Acute Pain and Blood Pressure
Acute pain leads to generalized arousal and increased sympathetic nerve activity. This has been shown in studies where sympathetic nerve activity is measured directly from electrodes inserted into the peroneal nerve, a technique that detects two types of sympathetic nerves: those going to skin, which are involved in thermoregulation, and others going to muscle, which are under the control of the baroreceptors. The most commonly used stimulus for inducing pain is the cold pressor test, where one hand is immersed in ice water. This produces a dramatic increase in muscle sympathetic nerve activity (MSNA), which is paralleled by a marked increase of blood pressure. Other types of painful stimuli do the same thing -- thus both MSNA and blood pressure increase during the application of physical pressure to the nail beds or the skin of the cheek, or during electrical stimulation of a digital nerve. Another widely used stimulus has been forearm ischemia produced by a cuff inflated to cut off the blood supply -- here the degree of pain correlates with the increase of blood pressure and vascular resistance.
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Cite this: Pain and Blood Pressure - Medscape - Sep 01, 2003.