The technology

Thora‑3Di uses a structured light plethysmography-based technique to measure respiratory function in children. The system consists of device software (PneumaView) and a 'head unit', comprising a visible-light projector and a single-printed circuit board assembly incorporating 2 video camera modules, a hardware processor and ethernet interface module.

During the measurement, which is non-contact and takes between 1 and 5 minutes, the patient must sit as still as possible. No special breathing manoeuvres (such as a deep breath or maximal forced breathing) are needed, because the device measures tidal (quiet) breathing. The measurement can be made on bare skin or through white, close-fitting shirts. A grid of visible light is projected on to the chest and abdominal wall. The software presents the data as a 3D representation of the chest wall, as well as graphically and numerically. Breathing patterns are described in terms of breathing timings (for example respiratory rate, inspiratory and expiratory time), synchronisation between regions (such as thorax to abdomen, left thorax to right thorax) and other outputs.

Compact Thora‑3Di is an identical system which can be dismantled to be transported.


The potential innovations are that Thora‑3Di measures respiratory parameters during normal breathing through a non-contact procedure, which doesn't need the patient to do any special breathing manoeuvres. This is designed to allow assessment in patients unable or unwilling to have conventional spirometry. In addition, Thora‑3Di measures right-versus-left lung function and paradoxical chest-abdominal movements, which are important in neuromuscular disorders. It also provides regional information about thoraco-abdominal wall movement, which spirometry does not.

Current care pathway

NICE is consulting on a draft diagnosing and monitoring asthma guideline which says that young people and children over 5 years who have suspected asthma should have an objective lung function test (including spirometry and a bronchodilator reversibility test). Children under 5 or those unable to perform objective tests should be observed and treated based on clinical judgement and regular clinical review. There is no definitive diagnostic test for asthma; diagnosis relies on assessment of respiration, clinical history and, occasionally, data from tests such exercise, exposure to allergens (skin prick), response to bronchodilators or measuring exhaled nitric oxide.

Population, setting and intended user

Thora‑3Di would most likely be used in secondary care instead of spirometry, typically in a children's respiratory clinic or ward, or lung function unit. The device can be used by any trained nurse or doctor or by a respiratory specialist. A half day's training is needed to use the device; specialists interested in advanced interpretation of the results can do a further day of training.


Technology costs

The company has estimated the cost per Thora‑3Di test as £8.33. This is based on a 5-year lifespan of the device and its being used to test 3 patients each day, 5 days per week, for 40 weeks per each year. A similar calculation for Compact Thora‑3Di equates to a cost-per-test of £5.00. These calculations do not include staff and consumable costs.

Table 1 Device costs



Additional information



Does not include potential purchase and laundering of white shirts.

Compact Thora‑3DI


*As well as capital purchase, the device is available on monthly lease or lease-purchase terms at a total cost equivalent to the capital purchase price.

Costs of standard care

The NICE draft guideline on diagnosing and monitoring asthma estimates the non-staff costs of spirometry to be £2.19 per test, based on an average of 300 tests per year. Combining the draft guideline and company estimates gives a range of costs for spirometry of £13.19 to £17.14 per test. The estimated cost for Thora‑3Di is between £11.98 and £15.63 per test. This includes a GP practice nurse spending 10 to 15 minutes for a spirometry test and 5 to 10 minutes for a Thora‑3Di test.

Resource consequences

Resource use is unclear as the relationship between the breathing parameters measured and spirometry is not established. Thora‑3Di may have the potential to be resource saving by reducing the time taken to measure breathing parameters versus spirometry and so releasing staff time.

Staff using Thora‑3Di must be appropriately trained. It would be used in a separate room, but this is similar to the requirements for spirometry.

Thora‑3Di is currently used in 9 NHS trusts.