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[The comparative effectiveness of different infusion and blood warming methods]
J H Schmidt1, W Weyland, U Fritz
1Zentrum Anaesthesiologie, Rettungs- und Intensivmedizin, Georg-August-Universität Göttingen.
Der Anaesthesist
|November 1, 1996
Summary
Warming intravenous (IV) fluids during surgery is crucial for preventing hypothermia. Different warming devices show varying effectiveness based on flow rate and fluid temperature, with some in-line warmers and pre-warming methods proving more efficient.
Area of Science:
- Anesthesiology
- Surgical Patient Care
- Thermoregulation
Background:
- Surgical procedures lead to significant heat loss, primarily to the environment and through infused fluids.
- Room-temperature intravenous (IV) fluids contribute substantially to intraoperative hypothermia, with a 1°C drop in body temperature possible from infusing 53 ml/kg of 20°C fluid.
- Warming IV fluids is a key strategy to mitigate heat loss during surgery.
Purpose of the Study:
- To evaluate the efficacy of various in-line fluid warming devices and pre-warming techniques.
- To determine the impact of flow rate, ambient temperature, fluid temperature, and infusion system length on warming performance.
- To identify optimal methods for maintaining IV fluid temperature during surgical procedures.
Main Methods:
- Tested multiple in-line fluid warmers (Hotline HL-90, System H-250/D-50, Astotherm IFT 260, RSLB 30 H Gamida, Bair Hugger 241 Prototype) and pre-warming methods (Clinitherm S, Autotherm/Autoline).
- Investigated variables including flow rates (50-15,000 ml/h), ambient temperatures (20°C, 25°C), infusion bag temperatures (6°C, 20°C, 39°C), and downstream infusion system length.
- Measured fluid temperature at the end of the delivery line using thermistors and recorded data for analysis, defining effective warming as >33°C.
Main Results:
- At high flow rates (>2,500 ml/h), the H-250/D-50 system demonstrated superior warming compared to the RSLB 30 H Gamida system, especially with 20°C fluids.
- Pre-warmed infusions were effective at >2,000 ml/h, and with 'active insulation' (Autotherm/Autoline), effective warming extended down to >80 ml/h.
- The Hotline HL-90 was most effective in low (<250 ml/h) and middle (250-2,500 ml/h) flow ranges, while the Astotherm IFT 260's efficacy decreased with longer downstream tubing.
Conclusions:
- The effectiveness of IV fluid warming strategies is highly dependent on the specific device used and the clinical conditions, particularly flow rate.
- The need for and importance of effective IV fluid warming increases proportionally with the volume of fluid administered during surgery.
- Optimal selection of warming methods is critical for preventing perioperative hypothermia.