BP definition of hypotension is variable, depending on baseline values for any patient. Some live comfortably w/SBP 90-100, while in others this would generate symptoms. Hypotension thus based on BP values coupled w/knowledge about baseline and identification symptoms of hypo-perfusion (i.e. lightheaded, weak, pre-syncope/syncope, etc.). Clinically, reasonable to consider hypotension in any patient < 100/70. To determine etiology, consider physiologic components of BP: Heart rate (too fast or too slow) x Stroke volume (preload) x Inotropy (contractility) x Systemic vascular resistance (peripheral vascular tone).