Hypothermia Following AnesthesiaPHRESNCT07839728
Study of the Prevalence of Postoperative Hypothermia in Adults Undergoing Non-Cardiac Surgery in Spanish Post-Anesthesia Care Units
An observational study of Hypothermia Following Anesthesia, run by Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz at 1 site in Spain.
Trial summary
The prevalence of Hypothermia in Spanish Post-Anesthesia Recovery Units (in Spanish: "Prevalencia de Hipotermia en las Reanimaciones Españolas" PHRES Study) is a prospective, multicenter observational study that will evaluate how often adults develop unintended low body temperature after non-cardiac surgery in… Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Hypothermia Following Anesthesia
- What is being tested?
- Postoperative temperature monitoring
- Type of treatment
- Medical device
- How many people
- 1,300 participants
- Where
- 1 siteSpain
- Study dates
- Nov 2026to Jan 2027
- How long will I take part?
- 1 Day
- Phase
- Observational
- 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
- Healthy volunteers accepted
- Adult, Older adult
Study population: The study population will consist of adult patients undergoing scheduled non-cardiac surgery under general, neuraxial, or combined anesthesia at participating public or private hospitals in Spain. Participating centers will be hospitals with operating rooms equipped with active patient warming systems and availability of core temperature monitoring in the postoperative recovery setting.
Who may be able to join
- American Society of Anesthesiologists (ASA) physical status I-III.
- Scheduled for non-cardiac surgical procedure.
- Anesthesia duration >60 minutes.
- General anesthesia, neuraxial anesthesia, or combined general and neuraxial/peripheral nerve block anesthesia.
- Written informed consent provided by the participant.
Who cannot join
- Signs or suspicion of active infection at the time of surgery.
- Surgical procedure performed under regional anesthesia with sedation only.
- Cognitive impairment preventing the participant from understanding the study information.
- Refusal to participate in the study.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
About this study
Official title: Prevalence of Postoperative Hypothermia in Spanish Recovery Units
The prevalence of Hypothermia in Spanish Post-Anesthesia Recovery Units (in Spanish: "Prevalencia de Hipotermia en las Reanimaciones Españolas" PHRES Study) is a prospective, multicenter observational study that will evaluate how often adults develop unintended low body temperature after non-cardiac surgery in post-anesthesia recovery units in Spain.
Unintended low body temperature, known as perioperative hypothermia, is a common problem after surgery and may be associated with complications such as shivering, increased bleeding, heart problems, discomfort, and delayed recovery. Although active warming devices and temperature monitoring are available in many Spanish hospitals, their use may vary between centers.
Read more
The study will include adults undergoing scheduled non-cardiac surgery lasting more than 60 minutes under general, regional, or combined anesthesia. Approximately 1,334 patients from 25-30 Spanish hospitals are expected to participate.
Patients will be included consecutively according to predefined eligibility criteria. The study will record information about the patient, the type and duration of surgery and anesthesia, and the measures used to prevent low body temperature before and during surgery, including active warming and temperature monitoring.
On arrival in the post-anesthesia recovery unit, the patient's core body temperature will be measured using the same non-invasive temperature monitoring technology in all participating centers. The main objective is to determine the proportion of patients with a core temperature below 36°C at the time of admission to the recovery unit.
The study will also investigate factors associated with postoperative hypothermia and record complications occurring shortly after surgery, such as shivering, hemodynamic instability, new-onset arrhythmias, significant bleeding, and the need for blood transfusion.
This is an observational study. The study will not determine or change how patients are warmed or how their temperature is monitored during surgery. These decisions will remain the responsibility of the treating anesthesia team according to local clinical practice. The additional temperature measurement performed for the study is non-invasive and does not involve any significant additional risk to participants.
Read the detailed description
Background
Unintended perioperative hypothermia, defined as a core body temperature below 36.0°C, is one of the most common complications associated with anesthesia and surgery. During the first hour after induction of anesthesia, the body's normal temperature regulation is impaired, causing heat to redistribute from the core to the peripheral tissues. Additional factors such as exposure to a cool operating room, administration of intravenous fluids, surgical duration, and the extent of the surgical procedure further increase the risk of heat loss.
Postoperative hypothermia has been associated with several adverse outcomes, including shivering, patient discomfort, increased blood loss and transfusion requirements, wound infection, cardiac complications, and prolonged recovery. International guidelines recommend routine temperature monitoring and the use of active warming techniques during surgery. However, the implementation of these recommendations varies considerably between hospitals, and contemporary national data from Spain are not available.
