28
V. Blazek
the observed skin/body region and the spatial resolution can be arbitrarily chosen,
depending on the utilized camera lens and distance between camera and measuring
object. To minimize motion artifacts, which can be created by the separation of the
camera sensor from the skin, different algorithm have been developed in the last
decade [77, 78]. Different research groups has already shown that robust and unobtrusive estimation of the HR and the HRV is possible by the PPGI, also by using low
cost cameras [79–81].
1.12 Conclusion
Sophisticated assessment strategies are required to analyze complex rhythmical
changes in dermal skin perfusion. The selected multi-sensor concepts allow to acquire
undistorted perfusion signals from human skin in vivo across a broad frequency
range. A comparative analyses of different sensor signals reveal that—next to
the known central rhythms (correlated to the heart beat and respiration)—certain
local oscillations, especially around 0.1 Hz, show high endogenous autonomy and
influenceability.
Using multi-wavelength PPG sensor concepts, peripheral venous saturation
behavior can be detected. Probably already in the near future, such concepts will attain
universal acceptance, analogous to the status enjoyed by arterial pulse oximetry.
With the PPG equipment available on the market so far, the low frequency rhythms
are invariably filtered out, due to the focus on capturing heart rate data for studying
the heartbeat and heart rate variability (HRV). From these vital signs other PPG
parameters can finally be calculated, which can throw insights into sensing stress or
pain.
With the present PPG technology, it also may be possible to investigate and understand the scientific basis for ancient Indian practices such as yoga and meditation,
based on deep and controlled breathing. For time-related interdisciplinary research
on the dermal rhythmic phenomena, the most important task continues to be clarification of the medical importance of an experimentally collected blood volume
rhythmic. It would be desirable to undertake the entire gamut of possible experiments,
in order to connect ancient Indian yoga teachings and classical western medicine on
an evidence-based level.
Another emerging perspective is a camera-based photoplethysmography imaging
for functional, contact-less, spatially resolved visualization of the dermal venous
and/or arterial perfusion behavior, for example, in the area of wounds.
Thus, the steady successful progress in PPG as a non-invasive technique with
old traditions and new perspectives leads to global clinical and also out-of-hospital
health monitoring systems with increasing relevance.
V. Blazek
the observed skin/body region and the spatial resolution can be arbitrarily chosen,
depending on the utilized camera lens and distance between camera and measuring
object. To minimize motion artifacts, which can be created by the separation of the
camera sensor from the skin, different algorithm have been developed in the last
decade [77, 78]. Different research groups has already shown that robust and unobtrusive estimation of the HR and the HRV is possible by the PPGI, also by using low
cost cameras [79–81].
1.12 Conclusion
Sophisticated assessment strategies are required to analyze complex rhythmical
changes in dermal skin perfusion. The selected multi-sensor concepts allow to acquire
undistorted perfusion signals from human skin in vivo across a broad frequency
range. A comparative analyses of different sensor signals reveal that—next to
the known central rhythms (correlated to the heart beat and respiration)—certain
local oscillations, especially around 0.1 Hz, show high endogenous autonomy and
influenceability.
Using multi-wavelength PPG sensor concepts, peripheral venous saturation
behavior can be detected. Probably already in the near future, such concepts will attain
universal acceptance, analogous to the status enjoyed by arterial pulse oximetry.
With the PPG equipment available on the market so far, the low frequency rhythms
are invariably filtered out, due to the focus on capturing heart rate data for studying
the heartbeat and heart rate variability (HRV). From these vital signs other PPG
parameters can finally be calculated, which can throw insights into sensing stress or
pain.
With the present PPG technology, it also may be possible to investigate and understand the scientific basis for ancient Indian practices such as yoga and meditation,
based on deep and controlled breathing. For time-related interdisciplinary research
on the dermal rhythmic phenomena, the most important task continues to be clarification of the medical importance of an experimentally collected blood volume
rhythmic. It would be desirable to undertake the entire gamut of possible experiments,
in order to connect ancient Indian yoga teachings and classical western medicine on
an evidence-based level.
Another emerging perspective is a camera-based photoplethysmography imaging
for functional, contact-less, spatially resolved visualization of the dermal venous
and/or arterial perfusion behavior, for example, in the area of wounds.
Thus, the steady successful progress in PPG as a non-invasive technique with
old traditions and new perspectives leads to global clinical and also out-of-hospital
health monitoring systems with increasing relevance.