Fig. 1

Needle and syringe designs that affect dead space. a Standard (high dead space) syringe with standard needle. Average dead space (99 μL). b Low dead space syringe with permanently attached needle. Average dead space (3 μL). c Standard syringe with low dead space needle. No needle and syringe programs sent us low dead space needles (c) or a low dead space syringe (d) with a standard needle. However, use of both of these has become more common. We obtained samples of c and d from the manufacturers: c Covidien and d Henke-Sass