The PHRES Study has been designed to determine the current prevalence of postoperative hypothermia in Spanish post-anesthesia recovery units and to describe perioperative temperature management practices across a wide range of hospitals.
Study Design
PHRES is a prospective, multicenter, observational study conducted in approximately 25-30 public and private hospitals throughout Spain. The study is coordinated by Spanish anesthesiologists and will recruit approximately 1,334 adult patients undergoing elective non-cardiac surgery.
Because this is an observational study, no aspect of routine clinical care will be modified. Decisions regarding prewarming, intraoperative active warming, temperature monitoring, fluid warming, anesthetic technique, and postoperative management will remain entirely under the responsibility of the treating anesthesia team according to local clinical practice.
Participants
Eligible participants are adults aged 18 years or older undergoing scheduled non-cardiac surgery with an expected anesthesia duration of more than 60 minutes. Patients receiving general anesthesia, neuraxial anesthesia, or combined techniques may be included. Patients with suspected infection, those undergoing surgery under regional anesthesia with sedation alone, or those unable to provide informed consent will be excluded.
Participants will be enrolled consecutively during predefined recruitment periods in each participating center in order to minimize selection bias.
Study Procedures
After written informed consent is obtained, demographic and clinical information will be collected from the medical record and anesthesia chart. Information recorded will include:
- Patient characteristics and comorbidities.
- Type and duration of anesthesia and surgery.
- Surgical specialty and operative approach.
- Use of preoperative and intraoperative active warming.
- Methods of intraoperative core temperature monitoring.
- Administration of fluids, vasoactive drugs, and irrigation fluids.
Upon admission to the post-anesthesia care unit (PACU), the patient's core temperature will be measured using the same non-invasive zero-heat-flux temperature monitoring system in all participating centers. Standardizing the postoperative temperature measurement minimizes variability related to different thermometry methods and allows reliable comparison between hospitals.
The study will also record immediate postoperative events including shivering, hemodynamic instability requiring vasoactive support, new-onset arrhythmias, significant bleeding, and the need for blood transfusion.
Study Objectives
The primary objective is to estimate the prevalence of postoperative hypothermia, defined as a core temperature below 36.0°C at admission to the PACU.
Secondary objectives are:
- To describe the use of prewarming, active intraoperative warming, and core temperature monitoring in Spanish hospitals.
- To identify patient- and procedure-related risk factors associated with postoperative hypothermia.
- To evaluate the relationship between postoperative hypothermia and immediate postoperative complications.
Importance of the Study
This study will provide the first large contemporary national estimate of postoperative hypothermia in Spain using a standardized method for postoperative core temperature measurement. The results are expected to identify opportunities to improve perioperative temperature management, promote adherence to evidence-based warming strategies, and ultimately improve patient safety and recovery after surgery.
- Conditions
- Hypothermia Following Anesthesia
- Being tested
- Postoperative temperature monitoring
- Keywords
- inadverted postoperative hypothermia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Postoperative temperature monitoringDevice
A non-invasive zero-heat-flux temperature sensor will be used to measure core body temperature upon admission to the post-anesthesia care unit. The same temperature monitoring system will be used in all participating centers to standardize postoperative temperature measurement. The measurement does not alter routine clinical care.
What is being measured
The primary outcome is the main question the study is designed to answer.
Prevalence of Postoperative Hypothermia
Proportion of patients with a core body temperature below 36.0°C at admission to the post-anesthesia care unit (PACU). Core temperature will be measured using a non-invasive zero-heat-flux temperature monitoring system.
Measured: At admission to the post-anesthesia care unit, immediately after surgery
Secondary outcomes (5)
Prevalence of Preoperative Active Warming
Proportion of patients who receive active warming for at least 10 minutes before transfer to the operating room.
Measured: During the preoperative period, before transfer to the operating room
Prevalence of Intraoperative Active Warming
Proportion of patients who receive active intraoperative warming and description of the warming method used, including forced-air warming, conductive warming, intravenous fluid warming, or irrigation fluid warming.
Measured: From induction of anesthesia until completion of surgery
Prevalence of Intraoperative Core Temperature Monitoring
Proportion of patients who undergo intraoperative core temperature monitoring and description of the monitoring method used.
