Biomedical instrumentation & technology / Association for the Advancement of Medical Instrumentation
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Biomed Instrum Technol · Mar 2003
Thermal control and design considerations for a high-performance fluid warmer.
The process of warming liquids for intravenous infusion presents several technical challenges for the engineer: Typical liquid inlet temperatures can range from 5 degrees C to 20 degrees C, flow requirements can vary from essentially zero ("Keep Vein Open," or K. V. O.) to 30 L/h, and desired outlet temperature is fixed at a maximum threshold of 41 degrees C to minimize the risk of thermally mediated hemolysis. ⋯ The most difficult aspect of this challenge is preventing the transient infusate temperature from exceeding 43 degrees C, even when the power requirement varies by orders of magnitude, such as occurs when the flow suddenly decreases from maximum to zero. Many current-generation fluid warmers are optimized for operation at either low or high flow rates; we believed that it was possible to design an easy-to-use device that could achieve good performance across the entire range of flow rates. This article describes some of the methods that were used successfully to meet these challenges in the design of the Augustine Medical Ranger blood fluid warmer.
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Biomed Instrum Technol · Mar 2003
The future of clinical engineering: technology that enables improved patient care.
Speakers at this year's ACCE Symposium will describe in detail the scope and depth of technological and other factors that are at work changing the healthcare delivery paradigm. Other presenters will explore the impact the changes will likely have on the clinical engineering profession. ⋯ The experts agree: clinical engineering is at a critical crossroads. No one who intends to pursue clinical engineering or healthcare technology management over the next 10 years can afford to miss this year's meeting.
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Biomed Instrum Technol · Jan 2003
Comparative Study Clinical TrialBlood flow measurement from plethysmographic pulse waves without venous occlusion.
An air plethysmograph with a sensitive phototransducer was constructed so that plethysmographic volume-change pulsations could be displayed in detail without using venous occlusion. Software was developed to allow analysis of the pulses using a modification of the backward extrapolation technique. This allowed calculation of the forward arterial blood flow and noninvasive derivation of the resting arterial flow waveform. ⋯ The mean blood flow for venous occlusion (rest and exercise) was 0.76 +/- 0.07 mL/beat (mean +/- SEM), and the mean blood flow for backward extrapolation (rest and exercise) was 0.74 +/- 0.09 mL/beat (mean +/- SEM). This corresponds to 3.86 +/- 0.36 mL/min/100 mL and 3.76 +/- 0.46 mL/min/100 mL, respectively. Important assumptions when using this method are that venous return is constant and that forward arterial flow is over before the end of the cardiac cycle.