126
H. Schmid-Schönbein
temperature in the so-called thermoregulatory indifference range (21 °C–24 °C, see
textbooks of physiology) is bound to produce most vivid fluctuations of the cutaneous vasoconstrictor activity in both the skin of either the ear lobe or the forehead
(of course only unless they are treated with a vasoparalytic procedure).
Therefore, initially the ear lobe and later the glabella region (mid of the forehead) were subjected to vasorelaxation (either by vasoparalytic ointment of the ear
lobe or the localised heating of the skin, 29 °C–31 °C). This made it possible to
identify a characteristic pattern of either LDA or PPG fluctuation in the frequency
range of about 0.15 Hz, in most cases associated with a marked beat phenomenon.
A typical example recorded in transmission photoplethysmography after pharmakological vasoparalysis of the ear lobe is shown in Fig. 7.1 the temporal evolution of
this activity in what is now called “ca 0.15 Hz band” is shown in Fig. 7.2. Note
that when measuring “naive subjects” during 60 min, the activity in this range is
gradually augmented, In addition, there is a low power fluctuating activity in the
range between 0.01 Hz and 0.1 Hz with variable peaks representing the variably
pronounced superposition of the 0.15 Hz activity (v.i.).
The ca 0.15 Hz band activity is also regularly found in the reflection photoplethysmographic records obtained in hyperemic forehead of subjects and patients
in physical relaxation, but only occasionally in the “perfect expression” (Fig. 7.3A).
In each volunteer or patient, it evolves in a different fashion (Fig. 7.3B–E), this
notwithstanding, subsequently reported measurements were only taken after this
“resting activity” had been established. Being thus in command of a novel interpretation of the physico-physiological “resting state”, it turned out to be easy to
observe a universally valid pattern for the perfusion and the blood content and the
blood cell displacement in the variable networks of microvessels in the subcutaneous
vasculature. In each and every subjects, the typical pattern originally established by
the group in Göthenburg with the help of joint measurement of neuronal activity
and either reflection photoplethysmography or LDA activity in the region supplying
by cutaneous vasoconstrictor neurons was found. As illustrated in Fig. 7.4, without
exception, an “episodic perfusion pattern” was found, characterised by
• Strict coherency between LDA and rPPG,
• Lack of regular periodicities and
• Marked asymmetry of both signals, with rapid decline and slow recovery of the
perfusion by way of a decrescendo–crescendo sequence (as detailed in Schmid–
Schönbein et al.).
As detailed in the communication mentioned, we have clearly shown that this
activity pattern governing the cutaneous perfusion under all conditions of normal
perfusion in “normal” ambient temperature conditions does not reflect myogenic
vasomation, but rather neurogenic vasoconstriction. Since 1994, the latter statement
could be corroborated by the simple experimental procedure of eliminating neurogenic drive (in taking measurements at ambient temperatures above 27 °C) while
enhancing myogenic activation (in placing the hand well below heart level, thus
enhancing intravascular pressure by gravitational effects). In this case, a totally
different pattern, albeit in the same frequency range can be regularly observed,
H. Schmid-Schönbein
temperature in the so-called thermoregulatory indifference range (21 °C–24 °C, see
textbooks of physiology) is bound to produce most vivid fluctuations of the cutaneous vasoconstrictor activity in both the skin of either the ear lobe or the forehead
(of course only unless they are treated with a vasoparalytic procedure).
Therefore, initially the ear lobe and later the glabella region (mid of the forehead) were subjected to vasorelaxation (either by vasoparalytic ointment of the ear
lobe or the localised heating of the skin, 29 °C–31 °C). This made it possible to
identify a characteristic pattern of either LDA or PPG fluctuation in the frequency
range of about 0.15 Hz, in most cases associated with a marked beat phenomenon.
A typical example recorded in transmission photoplethysmography after pharmakological vasoparalysis of the ear lobe is shown in Fig. 7.1 the temporal evolution of
this activity in what is now called “ca 0.15 Hz band” is shown in Fig. 7.2. Note
that when measuring “naive subjects” during 60 min, the activity in this range is
gradually augmented, In addition, there is a low power fluctuating activity in the
range between 0.01 Hz and 0.1 Hz with variable peaks representing the variably
pronounced superposition of the 0.15 Hz activity (v.i.).
The ca 0.15 Hz band activity is also regularly found in the reflection photoplethysmographic records obtained in hyperemic forehead of subjects and patients
in physical relaxation, but only occasionally in the “perfect expression” (Fig. 7.3A).
In each volunteer or patient, it evolves in a different fashion (Fig. 7.3B–E), this
notwithstanding, subsequently reported measurements were only taken after this
“resting activity” had been established. Being thus in command of a novel interpretation of the physico-physiological “resting state”, it turned out to be easy to
observe a universally valid pattern for the perfusion and the blood content and the
blood cell displacement in the variable networks of microvessels in the subcutaneous
vasculature. In each and every subjects, the typical pattern originally established by
the group in Göthenburg with the help of joint measurement of neuronal activity
and either reflection photoplethysmography or LDA activity in the region supplying
by cutaneous vasoconstrictor neurons was found. As illustrated in Fig. 7.4, without
exception, an “episodic perfusion pattern” was found, characterised by
• Strict coherency between LDA and rPPG,
• Lack of regular periodicities and
• Marked asymmetry of both signals, with rapid decline and slow recovery of the
perfusion by way of a decrescendo–crescendo sequence (as detailed in Schmid–
Schönbein et al.).
As detailed in the communication mentioned, we have clearly shown that this
activity pattern governing the cutaneous perfusion under all conditions of normal
perfusion in “normal” ambient temperature conditions does not reflect myogenic
vasomation, but rather neurogenic vasoconstriction. Since 1994, the latter statement
could be corroborated by the simple experimental procedure of eliminating neurogenic drive (in taking measurements at ambient temperatures above 27 °C) while
enhancing myogenic activation (in placing the hand well below heart level, thus
enhancing intravascular pressure by gravitational effects). In this case, a totally
different pattern, albeit in the same frequency range can be regularly observed,