Measured: During surgery
Risk Factors Associated With Postoperative Hypothermia
Association between patient characteristics, comorbidities, surgical and anesthetic characteristics, and perioperative temperature management practices and the occurrence of postoperative hypothermia, defined as core temperature below 36.0°C at admission to the PACU.
Measured: Perioperative/Periprocedural
Immediate Postoperative Complications Associated With Hypothermia
Association between postoperative hypothermia and immediate postoperative complications, including shivering, hemodynamic instability requiring vasoactive drugs, new-onset perioperative arrhythmia, perioperative bleeding greater than 500 mL, and need for blood transfusion.
Measured: Perioperative/Periprocedural
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Sep 2026
- Study startNov 2026 (estimated)
- Primary completionDec 2026 (estimated)
- Study completionJan 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for Hypothermia Following AnesthesiaStudies 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
- Case only
- Time perspective
- Prospective
- Enrolment
- 1,300 participants (estimated)
- Target duration
- 1 Day
Sponsor and investigators
- Lead sponsor
- Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07839728
- Sponsor's protocol ID
- EO150-26_FJD
- Acronym
- PHRES
- Status last verified
- Sep 2026
- First submitted
- 31 Aug 2026
- Last updated
- 24 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be shared because of privacy and data protection considerations. The study involves health-related information that will be collected and pseudonymized in accordance with applicable data protection regulations. Data will be used for the purposes specified in the study protocol and will not be made available for public sharing at the individual participant level.
Publications
Pedersen C, Munch P, Kjaergaard J, Gronlykke L, Brauer A. Accuracy of a zero-heat-flux thermometer in cardiac surgery, a prospective, multicentre, method comparison study. Sci Rep. 2024 Feb 7;14(1):3169. doi: 10.1038/s41598-024-53647-3.
PubMed 38326589Alfonsi P, Bekka S, Aegerter P; SFAR Research Network investigators. Prevalence of hypothermia on admission to recovery room remains high despite a large use of forced-air warming devices: Findings of a non-randomized observational multicenter and pragmatic study on perioperative hypothermia prevalence in France. PLoS One. 2019 Dec 23;14(12):e0226038. doi: 10.1371/journal.pone.0226038. eCollection 2019.
PubMed 31869333
Study at a glance
From the registry record, last updated by the sponsor on 24 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Prevalence of Postoperative Hypothermia in Spanish Recovery Units
- ClinicalTrials.gov ID
- NCT07839728
- Acronym / sponsor ID
- PHRES / EO150-26_FJD
- Conditions
- Hypothermia Following Anesthesia
- Keywords
- inadverted postoperative hypothermia
- Study type
- Observational
- Recruitment status
- Enrolling by invitation
- Enrolment
- 1,300 participants (estimated)
- Lead sponsor
- Instituto de Investigación Sanitaria de la Fundación Jiménez DíazUniversity, hospital or other
- Study start
- Nov 2026 (estimated)
- Primary completion
- Dec 2026 (estimated)
- Study completion
- Jan 2027 (estimated)
- First posted
- 24 Sep 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.
The prevalence of Hypothermia in Spanish Post-Anesthesia Recovery Units (in Spanish: "Prevalencia de Hipotermia en las Reanimaciones Españolas" PHRES Study) is a prospective, multicenter observational study that will evaluate how often adults develop unintended low body temperature after non-cardiac surgery in post-anesthesia recovery units in Spain.
Unintended low body temperature, known as perioperative hypothermia, is a common problem after surgery and may be associated with complications such as shivering, increased bleeding, heart problems, discomfort, and delayed recovery. Although active warming devices and temperature monitoring are available in many Spanish hospitals, their use may vary between centers.
The study will include adults undergoing scheduled non-cardiac surgery lasting more than 60 minutes under general, regional, or combined anesthesia. Approximately 1,334 patients from 25-30 Spanish hospitals are expected to participate.
Patients will be included consecutively according to predefined eligibility criteria. The study will record information about the patient, the type and duration of surgery and anesthesia, and the measures used to prevent low body temperature before and during surgery, including active warming and temperature monitoring.
On arrival in the post-anesthesia recovery unit, the patient's core body temperature will be measured using the same non-invasive temperature monitoring technology in all participating centers. The main objective is to determine the proportion of patients with a core temperature below 36°C at the time of admission to the recovery unit.
