Medical IV Fluid warming device interference with ECG monitors
Baieva, Svitlana (2024)
2024
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:amk-2024052214204
https://urn.fi/URN:NBN:fi:amk-2024052214204
Tiivistelmä
Medical technology companies have IV Fluid (intravenous fluids) devices where the IV solution circulates through the device to the patient. To prevent hypothermia, medical setup includes a warmer.
The IV liquid warming device under study consists of controller (power supply and temperature display), warmer (heating element and status/temperature indicators) and cartridge (metallic plate with fluid channel and dielectric coating). It is observed that low frequency noise is generated by the warmer. This noise can affect the ECG monitor cardiogram curve appearance. IV fluid warmer is designed to minimize the noise generated by the IV fluid heater to ECG signals. The device implementation patent is considered in detail. The purpose of this study is to clarify reason and source for low frequency noise generated by the warmer.
The noise coupling mechanisms are considered. Capacitive coupling is the mechanism which plays a main role in noise transfer to patient. The behaviour of main parts of liquid warming device is simulated using Matlab Simulink software. The different coupling elements (capacitor, inductance, resistor) are introduced between heater circuit and human blood model (capacitor and resistors).
It is concluded that MOSFETs that are used in the device as switches are the source of low frequency noise. Literature review suggests that the noise could be 1/f noise. Fluctuations of transistor intrinsic parameters lead to this type of low frequency noise. It is calculated that low frequency noise signal is attenuated by saline line when it is sufficiently long.
The IV liquid warming device under study consists of controller (power supply and temperature display), warmer (heating element and status/temperature indicators) and cartridge (metallic plate with fluid channel and dielectric coating). It is observed that low frequency noise is generated by the warmer. This noise can affect the ECG monitor cardiogram curve appearance. IV fluid warmer is designed to minimize the noise generated by the IV fluid heater to ECG signals. The device implementation patent is considered in detail. The purpose of this study is to clarify reason and source for low frequency noise generated by the warmer.
The noise coupling mechanisms are considered. Capacitive coupling is the mechanism which plays a main role in noise transfer to patient. The behaviour of main parts of liquid warming device is simulated using Matlab Simulink software. The different coupling elements (capacitor, inductance, resistor) are introduced between heater circuit and human blood model (capacitor and resistors).
It is concluded that MOSFETs that are used in the device as switches are the source of low frequency noise. Literature review suggests that the noise could be 1/f noise. Fluctuations of transistor intrinsic parameters lead to this type of low frequency noise. It is calculated that low frequency noise signal is attenuated by saline line when it is sufficiently long.