Skin Blood Perfusion and Cellular Response to Insertion of Insulin Pen Needles With Different Diameters

Abstract

Approximately 382 million people worldwide have diabetes, 1 half of the prevalent cases are not known or diagnosed, half of those diagnosed are not treated, and half of those treated are not controlled. 2,3 One of the reasons for poor treatment compliance is injection anxiety causing 20% of insulin users to sometimes skip their injections, and 10% to restrict their number of injections. 4 As many as 94% of insulin users exhibit symptoms of anxiety, distress, or phobia around blood and injury from injections, 5 22% of insulin users have to mentally prepare themselves for injections, 6 and 33% of insulin users dread their injections. 7 This underlines why it is of high importance to develop needle designs that cause as little fear, injury, and pain as possible. Pain perception is one of the preferred methods to evaluate new needle design. 8-18 Studies have shown how needle diameter correlates with both the magnitude of the perceived pain, typically measured on visual analog scales (VASs), and with pain occurrence, that is, how often the needle causes pain sensation. 11-13 However, pain is a subjective measure with a large number of biasing variables causing data with high variance. Therefore, a high sample size is needed to detect differences in pain, which makes it both costly and time-consuming to carry out the clinical trials. One alternative way to obtain information about the needle impact on tissue is to use animal models, where histology can be used to assess tissue trauma from, for example, a needle insertion. The needle insertion can cause tissue bleeding and initiate inflammation in the tissue. Pig models are especially useful when examining skin disease and wound 531099D STXXX10.

Pen needle design influences ease of insertion, pain, and skin trauma in subjects with type 2 diabetes

“…When comparing the SBP measurements of the present study to those previously obtained in pigs,14 the peak SBP increases and the AUC differences between different diameter needles are very similar in magnitude and in relation to different needles. Thus, SBP measurements on pigs can be used to predict SBP in humans, enabling future test of needle performance outside of clinical trials.…”

“…24 Nevertheless, in the present study pain score and increase in SBP did not differ significantly between NF-32 and NF-30 needles. In our previous pig study, the magnitude of the SBP increase also related positively to needle diameter with no significant difference between NF-32 and NF-30 needles 14. Thus, an agreement was seen between pain and SBP data in humans and between SBP data in humans and pigs, which implies a relation.…”

“…Immediately after removal of the third needle insertion and corresponding pain rating, the recording was resumed and continued for 15 min. The 15 min signal recording was chosen based on previous experience with SBP measurements in pigs,14 and the need for test subjects to remain immobile during the LASCA recordings in order to minimize signal noise. The experiments were carried out to meet the LASCA experimental recommendations outlined by Mahé et al 22 to minimize procedure responsible variation in the recordings.…”

“…The data sampling frequency was 10 images per second, and averaged over 10 images to an effective frame rate of one image per second. The LASCA data analysis was performed as described in previous tests on pigs 14. In brief, the mean value of each baseline recording was used as baseline reference.…”

“…Skin trauma was previously explored on pigs by the authors14 by using Laser Speckle Contrast Analysis (LASCA) technology15–18 to measure the increase of skin blood perfusion (SBP) following pen needle insertions, but it is unknown if and how SBP relates to pain and ease of skin penetration in humans.…”