Electronic nose can sniff out when a lung transplant is failing – research

By Nina Massey & Matt Gibson

An electronic nose can detect with 86% accuracy when a lung transplant is beginning to fail, new research suggests.

Experts suggest the finding could enable doctors to spot at an early stage when a lung transplant is failing, known as chronic allograft dysfunction (Clad), and allow them to provide treatments to prevent it getting worse.

However, more research needs to be carried out before the eNose could be used in the clinic for this purpose, the researchers say.

Nynke Wijbenga, a PhD student and technical physician at Erasmus University Medical Centre, Rotterdam, The Netherlands, presented the research at the European Respiratory Society International Congress.

She said: “About 50% of lung transplant patients are diagnosed with chronic allograft dysfunction or chronic rejection within five years of the transplant.

“Chronic rejection remains the most important cause of death after lung transplantation and, at the moment, there is no treatment available to reverse it.”

She added: “Once chronic rejection has been confirmed, patients can on average survive for between one and five years.

“A re-transplantation could be a last resort for specific patients with advanced chronic rejection.

“Therefore, it is of utmost importance to assess if we can predict or diagnose lung transplant dysfunction at an early stage, possibly enabling more successful early treatment.”

It can currently take several months to diagnose Clad.

Doctors test lung function at each visit, if it drops to 80% or lower, then they investigate further to exclude causes that might respond to treatment, such as lung infection.

Chronic rejection can only be confirmed after these investigations and if the decline in lung function persists for three months.

The eNose is a small device that contains sensors to detect chemicals called volatile organic compounds (VOCs).

These are present in about one percent of exhaled breath and can vary depending on metabolic processes.

When patients breathe out into the eNose, the sensors not only detect the pattern of VOCs in the breath, but also correct the results to take account of the ambient air that has been inhaled.

The results are analysed using artificial intelligence and what is described as the “breathprint” can be used to identify several lung diseases.

Researchers recruited 91 lung transplant patients, who were visiting Erasmus MC for outpatient appointments, between July and November 2020.

One eNose measurement was taken from each patient and then compared with the diagnoses that the patients’ consultants had already made.

The patients were aged between 35 and 73, 47% were male and the median time after having a lung transplant was 3.6 years.

In 86% of cases the eNose was able to discriminate between the 68 patients who had stable lung transplants and the 23 patients who had CLAD, the study found.

Ms Wijbenga said: “These results suggest that the eNose is a promising tool for detection of CLAD.

“However, more research is required before it can be used in the clinic.

“We need to assess whether repeated measurements in the same patients can provide more accurate diagnoses and even predict CLAD before it occurs.

“Also, we need to confirm our results in other groups of patients. Nonetheless, we aim to develop this as a technique for wide use across Europe.”

The researchers hope further research will be able to distinguish between the two types of chronic rejection: bronchitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS).

The e-Nose used in the study was SpiroNose made by Breathomix.

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