Use of finer needles for venipuncture increases in vitro haemolysis despite reducing persistent pain and nerve injury: A retrospective study.

BACKGROUND: Although venipuncture is minimally invasive, and is the most frequently performed medical procedure, it carries the small risk of causing persistent pain, including nerve damage. Recently, our hospital stopped using 22-gauge needles for venipuncture in outpatients and switched to using only 23- and 25-gauge needles. We investigated the impact of using only the finer needles on the incidence of persistent or neuropathic pain and the prevalence of haemolysis, as well as the impact of haemolysis associated with the needle change on other laboratory data. METHODS: We retrospectively collected and analysed data on venipuncture-associated pain complaints made during the 1-year period prior and 1-year period after the change in needles, as well as the frequency of haemolysis before and after the change. We also focused on 90 cases that showed significant haemolysis after the needle change and compared the serum aspartate aminotransferase, lactate dehydrogenase, and potassium levels before and after the needle change. RESULTS: The incidence of persistent pain was significantly reduced from 1 in 10,825 venipunctures before the change to 1 in 29,747 venipunctures after the change. Notably, no patients experienced neuropathic pain after the change. However, the prevalence of haemolysis was significantly increased. Additionally, the serum aspartate aminotransferase, lactate dehydrogenase, and potassium levels were significantly elevated in the cases that showed moderate to gross haemolysis after the needle change. CONCLUSION: Using finer needles involves both advantages and disadvantages, and careful consideration is needed to determine which type of needle is in the best interests of the patient.

Visual information of vehicle velocity acquired by pedestrians involved in road crossing accidents.

This paper describes a geometric optical relationship between the perceived visual information of approaching vehicles by pedestrians who intend to cross the road and the factors underlying pedestrian accidents in Japan. We create a model based on this visual information, wherein the retinal image corresponding to vehicle velocity perception is broken down into tangential components and normal components in a two-dimensional polar coordinate system that employs the nodal point of the eyeball as the origin. Our visual model uses the relationship between the tangential and normal components of the velocity to calculate the distance at which the velocity of the vehicle can be perceived by pedestrians. The maximum distance at which vehicle velocity can be perceived by pedestrians derived from the visual model is consistent with the timing at which a vehicle collides with a pedestrian most frequently in the pedestrian accidents gleaned from accident statistics. The result of the simulation of the visual model showed that the eye height of the pedestrian, the total height of the vehicle and the sensory threshold of motion determine the components by which the maximum perception distance of the vehicle velocity is given. These findings contribute to the enhancement of safety measures in traffic accidents from the pedestrian's perspective.