Tonometric Multi-Wavelength Photoplethysmography for Studying the Cutaneous Microvasculature of the Fingertip

Sirkiä, Jukka-Pekka; Panula, Tuukka; Kaisti, Matti

doi:10.1109/tim.2023.3293873

Cited by 4 publications

(10 citation statements)

References 52 publications

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“…External pressure was generated using a stepper motor (28BYJ‐48, generic brand) and a threaded shaft in a similar fashion to ref. [15, 33]. The rotation of the threaded shaft slowly lowers a bar, guided by two metal rods at the ends, to a fingertip, causing it to squeeze against the probe‐LED sensor configuration.…”

Section: Methodsmentioning

confidence: 99%

“…Oscillometry is a standard technique in arm cuff‐based automatic BP monitors, and the research group has demonstrated the tonometric version of the technique used in this study in ref. [15, 33]. Note that the proposed system records both pressure‐related oscillations, detected by the load cell, and volumetric oscillations, detected by the spectrometer.…”

Section: Methodsmentioning

confidence: 99%

“…These include parameters such as arteriolar‐PTT‐based BP, [ 11,12 ] systemic vascular resistance, [ 13 ] penetration depth‐dependent PPG, [ 14 ] and depth‐resolved BP and vasomotor activity. [ 15 ] Such multi‐wavelength PPG (MWPPG) systems use a photodiode and several time‐multiplexed LEDs. The theoretical foundation behind the technology is based on: i) the penetration ability of light into the skin depends on the wavelength [ 16,17 ] and ii) the organization of the cutaneous vasculature is such that deeply buried large arteries responsible for blood conduction branch out to blood flow regulating arterioles that themselves branch out to surrounding tissue maintaining capillaries.…”

Section: Related Workmentioning

confidence: 99%

See 2 more Smart Citations

Non‐Invasive Hemodynamic Monitoring System Integrating Spectrometry, Photoplethysmography, and Arterial Pressure Measurement Capabilities

Sirkiä,

Panula,

Kaisti

2024

Advanced Science

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Minimally invasive and non‐invasive hemodynamic monitoring technologies have recently gained more attention, driven by technological advances and the inherent risk of complications in invasive techniques. In this article, an experimental non‐invasive system is presented that effectively combines the capabilities of spectrometry, photoplethysmography (PPG), and arterial pressure measurement. Both time‐ and wavelength‐resolved optical signals from the fingertip are measured under external pressure, which gradually increased above the level of systolic blood pressure. The optical channels measured at 434–731 nm divided into three groups separated by a group of channels with wavelengths approximately between 590 and 630 nm. This group of channels, labeled transition band, is characterized by abrupt changes resulting from a decrease in the absorption coefficient of whole blood. External pressure levels of maximum pulsation showed that shorter wavelengths (<590 nm) probe superficial low‐pressure blood vessels, whereas longer wavelengths (>630 nm) probe high‐pressure arteries. The results on perfusion indices and DC component level changes showed clear differences between the optical channels, further highlighting the importance of wavelength selection in optical hemodynamic monitoring systems. Altogether, the results demonstrated that the integrated system presented has the potential to extract new hemodynamic information simultaneously from macrocirculation to microcirculation.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

See 1 more Smart Citation

Non‐Invasive Hemodynamic Monitoring System Integrating Spectrometry, Photoplethysmography, and Arterial Pressure Measurement Capabilities

Sirkiä,

Panula,

Kaisti

2024

Advanced Science

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“…These results have been comprehensively presented before. [22] Waveform correlation analysis between all three channels was performed for both SR and AF recordings using the dataset IIIb. Example signals are shown in Figure 5a with a younger and an older participant to demonstrate that no significant differences were observed in similarity depending on age, which is a major factor affecting the waveform morphology.…”

Section: Comparison Between Optical and Pressure Sensorsmentioning

confidence: 99%

Hemodynamic Bedside Monitoring Instrument with Pressure and Optical Sensors: Validation and Modality Comparison

Kaisti,

Panula,

Sirkiä

et al. 2024

Advanced Science

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Results from two independent clinical validation studies for measuring hemodynamics at the patient's bedside using a compact finger probe are reported. Technology comprises a barometric pressure sensor, and in one implementation, additionally, an optical sensor for photoplethysmography (PPG) is developed, which can be used to measure blood pressure and analyze rhythm, including the continuous detection of atrial fibrillation. The capabilities of the technology are shown in several form factors, including a miniaturized version resembling a common pulse oximeter to which the technology could be integrated in. Several main results are presented: i) the miniature finger probe meets the accuracy requirements of non‐invasive blood pressure instrument validation standard, ii) atrial fibrillation can be detected during the blood pressure measurement and in a continuous recording, iii) a unique comparison between optical and pressure sensing mechanisms is provided, which shows that the origin of both modalities can be explained using a pressure‐volume model and that recordings are close to identical between the sensors. The benefits and limitations of both modalities in hemodynamic monitoring are further discussed.

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“…Slapničar [19] used a modified RGB camera to estimate BP by measuring the PTT between different skin layers. Jukka-Pekka Sirkiä [20] developed a device that can receive signals from different depths of the cutaneous vasculature, proposed that PPG signals with longer wavelengths are more sensitive to pressure-induced vasodilatation than PPG signals with shorter wavelengths, and emphasized the potential of the MWPPG for BP prediction.…”

Section: Introductionmentioning

confidence: 99%

ACNN-BiLSTM: A Deep Learning Approach for Continuous Noninvasive Blood Pressure Measurement Using Multi-Wavelength PPG Fusion

Cui,

Dong,

Zhuang

et al. 2024

Bioengineering

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As an essential physiological indicator within the human body, noninvasive continuous blood pressure (BP) measurement is critical in the prevention and treatment of cardiovascular disease. However, traditional methods of blood pressure prediction using a single-wavelength Photoplethysmographic (PPG) have bottlenecks in further improving BP prediction accuracy, which limits their development in clinical application and dissemination. To this end, this study proposed a method to fuse a four-wavelength PPG and a BP prediction model based on the attention mechanism of a convolutional neural network and bidirectional long- and short-term memory (ACNN-BiLSTM). The effectiveness of a multi-wavelength PPG fusion method for blood pressure prediction was evaluated by processing PPG signals from 162 volunteers. The study compared the performance of the PPG signals with different individual wavelengths and using a multi-wavelength PPG fusion method in blood pressure prediction, assessed using mean absolute error (MAE), root mean squared error (RMSE) and AAMI-related criteria. The experimental results showed that the ACNN-BiLSTM model achieved a better MAE ± RMSE for a systolic BP and diastolic BP of 1.67 ± 5.28 and 1.15 ± 2.53 mmHg, respectively, when using the multi-wavelength PPG fusion method. As a result, the ACNN-BiLSTM blood pressure model based on multi-wavelength PPG fusion could be considered a promising method for noninvasive continuous BP measurement.

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Tonometric Multi-Wavelength Photoplethysmography for Studying the Cutaneous Microvasculature of the Fingertip

Cited by 4 publications

References 52 publications

Non‐Invasive Hemodynamic Monitoring System Integrating Spectrometry, Photoplethysmography, and Arterial Pressure Measurement Capabilities

Non‐Invasive Hemodynamic Monitoring System Integrating Spectrometry, Photoplethysmography, and Arterial Pressure Measurement Capabilities

Hemodynamic Bedside Monitoring Instrument with Pressure and Optical Sensors: Validation and Modality Comparison

ACNN-BiLSTM: A Deep Learning Approach for Continuous Noninvasive Blood Pressure Measurement Using Multi-Wavelength PPG Fusion

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