An interventional study of Forced-air warming and Resistive conductive warming in Perioperative Hypothermia, Inadvertent Perioperative Hypothermia and Hypothermia, sponsored by Masarykova Nemocnice v Usti nad Labem, Krajska Zdravotni a.s.. Not yet recruiting at 1 site in Czechia. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-02.
Sponsored by Masarykova Nemocnice v Usti nad Labem, Krajska Zdravotni a.s. · Not applicable, Interventional, and Prevention
Perioperative hypothermia (core temperature below 36.0 °C) is a common complication of surgery and is associated with increased blood loss, wound infection, cardiovascular events and patient discomfort. Forced-air warming (Bair Hugger) is the standard method of active warming. Resistive conductive warming (HotDog) transfers heat by direct contact and does not blow air into the operating room, which may be advantageous. This randomised trial will test whether resistive warming is not inferior to forced-air warming in preventing hypothermia on arrival in the post-anaesthesia care unit (PACU) in adults undergoing elective surgery under general anaesthesia.
Design: single-centre, prospective, randomised, controlled, parallel-group non-inferiority trial with 1:1 allocation, reported according to CONSORT and its extension for non-inferiority trials.
Randomisation: computer-generated block randomisation (random blocks of 4 and 6) using StudyRandomizer, stratified by type of surgery (laparoscopic/endoscopic in a body cavity; open body-cavity surgery; other procedures). Allocation is revealed only after eligibility is confirmed and written informed consent is obtained.
Interventions: all patients receive passive insulation with a reflective (silver) blanket from arrival in the pre-operative area until induction and during transfer to the PACU. After induction of general anaesthesia, patients receive active warming with either forced-air warming (Bair Hugger, upper- or lower-body blanket, 43 °C) or resistive conductive warming (HotDog, underbody mattress, 42 °C) until the end of surgery. Anaesthesia, fluids and operating-room temperature follow standard institutional practice and are recorded. If core temperature falls below 35.5 °C, the anaesthetist may add rescue warming; this is recorded as a protocol deviation. Duration of surgery is not restricted and is recorded.
Temperature measurement: core temperature is measured non-invasively with a zero-heat-flux sensor (3M SpotOn) placed on the forehead before induction and kept in place until the PACU; values are recorded at baseline, every 15 minutes during surgery, at the end of surgery, within 5 minutes of PACU arrival, 30 minutes after arrival and at PACU discharge.
PACU assessments: shivering (Bedside Shivering Assessment Scale), thermal comfort (5-point Likert scale), subjective feeling of cold ("Do you feel cold?") and objective signs of thermal discomfort (piloerection; cold, pale or mottled extremities; shivering; curling up; request for blankets; sweating; flushing; uncovering).
Blinding: operating-room staff cannot be blinded. Warming devices remain in the operating room and the PACU outcome assessor is blinded: PACU assessments are performed by staff not involved in intraoperative care and unaware of group allocation. Statistical analysis is performed with coded groups.
Sample size: assuming a hypothermia incidence of 12.5% in both groups, a non-inferiority margin of 7.5 percentage points, one-sided alpha 0.025 and 80% power, 305 patients per group are required; with 10% dropout, 340 patients per group (680 in total) will be enrolled.
Statistical analysis: the primary outcome is analysed as the risk difference (HotDog minus Bair Hugger) with a two-sided 95% confidence interval (Newcombe method). Non-inferiority is concluded if the upper limit is below 7.5 percentage points in both the intention-to-treat and per-protocol populations. If non-inferiority is shown, superiority is tested hierarchically. Sensitivity analyses include a stratum-adjusted (Mantel-Haenszel) risk difference and logistic regression adjusted for stratum, age, BMI, duration of surgery and operating-room temperature. Temperature over time is analysed with a linear mixed model. Secondary outcomes are exploratory.
449 studies on the registry are indexed under Hypothermia; 54 are open to participants now.
This study's planned enrollment of 680 is above the median of 77 across 328 interventional studies indexed under Hypothermia.
Browse Hypothermia studies →Masarykova Nemocnice v Usti nad Labem, Krajska Zdravotni a.s. is the lead sponsor of 21 studies on the registry; 14 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
ASA physical status
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Forced-air warming with a Bair Hugger upper- or lower-body blanket (according to surgical site), set to 43 °C, started immediately after induction of general anaesthesia and continued until the end of surgery. Passive reflective-blanket insulation before induction and during transfer to PACU.
