Dialysis centers in Connecticut continue to improve their overall quality of care, with 12 facilities reaching Medicare’s highest patient-care rating and just one scoring on the low end of the scale, the latest data show. That’s an improvement from the 2014 data, when six dialysis centers in the state scored low in quality-of-care ratings. Dialysis helps those with kidney failure remove waste from the body, regulate chemicals and control blood pressure. Most often, patients have their blood removed and cleaned in a machine called a dialyzer before it’s returned to the body. Another form of dialysis uses a cleaning fluid and the stomach as a filter.