6
V. Blazek
This mechanism regulates the blood volume flow in the vascular plexus. Arterioles
and precapillary sphincter are considered to be resistance vessels. Several different
control mechanisms exist, which are all interrelated and together affect the blood
distribution:
• neural (nervous) influence (from the brain, almost exclusively based on sympathetic activity),
• systemic humoral influence (control by hormones),
• local metabolic influence,
• hormonal influence (due to inflammation or allergies),
• self-regulation (mainly in the brain and in the kidneys),
• influence through local chemo-receptors (in skeletal muscles, with the nerves,
then signaling the blood distribution).
Skin perfusion is also supported by influences from the temperature controlloop. The local mechanisms are mostly more dominant than global mechanisms.
The interrelation of the above-mentioned mechanisms is currently not clear: they all
together, maybe in different ways and intensities contribute to the generation of the
vasomotor rhythms. Especially waves with a duration of 5–7/min (fast wave types of
third order, also called Traube-Hering-Mayer (THM) waves) are prevalent in blood
pressure recordings, while waves with a periodic length of about 1/min are dominant
in peripheral perfusion (skin, muscle). These dominant rhythms are called 10 s- and
1min-rhythms according to their preferred frequency.
The 10 s- and the breathing-rhythm show coupling in form of relative coordination
according to Golenhofen and Hildebrand [5]. The mechanism of this coupling is still
debated after many years of research. Since the 1 min-rhythm of dermal perfusion
is characterized by compensation of blood-content variations in connected vessel
districts nearby, the central pressure fluctuations probably don’t play a part in these
rhythms. The frequencies of all these fluctuation patterns are usually at see and are
at the bottom of a PPG signal spectrum.
1.2.4 Perfusion Rhythms and the Vegetative Nervous System
All major vascular and organ functions are regulated and controlled by the autonomic nervous system. This consists of two parts, the sympathetic and the parasympathetic. They branch out from the spinal canal at the top of the chest and are regulated by the medullary control centres in the brain. The sympathetic nervous system
drives the body and accelerates body activities. Parasympathetic activity inhibits body
activity. During physical exercise, the parasympathetic nervous system adjusts itself
more quickly to the new situation compared to the sympathetic and the organism
experiences oxygen- and nutrient-deficiency; this is moderated by reserves in the
blood.
The above-mentioned rhythms are mainly triggered by sympathetic nerves.
During anaesthesia, the decaying sympathetic becomes active first. The previously
V. Blazek
This mechanism regulates the blood volume flow in the vascular plexus. Arterioles
and precapillary sphincter are considered to be resistance vessels. Several different
control mechanisms exist, which are all interrelated and together affect the blood
distribution:
• neural (nervous) influence (from the brain, almost exclusively based on sympathetic activity),
• systemic humoral influence (control by hormones),
• local metabolic influence,
• hormonal influence (due to inflammation or allergies),
• self-regulation (mainly in the brain and in the kidneys),
• influence through local chemo-receptors (in skeletal muscles, with the nerves,
then signaling the blood distribution).
Skin perfusion is also supported by influences from the temperature controlloop. The local mechanisms are mostly more dominant than global mechanisms.
The interrelation of the above-mentioned mechanisms is currently not clear: they all
together, maybe in different ways and intensities contribute to the generation of the
vasomotor rhythms. Especially waves with a duration of 5–7/min (fast wave types of
third order, also called Traube-Hering-Mayer (THM) waves) are prevalent in blood
pressure recordings, while waves with a periodic length of about 1/min are dominant
in peripheral perfusion (skin, muscle). These dominant rhythms are called 10 s- and
1min-rhythms according to their preferred frequency.
The 10 s- and the breathing-rhythm show coupling in form of relative coordination
according to Golenhofen and Hildebrand [5]. The mechanism of this coupling is still
debated after many years of research. Since the 1 min-rhythm of dermal perfusion
is characterized by compensation of blood-content variations in connected vessel
districts nearby, the central pressure fluctuations probably don’t play a part in these
rhythms. The frequencies of all these fluctuation patterns are usually at see and are
at the bottom of a PPG signal spectrum.
1.2.4 Perfusion Rhythms and the Vegetative Nervous System
All major vascular and organ functions are regulated and controlled by the autonomic nervous system. This consists of two parts, the sympathetic and the parasympathetic. They branch out from the spinal canal at the top of the chest and are regulated by the medullary control centres in the brain. The sympathetic nervous system
drives the body and accelerates body activities. Parasympathetic activity inhibits body
activity. During physical exercise, the parasympathetic nervous system adjusts itself
more quickly to the new situation compared to the sympathetic and the organism
experiences oxygen- and nutrient-deficiency; this is moderated by reserves in the
blood.
The above-mentioned rhythms are mainly triggered by sympathetic nerves.
During anaesthesia, the decaying sympathetic becomes active first. The previously