HypoxemiaNCT03628560
Alternate Methodology of Pulse Oximeter Validation
A study testing RespirAct Step-Wise Normocapnia desaturation sequence, RespirAct Slope Normocapnia desaturation sequence and RespirAct Step-Wise Hypocapnia desaturation sequence in people with Hypoxemia and Desaturation of Blood, run by Duke University at 1 site in United States.
Trial summary
This study will determine if the replacement of the measured arterial blood oxygen saturation with expired (end-tidal) oxygen value is an acceptable method to calculate the accuracy of pulse oximeters. Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Hypoxemia, Desaturation of Blood
- What is being tested?
- RespirAct Step-Wise Normocapnia desaturation sequence, RespirAct Slope Normocapnia desaturation sequence and RespirAct Step-Wise Hypocapnia desaturation sequence
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 2 participants
- Where
- 1 siteUnited States
- Study dates
- 26 Sep 2018to 3 Jan 2019
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
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 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Aged 18 - 50 years
- Subject is willing to provide written informed consent and is able to comply with anticipated study procedures
Who cannot join
- Body Mass Index (BMI) < 18.0 or > 30.0
- Known significant respiratory, cardiovascular or medical condition that precludes study participation as judged by investigator
- Anemia [hemoglobin value below lower range of normal for gender]
- Abnormal hemoglobin electrophoresis result
- Exposure to nicotine [positive test at screening or study day]
- Abnormal drug screen [positive test at screening or on day of study]
Show all 12Show fewer
- Positive pregnancy test for females [serum test at screening; urine test on study day]
- Abnormal Allen's test for collateral circulation
- Abnormal Electrocardiogram
- Abnormal Pulmonary Function Test
- Abnormal venous blood gas result
- Intolerance of facemask
Trial locations and contacts
1 site in 1 country.
About this study
This study will determine if the replacement of the measured arterial blood oxygen saturation with expired (end-tidal) oxygen value is an acceptable method to calculate the accuracy of pulse oximeters.
Read the detailed description
Pulse oximeters are non-invasive devices that use light to display an estimate (denoted by SpO2) of the true arterial blood oxygen saturation (SaO2). The accuracy of the pulse oximeter is determined from desaturation sequences (reduction in SpO2 from 100 to 70%) performed in healthy volunteers. The current standard desaturation sequence is a step-wise reduction in 5% SpO2 increments, achieved by reduction in inspired oxygen delivered by a gas blender such as the ROBD (Reduced Oxygen Breathing Device). This mixes oxygen and nitrogen (components of air) to produce the desired gas mixture. Throughout the desaturation sequence arterial blood gas samples are drawn at each step. The blood gas samples are processed through a co-oximeter to measure the SaO2. For each SaO2 measurement there will be a corresponding SpO2 recorded. All data points from all subjects are amalgamated together to allow calculation of how well SpO2 corresponds to the SaO2 throughout the range of 70 - 100% oxygen saturation. Accuracy, A[RMS], is the unit of measure and this incorporates both bias and precision.
When the ROBD is used in a desaturation sequence, the subjects' arterial blood carbon dioxide (CO2) level will initially be normal (normocapnia). With the reduction in SpO2 during the desaturation sequence, the subjects' breathing rate will increase and this will cause the a physiological reduction in the blood CO2 value (hypocapnia). The extent of hypocapnia will vary from one subject to another. It is not known whether the presence of hypocapnia may have an effect upon the accuracy measurement.
The RespirAct is a gas blender which, in contrast to the ROBD, can control both the oxygen level as well as the carbon dioxide level. The end-tidal oxygen level (PAO2) is continuously displayed by the RespirAct during the desaturation sequence. The PAO2 closely approximates to arterial blood oxygen (PaO2) - the degree of closeness will be measured in the study. Through an accepted formula, the SaO2 can be derived from the measured PAO2. The derived SaO2 values can subsequently be used to measure the accuracy of the pulse oximeter. This A[RMS] can then be compared with the A[RMS] calculated from the blood gas co-oximeter PaO2 / SaO2 values. If the accuracies are comparable then this would remove the need for arterial line placement during pulse oximeter validation studies.
Eligible healthy volunteers will complete five (5) oxygen desaturation sequences with adjustment of sequence type and/or CO2 level. Two sequences will be delivered by step-wise reduction and two will be delivered by gradual slope. Two sequences will be delivered at normocapnia and two will be delivered at hypocapnia values. The ROBD sequence will be a step-wise reduction with CO2 value set by the subjects' own breathing control.