Device: Forced-air warming
Resistive conductive warming with a HotDog underbody mattress, set to 42 °C, started immediately after induction of general anaesthesia and continued until the end of surgery. Passive reflective-blanket insulation before induction and during transfer to PACU.
Device: Resistive conductive warming
Convective active warming system blowing warmed air through a disposable upper- or lower-body blanket (Bair Hugger, Solventum, formerly 3M), set to 43 °C, from induction of anaesthesia until the end of surgery.
Also known as: Bair Hugger
Air-free resistive polymer warming mattress placed under the patient, transferring heat by direct contact (HotDog, Augustine Surgical), set to 42 °C, from induction of anaesthesia until the end of surgery.
Also known as: HotDog
Incidence of hypothermia on PACU arrival
Proportion of patients with core temperature \< 36.0 °C measured by zero-heat-flux thermometry (3M SpotOn). Non-inferiority margin for the risk difference (resistive minus forced-air): 7.5 percentage points.
Time frame: Onf arrival in the PACU max up to 5 minutes from arrival
Core temperature at end of surgery
Core temperature (°C) measured by zero-heat-flux thermometry (3M SpotOn).
Time frame: At completion of skin closure up to 10 minutes from skin closure
Postoperative shivering
Incidence (BSAS \>= 1) and severity (highest Bedside Shivering Assessment Scale score, 0-3; higher score = more severe shivering).
Time frame: From PACU arrival to PACU discharge, assessed every 15 minutes (up to 4 hours)
Thermal comfort
Patient-rated 5-point Likert scale (1 = very cold, 2 = cold, 3 = comfortable, 4 = warm, 5 = too hot).
Time frame: Once fully oriented in PACU (Aldrete score >= 9), up to 4 hours after arrival
Subjective feeling of cold
Proportion of patients answering "yes" to the question "Do you feel cold?".
Time frame: On PACU arrival (if able to respond) and when fully oriented in PACU (Aldrete score >= 9), up to 4 hours after arrival
Objective signs of thermal discomfort
Proportion of patients with at least one sign of cold discomfort assessed by a blinded observer (piloerection; cold, pale or mottled extremities; shivering; curling up or pulling blankets; request for blankets or warming). Signs of heat discomfort (sweating, flushing, uncovering) are recorded separately.
Time frame: On PACU arrival and when fully oriented in PACU (Aldrete score >= 9), up to 4 hours after arrival
Lowest intraoperative core temperature
Lowest core temperature (°C) recorded during surgery by zero-heat-flux thermometry.
Time frame: From induction of anaesthesia to end of surgery (assessed during surgery) up to 4 hours from start of the surgery
Incidence of intraoperative hypothermia
Proportion of patients with any core temperature \< 36.0 °C during surgery.
Time frame: From induction of anaesthesia to end of surgery (assessed during surgery) maximum of 4 hours from start of the surgery
Core temperature over time
Core temperature (°C) at 15-minute intervals during surgery and at predefined PACU time points.
Time frame: From induction to end of surgery; PACU arrival, 30 minutes after arrival and PACU discharge (up to 4 hours)
Length of PACU stay
Time from PACU arrival to PACU discharge (minutes).
Time frame: From PACU arrival to discharge, up to 24 hours
Warming-related adverse events
Incidence of skin burns, pressure injury at the mattress site, hyperthermia \> 38.0 °C and device malfunction.
Time frame: From start of warming to PACU discharge (up to 24 hours)
Plan to share: No — Individual participant data will not be shared. Aggregated results will be published in a peer-reviewed journal.
Start is estimated for Nov 2026; primary completion for Oct 2027, 11 months later.
Of 132 non-industry interventional studies with no phase under Hypothermia, half reached primary completion within 16 months of starting (the median), counting those still running; a quarter within 6 and three quarters within 36. This study's planned 11 months is below that.
Counting every sponsor, half of 135 studies reached it within 16 months; a quarter within 6 and three quarters within 36.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Masarykova Nemocnice v Usti nad Labem, Krajska Zdravotni a.s.