title: Pain following controlled cutaneous insertion of needles with different diameters.
abstract: OBJECTIVE
  Needle injections are used daily by millions of people around the world for the administration of various drugs (e.g., insulin), venepuncture, and some neurophysiological procedures. The aim of this paper was to study the influence of the outer needle diameter on the pain evoked by controlled needle insertion.
  
  
  METHODS
  An automated needle injection system was used to perform a series of insertions where velocity, angle of insertion, and depth of injection were controlled. The frequency of pain following needle insertions (23G, 27G, 30G, 32G) was recorded together with the pain intensity (measured using the visual analogue scale--VAS) and the occurrence of bleeding.
  
  
  RESULTS
  The outer needle diameter was positively and significantly correlated to the frequency of the insertion pain; for example, 63% of insertions with 23G needles caused pain, 53% of insertions with 27G and 31% of insertions with the thinnest (32G) needle (p < 0.0001) caused pain. The thickest needle caused most insertions associated with bleeding. Bleeding insertions were approximately 1.3 times more painful (as indicated by VAS scores) than insertions without concomitant bleedings (p = 0.004).
  
  
  CONCLUSIONS
  By decreasing the outer diameter of a needle, the frequency of insertion pain can be reduced and may encourage patients to adhere to demanding injection regimens such as recurrent insulin administration.
authors.affiliation: Department of Health Sciences and Technology, Aalborg University, Laboratory for Experimental Pain Research, Center for Sensory-Motor Interaction, Aalborg, Denmark. LAN@smi.auc.dk
authors.forename: Lars
authors.initials: L
authors.lastname: Arendt-Nielsen
authors.forename: Henrik
authors.initials: H
authors.lastname: Egekvist
authors.forename: Peter
authors.initials: P
authors.lastname: Bjerring
mesh_terms: D006470:Hemorrhage / Q000209:etiology / Q000517:prevention & control; D006801:Humans; D007279:Injections, Subcutaneous / Q000009:adverse effects* / Q000295:instrumentation*; D009339:Needles / Q000009:adverse effects*; D010146:Pain / Q000209:etiology* / Q000517:prevention & control*; D010147:Pain Measurement; D012867:Skin