- Conditions
- Hypoxemia, Desaturation of Blood
- Being tested
- RespirAct Step-Wise Normocapnia desaturation sequence, RespirAct Slope Normocapnia desaturation sequence, RespirAct Step-Wise Hypocapnia desaturation sequence, RespirAct Slope Hypocapnia desaturation sequence, ROBD Step-Wise desaturation sequence
- Keywords
- Healthy volunteer, Oximetry, Pulse oximeter, Hypoxia
- Medical subject headings
- Hypoxia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
RespirAct Step-Wise Normocapnia desaturation sequenceDevice
Blood carbon dioxide controlled at normal value (normocapnia).
RespirAct Slope Normocapnia desaturation sequenceDevice
Blood carbon dioxide controlled at normal value (normocapnia).
RespirAct Step-Wise Hypocapnia desaturation sequenceDevice
Blood carbon dioxide controlled at lower than normal value (hypocapnia).
RespirAct Slope Hypocapnia desaturation sequenceDevice
Blood carbon dioxide controlled at lower than normal value (hypocapnia).
ROBD Step-Wise desaturation sequenceDevice
Blood carbon dioxide is controlled at normal or lower value by subject's own breathing rate.
| Study group | Role | What they receive |
|---|---|---|
| RespirAct Step-Wise Normocapnia desaturation sequence | Experimental | Reduction in oxygen saturation 100 to 70% in approximate 5% steps. Receives: Device: RespirAct Step-Wise Normocapnia desaturation sequence |
| RespirAct Slope Normocapnia desaturation sequence | Experimental | Reduction in oxygen saturation 100 to 70% as gradual slope. Receives: Device: RespirAct Slope Normocapnia desaturation sequence |
| RespirAct Step-Wise Hypocapnia desaturation sequence | Experimental | Reduction in oxygen saturation 100 to 70% in approximate 5% steps. Receives: Device: RespirAct Step-Wise Hypocapnia desaturation sequence |
| RespirAct Slope Hypocapnia desaturation sequence | Experimental | Reduction in oxygen saturation 100 to 70% as gradual slope. Receives: Device: RespirAct Slope Hypocapnia desaturation sequence |
| ROBD Step-Wise desaturation sequence | Active comparator | ROBD = Reduced Oxygen Breathing Device. Reduction in oxygen saturation 100 to 70% in approximate 5% steps. This represents the standard type of desaturation sequence for pulse oximeter accuracy testing. Receives: Device: ROBD Step-Wise desaturation sequence |
What is being measured
The primary outcome is the main question the study is designed to answer.
Accuracy of FDA-approved Pulse Oximeter When Calculated With RespirAct-derived End-tidal PAO2 Values
The unit of measure of accuracy is called Accuracy Root Mean Square Error (A[RMS]) and is a composite value of bias and precision. A[RMS] is reported as a single percentage value representing the overall accuracy of a medical device with lower values indicating better performance.
Measured: 1 study day
Accuracy of FDA-approved Pulse Oximeter When Calculated With Co-oximeter Measured Arterial PaO2 Values
The unit of measure of accuracy is called Accuracy Root Mean Square Error (A[RMS]) and is a composite value of bias and precision. A[RMS] is reported as a single percentage value representing the overall accuracy of a medical device with lower values indicating better performance.
Measured: 1 study day
PAO2 Values
A[RMS] of RespirAct-derived end-tidal PAO2 values with co-oximeter measured arterial PaO2 values. The unit of measure of accuracy is called Accuracy Root Mean Square Error (A[RMS]) and is a composite value of bias and precision. A[RMS] is reported as a single percentage value representing the overall accuracy of a medical device with lower values indicating better performance.
Measured: 1 study day
Secondary outcomes (2)
Accuracy, A[RMS], When a Step-wise Desaturation Sequence is Used Against a Slope Desaturation Sequence.
The unit of measure of accuracy is called Accuracy Root Mean Square Error (A[RMS]) and is a composite value of bias and precision. A[RMS] is reported as a single percentage value representing the overall accuracy of a medical device with lower values indicating better performance.
Measured: 1 study day
Level of PaCO2 (Hypocapnia Versus Normocapnia)
A[RMS] when hypocapnia desaturation is compared to normocapnia desaturation. A[RMS] is reported as a single percentage value representing the overall accuracy of a medical device with lower values indicating better performance.
Measured: 1 study day
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Aug 2018
- Study start26 Sep 2018
- Primary completion2 Jan 2019
- Study completion3 Jan 2019
Why it stopped: Limited staff availability
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for HypoxemiaStudies of the same condition, open and under way.
