Abstract

The aim of the present study was to assess injection flow rates of metal syringes, with an emphasis on injection speed and the generation of flow pulsations. A cohort of 64 operators (32 practitioners and 32 students) performed 3 consecutive ex vivo simulated injections (SIs) of 1.8-mL cartridges of anesthetic solution. Two needle diameters were tested (27-gauge and 30-gauge). Each SI was filmed and analyzed using a computer. In most cases, the SI lasted longer than 60 seconds with the 30-gauge needle (75%) but not with the 27-gauge needle (47.9%) (P < .0001). Practitioners and men delivered a full cartridge significantly faster than students and women, respectively (P  =  .0007 in both cases). All operators generated 1 pulse in at least 1 of the 3 SIs with both types of needles, especially during the first 3 seconds (254/384; 66.1%). Pulses occurred more frequently with practitioners (P  =  .0176) and with the 27-gauge needle (P  =  .005). Within its methodological limits, the present study showed how difficult it is to control injection pressure when using a metal syringe, especially at the beginning of the injection. Computerized systems may help overcome this problem.