Critical IllnessPULSEWARMNCT07792304
Local Warming to Improve Pulse Oximetry Accuracy in Critically Ill Patients
A study testing Protocolized Local Warming in people with Critical Illness and Low Peripheral Perfusion, run by Vastra Gotaland Region at 4 sites in Sweden.
Trial summary
Pulse oximeters are widely used in intensive care to continuously estimate the oxygen level in the blood. However, pulse oximeter measurements may be less accurate when blood flow to the fingers is poor, which is common in critically ill patients. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Critical Illness, Low Peripheral Perfusion, Pulse Oximetry Accuracy
- What is being tested?
- Protocolized Local Warming
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 240 participants
- Where
- 4 sitesSweden
- Study dates
- 1 Oct 2026to 1 Dec 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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
Who may be able to join
- Age 18 years or older.
- Admitted to an intensive care unit.
- Receiving invasive mechanical ventilation via endotracheal tube or tracheostomy.
- Existing arterial catheter placed for a clinical indication.
- Objectively verified low peripheral perfusion, defined as finger perfusion index (PFI) <1.0 at screening.
- Stable baseline pulse oximetry signal permitting calculation of the SpO2-SaO2 difference.
- Clinical condition considered sufficiently stable to allow study measurements without interfering with ongoing treatment.
Who cannot join
- Absence of a stable baseline pulse oximetry signal on all available sensors, preventing calculation of the SpO2-SaO2 difference.
- Skin injury, burn, infection, or other local skin condition of the hand or forearm that prevents safe application of the warming pad or pulse oximetry sensor.
- Clinical instability for which the treating physician considers study participation likely to interfere with acute treatment or patient safety.
- Known hypersensitivity to materials used in the warming pad or sensors.
- Participation in another ongoing interventional study that could affect the primary outcome.
Trial locations and contacts
4 sites in 1 country. Contact the study team or a site near you to ask about taking part.
Sweden4 sites
Sahlgrenska University Hospital
Gothenburg
Carl Sjödin, PhD student, 0707163277, carl.sjodin@vgregion.se
Kungälvs Sjukhus
Kungälv
Skaraborgs Sjukhus
Skövde
Norra Älvsborgs Sjukhus
Trollhättan
About this study
Official title: Effect of Local Warming on Pulse Oximetry Accuracy in Critically Ill Patients With Low Peripheral Perfusion: A Multicenter Randomized Controlled Trial
Pulse oximeters are widely used in intensive care to continuously estimate the oxygen level in the blood. However, pulse oximeter measurements may be less accurate when blood flow to the fingers is poor, which is common in critically ill patients.
This study will investigate whether warming the hand and lower part of the forearm can improve the accuracy of pulse oximeter measurements in mechanically ventilated adult intensive care patients with low blood flow to the fingers.
Read more
Participants will be randomly assigned to either a local warming strategy or usual care without warming. In the warming group, the hand and lower forearm will be warmed for 15 minutes to a target temperature of 41-42°C. Pulse oximeter measurements will be compared with oxygen saturation measured from an arterial blood sample before and after the intervention.
The main objective is to determine whether local warming reduces the difference between pulse oximeter oxygen saturation (SpO₂) and arterial oxygen saturation (SaO₂) 15 minutes after the start of the assigned strategy. The study will also assess whether any improvement persists at 60 minutes, how peripheral blood flow changes during 4 hours of follow-up, whether repeat warming is effective when blood flow decreases again, and whether the effect differs according to skin phototype. Safety related to the warming intervention will also be evaluated.
Read the detailed description
Pulse oximetry is a fundamental component of monitoring and oxygen titration in critically ill patients. Its accuracy may, however, be impaired by reduced peripheral perfusion. Low peripheral perfusion is common in mechanically ventilated intensive care patients and may contribute to clinically relevant differences between peripheral oxygen saturation measured by pulse oximetry (SpO₂) and arterial oxygen saturation measured by blood gas analysis (SaO₂).
Local warming increases cutaneous blood flow and is routinely used to improve peripheral perfusion during procedures such as capillary blood sampling. Preliminary single-center data suggest that local warming may also improve pulse oximetry accuracy in critically ill patients with low peripheral perfusion. Whether this effect is present when evaluated in a randomized controlled trial is unknown.
