The use of differential pressure as an inferred measurement of a liquid's rate of flow is well known. Differential pressure flowmeters are, by far, the most common units in use today. Estimates are that over 50 percent of all liquid flow measurement applications use this type of unit.
Between 1% and 15% of people globally are affected by kidney stones at some point in their life. In 2013, 49 million cases of occurred, resulting in about 15,000 deaths. They have become more common in the Western world since the 1970s. Generally, more men are affected than women.
More than 650,000 patients per year in the United States and an estimated 2 million patients worldwide are affected by end stage renal disease (ESRD). ESRD is increasing in the United States by 5% per year. Those who live with ESRD are 1% of the U.S. Medicare population but account for 7% of the Medicare budget. More than 100,000 patients in the United States are on the kidney transplant list, but each year there are less than 20,000 available donor kidneys.