Arterial Wall Penetration Forces in Needles versus Cannulas

Background: If safety is defined as the diminished ability to penetrate facial arteries, the goal of this study was to investigate whether different-sized cannulas are safer than correspondingly sized needles for the application of facial soft-tissue fillers. Methods: Two hundred ninety-four penetration procedures of the facial and superficial temporal arteries were performed in four fresh frozen cephalic specimens using both needles (20-, 22-, 25-, and 27-gauge) and cannulas (22-, 25-, and 27-gauge). Continuously increasing force was applied and measured until intraarterial penetration occurred. Results: No statistically significant differences were detected when comparing forces required to penetrate the facial arterial vasculature between different sexes, arteries, or sides of the face (all p > 0.05). Forces needed to penetrate significantly (p < 0.001) decreased with smaller diameter needles (20-gauge, 1.12 +/- 0.29 N; 22-gauge, 1.08 +/- 0.25 N; 25-gauge, 0.69 +/- 0.24 N; and 27-gauge, 0.70 +/- 0.29 N) and in cannulas (22-gauge, 1.50 +/- 0.31 N; 25-gauge, 1.04 +/- 0.36 N; and 27-gauge, 0.78 +/- 0.35 N). Comparing 27-gauge injectors, no statistically significant difference was detected between needles and cannulas; an artery could be penetrated with a similar force independent of whether the injector was a needle or a cannula (0.70 +/- 0.29 N versus 0.78 +/- 0.35 N; p = 0.558). Conclusions: Cannulas, in all measured sizes except 27-gauge, required greater forces for intraarterial penetration compared with correspondingly sized needles, confirming the safety of 22-and 25-gauge cannulas; 27-gauge cannulas, however, required similar forces as 27-gauge needles, indicating that 27-gauge cannulas are not safer than 27-gauge needles.