Zusammenfassung
Ziel der Studie: Ziel der vorliegenden Probandenstudie war die Bestimmung des Wärmetransfers durch Wassermatten bei Anwendung unter dem Rücken und über den Beinen. Methodik: Mit Zustimmung der örtlichen Ethikkommission wurden bei acht Probanden sechs Wärmeflusssensoren auf dem Rücken und weitere acht Sensoren an beiden Beinen platziert. Die Probanden mussten sich dann auf eine Wassermatte (ComfortPad Plus®, Cincinnati Sub-Zero Products Inc., Cincinnati, OH, USA) mit Gelauflage (Granulab International, Armersfoort, Niederlande) legen. Über beide Beine wurde eine weitere Wassermatte (Plastipad™, Cincinnati Sub-Zero Products Inc.) gelegt. Beide Matten wurden mit einem Hico-Variotherm 530 (Hirtz & Co. Hospitalwerk, Köln) auf 41 °C gewärmt. Nach Bestimmung der Kontaktfläche wurde durch Multiplikation des gemessenen Wärmeflusses pro Fläche der Wärmetransfer errechnet. Ergebnisse: Der Wärmefluss pro Fläche zum Rücken betrug 45,6 ± 4,5 W m- 2, die Kontaktfläche war 0,39 ± 0,03 m2. Daraus errechnete sich ein Wärmetransfer von 18,0 ± 2,4 W. Der Wärmefluss pro Fläche zu den Beinen betrug 24,7 ± 4,3 W m- 2, die Kontaktflächenmessung ergab 0,12 ± 0,01 m2. Daraus errechnete sich ein Wärmetransfer von 2,9 ± 0,6 W. Schlussfolgerung: Durch die Wassermatte unter dem Rücken konnte ein deutlich höherer Wärmetransfer erzielt werden als mit der Wassermatte über den Beinen. Dennoch ist die Wärmung der Beine zur Hypothermieprophylaxe wichtiger, da Modellrechnungen zeigen, dass dadurch ein stärkerer Einfluss auf die Wärmebilanz ausgeübt wird.
Abstract
Aim of the study: To determine the heat transfer by circulating-water mattresses placed under the back and over both legs of human volunteers. Methods: With approval by the local ethics committee and informed consent eight minimally clothed volunteers were included in the study. Six calibrated heat flux transducers were placed on the back and additionally eight sensors were placed on both legs of each volunteer. The volunteers reclined on a circulating-water mattress (ComfortPad Plus®, Cincinnati Sub-Zero Products Inc., Cincinnati, OH, USA) coated with gel (Granulab International, Armersfoort, Niederlande). Another circulating-water mattress (Plastipad™, Cincinnati Sub-Zero Products Inc.) was placed over both legs. Both devices were heated to 41 °C by a hypo-hyperthermia system (Hico-Variotherm 530, Hirtz & Co. Hospitalwerk, Cologne, Germany). Heat flux data were sampled during steady-state conditions. After determination of the contact area between the mattresses and the skin, heat transfer was calculated by multiplication of the heat flux per area by the contact area. Results: Heat flux per area to the back was 45.6 ± 4.5 W m- 2, the contact area was 0.39 ± 0.03 m2. This resulted in a heat transfer of 18.0 ± 2.4 W. Heat flux per area to the legs was 24.7 ± 4.3 W m- 2, the contact area was 0.12 ± 0.01 m2. This resulted in a heat transfer of 2.9 ± 0.6 W. Conclusion: The heat transfer of the circulating-water mattress to the back was much higher than the heat transfer to the legs. Nevertheless, model calculations show that conductive warming of the legs is more important for the prevention of perioperative hypothermia than conductive warming of the back, because it has a higher impact on the heat balance.
Schlüsselwörter
Perioperative Hypothermie - Wassermatte - Wärmeaustausch - Wärmeflussmessung - Wärmebilanz
Key words
Perioperative hypothermia - circulating-water mattress - heat exchange - heat flux measurements - heat balance
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Dr. med. Anselm Bräuer DEAA
Zentrum Anästhesiologie, Rettungs- und Intensivmedizin ·
Georg-August-Universität · Robert-Koch-Straße 40 · 37075 Göttingen
eMail: abraeue@gwdg.de
