Accidental HypothermiaNCT06342726
The Effect of Active External Rewarming on Rewarming Rate in Simulated Prehospital Accidental Hypothermia
A study testing PAX Warming Blanket and Passive insulation in people with Accidental Hypothermia, run by Haukeland University Hospital at 1 site in Norway.
Trial summary
In this study, we aim to compare the effect of active external rewarming to passive rewarming in healthy research participants on core temperature. The participants will be cooled to a core temperature of 35 degress C, the rewarmed using 2 different scenarios. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Accidental Hypothermia
- What is being tested?
- PAX Warming Blanket and Passive insulation
- Type of treatment
- Medical device
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 11 participants
- Where
- 1 siteNorway
- Study dates
- 28 May 2024to 2 Jun 2024
- Phase
- Interventional
- 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
- Healthy volunteers accepted
- Adult, Older adult
Participants are eligible to be included in the study only if all of the following criteria apply:
Age
- Participant must be over 18 and under 40 years of age at the time of signing the informed consent. Type of Participant and Disease Characteristics
- Participants who are overtly healthy as determined by their medical history. The participants will be asked to fill out a health-report stating to be healthy, using no relevant medication, and having no relevant allergies or hypersensitivity to the active substances or to any of the excipients of the medications used. Weight
- BMI under 30 kg/m2 Sex and Contraceptive/Barrier Requirements 4. Both male and female participants can be included. Female participants of childbearing potential will be asked to take a pregnancy test to confirm the absence of pregnancy prior to study drug administration on both visit 1 and 2.
Informed Consent 5. Capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol.
Exclusion Criteria Ahead of trial the participants will be contacted by a medical physician in the research group who will go through a medical questionnaire mainly based on the SmPC of Meperidine, Buspirone and Sodium chloride in "Felleskatalogen" with the following exclusion criteria.
- Drugs: Concomitant use of sedatives, MAO-inhibitors, SSRI, ritonavir, cimetidine, chlorpromazine, phenytoin, erythromycin, itraconazole, platelet inhibitors, Apomorphine, alcohol (during the trial period) or other opioids or opioid antagonists (during the trial period). History of drug dependency.
- Recent head injury (last. 12 months), known increased ICP, seizures or epilepsy
- Other: Known reduced liver- or kidney function, reduced respiratory drive, known supraventricular tachycardia or prolonged QTc, hypertrophy of the prostate or urinary constriction, ongoing pregnancy or breastfeeding. Known acute glaucoma, myasthenia gravis. Previous abdominal surgery. History of cold injuries or frostbites.
- Planned MRI the next two days after ingestion of temperature capsule.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: The Effect of Active External Rewarming on Rewarming Rate in Simulated Prehospital Accidental Hypothermia - an Experimental Field Study
In this study, we aim to compare the effect of active external rewarming to passive rewarming in healthy research participants on core temperature.
The participants will be cooled to a core temperature of 35 degress C, the rewarmed using 2 different scenarios. Scenario 1 will be with passive rewarming, scenario 2 with active rewarming. Shivering will be pharmacologically inhibited using Buspirone and Meperidine.
Read the detailed description
Accidental hypothermia is defined as an involuntary drop in core body temperature below 35°C. Hypothermia is a risk factor for cardiac arrythmia, pulmonary oedema, coagulopathy and neurological pathology. Isolated accidental hypothermia is potentially lethal on its own, and it is also an independent risk factor for increased mortality in patients with traumatic injury.
When core temperature drops, the body will automatically activate compensatory mechanisms in order to both increase thermic production and minimize heat loss in order to restore normal temperature. The mechanisms for thermal homeostasis are complex, strictly regulated and effective.
Until quite recently, active external rewarming was considered to be harmful and dangerous for patients with accidental hypothermia. A fear of fatal complications such as increased afterdrop and "rearming syndrome" leading to dangerous arrythmias and a drop in blood pressure which in a worst case scenario could lead to circulatory collapse, shock and potentially death.
Given the potentially detrimental consequences of being cold, any advice to abstain from warming patients should be well-documented, and the adverse effects of warming should outweigh those of being hypothermic. The lack of evidence for this claim that active external rewarming is dangerous along with many reports of successful external rewarming is leading to a change in most guidelines where active external rewarming is now an advisable treatment option.
A variety of different technological devices exist for the purpose of rewarming, but there is no established standard which is proven superior to others. Several trials have compared different rewarming methods, but evidence is limited. There is particularly deficient evidence regarding the amount of heat available for transfer from different methods and also the required amount of heat transfer for the rewarming to have a significant clinical impact.
Given the relatively short time in which active external rewarming has been advised, we suspect there is still a huge amount of room for improvement of care and technological innovation.
