Most specific for shock is
a. A low brachial systolic pressure can serve as an indicator of shock, though what constitutes a significantly low value depends to an extent on the age of the patient .
b. In an adult, a low brachial systolic pressure (below 110 mm Hg) frequently indicates shock; a very low brachial peak-systolic pressure (below 89 mm Hg) almost always does, especially in a patient who is under stress.
c. A patient whose brachial systolic pressure is low in the presence of stress can be assumed to be in shock.
d. A sustained (> 30 seconds) systolic pressure drop greater than 10 mm Hg in a patient who has arisen from a supine to an upright position can also be an indicator of underlying shock.
e. The stress imposed by all forms of shock in the absence of diuretic use, high alcohol levels, or administration of radiographic contrast agents stimulates the release of vasopressin (antidiuretic hormonE. and aldosterone (through activation of the angiotensin system).The result is oliguria, which is a sign of stress at the very least and a sign of decreased blood flow to the kidneys in extreme cases.