Contributors
Preface
Foreword
Contents
Chapter 1: Introduction to photoplethysmography
1.1 Principle of photoplethysmography
1.2 History of photoplethysmography
1.3 Chapter overview
References
Chapter 2: The origin of photoplethysmography
2.1 Introduction
2.2 PPG basic working principle
2.3 Theoretical background
2.3.1 The generic Beer–Lambert law
2.3.2 The modified Beer–Lambert law
2.3.3 TheBeer–Lambertlawwithmultipleabsorbers
2.3.4 The Beer–Lambert law in PPG
2.3.5 The Beer–Lambert law in pulseoximetry
2.4 The origin of the photoplethysmogram
2.4.1 Different hypotheses relating to the origin of PPG signal
2.4.2 Light–tissue interactions in photoplethysmography
2.4.3 Optical path and penetration depth analysis
2.4.4 Optical absorbance analysis
2.5 Conclusion
References
Chapter 3: Photoplethysmography technology
3.1 Introduction
3.2 Single Wavelength Instrumentation
3.2.1 Optical components
3.2.2 Emitter driver
3.2.3 Transimpedance amplifier
3.2.4 Signal conditioning
3.2.5 Analog-to-digital conversion
3.3 Multiwavelength instrumentation
3.3.1 Multi-wavelengthemitterdrivers
3.3.2 TIA
3.3.3 Sample-and-holdamplifier
3.4 Future Trends
References
Chapter 4: Photoplethysmography signal processing and synthesis
4.1 Introduction
4.2 The Photoplethysmogram Signal
4.2.1 Physiological origins
4.2.2 Presentation of the photoplethysmogram signal
4.2.3 Signal acquisition
4.3 Photoplethysmogram Signal Processing
4.3.1 Preprocessing
4.3.2 Time domain analysis
4.3.3 Frequency domain analysis
4.3.4 Machine learning
4.3.5 Nonlinear analysis in phase space
4.3.6 Estimating physiological parameters
4.4 Photoplethysmogram Signal Synthesis
4.4.1 Simulating photoplethysmogram pulse waves
4.4.2 Simulating photoplethysmogram signals
4.5 Conclusion
Acknowledgment
References
Chapter 5: Photoplethysmography in oxygenation and blood volume measurements
5.1 Introduction
5.2 PPG in pulseoximetry
5.2.1 Oxygen saturation
5.2.2 The optical properties of hemoglobin
5.2.3 History of pulseoximetry
5.2.4 Principles of conventional pulseoximetry
5.2.5 Pulseoximetry technology
5.2.6 Measurement sites
5.2.7 Applications of pulseoximetry
5.2.8 Limitations of pulseoximetry
5.2.9 Future of pulseoximetry
5.3 PPG for assessing tissue blood volume and perfusion
5.3.1 Blood volume assessment with PPG
5.3.2 The perfusion index
5.3.3 PPG in tissue oxygenation alongside perfusion and blood volume measurements
5.4 Summary
Acknowledgment
References
Chapter 6: Photoplethysmography for the assessment of peripheral vascular disease
6.1 Introduction
6.2 PPG assessment of the peripheral arteries
6.2.1 PPG technology and measurement considerations
6.2.2 PPG detection of occlusive peripheral arterial disease
6.3 PPG for microcirculation assessment
6.3.1 Microvascular blood flow and tissue viability
6.3.2 Vasospastic conditions(Raynaud’s phenomenon)
6.4 PPG for venous assessment
6.5 Conclusions
References
Chapter 7: Photoplethysmographic assessment of arterial stiffness and endothelial function
7.1 Introduction
7.2 Arterial stiffness
7.2.1 Structure and stiffness of elastic arteries
7.2.2 Clinical significance of arterial stiffness
7.2.3 Arterial stiffness measurement using photoplethysmography
7.3 Endothelial function
7.3.1 Anatomy and function of the endothelium
7.3.2 Endothelial dysfunction and its clinical importance
7.3.3 Measurement of endothelial function by flow-mediated vasodilatation
7.3.4 Signal processing of PPG-based FMD
7.3.5 Representative studies of EF assessment using PPG
7.4 Conclusion
References
Chapter 8: Low-frequency variability in photoplethysmography and autonomic function assessment
8.1 Introduction
8.2 Vasomotor waves and PPG variability
8.2.1 Low frequency changes in PPG pulse features and quantification
8.2.2 Changes in PPG with controlled respiratory challenges
8.2.3 Changes in PPG pulses with controlled body tilt maneuver
8.3 Monitoring of blood pressure variability, pulseratevariability, and heart-rate-variability
