Conventional insulin concentration units (IU/mL or just U/mL) are bioefficacy based, whereas the Système International (SI) units (pmol/L) are mass based. In converting between these two different approaches, there are at least 2 well-accepted conversion factors, where there should be only 1. The correct value is not the most-used or well-accepted using online calculators, some journal styles, laboratory reports, and published articles. In short, an incorrect insulin conversion factor is widely used which underreports insulin concentrations by ~15%, with potentially significant research and clinical implications. This short commentary describes the history of insulin IU definitions and conversion factors, and highlights the widespread nature of conversion factor misuse, to provoke deeper interest and thought regarding numbers we so often use without thinking.

No abstract

No abstract

A low-cost but reliable flow and pressure sensor is an impediment to development of medical equipment, and studies of human respiratory function, which is characterised by relatively low pressures and flows. A Venturi tube (D 1 ¼ 15 mm; D 2 ¼ 10 mm) connected to a differential pressure sensor (SDP816-125 Pa) allows accurate measurement of flow between 5 À 75 L Á min À1 , with Pearson Correlation over 4 min at 50 Hz P 0:97, and distance correlation P 0:96. The pressure measurement was similarly accurate using a MPVZ4006GW7U. Both sensors provide an analogue output from a 5:0 V supply, aiding compatibility and customisation. Each populated PCB costs approximately $50USD, and each Venturi sensor costs approximately $1USD. Multiple configurations exist, allowing flow rates up to 250 L Á min À1 , increased resolution for specific ranges, and different physical characteristics.

No abstract