. Blood extraction from lancet wounds using vacuum combined with skin stretching. J Appl Physiol 92: 1089-1096, 2002; 10.1152/japplphysiol.00798.2001.-Key factors and practical limits of blood extraction from lancet wounds on body sites other than the finger were determined by testing a large number of conditions. During these tests, the pain associated with lancing alternate body sites was rated as less painful than a fingerstick 98% of the time. Vacuum combined with skin stretching was effective in extracting an adequate volume of blood from the forearm for glucose testing, up to an average of 16 l in 30 s. The amount of blood extracted increases with the application of heat or vacuum before lancing, the level of vacuum, the depth of lancing, the time of collection, and the amount of skin stretching. Vacuum and skin stretching led to significant increases, up to fivefold in the perfusion of blood in the skin as measured by laser Doppler. Our observations suggest that vacuum combined with skin stretching increases blood extraction at alternate sites by increasing the lancet wound opening, increasing the blood available for extraction by vasodilatation, and reducing the venous return of blood through capillaries. suction; diabetes; diagnostics; alternate site; glucose measurement THE MOST COMMON METHOD OF obtaining small amounts of blood from humans for diagnostic testing is by lancing the finger. The finger is typically lanced because it can be squeezed to expel more blood. People with diabetes lance their fingers several times a day. Whereas the finger can readily supply the volume of blood needed for conventional test strips, 3-10 l (16), the process is painful and results in soreness that can last for several days. Thus the development of painless and convenient methods to access blood for measurement, particularly glucose, has been an active area of research.Interstitial fluid has been accessed by suction effusion (19), transcutaneous microdialysis (12), intradermal pressure harvesting with a cannula (31), iontophoresis (35), and low-frequency ultrasound (20, 26); however, analysis of samples collected using these techniques is difficult because of the small amount of glucose extracted and dilution of the sample. Several mechanical lancet devices have been developed to harvest capillary blood from lancet wounds on sites other than the finger by applying pressure or vacuum around the lanced site (2,13,40). Lancet sticks at alternate sites are virtually pain free, with 60% of the sticks being rated as painless and 90-97% being rated as less painful than a fingerstick (9,13,14,40). Unfortunately, these mechanical devices require multiple manual manipulation steps that may be poorly controlled by the user. We are unaware of studies reporting the amount of blood extracted or factors that may be associated with the successful extraction of blood with the mechanical devices. In a published study, our laboratory reported the distribution of blood volumes obtained from diabetic subjects by vacuum-assisted lancing of...