Some diseases can be smelled. A slightly sweet and fruity acetone smell, for example, indicates diabetes, while an ammonia smell indicates kidney failure. Someone whose breath smells of fresh bread could be suffering from typhoid fever. In addition to human sniffers, there are now also electronic sniffers that analyze breath, or more precisely its odor molecules. The alcohol test, among others, is also based on this principle.
Invention of breath analysis
Around 1970, the American Nobel Prize winner Linus Pauling had discovered that human breath contains more than 200 different gaseous substances.
Much has happened in research since then: a method has been developed in America to diagnose diseases via breath samples. This method proved promising in initial tests, for example for breast cancer.
Prof. Michael Phillips of New York Medical College and founder of Menssana Research has been involved in breath analysis for many years, meanwhile conducting successful studies to identify markers for lung cancer and breast cancer.
Molecules in the air we breathe
Human breath contains about 3,000 volatile substances. To analyze these substances, Phillips collects organic compounds by binding them to activated carbon. The procedure takes only about two minutes for the patient: The patient simply breathes into the breathing apparatus. Using a technical process, the marker substances obtained in this way are dissolved from the activated carbon and analyzed using gas chromatography.
The gas chromatograph separates the molecules. In the process, patterns of chain-shaped carbon atoms, so-called branched alkanes, become recognizable. These allow conclusions to be drawn about metabolic activities.
By comparing the patterns, changes such as those that occur in diseases can be identified. Depending on which organ is affected, this creates a kind of gaseous fingerprint that can serve as an indicator for the physician.
Breath gas analysis for breast cancer and other diseases
Prof. Phillips discovered that breath gas analysis is also useful for diagnosing patients with breast cancer. Initial studies using the new breath tests proved promising. So in the long term, this method could significantly reduce the number of mammograms. In addition, the patient is not exposed to radiation.
Breath tests can also be used to diagnose rejection reactions after heart transplants or lipometabolic disorders. Prof. Risby (Department of Environmental Health Sciences, Johns Hopkins University, Baltimore) was able to demonstrate that high ethane concentrations in the breath of children are due to a deficiency of selenium and vitamin E.
Diagnosing lung cancer by breath analysis?
Breath analysis also showed great promise in lung cancer patients. In the meantime, various electrical devices, such as the Cyranose Electronic Nose, have been developed. Research continues into the precise markers that can be used, for example, to distinguish a lung tumor from asthma or COPD.
This should soon make it possible to diagnose lung cancer on the basis of exhaled air and make breath tests an alternative to conventional methods. Where a biopsy was previously necessary, the examination could then be carried out risk-free via the breath. But the cost of such analysis is still very high.
The electronic nose for reliable diagnosis
But other diseases, such as bacterial infections of the respiratory tract that can lead to pneumonia, can also be detected with the help of an “electronic nose.” Bacteria leave characteristic traces in the breath. The device detects whether an illness is a bacterial infection and thus helps the doctor decide whether to administer antibiotics. In this way, incorrect treatment can be avoided.
Such devices are also already in use in Europe, for example for the detection of 13C-labeled carbon dioxide in exhaled air. For example, the bacterium Helicobacter pylori can be detected in the stomach, which is responsible for stomach diseases and stomach ulcers.
