Effects of Preoperative Warming of Patients on Postoperative Hypothermia and Shivering

Study Overview
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Brief Summary
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The investigators want to evaluate the effect of prewarming on the rate of postoperative hypothermia and shivering and to compare sublingual versus tympanic temperature assessment during the perioperative period in patients. Patients will be randomly assigned to 4 groups with different duration of prewarming. Body temperature will be recorded regularly by sublingual and tympanic (by thermocouple) measurement. Incidence of hypothermia (temp. < 36°C) and shivering will be assessed postoperatively.

Detailed Description
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Inadvertent perioperative hypothermia causes many serious complications. Therefore, prevention from, detection and therapy of hypothermia is essential. The appropriate methods of temperature assessment are still under debate as well as the effect and necessary duration of active prewarming of patients to avoid postoperative hypothermia and shivering. The aim of our study is to evaluate the effect of prewarming on the rate of postoperative hypothermia and shivering and to compare sublingual versus tympanic temperature assessment during the perioperative period in patients undergoing elective minor surgery. The investigators plan to include patients scheduled for routine minor surgery of approximately 1h duration. Patients will be randomly assigned to 4 groups with different duration of active prewarming. Body temperature will be recorded regularly by sublingual and tympanic (by thermocouple) measurement. Incidence of hypothermia (temp. < 36°C) and shivering will be assessed postoperatively.

Official Title
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Effects of Preoperative Warming of Patients on Postoperative Hypothermia and Shivering.

Conditions
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Hypothermia

Intervention / Treatment
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* Procedure: duration of preoperative active warming


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients scheduled for minor surgery (planned duration approximately <1h). Age 18-75yrs, ASA I-II physical status Exclusion Criteria: Emergency surgery, pregnant patients, patients not able to give informed consent, duration of surgery >2h, necessary postoperative mechanical ventilation

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Group 1<br>Control group - no intervention: no preoperative warming | |
| Active Comparator: Group 2 - 10 min prewarming<br>10 min prewarming preoperatively | Procedure: duration of preoperative active warming<br>* duration of prewarming by forced air warming<br>|
| Active Comparator: Group 3 - 20 min prewarming<br>20 min prewarming preoperatively | Procedure: duration of preoperative active warming<br>* duration of prewarming by forced air warming<br>|
| Active Comparator: Group 4 - 30 min prewarming<br>30 min prewarming preoperatively | Procedure: duration of preoperative active warming<br>* duration of prewarming by forced air warming<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of hypothermic (body temperature < 36°C) patients at postoperative arrival at postoperative care unit (PACU) | After surgery patients will be admitted to PACU. Body temperature will be evaluted here to study the number of hypothermic patients depended from duration of preoperative warming.Time frame for assessment of data: 5 min after postoperative arrival at PACU (one single measurement, duration: 30 sec).Afterwards patients will be observed for about 2h. | postoperative arrival at PACU (once) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Performance of sublingual vs. tympanic temperature assessment preoperatively in awake patients. | Sublingual and tympanic body temperature will be assessed simultaneously once at patients' preoperative arrival at PACU and compared to each other with analysis of correlation. This means that one sublingual and one tympanic temperature value will be measured to be compared to each other.Time frame for assessment of data: one single measurement immediately (1 min) after patients' arrival at PACU. Afterwards: observation of patients for about 2h. | preoperatively (once) at arrival at PACU | 
| Performance of sublingual vs. tympanic temperature assessment intraoperatively in anaesthetised patients. | Sublingual and tympanic body temperature will be assessed simultaneously (once) 30 min after start of surgery and compared to each other with analysis of correlation. This means that one sublingual and one tympanic temperature value will be measured to be compared to each other.Time frame for data assessment: 1 min after 30 min after start of surgery.Afterwards patients will be observed for about 3h. | intraoperatively (30 min after start of surgery), once | 
| Performance of sublingual vs. tympanic temperature assessment postoperatively in awake patients. | Sublingual and tympanic body temperature will be assessed simultaneously (once) at patients' postoperative arrival at PACU and compared to each other with analysis of correlation. This means that one sublingual and one tympanic temperature value will be measured to be compared to each other.Time frame for data assessment: 30 sec immediately after patients' arrival at PACU. | at postoperative arrival at PACU, once | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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hypothermia, accidental, prewarming, body temperature monitoring, preoperative warming, sublingual temperature assessment, tympanic temperature assessment