Skin-puncture and blood-collecting technique for infants: update and problems.

This is updated information on acceptable practice in skin puncture and blood collection in infants, as well as on the devices used, with the additional aim of emphasizing major problem areas and some tentative solutions. Consensus standards for skin puncture have little experimental support, and evade the hard fact that studies are needed to clarify optimum sites for puncture and depth and width of lancets, and to assess the effects of compression and skin resistance in the puncturing process. Preliminary data revealed that the puncturing depth of 2.4 mm recommended for the newborn is excessive. In four of 14 newborns at necropsy, the distance from posterior planar skin surface to underlying bone ranged between 2.0 and 2.2 mm. An experimental lancet, with a 1.8-mm tip length and a diameter of 0.79 mm yielded customary blood volumes from newborns in three of the four pediatric centers where it was tested. Lack of success with the lancet was attributed to inexperienced phlebotomists, not to the lancet's decreased size. Also reviewed are problems with common devices used, and the need for examining the "economy" of blood collection.