... 273). Another Chapter 046. Sodium and Water (Part 4) Extrarenal Nonrenal causes of hypovolemia include fluid loss from the gastrointestinal tract, skin, and respiratory system and third-space ... plasma volume and hypotension. Hypotension is due to decreased venous return (preload) and diminished cardiac output; it triggers baroreceptors in the carotid sinus and aortic arch and leads to ... tachycardia, peripheral vasoconstriction, and hypoperfusion—cyanosis, cold and clammy extremities, oliguria, and altered mental status. Diagnosis A thorough history and physical examination are generally...