CT scan of chest showing heart and lungs
Credit: Alfred Pasieka / Science Photo Library / Getty Images

Chemicals in the breath of patients admitted to hospital can identify which underlying cardiorespiratory disease they are suffering from, research suggests.

Exhaled volatile organic compounds were able to distinguish heart failure, asthma, chronic obstructive pulmonary disease (COPD) and pneumonia, according to the study published in Science Translational Medicine.

The “breathomics” analysis identified a cluster of related hydrocarbons and carbonyls that were associated with heart failure among patients with acute breathlessness.

Reduced levels of a separate set of highly correlated aldehydes further distinguished acute exacerbations of asthma from those of COPD and pneumonia.

The study revealed that a score incorporating more than 100 breath markers had high sensitivity and specificity and was able to predict all-cause mortality.

“The main clinical relevance is that by taking images of the chemicals in human breath we could identify patients that were acutely ill with a heart or lung problem from those that were not,” explained researcher Salman Siddiqui, a professor of respiratory medicine at the National Heart and Lung Institute in London, U.K.

“In addition, we could identify the causes of the illness e.g., acute asthma, COPD exacerbations etc.,” he told Inside Precision Medicine.

“The research will be developed further to test point of care sensors in clinical trials for these chemicals signatures in emergency departments to identify patient diagnosis early.”

This could be used at emergency department triage and potentially also to identify patients that may not need acute treatments in hospital, Siddiqui added.

Breathlessness due to cardiorespiratory diseases accounts for more than one in eight of all emergency admissions to hospital and diagnosis is heavily reliant on blood-based testing and radiological procedures.

In an attempt to investigate alternatives, the researchers collected exhaled breath samples from 277 individuals between May 2017 and December 2018, including 55 aged-matched healthy volunteers.

Overall, 65 patients had acute severe asthma, 58 acute, severe COPD, 55 with community-acquired pneumonia, and 44 had acute, severe heart failure. Thirty required supplemental oxygen.

To determine the predictive value of volatile exhaled compounds for different disease groups, patients were divided into a discovery cohort of 139 participants and a replication cohort of 138 participants.

The team found that a score incorporating 101 breath biomarkers had sensitivity and specificity of at least 80 per cent and was associated with all-cause mortality at 2 years.

Interesting, not all the compounds that were captured during breath analysis were considered endogenous, with 27 potentially attributable to cosmetics that may have been captured due to their proximity on participants’ faces.

The researchers conclude: “This research provides pivotal evidence that shows how breath biomarker platforms may be used in acute care and demonstrates the potential for translation of this technology into a real-world clinical setting.”

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