine the Effect of Skin Tone on the Diagnostic Accuracy of Pulse Oximeters
- ClinicalTrials.gov ID
- NCT05481515
- Acronym / sponsor ID
- EXAKT / EXAKT Sub-Study
- Conditions
- Critical Illness, Hypoxemia
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 903 participants (actual)
- Lead sponsor
- Intensive Care National Audit & Research CentreUniversity, hospital or other
- Collaborators
- Lewisham Council, Centre Ethnic Health Research
- Study start
- 24 Jun 2022 (actual)
- Primary completion
- 15 Aug 2024 (actual)
- Study completion
- 31 Oct 2024 (actual)
- First posted
- 1 Aug 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study within a trial (SWAT) will be a sub-study of the UK-ROX trial (ISRCTN13384956), which is currently running in intensive care units across the UK. UK-ROX is large-scale randomised controlled trial evaluating conservative oxygen therapy (a target SpO2 of 88-92%) versus usual oxygen therapy in mechanically ventilated adult patients admitted to ICUs in the UK. The purpose of this observational sub-study is to compare pulse oximeter-derived peripheral oxygen saturation (SpO2) values to co-oximeter-derived arterial oxygen saturation (SaO2) measurements from arterial blood gas (ABG) samples, for a range of fingertip pulse oximeters in an ethnically diverse group of adult patients admitted to UK intensive care units (ICUs). Approximately 900 patients will be recruited over 12 month period from 24 sites to provide an anticipated 10,800 paired SpO2 and SaO2 measurements. Patient skin tone will be objectively measured using a handheld spectrophotometer. Data from the sub-study will be used to determine the accuracy of the tested pulse oximeters across a range of skin tones and arterial oxygenation levels.
Detailed description
Research question: What is the diagnostic accuracy of different pulse oximeters at peripheral oxygen saturation levels (SpO2) relevant to their use by patients at home and how does this vary in people with darker skin pigmentation?
Primary objective: To compare pulse oximeter-derived SpO2 values to co-oximeter-derived arterial oxygen saturation (SaO2) measurements from arterial blood gas (ABG) samples, for a range of fingertip pulse oximeters in an ethnically diverse group of adult patients with a broad spectrum of skin tones admitted to UK intensive care units (ICUs).
Design: This study within a trial (SWAT) that will form an observational sub-study of the NIHR HTA funded UK-ROX trial (https://fundingawards.nihr.ac.uk/award/NIHR130508), which is currently running in ICUs across the UK. Twenty four ICUs enrolling patients into the UK-ROX trial trial will be randomly allocated two brands of pulse oximeter to evaluate. Over a period of 24 hours for each participant, SpO2 values from the test pulse oximeters will be compared to simultaneous SaO2 values from ABG samples analysed on a standard ICU ABG co-oximeter machine. Patient skin tone will be objectively measured using a handheld spectrophotometer. The difference between SpO2 and SaO2 will be compared across skin tones and across a range of arterial oxygenation levels.
Setting: The UK-ROX trial is large-scale, multi-centre, data-enabled, registry embedded randomised controlled trial (RCT) evaluating conservative oxygen therapy (a target SpO2 of 88-92%) versus usual oxygen therapy in mechanically ventilated adult patients admitted to ICUs in the United Kingdom.
Target population: 900 mechanically ventilated adults screened for enrolment into the UK-ROX trial.
Primary outcome: The accuracy of SpO2 measurement in the evaluated pulse oximeters, validated against co-oximeter-derived SaO2 ABG sample analysis.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Critically ill adults | – | Device: Pulse oximetry, Device: SpectrophotometryAdult patients admitted to an intensive care unit who require mechanical ventilation and supplemental oxygen |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult patients admitted to an ICU who require mechanical ventilation and supplemental oxygen.
Key inclusion criteria (3 listed)
- Adult (aged ≥18 years)
- Receiving invasive mechanical ventilation in the ICU following an unplanned ICU admission OR invasive mechanical ventilation started in the ICU (i.e. the patient was intubated in the ICU).
- Receiving supplemental oxygen (> 21% oxygen) at the time of enrolment
Key exclusion criteria (2 listed)
- The clinician considers that one study treatment arm is either indicated or contraindicated.
- In order in increase the number of patients eligible for this observational diagnostic accuracy study, we will have also received ethical approval to enrol mechanically ventilated adult patients who have been screened for, but not enrolled into, the UK-ROX trial. These may include patients who missed the 12 hour recruitment window for the main trial and patients in whom the clinical team decided that one study treatment arm is either indicated or contraindicated.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Pulse oximetryPulse oximeters will be evaluated against routine arterial blood gas measurements | Device | Critically ill adults |
| SpectrophotometrySpectrophotometry will be used to measure skin tone | Device | Critically ill adults |
Primary outcome
Accuracy of SpO2 measurements
Time frame: Over 24 hour observation window
Accuracy of SpO2 measurement, validated against co-oximeter derived SaO2 arterial blood gas analysis (calculated as SpO2 minus paired SaO2)
2 secondary outcomes
Detection of hypoxaemia
Time frame: Over 24 hour observation window
Detection of occult hypoxaemia
Time frame: Over 24 hour observation window
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 12 Mar 2025.
- Derived from this study: PubMed 41534914Martin DS, Doidge JC, Gould D, Shahid T, Cowden A, Charles WN, Francis Johnson A, Garrett R, Mbema C, Olusanya O, Healy E, Rowan K, Mouncey P, Harrison DA; EXAKT Study Investigators. The impact of skin tone on performance of pulse oximeters used by NHS England COVID Oximetry @home scheme: measurement and diagnostic accuracy study. BMJ. 2026 Jan 14;392:e085535. doi: 10.1136/bmj-2025-085535.
- Individual participant dataSharing planned: Undecided. If requested, we aim to make the IPD data available to other investigators. This will include anonymised data related to the accuracy of the tested pulse oximeters.
Related trials for Critical Illness
Recruiting
KInetics of Procalcitonin to Reduce Unnecessary aNtibiotic Use - Comparing Procalcitonin Kinetics-guided and Absolute Procalcitonin Value-guided Antibiotic Initiation in Reducing Unnecessary Antibiotic Use in Critically Ill Patients
Infection, Sepsis
Not yet recruitingObservational study
Capillary Refill Time Variation to Predict Oxygen Comsumption Variation After FLuid Challenge (CARTOFL)
Critically Ill Patients, Circulatory Shock
RecruitingPhase 4
CONTinuous Infusion Versus Intermittent Dosing of ceftaZidime/AVIbactam in Critically Ill Patients
Severe Infection
Not yet recruitingObservational study
Lactate/Albumin Ratio and Mortality in Respiratory Failure
Acute Respiratory Failure, Critical Illness
RecruitingObservational study
Respiratory Physiotherapy and Inflammatory Biomarkers in Critically Ill Patients With Pneumonia
Pneumonia, Critical Illness
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Critical Illness and Hypoxemia, run by Intensive Care National Audit & Research Centre at 1 site in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 12 Mar 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Accuracy of SpO2 measurements (time frame: Over 24 hour observation window). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05481515, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 12 Mar 2025.