- More trials run by Duke UniversityThe sponsor's other registered studies.
- 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 2 participants (actual)
Sponsor and investigators
- Lead sponsor
- Duke University
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- David B MacLeod, FRCA, Principal investigator, Duke University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03628560
- Sponsor's protocol ID
- Pro00100105
- Status last verified
- Mar 2023
- First submitted
- 9 Aug 2018
- Last updated
- 11 Aug 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 11 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Alternate Methodology of Pulse Oximeter Validation
- ClinicalTrials.gov ID
- NCT03628560
- Acronym / sponsor ID
- Pro00100105
- Conditions
- Hypoxemia, Desaturation of Blood
- Keywords
- Healthy volunteer, Oximetry, Pulse oximeter, Hypoxia
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: Limited staff availability
- Enrolment
- 2 participants (actual)
- Lead sponsor
- Duke UniversityUniversity, hospital or other
- Study start
- 26 Sep 2018 (actual)
- Primary completion
- 2 Jan 2019 (actual)
- Study completion
- 3 Jan 2019 (actual)
- First posted
- 14 Aug 2018 (actual)
- Results
- Posted 11 Aug 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study will determine if the replacement of the measured arterial blood oxygen saturation with expired (end-tidal) oxygen value is an acceptable method to calculate the accuracy of pulse oximeters.
Detailed description
Pulse oximeters are non-invasive devices that use light to display an estimate (denoted by SpO2) of the true arterial blood oxygen saturation (SaO2). The accuracy of the pulse oximeter is determined from desaturation sequences (reduction in SpO2 from 100 to 70%) performed in healthy volunteers. The current standard desaturation sequence is a step-wise reduction in 5% SpO2 increments, achieved by reduction in inspired oxygen delivered by a gas blender such as the ROBD (Reduced Oxygen Breathing Device). This mixes oxygen and nitrogen (components of air) to produce the desired gas mixture. Throughout the desaturation sequence arterial blood gas samples are drawn at each step. The blood gas samples are processed through a co-oximeter to measure the SaO2. For each SaO2 measurement there will be a corresponding SpO2 recorded. All data points from all subjects are amalgamated together to allow calculation of how well SpO2 corresponds to the SaO2 throughout the range of 70 - 100% oxygen saturation. Accuracy, A[RMS], is the unit of measure and this incorporates both bias and precision.
When the ROBD is used in a desaturation sequence, the subjects' arterial blood carbon dioxide (CO2) level will initially be normal (normocapnia). With the reduction in SpO2 during the desaturation sequence, the subjects' breathing rate will increase and this will cause the a physiological reduction in the blood CO2 value (hypocapnia). The extent of hypocapnia will vary from one subject to another. It is not known whether the presence of hypocapnia may have an effect upon the accuracy measurement.
The RespirAct is a gas blender which, in contrast to the ROBD, can control both the oxygen level as well as the carbon dioxide level. The end-tidal oxygen level (PAO2) is continuously displayed by the RespirAct during the desaturation sequence. The PAO2 closely approximates to arterial blood oxygen (PaO2) - the degree of closeness will be measured in the study. Through an accepted formula, the SaO2 can be derived from the measured PAO2. The derived SaO2 values can subsequently be used to measure the accuracy of the pulse oximeter. This A[RMS] can then be compared with the A[RMS] calculated from the blood gas co-oximeter PaO2 / SaO2 values. If the accuracies are comparable then this would remove the need for arterial line placement during pulse oximeter validation studies.
Eligible healthy volunteers will complete five (5) oxygen desaturation sequences with adjustment of sequence type and/or CO2 level. Two sequences will be delivered by step-wise reduction and two will be delivered by gradual slope. Two sequences will be delivered at normocapnia and two will be delivered at hypocapnia values. The ROBD sequence will be a step-wise reduction with CO2 value set by the subjects' own breathing control.
