History of human odor analysis in disease diagnosis
The use of the sense of smell as an indicator of human disease probably originated with Hippocrates (circa 400 BC). Early medical practitioners recognized that the presence of human diseases changed the odors released from the body and breath. Physicians once relied heavily on their sense of smell to provide useful clues for identifying the causes of human ailments. Descriptive terms were used to describe odors (or aromas) associated with specific human diseases and disorders (Fig. 1). This odor information was a valuable tool for physicians to assess patients’ conditions and help diagnose diseases centuries before modern analytical instruments became available for this purpose. Odor recognition by human smell was used by doctors (with diminishing emphasis) up until the early 1980’s, just before electronic noses (e-noses) came on the scene.

Fig. 1. Aroma descriptions for diagnoses of specific diseases.

Analysis of disease biomarkers in human breath
Analysis of expired human breath is particularly valuable because it can be monitored noninvasively. Diseases of the human body arise from different mechanisms, such as from metabolic disorders, exposure to toxins, and through microbial disease-causing agents that alter normal physiological processes of the human body. These mechanisms of disease result in the production of unique mixtures of abnormal chemicals (biomarker metabolites) in the body that are characteristic of specific diseases. Regardless of where these abnormal chemicals are produced or originate in the body, they are picked up by the circulatory system and eventually expelled out through the lungs. Consequently, analysis of the complex gaseous mixtures of volatile organic compounds (VOCs) released from the lungs through the breath provide very useful diagnostic clues to the presence of disease processes occurring in the body (Fig. 2).

Early disease diagnoses using e-noses
Electronic nose (e-nose) devices are relatively new gas-detection technologies adapted for use as medical tools for various clinical applications. These small, simple and portable devices are particularly useful for the noninvasive early detection of human diseases. A major advantage of using e-noses, such as for disease diagnoses by human breath analysis, is that they provide quicker, more efficient diagnostic results and cause less stress, anxiety, and no pain to patients.

Fig. 2. E-nose analysis of volatile biomarker metabolites in the human breath

Importance of this review: why use e-noses and biomarkers in early disease detection?
Conventional methods utilized for clinical diagnostics are very expensive, time-consuming, and often result in delays in diagnoses and treatments for human diseases. Electronic-nose devices are not yet widely used in clinical practice, but significant progress is currently underway. The benefits of early detection using e-noses, allowing early treatments of diseases, are obvious as prognoses are greatly improved. Many patients often avoid regular prophylactic checkups and early disease screenings because many current methods (e.g., colonoscopies, X-ray mammographies, tissue biopsies, etc.) still involve invasive, painful, or expensive procedures. Many of these methods also present risks of significant negative side effects and often are sufficiently painful to discourage patients from participating in preemptive, prophylactic disease-screening procedures. Recent advancements in the use of e-nose devices to analyze human breath profiles for the presence of specific volatile metabolites (unique biomarkers of specific human diseases), is providing the potential for these new noninvasive tools to facilitate point-of-care clinical disease diagnoses. This exciting new area of e-nose disease detection and diagnosis promises to yield much faster and earlier detection of human diseases, allowing earlier and more effective treatments with more rapid patient recovery. This review article provides a brief summary of recent progress in the development of e-nose applications and technologies for clinical examinations through human breath analysis.

A. Dan Wilson
Pathology Department, Southern Hardwoods Laboratory, Center for Bottomland Hardwoods Research
Southern Research Station, USDA Forest Service
Stoneville, USA

Publication

Advances in electronic-nose technologies for the detection of volatile biomarker metabolites in the human breath.
Wilson AD.
Metabolites. 2015 Mar 2

Read offline:     

Related Articles:

	Can we accurately diagnose different clinical… Progressive Supranuclear Palsy (PSP) is the second most common degenerative parkinsonian syndrome after idiopathic Parkinson’s disease. PSP is a clinically heterogeneous disorder with several clinical variants. The two most common…
	Emerald Ash Borer attacks trees revealing early… The Emerald Ash Borer (EAB), Agrilus planipennis, is a major global forest pest (a buprestid beetle) that has decimated ash trees (Fraxinus species) throughout Europe and Asia. Since this nonnative…
	DARC - A light at the end of the tunnel Glaucoma is the leading cause of irreversible blindness, affecting more than 70 million people worldwide. Visual loss is attributed to death of nerve cells, called retinal ganglion cells (RGCs), in…
	Historical stability of the human aging rate and its… Using age-related mortality data for 40 countries, it is shown that the rate of aging does not change significantly over history and is almost the same for different countries from…
	The use of olfactory neuronal precursors for… Alzheimer’s disease (AD) is a disabling and progressive illness that causes a high social cost and economic burden. Current diagnosis has been done by clinical appreciation based on the Diagnostic…
	Specific and non-specific biomarkers in… Neuroendocrine tumors (NETs) are a heterogeneous group of rare malignancies that can arise in almost all organs, although gastroenteropancreatic site (GEP) is the most common. Symptoms are rarely specific, and…