HOW DO pH INDICATORS WORK? pH indicators detect the presence of H+ and OH-. They do this by reacting with H+ and OH-: they are themselves. weak acids and bases. If an indicator is a weak acid and is coloured and its conjugate base has a different. colour, deprotonation causes a colour change.
Have varicose veins, which are a common cause of superficial thrombophlebitis. Have a pacemaker or have a thin, flexible tube (catheter) in a central vein, for treatment of a medical condition, which may irritate the blood vessel wall and decrease blood flow. Are pregnant or have just given birth.
Deep Vein Thrombosis (or DVT) occurs when a blood clot forms deep within a veinâtypically in regions such as the thigh or calf. Oftentimes, existence of a DVT causes no pain or symptoms. However, if the DVT blocks off blood flow completely (or even partially); pain and swelling will occur around surface veins, and movement may become difficult.