Evaluation der Effektivität eines neuen konduktiven Wärmesystems zur Prävention perioperativer Hypothermie in der Hals-Nasen-Ohren-Chirurgie

Evaluation of a new conductive active warming system for prevention of perioperative hypothermia in the ear, nose and throat surgery

by Christine Blecken
Doctoral thesis
Date of Examination:2015-12-01
Date of issue:2015-11-24
Advisor:Prof. Dr. Anselm Bräuer
Referee:Prof. Dr. Anselm Bräuer
Referee:PD Dr.Dr. Alexander Meyer
Persistent Address: http://dx.doi.org/10.53846/goediss-5376

 

 

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Abstract

English

Unintentional perioperative hypothermia is still a very common problem during general anaesthesia and it occurs in up to 50% in ear, nose and throat surgery (ENT). Hypothermia is associated with many complications and aggravates perioperative morbidity by impairment of wound healing, higher blood loss and a greater risk of cardiovascular ischaemic events. Active warming can reduce the risk of perioperative hypothermia. New active warming devices have to be evaluated if they are effective. In a randomized controlled study the hypothesis was tested if the new conductive warming blanket (Barrier® Easywarm®, Mölnlycke Health Care Erkrath, Germany) is better in reducing perioperative hypothermia in ENT surgery than passive insulation with a conventional hospital duvet alone. Secondary, the incidence of perioperative hypothermia during ENT surgery was evaluated. 80 patients who underwent ENT surgery with a planned operation time between 60 and 180 minutes were recruited and randomized in two groups of 40 patients. The control group was insulated with a standard hospital duvet without prewarming. The study group was prewarmed at least 30 minutes bevor induction of anaesthesia and for the whole intraoperative time with the new conductive warming blanket (Barrier® Easywarm®). Preoperative core temperature was measured sublingual using a clinical thermometer and intraoperative core temperature was measured in the esophagus by a temperature probe. For statistical analyses patients of both groups had to be excluded because they did not match the study protocol or the planned operation time. Therefore 29 patients of the study group and 32 patients of the control group could be included. Data were tested by Student’s t test or Mann-Whitney U test as appropriate and showed no difference between the groups for age, gender, body weight and height, preoperative core temperature or duration of anaesthesia or duration of procedure time. The ANOVA (repeated measures analyses of variance) and post hoc Scheffé’s test were used to analyse time depended changes in core temperature. These tests could not identify a significant higher core temperature in the study group at any time point. Furthermore, Fisher’s exact test showed no differences in the incidence of intraoperative (12 out of 29 versus 10 out of 32 patients, p=0.13) or postoperative hypothermia (12 out of 29 versus 9 out of 32 patients, p=0.30) between the groups. Overall, the incidence of perioperative hypothermia was high with 36%. In conclusion the new conductive warming blanket (Barrier® Easywarm®) was ineffective to reduce perioperative hypothermia compared to conventional passive insulation alone. Furthermore, patients who underwent ENT surgery are still at a high risk for perioperative hypothermia, which should be avoided by using effective active warming devices.
Keywords: perioperative hypothermia; conductive warming; material testing; ENT surgery
Schlagwörter: Perioperative Hypothermie; Konduktive Wärme; Evaluation Material; Hals-Nasen-Ohren-Chirurgie
 
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