This is a prospective, multicenter, parallel-group randomized controlled strategy trial conducted in four intensive care units. Mechanically ventilated adult ICU patients with an arterial catheter and a finger perfusion index (PFI) <1.0 will be randomized in a 1:1 ratio to a protocolized local warming strategy or usual care without protocolized warming. Randomization will be stratified by study site and Fitzpatrick skin phototype.
In the intervention group, local warming will be applied to the dorsum of the hand and distal forearm for 15 minutes, with a target interface temperature of 41-42°C. Repeat warming is permitted during follow-up if finger PFI decreases below 0.5 according to the prespecified study strategy. The control group will receive usual care without protocolized local warming.
SpO₂, finger PFI, earlobe PFI, and arterial SaO₂ will be assessed at baseline, 15 minutes, and 60 minutes. Additional PFI measurements will be obtained at 120 and 240 minutes. Oxygen therapy will otherwise be managed according to standard clinical care.
The primary objective is to compare pulse oximetry bias between the randomized groups at 15 minutes. Bias is defined as SpO₂ minus SaO₂, expressed in percentage points. The primary analysis will compare the groups using an analysis of covariance adjusted for baseline SpO₂-SaO₂ bias and study site.
Secondary objectives include assessment of pulse oximetry accuracy at 60 minutes, the proportion of measurements within ±2 percentage points of SaO₂, changes in peripheral perfusion during 4 hours of follow-up, the local versus systemic perfusion response assessed using finger and earlobe PFI, the response to repeat warming, safety outcomes, and possible treatment-effect modification according to Fitzpatrick skin phototype.
The planned sample size is 240 participants, with 120 participants allocated to each study group.
A prespecified single-center device-comparison substudy will be conducted within a subset of participants enrolled at Sahlgrenska University Hospital. In both the randomized warming and control groups, simultaneous pulse oximetry measurements will be obtained using multiple complete pulse oximetry systems applied to different fingers together with a non-warmed forehead pulse oximeter. Measurements will be obtained at the same predefined study time points and compared with SaO2 measured by blood gas analysis. The substudy will assess device-specific SpO2-SaO2 bias, differences in accuracy between pulse oximetry systems, and whether the effect of local warming on pulse oximetry accuracy differs across devices. The forehead sensor will provide a non-warmed comparison site. Mixed-effects models will include device, randomized treatment group, time, and their interactions, with repeated measurements within participants accounted for.
- Being tested
- Protocolized Local Warming
- Keywords
- Pulse oximetry Oxygen saturation, SpO₂, SaO₂, Peripheral perfusion Perfusion index, Skin pigmentation, Local warming, Fitzpatrick skin phototype, Critically ill patients, Arterial blood gas, Mechanical ventilation
- Medical subject headings
- Critical Illness, Pigmentation Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Protocolized Local WarmingOther
Local warming is applied to the dorsum of the hand and distal forearm for 15 minutes using a warming device adjusted to achieve a target interface temperature of 41-42°C. During follow-up, repeat warming is permitted if finger perfusion index decreases below 0.5.
| Study group | Role | What they receive |
|---|---|---|
| Protocolized Local Warming | Experimental | Participants receive protocolized local warming applied to the dorsum of the hand and distal forearm for 15 minutes, targeting an interface temperature of 41-42°C. Repeat warming is permitted during follow-up if finger perfusion index decreases below 0.5. Receives: Other: Protocolized Local Warming |
| Usual Care Without Protocolized Warming | No intervention | Participants receive usual care without protocolized local warming. Oxygen therapy and all other clinical management are provided according to standard intensive care practice. |
What is being measured
The primary outcome is the main question the study is designed to answer.
SpO2-SaO2 Bias at 15 Minutes
Pulse oximetry bias is defined as peripheral oxygen saturation measured by pulse oximetry (SpO2) minus arterial oxygen saturation measured by blood gas analysis (SaO2), expressed in percentage points. The primary analysis will compare SpO2-SaO2 bias between the local warming and control groups at 15 minutes, adjusted for baseline bias and study site.
