Impedimed (ASX:IPD) shares are on the rise this morning after US regulators expanded clearance for its SOZO bioimpedance spectroscopy device to make it more useful for heart failure patients and their doctors.

The US Food and Drug Administration said the device could include a heart failure index derived from fluid levels, helping doctors monitor patients.

Fluid overload is a common symptom of heart failure patients, as less blood to the kidneys can cause water retention, swelling the lungs, legs and abdomen.

Somewhat similar to the body fat monitors seen in some gyms, the SOZO device runs a painless electrical current through the body to measure its composition.

The HF-Dex index will present clinicians with a patient’s fluid levels over time, together with a normal fluid volume range.

“This is a major step forward in SOZO becoming the standard of care for the management of heart failure patients,” said Impedimed chief executive Richard Carreon.

“The use of HF-Dex will provide clinicians unparalleled insights into the extracellular fluid accumulation in heart failure patients that has not otherwise been readily available to them before.”

At 11.24am, Impedimed shares were up 13 per cent to 13c.