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An algorithm to detect dicrotic notch in arterial blood pressure and photoplethysmography waveforms using the
Ravi Pal1, Akos Rudas2, Sungsoo Kim1
1Department of Anesthesiology & Perioperative Medicine, University of California, Los Angeles, CA, USA.
Computer Methods and Programs in Biomedicine
|June 20, 2024
Summary
A new iterative envelope mean (IEM) algorithm accurately detects the dicrotic notch (DN) in arterial blood pressure (ABP) and photoplethysmography (PPG) signals. This fast and reliable method enhances cardiovascular monitoring and noninvasive blood pressure estimation.
Area of Science:
- Cardiovascular Physiology
- Biomedical Signal Processing
- Machine Learning in Healthcare
Background:
- The dicrotic notch (DN) is a critical feature in arterial blood pressure (ABP) and photoplethysmography (PPG) waveforms.
- Accurate DN detection is vital for assessing cardiac output, pulse wave velocity, and left ventricular ejection time.
- Existing methods for DN detection can be computationally intensive or less accurate, especially in challenging signals.
Purpose of the Study:
- To introduce a novel algorithm based on the iterative envelope mean (IEM) method for automated DN detection.
- To evaluate the algorithm's performance on both ABP and PPG waveforms using a large clinical dataset.
- To assess the algorithm's robustness in detecting DN in signals with varying signal-to-noise ratios (SNRs).
Main Methods:
- Developed an algorithm utilizing the iterative envelope mean (IEM) technique for DN detection.
- Evaluated the algorithm on a large perioperative dataset (MLORD) with over 1.1 million ABP and 3.4 million PPG cardiac cycles.
- Compared algorithm performance against researcher-marked DNs and an established second-derivative method using correlation, regression, and Bland-Altman analyses.
Main Results:
- Demonstrated strong correlation between algorithm-estimated and researcher-marked systolic phase duration (SPD) for both ABP (R²=0.99) and PPG (R²=0.98) waveforms.
- Achieved significantly lower mean DN detection errors compared to the second-derivative method (e.g., 0.0047s vs. 0.0693s for ABP).
- Showcased robust performance with high detectability rates even at low SNRs (-9 dB for ABP, -12 dB for PPG).
Conclusions:
- The proposed IEM-based algorithm offers a computationally efficient and reliable method for DN detection in ABP and PPG signals.
- The algorithm performs well even on 'DN-less signals' where the notch is not distinctly visible.
- This tool can significantly benefit medical applications requiring accurate extraction of DN-based features for patient monitoring and diagnosis.
Keywords:
Arterial blood pressure (ABP) waveformsDicrotic notch (DN)Iterative envelope mean (IEM) methodPhotoplethysmography (PPG) waveformsSystolic phase duration (SPD)More Related Videos
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