There is however reason to be cautious with active external rewarming of hypothermic patients. In a normothermic patient with normal circulatory function, thermal energy will be absorbed by the blood which flows back into central circulation distributing the heat evenly into a large volume. In a hypothermic patient there will be less cutaneous blood flow and less heat will be transferred to systemic circulation. This means that heat will accumulate on the skin surface and increase the risk of cutaneous injury, and there are several reported cases of this.
Hypothermia research with volunteer research participants is a complicated matter for many reasons. One complicating factor is shivering, which is an autonomic defense mechanism in which the muscles contract rapidly producing heat. It is the most effective method for the body to increase the metabolic heat production and re-establish normothermia. The shivering response is complicated in a research setting because there is a large interindividual variation in temperature threshold for initiation of shivering and in shivering intensity. This means that if you cool research participants down they will start to shiver at different core temperatures and with different intensities. Standardization of data is therefore impossible, and the researcher will be measuring the interindividual shivering abilities of the different research participants instead of the effect of the intervention. Shivering must therefore be inhibited in order to achieve reliable data.
- Conditions
- Accidental Hypothermia
- Being tested
- PAX Warming Blanket, Passive insulation
- Medical subject headings
- Hypothermia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
PAX Warming BlanketDevice
Electric resistive active external warming blanket
Passive insulationDevice
3-layered wrapping model
| Study group | Role | What they receive |
|---|---|---|
| Passive rewarming | Placebo comparator | Wrapping of participants using a 3-layered model with a vapor barrier, insulating materials and an outer shell. Receives: Device: Passive insulation |
| Active rewarming | Active comparator | Same as "Passive rewarming" but with an added external heat source Receives: Device: PAX Warming Blanket; Device: Passive insulation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Core body temperature
Esophageal measurement
Measured: 2 hour cooling phase, 1 hour rewarming phase
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Apr 2024
- Study start28 May 2024
- Primary completion2 Jun 2024
- Study completion2 Jun 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 Accidental HypothermiaStudies of the same condition, open and under way.
- More trials run by Haukeland University HospitalThe 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
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- The study will use a crossover design on where research participants will undergo repetitions of the same scenario with different interventions in order to serve as their own control. The research participants will be healthy volunteers providing both oral and written consent. Before the start of experiment, the research participant will be cooled in an ice cave wearing wet clothing and with 2-3 m/s wind to a core temperature of 35.0 °C using the established protocol for inhibition of shivering. The maximum cooling time will be 2 hours (120 minutes). The order of interventions will be randomized. When the research subjects reach the target temperature of 35.0°C or the maximum cooling time of 2 hours, they will be subjected to one of the two scenarios listed below, with a rewarming phase of maximum 60 minutes.
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 11 participants (actual)
Sponsor and investigators
- Lead sponsor
- Haukeland University Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06342726
- Sponsor's protocol ID
- 2024/714469
- Status last verified
- Feb 2025
- First submitted
- 26 Mar 2024
- Last updated
- 27 Feb 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Mydske S, Helland AM, Borasio N, Brattebo G, Osteras O, Wiggen O, Assmus J, Strapazzon G, Thomassen O. Effect of active external rewarming on esophageal temperature in simulated prehospital accidental hypothermia: a randomized crossover trial. Scand J Trauma Resusc Emerg Med. 2025 Dec 12;34(1):8. doi: 10.1186/s13049-025-01528-7.
PubMed 41388306
Study at a glance
From the registry record, last updated by the sponsor on 27 Feb 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Active External Rewarming on Rewarming Rate in Simulated Prehospital Accidental Hypothermia - an Experimental Field Study
- ClinicalTrials.gov ID
- NCT06342726
- Acronym / sponsor ID
- 2024/714469
- Conditions
- Accidental Hypothermia
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 11 participants (actual)
- Lead sponsor
- Haukeland University HospitalUniversity, hospital or other
- Study start
- 28 May 2024 (actual)
- Primary completion
- 2 Jun 2024 (actual)
- Study completion
- 2 Jun 2024 (actual)
- First posted
- 2 Apr 2024 (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.
In this study, we aim to compare the effect of active external rewarming to passive rewarming in healthy research participants on core temperature.
The participants will be cooled to a core temperature of 35 degress C, the rewarmed using 2 different scenarios. Scenario 1 will be with passive rewarming, scenario 2 with active rewarming. Shivering will be pharmacologically inhibited using Buspirone and Meperidine.
Detailed description
Accidental hypothermia is defined as an involuntary drop in core body temperature below 35°C. Hypothermia is a risk factor for cardiac arrythmia, pulmonary oedema, coagulopathy and neurological pathology. Isolated accidental hypothermia is potentially lethal on its own, and it is also an independent risk factor for increased mortality in patients with traumatic injury.
