The technology

The L‑Dex U400 (Impedimed Ltd.) uses bioimpedance spectroscopy to detect unilateral lymphoedema in the limbs (particularly the arms) after treatment for breast cancer that has removed or damaged the lymph nodes. It may also be used to detect leg lymphoedema in men, but this is beyond the scope of this briefing. In bioimpedance spectroscopy, a small electrical current is passed through the affected limb and the resistance to the current is compared with the unaffected limb. The resistance is used to calculate the total water content in the body, which can be used to detect lymphoedema (Bundred et al. 2015).

Lymphoedema is the build-up of lymphatic fluid in the body, particularly in the limbs, which causes swelling and enlargement. Although it is a chronic condition, detecting lymphoedema earlier may allow more conservative management and better clinical outcomes (Stout et al. 2012; International Society of Lymphology 2013).

The L‑Dex U400 is a small, portable desktop system with a built-in display screen. To use it, the patient lies on their back and a nurse or physiotherapist places 1 electrode on the back of each hand and 1 on the right foot. Colour-coded leads are attached to the electrodes to connect them to the L‑Dex U400, and measurements are taken following the on-screen instructions. The results appear on the screen, given as an L‑Dex ratio. The accumulation of extracellular fluid in the limb causes the L‑Dex ratio value to increase.

The L‑Dex ratio is calculated by dividing the bioimpedance reading from the affected arm by that from the unaffected arm. The normal range of the L‑Dex ratio is −10 to +10. L‑Dex ratio values above the normal range, or values that have changed by at least 10 L‑Dex units from the baseline, may suggest early signs of lymphoedema.

Results can be analysed on the L‑Dex U400, which can store over 1,000 records and includes analysis software. Results can also be uploaded through the network port onto a Windows computer for storage and additional analysis using the Impsoft Unilateral Lymphedema Analysis Software. The software on the L‑Dex U400 device allows readings to be tracked over time to detect increases in fluid accumulation.


Other methods for diagnosing lymphoedema, such as water displacement and tape measurement, are not able to distinguish between lymphatic fluid and the healthy tissues of the body. These methods can therefore be inaccurate, especially if there are changes to the body tissues, such as weight loss or gain. The L‑Dex U400 uses bioimpedance spectroscopy, which can specifically measure extracellular fluid. This is designed to enable earlier detection of lymphoedema.

Current care pathway

Lymphoedema of the arm happens in around 1 in 5 people who have had treatment for breast cancer, involving removal of the lymph nodes or radiotherapy. Lymphoedema is considered to be a chronic condition. Most patients with lymphoedema (around 90%) will not need surgery, but around 10% need invasive treatment such as surgery (Lymphoedema Support Network). Some patients (10%) will develop serious complications, such as cellulitis (Asdourian et al. 2016).

The most commonly used method of lymphoedema detection in current NHS practice is periodic measurement of limb circumference using a tape measure, combined with a clinical assessment of the patient's skin and their mobility. The limb circumference measurements are compared to measurements taken before treatment, or compared with the unaffected limb.

Limb volume measurement may also be done, depending on clinical preference. Methods include:

  • Water displacement – where the affected limb is placed in a tank of water and the amount of water that is displaced is measured.

  • Perometry – where infrared light is used to measure the outline of an affected limb and calculate its volume.

Treatment options for people with lymphoedema include skin care, exercises, use of compression garments and lymphatic drainage massage, which are designed to reduce swelling. In a small number of cases surgical techniques, such as liposuction to remove excess fat from the affected limb, may also be used (NHS Choices 2016).

The 2002 NICE cancer service guideline on improving outcomes in breast cancer recommended that networks should agree guidelines for identification and management of lymphoedema and that a lymphoedema service, staffed by trained nurses and physiotherapists, should be available for all patients who have symptoms of lymphoedema. Current provision of lymphoedema services is variable.

Population, setting and intended user

The L‑Dex U400 would be used in secondary care to detect and monitor lymphoedema in people who have had chemotherapy, radiotherapy or surgery for breast cancer. The L‑Dex U400 is typically used by an appropriately trained nurse or physiotherapist, as a part of routine screening.


Technology costs

The capital cost of the L‑Dex U400 is £7,500 per unit and it has a 5‑year lifespan with no maintenance costs, and no calibration is needed. For each patient, 3 single-use electrodes are used at a total cost of £3.75 per patient (£75 per pack of 60 electrodes). Training for staff using the L‑Dex U400 is provided by the manufacturer at no additional cost and includes a video and online training materials. The L‑Dex U400 could be used during routine follow-up after breast cancer treatment. Currently, the cost of a breast cancer specialty clinic visit is £168 for a first visit and £96 for each subsequent visit.

Costs of standard care

Clinical practice for lymphoedema diagnosis varies across the NHS. However, lymphoedema is generally diagnosed through arm circumference measurements. These can be completed during routine clinic visits after breast cancer treatment and are not expected to incur additional costs. Perometry or water displacement tests can also be done in specialist centres.

Resources used in the treatment of lymphoedema can include compression bandages (£3.56 each), sleeves (£8.92 each) and physiotherapist-led exercise (£34 per hour). If the condition becomes more serious, then surgical procedures (such as liposuction) may be needed. The cost of liposuction is expected to be at least £2,000 per procedure (NHS Choices 2015). Lymphoedema can be associated with secondary conditions, such as cellulitis, needing further treatment.

A US study estimated that the medical costs associated with lymphoedema in women with breast cancer were $8,290 over 2 years (Shih et al. 2009). A second study done in the US has reported that early detection of lymphoedema can lead to cost savings of $2,489 per person, per year, because early intervention reduces the need for extensive rehabilitation (Stout et al. 2012).

Resource consequences

The L‑Dex U400 is currently being used by 21 NHS trusts.

Use of the L‑Dex U400 is expected to add about 15 minutes to each clinic appointment, which may increase the cost of each appointment by about £42. Assuming the L‑Dex U400 is used on average 5 times per day, over a 5 year period this gives a cost per use of £1.15, plus £3.75 per assessment for the single-use electrodes. Each patient would have 17 assessments with the L‑Dex U400 over the course of 5 years.

A US study comparing the budget impact of the L‑Dex U400 with standard care for lymphoedema detection showed that use of the L‑Dex U400 led to cost savings of $315,711 for a hypothetical cohort of 627 people with breast cancer in a total population of 1 million people (Bilir et al. 2012). If the L‑Dex U400 leads to early detection of lymphoedema as part of routine screening, then cost savings may be realised in reduced treatment costs for later-stage lymphoedema. However, the US care pathway may be different to the UK and there is currently no evidence showing similar savings in an NHS setting.