1 Skin Perfusion Studies: Historical Notes and Modern Measuring …
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made measurements on subjects who are under anaesthesia or just awakening as well
as from anaesthetized animals are therefore not meaningful. Since the frequency
spectrum and probably also the operating and control parameters of all these loops
overlap, causal investigations hardly make sense. They should include the entire
contiguous vegetative scheme. Many vegetative rhythms fluctuate in frequency, if
they are assessed over long periods of time. Mostly, they are synchronized with each
other at integer harmonics.
1.2.5 Rhythmic Perfusion Patterns in Peripheral Venous
Network Related to Active Body Exercise
The main application of photoplethysmography to map venous blood flow has been
en vogue for more than 30 years and provides functional evaluation of total blood
displacement in the venous system of the upper extremities. To obtain a PPG for
venous blood flow analysis, the PPG sensor is fixed about 10 cm above the inner ankle
using a double adhesive ring. The seated patient performs the classical, worldwide
standardized muscle pump test (MPT): 8 dorsal extensions in 16 s [19–24]. In an adult
with healthy leg veins, the venous blood pool that has been pumped by the dorsal
flexions uphill, back to the heart will not flow back due to of the venous valves. As
a result the venous blood volume in the foot/leg part reduces which causes the PPG
signal to rise. From the venodynamic behavior during such active MPT exercise,
several functional parameters like venous refilling time and venous drainage can be
calculated (see Chap. 5).
1.3 Photoplethysmography—Historical Notes
For many years, classical photoplethysmography has been one of the most popular
non-invasive methods for functional monitoring of peripheral vascular (venous
and/or arterial) status. After ground-breaking works by Cartwright [25], Haxthausen,
Mathes [26], and Molitor et al. [27], in 1937 Alrick B. Hertzman (1898–1991), a
physiologist at St. Louis University School of Medicine, discovered the relationship
between the intensity of backscattered polychromatic light and blood volume in the
skin [28]. The instruments consisted of three essential components which are still
essential in modern systems: a light source, a light detector and a registration unit.
He called the device Photoelectric Plethysmograph and summarized his findings as
follows ([29], p. 336) (Fig. 1.3):
The volume pulse of the skin as an indicator of the state of the skin circulation at rest
Amplitude of volume pulse as a measure of the blood supply of the skin
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made measurements on subjects who are under anaesthesia or just awakening as well
as from anaesthetized animals are therefore not meaningful. Since the frequency
spectrum and probably also the operating and control parameters of all these loops
overlap, causal investigations hardly make sense. They should include the entire
contiguous vegetative scheme. Many vegetative rhythms fluctuate in frequency, if
they are assessed over long periods of time. Mostly, they are synchronized with each
other at integer harmonics.
1.2.5 Rhythmic Perfusion Patterns in Peripheral Venous
Network Related to Active Body Exercise
The main application of photoplethysmography to map venous blood flow has been
en vogue for more than 30 years and provides functional evaluation of total blood
displacement in the venous system of the upper extremities. To obtain a PPG for
venous blood flow analysis, the PPG sensor is fixed about 10 cm above the inner ankle
using a double adhesive ring. The seated patient performs the classical, worldwide
standardized muscle pump test (MPT): 8 dorsal extensions in 16 s [19–24]. In an adult
with healthy leg veins, the venous blood pool that has been pumped by the dorsal
flexions uphill, back to the heart will not flow back due to of the venous valves. As
a result the venous blood volume in the foot/leg part reduces which causes the PPG
signal to rise. From the venodynamic behavior during such active MPT exercise,
several functional parameters like venous refilling time and venous drainage can be
calculated (see Chap. 5).
1.3 Photoplethysmography—Historical Notes
For many years, classical photoplethysmography has been one of the most popular
non-invasive methods for functional monitoring of peripheral vascular (venous
and/or arterial) status. After ground-breaking works by Cartwright [25], Haxthausen,
Mathes [26], and Molitor et al. [27], in 1937 Alrick B. Hertzman (1898–1991), a
physiologist at St. Louis University School of Medicine, discovered the relationship
between the intensity of backscattered polychromatic light and blood volume in the
skin [28]. The instruments consisted of three essential components which are still
essential in modern systems: a light source, a light detector and a registration unit.
He called the device Photoelectric Plethysmograph and summarized his findings as
follows ([29], p. 336) (Fig. 1.3):
The volume pulse of the skin as an indicator of the state of the skin circulation at rest
Amplitude of volume pulse as a measure of the blood supply of the skin