The smell of lung disease: a review of the current status of electronic nose technology

Abstract

There is a need for timely, accurate diagnosis, and personalised management in lung diseases. Exhaled breath reflects inflammatory and metabolic processes in the human body, especially in the lungs. The analysis of exhaled breath using electronic nose (eNose) technology has gained increasing attention in the past years. This technique has great potential to be used in clinical practice as a real-time non-invasive diagnostic tool, and for monitoring disease course and therapeutic effects. To date, multiple eNoses have been developed and evaluated in clinical studies across a wide spectrum of lung diseases, mainly for diagnostic purposes. Heterogeneity in study design, analysis techniques, and differences between eNose devices currently hamper generalization and comparison of study results. Moreover, many pilot studies have been performed, while validation and implementation studies are scarce. These studies are needed before implementation in clinical practice can be realised. This review summarises the technical aspects of available eNose devices and the available evidence for clinical application of eNose technology in different lung diseases. Furthermore, recommendations for future research to pave the way for clinical implementation of eNose technology are provided.

Diagnostic Performance of Electronic Noses in Cancer Diagnoses Using Exhaled Breath

“…Furthermore, the accuracy of e-noses is affected by endogenous and exogenous factors, such as comorbidities, smoking, diet, body mass index, and ambient air. 13 These factors may alter detected VOC patterns in exhaled breath. 14 E-nose technologies analyzing exhaled breath have been extensively studied for oncologic indications and have been demonstrated to have promising results with high diagnostic accuracies.…”

“…Several reviews 13 , 15 , 19 have investigated the diagnostic accuracy of available e-noses for different indications. Reviewers have uniformly concluded that e-noses have the potential to become promising diagnostic tools in everyday clinical practice.…”

Accuracy of the Electronic Nose Breath Tests in Clinical Application: A Systematic Review and Meta-Analysis

“…After we ruled out studies that reported extraordinarily high-accuracy studies to obtain a more reliable accuracy in clinical breath tests, the heterogeneity was improved and showed no publication bias. Because the preparation of breath tests, collection of breath, storage of breath samples, and preprocessing sensor array data will influence the results of breath tests [ 16 ], current studies lack the standardization procedures of breath collection and machine learning analysis, which might cause heterogeneity from unknown sources. We suggested that a depository of analytical procedures before the implementation of statistical modeling might be essential to prevent heterogeneity in the diagnostic accuracy of breath tests.…”

“…The current knowledge gap on the application of E-noses to clinical diagnosis remains uncertain. Due to the advancement of material sciences, many types of E-nose sensors have been developed in recent years [ 16 ]. Although many types of sensors have been designed to detect more diseases in recent years, E-noses have not yet been applied in clinical practice.…”

The potential of electronic nose technology in lung transplantation: a proof of principle

“…Consequently, using an eNose to collect real-time measurements of the breathprint has potential as a cheap and fast point-of-care tool in clinical practice. In recent years, exhaled breath analysis using eNose technology has gained increasing attention and has demonstrated great potential as a real-time noninvasive diagnostic tool, where different vendors are available [ 3 ]. For example, promising results were demonstrated in diagnosis of asthma phenotypes and interstitial lung diseases, with international confirmation studies ongoing to bring this technology to outpatient clinics [ 3 – 5 ].…”