Comparison of Internal Rotation, Local Cold and ShotBlocker on Intramuscular Injection Pain and Comfort

Overview

This single-centre, randomized, counterbalanced, within-subjects clinical trial compared four techniques for reducing pain and improving comfort during ventrogluteal intramuscular cyanocobalamin injection in adults. Participants presenting to a family health centre for prescribed vitamin B12 injection each received four injections, one with each technique: standard injection, internal rotation of the extremity, local cold application, and ShotBlocker. Technique order was assigned using a 4 x 4 Latin-square randomization. Pain and comfort were measured immediately after each injection using 0-10 participant-reported scales.

Adults aged 18 years or older who presented to TOKI Family Health Centre in Sivas, Turkey for prescribed cyanocobalamin intramuscular injection were enrolled between July and December 2019. Each participant received all four ventrogluteal injection techniques across four visits scheduled 24-48 hours apart. The order of techniques was randomized and counterbalanced using a 4 x 4 Latin-square sequence, with allocation concealed in sealed, opaque, sequentially numbered envelopes. Blinding of participants and the administering nurse was not feasible because the procedural techniques were visibly distinct, but the outcome assessor who entered and analyzed pain and comfort scores was blinded to sequence assignment until database lock. All injections were administered by the same experienced registered nurse using cyanocobalamin 1 mg in 1 mL and a 22-gauge, 38-mm needle. Pain was assessed using a 0-10 Visual Analogue Scale and comfort using a 0-10 numerical comfort scale immediately after each injection.