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 5
| Arm | Type | Receives |
|---|---|---|
| RespirAct Step-Wise Normocapnia desaturation sequence | Experimental | Device: RespirAct Step-Wise Normocapnia desaturation sequenceReduction in oxygen saturation 100 to 70% in approximate 5% steps. |
| RespirAct Slope Normocapnia desaturation sequence | Experimental | Device: RespirAct Slope Normocapnia desaturation sequenceReduction in oxygen saturation 100 to 70% as gradual slope. |
| RespirAct Step-Wise Hypocapnia desaturation sequence | Experimental | Device: RespirAct Step-Wise Hypocapnia desaturation sequenceReduction in oxygen saturation 100 to 70% in approximate 5% steps. |
| RespirAct Slope Hypocapnia desaturation sequence | Experimental | Device: RespirAct Slope Hypocapnia desaturation sequenceReduction in oxygen saturation 100 to 70% as gradual slope. |
| ROBD Step-Wise desaturation sequence | Active comparator | Device: ROBD Step-Wise desaturation sequenceROBD = Reduced Oxygen Breathing Device. Reduction in oxygen saturation 100 to 70% in approximate 5% steps. This represents the standard type of desaturation sequence for pulse oximeter accuracy testing. |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (2 listed)
- Aged 18 - 50 years
- Subject is willing to provide written informed consent and is able to comply with anticipated study procedures
Key exclusion criteria (12 listed)
- Body Mass Index (BMI) < 18.0 or > 30.0
- Known significant respiratory, cardiovascular or medical condition that precludes study participation as judged by investigator
- Anemia [hemoglobin value below lower range of normal for gender]
- Abnormal hemoglobin electrophoresis result
- Exposure to nicotine [positive test at screening or study day]
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 |
|---|---|---|
| RespirAct Step-Wise Normocapnia desaturation sequenceBlood carbon dioxide controlled at normal value (normocapnia). | Device | RespirAct Step-Wise Normocapnia desaturation sequence |
| RespirAct Slope Normocapnia desaturation sequenceBlood carbon dioxide controlled at normal value (normocapnia). | Device | RespirAct Slope Normocapnia desaturation sequence |
| RespirAct Step-Wise Hypocapnia desaturation sequenceBlood carbon dioxide controlled at lower than normal value (hypocapnia). | Device | RespirAct Step-Wise Hypocapnia desaturation sequence |
| RespirAct Slope Hypocapnia desaturation sequenceBlood carbon dioxide controlled at lower than normal value (hypocapnia). | Device | RespirAct Slope Hypocapnia desaturation sequence |
| ROBD Step-Wise desaturation sequenceBlood carbon dioxide is controlled at normal or lower value by subject's own breathing rate. | Device | ROBD Step-Wise desaturation sequence |
Primary outcome
Accuracy of FDA-approved Pulse Oximeter When Calculated With RespirAct-derived End-tidal PAO2 Values
Time frame: 1 study day
The unit of measure of accuracy is called Accuracy Root Mean Square Error (A[RMS]) and is a composite value of bias and precision. A[RMS] is reported as a single percentage value representing the overall accuracy of a medical device with lower values indicating better performance.
Accuracy of FDA-approved Pulse Oximeter When Calculated With Co-oximeter Measured Arterial PaO2 Values
Time frame: 1 study day
The unit of measure of accuracy is called Accuracy Root Mean Square Error (A[RMS]) and is a composite value of bias and precision. A[RMS] is reported as a single percentage value representing the overall accuracy of a medical device with lower values indicating better performance.
PAO2 Values
Time frame: 1 study day
A[RMS] of RespirAct-derived end-tidal PAO2 values with co-oximeter measured arterial PaO2 values. The unit of measure of accuracy is called Accuracy Root Mean Square Error (A[RMS]) and is a composite value of bias and precision. A[RMS] is reported as a single percentage value representing the overall accuracy of a medical device with lower values indicating better performance.
2 secondary outcomes
Accuracy, A[RMS], When a Step-wise Desaturation Sequence is Used Against a Slope Desaturation Sequence.
Time frame: 1 study day
Level of PaCO2 (Hypocapnia Versus Normocapnia)
Time frame: 1 study day
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 11 Aug 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Human Pharmacology \& Physiology Lab at Duke UniversityLink provided by the sponsor.
- Individual participant dataSharing planned: No
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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.
David B MacLeod, FRCA principal investigator
Duke University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing RespirAct Step-Wise Normocapnia desaturation sequence, RespirAct Slope Normocapnia desaturation sequence and RespirAct Step-Wise Hypocapnia desaturation sequence in people with Hypoxemia and Desaturation of Blood, run by Duke University at 1 site in United States.
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 2 inclusion and 12 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: stopped early, as of the sponsor's last update on 11 Aug 2026. 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 States. 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?
Yes. Results are posted in the registry (first posted 11 Aug 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
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 FDA-approved Pulse Oximeter When Calculated With RespirAct-derived End-tidal PAO2 Values (time frame: 1 study day). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 11 Aug 2026.