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A vagal maneuver is an action used to stimulate the parasympathetic nervous system by activating the vagus nerve.The vagus nerve is the longest nerve of the autonomic nervous system and helps regulate many critical aspects of human physiology, including heart rate, blood pressure, sweating, and digestion through the release of acetylcholine.
The carotid sinus baroreceptor can be oversensitive to manual stimulation from the pressure applied at the carotid sinus at the carotid bifurcation. It is a condition known as 'carotid sinus hypersensitivity' (CSH), 'carotid sinus syndrome' or 'carotid sinus syncope', in which manual stimulation causes large changes in heart rate and blood ...
The Czermak–Hering test is a vagal maneuver consisting of the application of external digital pressure to the carotid sinus. [1] The test is performed at the patient's bedside by imposing moderate pressure with the fingers, repeatedly massaging the left or the right carotid arteries .
These manoeuvres include carotid sinus massage (pressure on the carotid sinus in the neck) and the Valsalva manoeuvre (increasing the pressure in the chest by attempting to exhale against a closed airway by bearing down or holding one's breath).
[8] [9] Electrical stimulation of the external surfaces of the carotid sinus activates baroreceptors believed to be in the adventitia of the artery. This stimulates an afferent limb which activates central nervous system pathways that in turn exert two different but synergistic autonomic effects on the body.
Neurally mediated syncope may also occur when an area in the neck known as the carotid sinus is pressed. [1] A normal response to carotid sinus massage is reduction in blood pressure and slowing of the heart rate. Especially in people with hypersensitive carotid sinus syndrome this response can cause syncope or presyncope. [9]
The Valsalva maneuver is performed by a forceful attempt of exhalation against a closed airway, usually done by closing one's mouth and pinching one's nose shut while expelling air, as if blowing up a balloon.
It conveys information from the baroreceptors of the carotid sinus to the vasomotor center in the brainstem (in order to mediate blood pressure homeostasis), and from chemoreceptors of the carotid body [further explanation needed] (mainly conveying information about partial pressures of blood oxygen, and carbon dioxide).