The technology

Clarity RMS (RenalSense) is a critical care monitoring system that continuously measures urine flow and automatically sends data and alerts of fluctuations to medical staff in real‑time. This is done on a '24 hours a day, 7 days a week' basis. Information on changes in renal function provides an early indication of acute kidney injury (AKI) risk and allows rapid intervention. It also helps monitor treatment efficacy and manage fluid balance.

RenalSense Clarity RMS consists of 3 components:

  • Clarity RMS electric sensor: connects to a Foley catheter and continuously measures critical fluctuations in urine flow. When a temperature-sensing Foley catheter is used, the sensors can also measure real‑time core body temperature.

  • Clarity RMS console: the embedded technology in this battery‑powered bedside monitor continuously calculates and sends real‑time data from the sensor directly to all hospital information systems.

  • Clarity RMS intelligent notification system: notifies the medical team when the patient's urine flow is below the threshold set by the user for urine output (ml/kg/hour), based on the risk, injury, failure, loss and end‑stage kidney disease (RIFLE), AKI network (AKIN) and kidney disease: improving global outcomes (KDIGO) criteria.


The company claims that the automated system replaces a step in the current patient pathway (urometer) by measuring the urine flow in real time, displaying this data on the console and sending it to hospital information systems. The company claims that this limits the need for manual intervention and that Clarity RMS is more consistent, reliable and accurate than nursing records.

Current care pathway

Those at risk of AKI should be monitored and can be diagnosed based on an acutely rising serum creatinine or reduction in urine output.

AKI is present if 1 or more of the following criteria is met:

  • a rise in serum creatinine of at least 0.3 mg/100 ml within 48 hours

  • a rise in serum creatinine to more than 1.5 times baseline, which is known or presumed to have happened in the past 7 days (in practice, you can use the lowest value from the past 3 months as the baseline for the patient) or

  • urine volume of less than 0.5 ml/kg/hour for at least 6 hours.

Urine output is measured manually using a urometer that is attached to a urinary catheter and placed within the sealed catheter bag. Measurements are done hourly or for a set time. Expert advice noted that the AKI criteria above only apply after any dehydration has been corrected.

The following publications have been identified as relevant to this care pathway:

Population, setting and intended user

RenalSense Clarity RMS is intended to automatically monitor urine output for people weighing more than 50 kg, who have an indwelling Foley catheter. It can be used for people with catheters who are on an intensive care unit (ICU) or ward, who are at risk of developing AKI. It can also be used for people who have AKI.

AKI is seen in 10% to 20% of people admitted to hospital as emergencies, with an inpatient mortality over 20%. The overall incidence of AKI in the ICU is higher at 20% to 50% and it is associated with mortality over 50% (BMJ best practice: AKI).

The technology can be used in both secondary and tertiary care by consultant nephrologists, consultant intensivists, ICU nurses, high dependency unit nurses and ward nurses, who care for people with catheters.

The company states that the console is simple to use and needs minimal training. The training is included in the cost of the device for free, lasts 30 to 40 minutes and is done either face‑to‑face or via Microsoft Teams.


Technology costs

  • Clarity RMS console: £3,810.

  • Disposable sensor kit: £65 per person.

The company states that the lifespan of the console is between 5 and 10 years.

Costs of standard care

  • Urometer: £8 to £10 per person.

Resource consequences

The company states that the technology is currently not used in the NHS. However, they are in discussion with 2 pilot sites to adopt and evaluate the technology in 2021.

The company claims that the automation of measuring urine flow replaces manual intervention by healthcare assistants and therefore could use less staff resource. The company also claims that Clarity RMS allows earlier or more accurate diagnosis, which may reduce the length of hospital stay or allow earlier discharge.

The company states that for the hospital to realise the full benefit of the technology, the system needs to be integrated into the hospital information system. Clarity RMS currently needs an ethernet connection at the patient's bedside; however, the company states that wireless connectivity is under development and will be available in 2021.