ABSTRACT
Therefore, in normal subjects, postural reduction in
blood pressure is usually 20/10 mmHg and increase in heart rate is 30 beats/min. Any abnormalities in the arterial or cardiopulmonary baroreceptors, afferent nerves, the
nucleus tractus solitarius where the afferent nerves termi-
nate, and the efferent nerve output in the sympathetic
nervous system to increase norepinephrine release to the
heart and blood vessels can lead to OH. On the other
hand, patients with severe reduction in intravascular
volume may experience OH or tachycardia despite intact
autonomic nervous system function.
