An observational study in Intraoperative Temperature Monitoring and Body Temperature, sponsored by Khon Kaen University. Not yet recruiting at 1 site in Thailand. Open to participants aged 18 Years to 85 Years. Per ClinicalTrials.gov, last updated 2026-08-06.
Sponsored by Khon Kaen University · Observational
Keeping a patient's body temperature normal during surgery is an important part of safe anesthetic care. When the body temperature drops below 36°C (called inadvertent perioperative hypothermia), patients face higher risks of bleeding, wound infection, heart problems, and a slower recovery. To prevent these complications, anesthesiologists monitor core body temperature continuously during surgery.
Three monitoring methods are commonly used in clinical practice: (1) a nasopharyngeal probe - a small soft sensor inserted through the nose and placed at the back of the throat, which provides continuous readings and is considered the gold standard; (2) an infrared tympanic thermometer (TaiDoc TD-1261) - a handheld device that measures ear temperature in about one second; and (3) the 3M SpotOn™ sensor - a non-invasive adhesive patch placed on the forehead that continuously estimates core temperature without requiring insertion into any body cavity.
Although all three methods are used interchangeably at Srinagarind Hospital, no study has directly compared all three simultaneously in the same patient to determine how well they agree with each other. If significant differences exist between methods, a clinician who switches from one device to another may unknowingly under-detect or over-estimate hypothermia.
This study will enroll 92 adult patients scheduled for elective surgery under general anesthesia at Srinagarind Hospital, Khon Kaen University. All three temperature sensors will be applied at the same time, and readings will be recorded simultaneously every 15 minutes throughout the operation. The main goal is to determine whether each device gives results close enough to the nasopharyngeal probe to be safely used as an alternative. The study is observational - no medications or procedures will be added to routine care.
Background: Inadvertent perioperative hypothermia (IPH), defined as a core body temperature \< 36.0°C, affects 20-90% of patients undergoing general anesthesia and is associated with coagulopathy, surgical site infection, morbid cardiac events, and prolonged drug metabolism. Accurate intraoperative temperature monitoring is mandated by professional society guidelines.
Study design: Prospective, single-center, triple-method observational agreement study at Srinagarind Hospital, Khon Kaen University, Thailand. All three thermometry modalities are applied simultaneously in each participant. No intervention is assigned; temperature monitoring is additional to standard perioperative care.
Methods: After induction of general anesthesia and tracheal intubation, the nasopharyngeal (NP) probe (reference standard), TaiDoc TD-1261 infrared tympanic thermometer (test method 1), and 3M SpotOn™ zero-heat-flux forehead sensor (test method 2) are placed. Simultaneous temperature readings are recorded at 15-minute intervals from 15 minutes after induction until surgery end. For the TD-1261, two consecutive readings are taken at each time point and averaged; pinna retraction and fresh disposable probe cover are used at every measurement. The SpotOn™ sensor requires a 10-minute equilibration period before the first recorded value.
Statistical analysis: Primary analysis uses repeated-measures Bland-Altman analysis (Myles \& Cui, 2007 framework) to estimate bias and limits of agreement (LoA) for each method pair against the NP probe. Pre-specified clinical acceptability criterion: LoA within ±0.5°C (Sessler, 2008). Variance of differences is decomposed into between-subject (σ²_B) and within-subject (σ²_W) components. Secondary analyses: proportional bias assessment, sensitivity/specificity for hypothermia detection (NP \< 36.0°C), intraclass correlation coefficient (ICC, two-way mixed-effects model), and multivariable linear mixed-effects regression for clinical covariates. Sample size: 92 patients (Lu et al., 2016 method; 80% power; α = 0.05; SD of differences = 0.30°C for NP vs. TM; LoA acceptability threshold ±0.50°C; 15% dropout allowance).
This study provides the first institution-specific, population-specific evidence on temperature monitoring agreement in Thai surgical patients and constitutes the first published intraoperative validation of the TaiDoc TD-1261 infrared tympanic thermometer.
Khon Kaen University is the lead sponsor of 161 studies on the registry; 24 are open to participants now.