The study will also investigate factors associated with postoperative hypothermia and record complications occurring shortly after surgery, such as shivering, hemodynamic instability, new-onset arrhythmias, significant bleeding, and the need for blood transfusion.
This is an observational study. The study will not determine or change how patients are warmed or how their temperature is monitored during surgery. These decisions will remain the responsibility of the treating anesthesia team according to local clinical practice. The additional temperature measurement performed for the study is non-invasive and does not involve any significant additional risk to participants.
Detailed description
Background
Unintended perioperative hypothermia, defined as a core body temperature below 36.0°C, is one of the most common complications associated with anesthesia and surgery. During the first hour after induction of anesthesia, the body's normal temperature regulation is impaired, causing heat to redistribute from the core to the peripheral tissues. Additional factors such as exposure to a cool operating room, administration of intravenous fluids, surgical duration, and the extent of the surgical procedure further increase the risk of heat loss.
Postoperative hypothermia has been associated with several adverse outcomes, including shivering, patient discomfort, increased blood loss and transfusion requirements, wound infection, cardiac complications, and prolonged recovery. International guidelines recommend routine temperature monitoring and the use of active warming techniques during surgery. However, the implementation of these recommendations varies considerably between hospitals, and contemporary national data from Spain are not available.
The PHRES Study has been designed to determine the current prevalence of postoperative hypothermia in Spanish post-anesthesia recovery units and to describe perioperative temperature management practices across a wide range of hospitals.
Study Design
PHRES is a prospective, multicenter, observational study conducted in approximately 25-30 public and private hospitals throughout Spain. The study is coordinated by Spanish anesthesiologists and will recruit approximately 1,334 adult patients undergoing elective non-cardiac surgery.
Because this is an observational study, no aspect of routine clinical care will be modified. Decisions regarding prewarming, intraoperative active warming, temperature monitoring, fluid warming, anesthetic technique, and postoperative management will remain entirely under the responsibility of the treating anesthesia team according to local clinical practice.
Participants
Eligible participants are adults aged 18 years or older undergoing scheduled non-cardiac surgery with an expected anesthesia duration of more than 60 minutes. Patients receiving general anesthesia, neuraxial anesthesia, or combined techniques may be included. Patients with suspected infection, those undergoing surgery under regional anesthesia with sedation alone, or those unable to provide informed consent will be excluded.
Participants will be enrolled consecutively during predefined recruitment periods in each participating center in order to minimize selection bias.
Study Procedures
After written informed consent is obtained, demographic and clinical information will be collected from the medical record and anesthesia chart. Information recorded will include:
- Patient characteristics and comorbidities.
- Type and duration of anesthesia and surgery.
- Surgical specialty and operative approach.
- Use of preoperative and intraoperative active warming.
- Methods of intraoperative core temperature monitoring.
- Administration of fluids, vasoactive drugs, and irrigation fluids.
Upon admission to the post-anesthesia care unit (PACU), the patient's core temperature will be measured using the same non-invasive zero-heat-flux temperature monitoring system in all participating centers. Standardizing the postoperative temperature measurement minimizes variability related to different thermometry methods and allows reliable comparison between hospitals.
The study will also record immediate postoperative events including shivering, hemodynamic instability requiring vasoactive support, new-onset arrhythmias, significant bleeding, and the need for blood transfusion.
Study Objectives
The primary objective is to estimate the prevalence of postoperative hypothermia, defined as a core temperature below 36.0°C at admission to the PACU.
Secondary objectives are:
- To describe the use of prewarming, active intraoperative warming, and core temperature monitoring in Spanish hospitals.
- To identify patient- and procedure-related risk factors associated with postoperative hypothermia.
- To evaluate the relationship between postoperative hypothermia and immediate postoperative complications.
Importance of the Study
This study will provide the first large contemporary national estimate of postoperative hypothermia in Spain using a standardized method for postoperative core temperature measurement. The results are expected to identify opportunities to improve perioperative temperature management, promote adherence to evidence-based warming strategies, and ultimately improve patient safety and recovery after surgery.
Study design
- Observational model
- Case only
- Time perspective
- Prospective
- Target follow-up
- 1 Day
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- The study population will consist of adult patients undergoing scheduled non-cardiac surgery under general, neuraxial, or combined anesthesia at participating public or private hospitals in Spain. Participating centers will be hospitals with operating rooms equipped with active patient warming systems and availability of core temperature monitoring in the postoperative recovery setting.
