RESUMO
BACKGROUND: Lidocaine is used to alleviate procedural pain but paradoxically increases pain during injection. Pain perception can be modulated by non-noxious stimuli such as temperature or touch according to the gate control theory of pain. We postulated that lidocaine dripped onto the skin prior to injection would cool or add the sensation of touch at the skin surface to reduce pain perception from the procedure. METHODS: A randomized clinical trial of patients referred to the procedure service from February 2011 through March 2015 was conducted. All patients received 1% subcutaneous lidocaine injection. Patients randomized to the intervention group had approximately 1 to 2 ml of lidocaine squirted onto the skin surface prior to subcutaneous lidocaine injection. Patients were blinded to the details of the intervention and were surveyed by a blinded investigator to document the primary outcome (severity of pain from the procedure) using a visual analog scale. RESULTS: A total of 481 patients provided consent and were randomized to treatment. There was a significant improvement in the primary outcome of procedural pain (control, 16.6 ± 24.8 mm vs 12.2 ± 19.4 mm; P = .03) with the intervention group as assessed by using the visual analog scale score. Pain scores were primarily improved for peripherally inserted central catheters (control, 18.8 ± 25.6 mm vs 12.2 ± 18.2 mm; P = .02) upon subgroup analysis. CONCLUSIONS: Bedside procedures are exceedingly common. Data regarding the severity of procedural pain and strategies to mitigate it are important for the informed consent process and patient satisfaction. Overall, pain reported from common bedside procedures is low, but pain can be further reduced with the addition of lidocaine onto the skin surface to modulate pain perception. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01330134; URL: www.clinicaltrials.gov.
