Critical Design Requirements for an Electrosurgical Unit used in Low-Middle Income Countries

Critical Design Requirements for an Electrosurgical Unit used in Low-Middle Income Countries

Cranz, Felix (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Medical Instruments & Bio-Inspired Technology)

Dankelman, J. (mentor)
Oosting, R.M. (mentor)
Diehl, J.C. (graduation committee)
Wauben, L.S.G.L. (graduation committee)

Delft University of Technology

2018-03-12

Introduction: Over five billion people in mainly low and middle income countries (LMICs) do not have access to safe surgery. This is due to a lack of available and functional medical equipment, where up to 70% of the existing equipment is broken. Some reasons for this shortage in medical equipment are a lack of funding, maintenance, training, educated procurement and infrastructure. To improve access to affordable quality equipment in LMICs, the design of a low cost and high quality Electrosurgical unit (ESU) is suggested. An ESU is an essential operating tool to assist surgeons on various operations. To start the design process, critical design requirements are laid out in this paper based on the properties and thermal performance of three existing devices.Theoretical Background: Electrosurgery is used in various operations to cut and coagulate tissue through high frequency current. By changing the power intensity and waveform of the current, tissue can be heated to different levels. The coagulation of tissue occurs between 60-100°C, while vaporization occurs >100°C. Hazards in electrosurgery include current leakage and the detachment of the return electrode, which can cause burns to the user, staff or patient. Methods: The design requirements were obtained by conducting experiments and comparing three ESUs. Two of the ESUs are regarded as high-end devices, while the third, due to a low price and a simplified design, can be seen as a low-end device. Through a Property Test and a Thermal Camera Test, cut and coagulation modes were tested for each electrosurgical device at different powers and loads. For the Property Test the power, waveforms, crest factor, current and voltage at activation were measured and analysed. To understand the effects of the measured properties, a thermal camera was used to measure the heat map on tofu samples (simulating human tissue) that were exposed to currents from each of the three ESUs.Results: The actual power was measured to be lower than the set power at rated loads for all three ESUs. The wave-shape of all three devices differed considerably, producing a different thermal output on the tofu samples. All devices dropped their power with an increase in load. One ESU exceeded the 100 mA current leakage limit set by standards. In the Thermal Camera Test, high end devices produced temperature values more similar to those expected from literature. Discussion: The most important design requirements to consider include an efficient waveform design and a steady power control. With a small, light weight, and repairable hardware using sterilisable accessories, the ESU would become more transportable, robust, and independent from the manufacturer; therefore also more suitable for a LMICs. A split return electrode and low leakage are important design criteria to prevent any injury to patients and users. Improvements to the study include a wider pool of different ESUs for a better market analysis, using a camera with a higher temperature measurement than 177°C and larger tofu samples for a better thermal analyses.

Electrosurgery
Erbe
Valleylab
RDE
LMICs
Design

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2023-03-12

Student theses

master thesis

© 2018 Felix Cranz