Key inclusion criteria (5 listed)
- American Society of Anesthesiologists (ASA) physical status I-III.
- Scheduled for non-cardiac surgical procedure.
- Anesthesia duration >60 minutes.
- General anesthesia, neuraxial anesthesia, or combined general and neuraxial/peripheral nerve block anesthesia.
- Written informed consent provided by the participant.
Key exclusion criteria (4 listed)
- Signs or suspicion of active infection at the time of surgery.
- Surgical procedure performed under regional anesthesia with sedation only.
- Cognitive impairment preventing the participant from understanding the study information.
- Refusal to participate in the study.
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 |
|---|---|---|
| Postoperative temperature monitoringA non-invasive zero-heat-flux temperature sensor will be used to measure core body temperature upon admission to the post-anesthesia care unit. The same temperature monitoring system will be used in all participating centers to standardize postoperative temperature measurement. The measurement does not alter routine clinical care. | Device | – |
Primary outcome
Prevalence of Postoperative Hypothermia
Time frame: At admission to the post-anesthesia care unit, immediately after surgery
Proportion of patients with a core body temperature below 36.0°C at admission to the post-anesthesia care unit (PACU). Core temperature will be measured using a non-invasive zero-heat-flux temperature monitoring system.
5 secondary outcomes
Prevalence of Preoperative Active Warming
Time frame: During the preoperative period, before transfer to the operating room
Prevalence of Intraoperative Active Warming
Time frame: From induction of anesthesia until completion of surgery
Prevalence of Intraoperative Core Temperature Monitoring
Time frame: During surgery
Risk Factors Associated With Postoperative Hypothermia
Time frame: Perioperative/Periprocedural
Immediate Postoperative Complications Associated With Hypothermia
Time frame: Perioperative/Periprocedural
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 24 Sep 2026.
- Background: PubMed 38326589Pedersen C, Munch P, Kjaergaard J, Gronlykke L, Brauer A. Accuracy of a zero-heat-flux thermometer in cardiac surgery, a prospective, multicentre, method comparison study. Sci Rep. 2024 Feb 7;14(1):3169. doi: 10.1038/s41598-024-53647-3.
- Background: PubMed 31869333Alfonsi P, Bekka S, Aegerter P; SFAR Research Network investigators. Prevalence of hypothermia on admission to recovery room remains high despite a large use of forced-air warming devices: Findings of a non-randomized observational multicenter and pragmatic study on perioperative hypothermia prevalence in France. PLoS One. 2019 Dec 23;14(12):e0226038. doi: 10.1371/journal.pone.0226038. eCollection 2019.
- Official website of the PHRES Study, providing information about the study, participating centers, study documentation, ethics approval, and instructions for investigators interested in participating.Link provided by the sponsor.
- Individual participant dataSharing planned: No. Individual participant data will not be shared because of privacy and data protection considerations. The study involves health-related information that will be collected and pseudonymized in accordance with applicable data protection regulations. Data will be used for the purposes specified in the study protocol and will not be made available for public sharing at the individual participant level.
Related trials for Hypothermia Following Anesthesia
Recruiting
Goal-Directed Temperature Management During Prolonged Abdominal Surgery
Hypothermia Following Anesthesia, Intraoperative Complications
Active, not recruitingObservational study
Incidence and Risk Factors of Intraoperative Hypothermia in Adult Patients After Protocol Implementation
Hypothermia Following Anesthesia
Recruiting
The Effect of Heating the Intensive Care Room in the Early Postoperative Period on Patient Outcomes
Abdominal Surgery Complications, Hypothermia Following Anesthesia
Not yet recruiting
Comparison of the Effect of Prewarming on Intraoperative Hypothermia in Patients Undergoing Holmium Laser Prostatectomy
Prewarming, Holmium Laser Prostate Surgery
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.
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 Hypothermia Following Anesthesia, run by Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz at 1 site in Spain.
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 5 inclusion and 4 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: enrolling by invitation, as of the sponsor's last update on 24 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 1 site in Spain. 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?
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?
Prevalence of Postoperative Hypothermia (time frame: At admission to the post-anesthesia care unit, immediately after surgery). 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 NCT07839728, which also lists 2 linked publications.
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 24 Sep 2026.