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Adult patients scheduled for elective surgery under general anesthesia with tracheal intubation at Srinagarind Hospital and Queen Sirikit Heart Center of the Northeast, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand, with expected surgical duration ≥ 60 minutes and ASA Physical Status I-III.
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Group 1: Cardiac surgery Group 2: Thoracic surgery Group 3: General surgery, including neurosurgery
Exclusion Criteria:
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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.
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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.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Adult patients (age ≥ 18 years) undergoing elective surgery under general anesthesia with tracheal intubation at Srinagarind Hospital and Queen Sirikit Heart Center of the Northeast, Khon Kaen University, with an expected surgical duration ≥ 60 minutes and ASA Physical Status I-III. All participants have all three temperature monitoring devices (NP probe, TaiDoc TD-1261 IR tympanic thermometer, and 3M SpotOn™ ZHF sensor) applied simultaneously following induction of anesthesia.
Limits of Agreement Between Each Test Method and the Nasopharyngeal Probe
The 95% limits of agreement (LoA = Bias ± 1.96 × SD\_total) between (i) the TaiDoc TD-1261 infrared tympanic thermometer and the nasopharyngeal probe, and (ii) the 3M SpotOn™ sensor and the nasopharyngeal probe, estimated by repeated-measures Bland-Altman analysis. Pre-specified clinical acceptability criterion: LoA must be contained within ±0.5°C with both 95% CI limits of the upper and lower LoA falling within this range.
Time frame: From 15 minutes after anesthesia induction until end of surgery; measurements recorded at 15-minute intervals (estimated total observation window: 60-195 minutes per participant)
Systematic Bias (Mean Difference) of Each Test Method vs. NP Probe
Mean difference (°C) with 95% CI between each test method and the NP probe across all paired observations, estimated from the repeated-measures Bland-Altman model
Time frame: From 15 minutes after anesthesia induction until surgery end (15-minute intervals)
Proportional Bias Assessment
Linear regression of the difference (test - reference) on the mean of both methods, with cluster-robust standard errors; Pitman's test for correlation between sum and difference
Time frame: From 15 minutes after anesthesia induction until surgery end
Sensitivity and Specificity for Hypothermia Detection
Sensitivity, specificity, PPV, and NPV of each test method for detecting intraoperative hypothermia defined as NP temperature \< 36.0°C, with AUROC estimated by DeLong's method
Time frame: From 15 minutes after anesthesia induction until surgery end
Intraclass Correlation Coefficient
ICC (two-way mixed-effects model, absolute agreement) with 95% CI for each method pair
Time frame: From 15 minutes after anesthesia induction until surgery end
Percentage of Paired Measurements Within ±0.5°C
Percentage of all paired simultaneous readings in which the test method falls within ±0.5°C of the simultaneous NP reference reading
Time frame: From 15 minutes after anesthesia induction until surgery end
Clinical Covariate Association With Method Difference
Association between clinical covariates (age, sex, BMI, ASA status, surgical duration, anesthetic technique, active warming use, ambient OR temperature, baseline core temperature) and the absolute method difference, estimated by multivariable linear mixed-effects regression
Time frame: Baseline characteristics collected before surgery; temperature data from 15 minutes post-induction until surgery end
Incidence of Device-Related Adverse Events
Rate of epistaxis (NP probe), aural discomfort or canal injury (TD-1261), and adhesive skin reaction (SpotOn™) during the monitoring period
Time frame: From device placement until surgery end
Plan to share: Yes — Deidentified individual participant temperature measurement data, baseline characteristics, and covariate data will be made available to qualified researchers following publication of the primary results in a peer-reviewed journal, subject to a data sharing agreement. Requests should be directed to the principal investigator.
Supporting information: Study protocol
Time frame: Starting 6 months after publication of the primary manuscript; available for 5 years thereafter
Access criteria: Qualified researchers submitting a methodologically sound research proposal. Requests will be reviewed by the Principal Investigator. A signed data sharing agreement is required. Data will be provided in de-identified format via secure file transfer.
Start is estimated for Aug 2026; primary completion for Feb 2027, 6 months later.
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