Pressure measurement artifact with analog-to-digital conversion

Area of Science:

• Biomedical Engineering
• Medical Instrumentation
• Signal Processing

Background:

• Accurate physiological pressure measurement is crucial for clinical diagnosis and research.
• Standard medical monitoring equipment uses fluid-filled catheters for pressure transduction.
• Analog-to-digital conversion (ADC) is essential for digital signal processing of physiological data.

Purpose of the Study:

• To identify and characterize an artifact observed during pressure signal acquisition.
• To determine the cause of the observed artifact during analog-to-digital conversion.
• To evaluate the effectiveness of electrical filtering in eliminating the artifact.

Main Methods:

• Pressure signals were acquired using a fluid-filled catheter and standard medical monitoring equipment.
• The signal was sampled at 200 Hz using an analog-to-digital converter.
• A 100-Hz low-pass filter was applied to the acquired pressure signal.

Main Results:

• A 3.5-Hz artifact with an amplitude of 0.3 to 0.9 mm Hg was observed during ADC.
• The artifact was identified as aliasing from the transducer's 2,403.5-Hz electrical excitation signal.
• A 100-Hz low-pass filter completely eliminated the artifactual signal.

Conclusions:

• Electrical filtering is essential for accurate pressure measurement acquisition via ADC, even when Nyquist criterion is met.
• Aliasing artifacts can occur due to electrical noise contamination, impacting data accuracy.
• While clinically minor, these artifacts are significant in research requiring precise pressure measurements.