Measured: 15 minutes after initiation of the randomized strategy
Secondary outcomes (6)
SpO2-SaO2 Bias at 60 Minutes
Pulse oximetry bias is defined as SpO2 minus SaO2, expressed in percentage points. Bias at 60 minutes will be compared between randomized groups to evaluate durability of the effect of the warming strategy.
Measured: 60 minutes after initiation of the randomized strategy
Proportion of SpO2 Measurements Within ±2 Percentage Points of SaO2
The proportion of participants with an absolute difference between SpO2 and SaO2 of 2 percentage points or less will be determined at 15 and 60 minutes and compared between randomized groups.
Measured: 15 and 60 minutes after initiation of the randomized strategy
Change in Finger Perfusion Index
Finger perfusion index (PFI) will be measured serially to assess the peripheral perfusion response to the randomized strategy and its durability during 4 hours of follow-up.
Measured: Baseline and 15, 60, 120, and 240 minutes
Difference Between Finger and Earlobe Perfusion Index Response
Changes in perfusion index measured at the finger and earlobe will be compared to assess whether the perfusion response to local warming is predominantly local rather than systemic.
Measured: Baseline, 15 minutes, and 60 minutes
Perfusion Index Response to Repeat Local Warming
Among participants in the warming group who undergo repeat warming because finger PFI decreases below 0.5 during follow-up, the change in finger PFI following repeat warming will be assessed to evaluate repeatability of the perfusion response.
Measured: Up to 240 minutes after randomization
Warming-Related Adverse Events
Number of participants experiencing adverse events considered related to local warming, including skin injury, erythema requiring discontinuation of warming, or other prespecified adverse reactions during the study period.
Measured: From initiation of the randomized strategy through 240 minutes
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Aug 2026
- Study start1 Oct 2026 (estimated)
- Primary completion1 Oct 2028 (estimated)
- Study completion1 Dec 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Critical IllnessStudies of the same condition, open and under way.
- More trials run by Vastra Gotaland RegionThe 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
- Supportive care
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Participants are randomized 1:1 to protocolized local warming or control without protocolized warming. In a prespecified single-center substudy, participants in both randomized groups undergo simultaneous measurements using multiple finger-based pulse oximetry systems and a non-warmed forehead pulse oximeter, allowing evaluation of device-specific accuracy and whether the effect of warming differs across pulse oximetry systems.
- Masking
- None (open label)
- Enrolment
- 240 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Vastra Gotaland Region
- Sponsor type
- Other government
- Collaborators
- North Älvsborg County Hospital, Trollhättan, Skaraborg Hospital, Kungälvs sjukhus
- Responsible party
- Principal investigator, Carl Sjödin, Vastra Gotaland Region
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07792304
- Sponsor's protocol ID
- PULSEWARM-RCT-01
- Acronym
- PULSEWARM
- Status last verified
- Sep 2026
- First submitted
- 24 Aug 2026
- Last updated
- 25 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: The feasibility and conditions for sharing de-identified individual participant data have not yet been determined. Any future data sharing will be subject to applicable ethical approvals, data protection regulations, institutional policies, and appropriate data-sharing agreements.
Study at a glance
From the registry record, last updated by the sponsor on 25 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Local Warming on Pulse Oximetry Accuracy in Critically Ill Patients With Low Peripheral Perfusion: A Multicenter Randomized Controlled Trial
- ClinicalTrials.gov ID
- NCT07792304
- Acronym / sponsor ID
- PULSEWARM / PULSEWARM-RCT-01
- Keywords
- Pulse oximetry Oxygen saturation, SpO₂, SaO₂, Peripheral perfusion Perfusion index, Skin pigmentation, Local warming, Fitzpatrick skin phototype, Critically ill patients
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 240 participants (estimated)
- Lead sponsor
- Vastra Gotaland RegionOther government
- Collaborators
- North Älvsborg County Hospital, Trollhättan, Skaraborg Hospital, Kungälvs sjukhus
- Study start
- 1 Oct 2026 (estimated)
- Primary completion
- 1 Oct 2028 (estimated)
- Study completion
- 1 Dec 2028 (estimated)
- First posted
- 28 Aug 2026 (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.