8.3.1 Blood pressure variability and tracking
8.3.2 Pulse rate variability assessment
8.4 Wider application areas for PPG in autonomic-related assessments
8.4.1 Sleep studies
8.4.2 Pregnancy monitoring
8.4.3 Pain assessment
8.4.4 Mental health and wellbeing
8.4.5 Other neurophysiological assessments using PPG
8.4.6 PPG applications in unique and challenging situations
8.5 Conclusions
References
Chapter 9: Physical and physiological interpretations of the PPG signal
9.1 Introduction
9.2 Plethysmography
9.3 Interpretation of the photoplethysmographic signal
9.3.1 Light absorption increase due to blood volume increase during systole
9.3.2 PPG in a rigid envelope and systolic flow increase model
9.3.3 Linearity of the PPG signal with blood volume increase
9.3.4 Cardiac-induced blood volume pulses in veins
9.4 Conclusions
References
Chapter 10: PPG in clinical monitoring
10.1 Introduction
10.2 Clinical monitoring uses
10.2.1 Blood oxygen saturation
10.2.2 Cardiac arrhythmia,heart-rate-variability, and pulse transit time measurement
10.2.3 Respiratory rate
10.2.4 Blood pressure
10.2.5 Cardiac output
10.3 PPG waveform morphology assessments
10.3.1 Time domain analysis (pulse amplitude and other parameters)
10.3.2 Dicrotic notch and PPG augmentation index
10.3.3 Local arterial compliance
10.3.4 PPG and functional hemodynamics
10.4 Conclusions
References
Chapter 11: Photoplethysmography in noninvasive blood pressure monitoring
11.1 Introduction
11.2 Clinical BP measurement methods
11.3 Photoplethysmography
11.4 Volume clamping via finger cuff-PPG devices
11.5 Oscillometry via PPG-force sensor units
11.6 Pulse transit time detected via PPG waveform(s)
11.7 PPG waveform feature extraction
11.8 Conclusions
Acknowledgment
References
Chapter 12: Wearable photoplethysmography devices
12.1 Introduction
12.1.1 Overview
12.1.2 Recommended reading
12.2 Hardware configurations for wearable photoplethysmography devices
12.2.1 Measurement site
12.2.2 Sensor design
12.2.3 Additional signals
12.3 Physiological parameters
12.3.1 Heart rate
12.3.2 Identifying an irregular pulse
12.3.3 Arterial oxygen saturation(SpO2)
12.3.4 Respiratory rate
12.3.5 Blood pressure
12.3.6 Sleep assessment
12.3.7 Energy expenditure
12.3.8 Maximal oxygen consumption
12.3.9 Pulse rate variability
12.3.10 Arterial stiffness
12.4 Commercially available devices
12.4.1 Form factors
12.4.2 Functionality
12.4.3 Marketing models
12.4.4 Batteries
12.5 Applications
12.5.1 Menstrual cycle monitoring
12.5.2 Identifying orthostatic hypotension
12.5.3 Seizure detection in epilepsy
12.5.4 Anesthesia and pain monitoring
12.5.5 Chronic kidney disease monitoring
12.5.6 Biometric authentication
12.5.7 Health insurance
12.6 Conclusion and future work
12.6.1 Areas for future work
Acknowledgements
References
Chapter 13: Imaging photoplethysmography and its applications
13.1 Introduction: Fundamentals of imaging photoplethysmography
13.2 Heart rate and heart-rate-variability monitoring
13.3 Evaluation of neurogenic reactivity and fractional blood flow of the musculocutaneous vessels
13.4 Objective early diagnosis of Raynaud’s phenomenon assessing vascular response to coldex posure by IPPG
13.5 IPPG to assess endothelial function during heat exposure
13.6 Revealing microcirculation parameters in scleroderma skin lesions
13.7 Assessment of vascular reactivity in response to topical capsaicin application and other pharmacological impact
13.8 Intraoperative monitoring of cortical blood flow parameters
13.9 Identification of functioning skin capillaries
13.10 Summary
Acknowledgments
References
Chapter 14: Photoplethysmography: New trends and future directions
14.1 Photoplethysmography in biometrics
14.1.1 Introduction
14.1.2 Methodsof PPG biometrics
14.1.3 Summary
14.2 Photoplethysmography phantoms and simulators
14.2.1 Introduction
14.2.2 PPG phantoms
14.2.3 PPG simulators
14.2.4 Summary
14.3 Future directions
References
Index