Acupuncture is performed after a patient is positioned comfortably, either sitting, lying down. Often heat is applied to optimize vitality flow including the flow of blood, lymph, and interstitial fluid. Acupuncturists identify target areas to needle, and insert fine needles either vertically or obliquely to an appropriate depth. Depending on types of needles used, the degree of rigidity and the adjacency of the needled target tissues, patients would feel a range of sensations including sharp, dull, heavy, and radiating. While needles are often retained for about 5-20 minutes, lancet acupuncture will be withdrawn immediately since it aims at bleeding retained deoxygenated blood in the varicose and spider veins.