Pulse oximeters are widely used in intensive care to continuously estimate the oxygen level in the blood. However, pulse oximeter measurements may be less accurate when blood flow to the fingers is poor, which is common in critically ill patients.
This study will investigate whether warming the hand and lower part of the forearm can improve the accuracy of pulse oximeter measurements in mechanically ventilated adult intensive care patients with low blood flow to the fingers.
Participants will be randomly assigned to either a local warming strategy or usual care without warming. In the warming group, the hand and lower forearm will be warmed for 15 minutes to a target temperature of 41-42°C. Pulse oximeter measurements will be compared with oxygen saturation measured from an arterial blood sample before and after the intervention.
The main objective is to determine whether local warming reduces the difference between pulse oximeter oxygen saturation (SpO₂) and arterial oxygen saturation (SaO₂) 15 minutes after the start of the assigned strategy. The study will also assess whether any improvement persists at 60 minutes, how peripheral blood flow changes during 4 hours of follow-up, whether repeat warming is effective when blood flow decreases again, and whether the effect differs according to skin phototype. Safety related to the warming intervention will also be evaluated.
Detailed description
Pulse oximetry is a fundamental component of monitoring and oxygen titration in critically ill patients. Its accuracy may, however, be impaired by reduced peripheral perfusion. Low peripheral perfusion is common in mechanically ventilated intensive care patients and may contribute to clinically relevant differences between peripheral oxygen saturation measured by pulse oximetry (SpO₂) and arterial oxygen saturation measured by blood gas analysis (SaO₂).
Local warming increases cutaneous blood flow and is routinely used to improve peripheral perfusion during procedures such as capillary blood sampling. Preliminary single-center data suggest that local warming may also improve pulse oximetry accuracy in critically ill patients with low peripheral perfusion. Whether this effect is present when evaluated in a randomized controlled trial is unknown.
This is a prospective, multicenter, parallel-group randomized controlled strategy trial conducted in four intensive care units. Mechanically ventilated adult ICU patients with an arterial catheter and a finger perfusion index (PFI) <1.0 will be randomized in a 1:1 ratio to a protocolized local warming strategy or usual care without protocolized warming. Randomization will be stratified by study site and Fitzpatrick skin phototype.
In the intervention group, local warming will be applied to the dorsum of the hand and distal forearm for 15 minutes, with a target interface temperature of 41-42°C. Repeat warming is permitted during follow-up if finger PFI decreases below 0.5 according to the prespecified study strategy. The control group will receive usual care without protocolized local warming.
SpO₂, finger PFI, earlobe PFI, and arterial SaO₂ will be assessed at baseline, 15 minutes, and 60 minutes. Additional PFI measurements will be obtained at 120 and 240 minutes. Oxygen therapy will otherwise be managed according to standard clinical care.
The primary objective is to compare pulse oximetry bias between the randomized groups at 15 minutes. Bias is defined as SpO₂ minus SaO₂, expressed in percentage points. The primary analysis will compare the groups using an analysis of covariance adjusted for baseline SpO₂-SaO₂ bias and study site.
Secondary objectives include assessment of pulse oximetry accuracy at 60 minutes, the proportion of measurements within ±2 percentage points of SaO₂, changes in peripheral perfusion during 4 hours of follow-up, the local versus systemic perfusion response assessed using finger and earlobe PFI, the response to repeat warming, safety outcomes, and possible treatment-effect modification according to Fitzpatrick skin phototype.
The planned sample size is 240 participants, with 120 participants allocated to each study group.
A prespecified single-center device-comparison substudy will be conducted within a subset of participants enrolled at Sahlgrenska University Hospital. In both the randomized warming and control groups, simultaneous pulse oximetry measurements will be obtained using multiple complete pulse oximetry systems applied to different fingers together with a non-warmed forehead pulse oximeter. Measurements will be obtained at the same predefined study time points and compared with SaO2 measured by blood gas analysis. The substudy will assess device-specific SpO2-SaO2 bias, differences in accuracy between pulse oximetry systems, and whether the effect of local warming on pulse oximetry accuracy differs across devices. The forehead sensor will provide a non-warmed comparison site. Mixed-effects models will include device, randomized treatment group, time, and their interactions, with repeated measurements within participants accounted for.