When core temperature drops, the body will automatically activate compensatory mechanisms in order to both increase thermic production and minimize heat loss in order to restore normal temperature. The mechanisms for thermal homeostasis are complex, strictly regulated and effective.
Until quite recently, active external rewarming was considered to be harmful and dangerous for patients with accidental hypothermia. A fear of fatal complications such as increased afterdrop and "rearming syndrome" leading to dangerous arrythmias and a drop in blood pressure which in a worst case scenario could lead to circulatory collapse, shock and potentially death.
Given the potentially detrimental consequences of being cold, any advice to abstain from warming patients should be well-documented, and the adverse effects of warming should outweigh those of being hypothermic. The lack of evidence for this claim that active external rewarming is dangerous along with many reports of successful external rewarming is leading to a change in most guidelines where active external rewarming is now an advisable treatment option.
A variety of different technological devices exist for the purpose of rewarming, but there is no established standard which is proven superior to others. Several trials have compared different rewarming methods, but evidence is limited. There is particularly deficient evidence regarding the amount of heat available for transfer from different methods and also the required amount of heat transfer for the rewarming to have a significant clinical impact.
Given the relatively short time in which active external rewarming has been advised, we suspect there is still a huge amount of room for improvement of care and technological innovation.
There is however reason to be cautious with active external rewarming of hypothermic patients. In a normothermic patient with normal circulatory function, thermal energy will be absorbed by the blood which flows back into central circulation distributing the heat evenly into a large volume. In a hypothermic patient there will be less cutaneous blood flow and less heat will be transferred to systemic circulation. This means that heat will accumulate on the skin surface and increase the risk of cutaneous injury, and there are several reported cases of this.
Hypothermia research with volunteer research participants is a complicated matter for many reasons. One complicating factor is shivering, which is an autonomic defense mechanism in which the muscles contract rapidly producing heat. It is the most effective method for the body to increase the metabolic heat production and re-establish normothermia. The shivering response is complicated in a research setting because there is a large interindividual variation in temperature threshold for initiation of shivering and in shivering intensity. This means that if you cool research participants down they will start to shiver at different core temperatures and with different intensities. Standardization of data is therefore impossible, and the researcher will be measuring the interindividual shivering abilities of the different research participants instead of the effect of the intervention. Shivering must therefore be inhibited in order to achieve reliable data.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- The study will use a crossover design on where research participants will undergo repetitions of the same scenario with different interventions in order to serve as their own control. The research participants will be healthy volunteers providing both oral and written consent. Before the start of experiment, the research participant will be cooled in an ice cave wearing wet clothing and with 2-3 m/s wind to a core temperature of 35.0 °C using the established protocol for inhibition of shivering. The maximum cooling time will be 2 hours (120 minutes). The order of interventions will be randomized. When the research subjects reach the target temperature of 35.0°C or the maximum cooling time of 2 hours, they will be subjected to one of the two scenarios listed below, with a rewarming phase of maximum 60 minutes.
| Arm | Type | Receives |
|---|---|---|
| Passive rewarming | Placebo comparator | Device: Passive insulationWrapping of participants using a 3-layered model with a vapor barrier, insulating materials and an outer shell. |
| Active rewarming | Active comparator | Device: PAX Warming Blanket, Device: Passive insulationSame as "Passive rewarming" but with an added external heat source |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
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 |
|---|---|---|
| PAX Warming BlanketElectric resistive active external warming blanket | Device | Active rewarming |
| Passive insulation3-layered wrapping model | Device | Active rewarming, Passive rewarming |
Primary outcome
Core body temperature
Time frame: 2 hour cooling phase, 1 hour rewarming phase
Esophageal measurement
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 27 Feb 2025.
- Derived from this study: PubMed 41388306Mydske S, Helland AM, Borasio N, Brattebo G, Osteras O, Wiggen O, Assmus J, Strapazzon G, Thomassen O. Effect of active external rewarming on esophageal temperature in simulated prehospital accidental hypothermia: a randomized crossover trial. Scand J Trauma Resusc Emerg Med. 2025 Dec 12;34(1):8. doi: 10.1186/s13049-025-01528-7.
- 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.
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?
A study testing PAX Warming Blanket and Passive insulation in people with Accidental Hypothermia, run by Haukeland University Hospital at 1 site in Norway.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
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 27 Feb 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 Norway. 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. Some participants in this study may receive a placebo. 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?
Core body temperature (time frame: 2 hour cooling phase, 1 hour rewarming phase). 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 NCT06342726, 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 27 Feb 2025.