A Pilot Study To Measure the Compressive and Tensile Forces Required To Use Retractable Intramuscular Safety Syringes

BACKGROUND/OBJECTIVES: Even though retractable intramuscular safety syringes are designed to be activated while still in the patientʹs muscle or subcutaneous tissue, there are reports of healthcare workers activating these devices outside of the patient. This may be due to perceptions that the force required to activate the retraction mechanism may cause added discomfort to the patient. If such concerns could be substantiated, the possibility for a sharps injury still exists if these safety devices are not utilized correctly, in essence defeating their intended purpose. The objective of this pilot study was to determine the forces required to operate retractable safety syringes in order to evaluate potential adverse occupational health and patient safety issues. METHODS: A newly-developed product evaluation laboratory at the James A. Haley Veterans Administration Patient Safety Center in Tampa, Florida, provided the controlled setting for evaluating safer needle devices in this pilot study. Four brands (100 each) of retractable syringes were tested, using a digital force gauge, in air and in a simulated patient material (SPM). Compressive forces were measured while activating the retraction mechanism in both air and SPM. Tensile forces were measured while withdrawing 2 cc of saline into the syringe barrel. Two-way analysis of variance and Duncanʹs Multiple Range test were used in the statistical analysis. RESULTS: The compressive forces demonstrated by the four devices in both air and SPM measured from a low of 0.52 lbs to a high of 22.02 lbs (range = 21.97 lbs). The mean compressive force was greater in SPM than in air in all four devices. There was a statistically significant compressive force difference between activation in air and SPM in devices 1 and 2 (p ≤ 0. 05). The tensile forces measured from a low of 0.06 lbs to a high of 2.18 lbs (range = 2.12 lbs). The tensile forces for all devices were lower than the compressive forces. Analysis of variance demonstrated a significant difference between the means of the four tensile groups (p < 0.001). CONCLUSIONS: There was considerable variability in the measured compressive force between devices yet the compressive force was still greater in SPM than in air. The results of this pilot study pose needlestick injury potential and device training issues for healthcare workers, as well as possible future impacts on the design of this type of safety device. The cumulative ergonomic effects of compressive and tensile forces require further investigation. Replication of this study by multiple researchers, using numerous needles and syringe sizes, is recommended.