Study design
- Primary purpose
- Supportive care
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- Participants are randomized 1:1 to protocolized local warming or control without protocolized warming. In a prespecified single-center substudy, participants in both randomized groups undergo simultaneous measurements using multiple finger-based pulse oximetry systems and a non-warmed forehead pulse oximeter, allowing evaluation of device-specific accuracy and whether the effect of warming differs across pulse oximetry systems.
| Arm | Type | Receives |
|---|---|---|
| Protocolized Local Warming | Experimental | Other: Protocolized Local WarmingParticipants receive protocolized local warming applied to the dorsum of the hand and distal forearm for 15 minutes, targeting an interface temperature of 41-42°C. Repeat warming is permitted during follow-up if finger perfusion index decreases below 0.5. |
| Usual Care Without Protocolized Warming | No intervention | –Participants receive usual care without protocolized local warming. Oxygen therapy and all other clinical management are provided according to standard intensive care practice. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Age 18 years or older.
- Admitted to an intensive care unit.
- Receiving invasive mechanical ventilation via endotracheal tube or tracheostomy.
- Existing arterial catheter placed for a clinical indication.
- Objectively verified low peripheral perfusion, defined as finger perfusion index (PFI) <1.0 at screening.
Key exclusion criteria (5 listed)
- Absence of a stable baseline pulse oximetry signal on all available sensors, preventing calculation of the SpO2-SaO2 difference.
- Skin injury, burn, infection, or other local skin condition of the hand or forearm that prevents safe application of the warming pad or pulse oximetry sensor.
- Clinical instability for which the treating physician considers study participation likely to interfere with acute treatment or patient safety.
- Known hypersensitivity to materials used in the warming pad or sensors.
- Participation in another ongoing interventional study that could affect the primary outcome.
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 |
|---|---|---|
| Protocolized Local WarmingLocal warming is applied to the dorsum of the hand and distal forearm for 15 minutes using a warming device adjusted to achieve a target interface temperature of 41-42°C. During follow-up, repeat warming is permitted if finger perfusion index decreases below 0.5. | Other | Protocolized Local Warming |
Primary outcome
SpO2-SaO2 Bias at 15 Minutes
Time frame: 15 minutes after initiation of the randomized strategy
Pulse oximetry bias is defined as peripheral oxygen saturation measured by pulse oximetry (SpO2) minus arterial oxygen saturation measured by blood gas analysis (SaO2), expressed in percentage points. The primary analysis will compare SpO2-SaO2 bias between the local warming and control groups at 15 minutes, adjusted for baseline bias and study site.
6 secondary outcomes
SpO2-SaO2 Bias at 60 Minutes
Time frame: 60 minutes after initiation of the randomized strategy
Proportion of SpO2 Measurements Within ±2 Percentage Points of SaO2
Time frame: 15 and 60 minutes after initiation of the randomized strategy
Change in Finger Perfusion Index
Time frame: Baseline and 15, 60, 120, and 240 minutes
Difference Between Finger and Earlobe Perfusion Index Response
Time frame: Baseline, 15 minutes, and 60 minutes
Perfusion Index Response to Repeat Local Warming
Time frame: Up to 240 minutes after randomization
Warming-Related Adverse Events
Time frame: From initiation of the randomized strategy through 240 minutes
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 25 Sep 2026.
- Individual participant dataSharing planned: Undecided. The feasibility and conditions for sharing de-identified individual participant data have not yet been determined. Any future data sharing will be subject to applicable ethical approvals, data protection regulations, institutional policies, and appropriate data-sharing agreements.
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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.
4 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Protocolized Local Warming in people with Critical Illness and Low Peripheral Perfusion, run by Vastra Gotaland Region at 4 sites in Sweden.
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 7 inclusion and 5 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: opening soon, as of the sponsor's last update on 25 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 4 sites in Sweden. 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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Carl Sjödin, PhD student (0707163277, carl.sjodin@vgregion.se), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
SpO2-SaO2 Bias at 15 Minutes (time frame: 15 minutes after initiation of the randomized strategy). 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 25 Sep 2026.