Desaturation measured peripheral Sympathetic muscle outflow [microcirculation/vasoconstriction) Sympathetic skin outflow [increase in skin conductance peaks) Emotional stress without arousal   No influence Yes Arousal stimuli such as sudden inspiration, chest compression, sudden electrical skin shock. Desaturation without general hypoxia but probably due to hypoperfusion Yes, vasoconstriction Yes Frightening situation Desaturation without general hypoxia but probably due to hypoperfusion Yes, vasoconstriction Yes Cooling Desaturation without general hypoxia but probably due to hypoperfusion Yes, vasoconstriction No influence Warming   Yes, inhibited outflow vasodilatation No influence Respiratory rhythm   Yes, influence No influence Apnea Desaturation with general hypoxia Yes, influence No influence Hypoxia Desaturation with general hypoxia Yes, vasoconstriction Not studied Baroreflex control   Yes, influence No influence Valsalva manoeures   Yes, influence No influence Carotid sinus nerve stimulation   Yes, inhibited outflow, vasodilatation. No influence

Table 1: This table includes an overview of the neurophysiological papers where the activity of the sympathetic nervous system when acting on the microcirculation and skin is decribed. The sympathetic nervous system acts differently through the microcirculation compared to when it acts through the skin inducing changes in palmar or plantar skin conductance. The activation depends on which stimulus that occurs. Furthermore, this table describes how the different situations will influence the peripheral oxygen saturation.