You can smell some illnesses. A slightly sweetish-fruity smell of acetone, for example, indicates diabetes, an ammonia smell indicates kidney failure. Whose breath smells of fresh bread could be typhoid. In the meantime, in addition to human beings, there are also electronic noses that analyze the breath, or more precisely its scent molecules. Among other things, the alcohol test is based on this principle.
Invention of the respiratory gas analysis
The American Nobel laureate Linus Pauling discovered around 1970 that human breath contains more than 200 different gaseous substances.
A lot has happened in research since then: In America, a procedure was developed to diagnose illnesses via breath sampling. This method proved promising in initial tests, such as breast cancer.
Prof. Michael Phillips of New York Medical College and founder of Menssana Research has been involved in respiratory gas analysis for many years and has successfully completed studies to identify markers of lung cancer and breast cancer.
Molecules in the air
About 3, 000 volatile substances contain the human breath. In order to analyze these substances, Phillips collects organic compounds by binding to activated carbon. The procedure takes only about two minutes for the patient: he simply breathes into the respiratory gas apparatus. With a technical method, the marker substances thus obtained are released from the activated carbon and analyzed by gas chromatography.
The gas chromatograph separates the molecules. In this case, patterns of chain-shaped carbon atoms, so-called branched alkanes, can be seen. These allow conclusions about metabolic activities.
By comparing the patterns, changes that occur in diseases can be identified. Depending on which organ is affected, this creates a kind of gaseous fingerprint, which can serve as an indicator for the doctor.
Breathing gas analysis for breast cancer and other diseases
Prof. Phillips discovered that the respiratory gas analysis is also suitable for the diagnosis of breast cancer patients. Initial studies with the new breath tests proved promising. In the long term, this method could significantly reduce the number of mammograms. In addition, the patient is not exposed to radiation exposure.
Also rejection reactions after heart transplants or lipid metabolism disorders can be diagnosed by breath tests. Prof. Risby (Department of Environmental Health Sciences, Johns Hopkins University, Baltimore) has shown that high levels of ethane in children's breath are due to selenium and vitamin E deficiency.
Diagnose lung cancer via respiratory gas analysis?
Respiratory analysis was also very promising in lung cancer patients. Meanwhile, various electrical appliances, such as the Cyranose® Electronic Nose, have been developed. Furthermore, researchers are researching the exact markers with which, for example, a lung tumor can be differentiated from asthma or COPD.
This will enable lung cancer to be soon diagnosed using expired air and breath tests to be an alternative to traditional methods. Where previously a tissue sampling, a biopsy, was necessary, the investigation could then be carried out without risk of the breath. But the cost of such an analysis is still very high.
The electronic nose for a reliable diagnosis
But other diseases, such as bacterial respiratory infections, which can lead to pneumonia, can be detected with the help of an "electronic nose". Bacteria leave characteristic traces in the breath. The device detects if a disease is a bacterial infection and helps the clinician decide on the administration of antibiotics. This can avoid wrong treatment.
In Europe, such devices are already in use, for example, for the detection of 13C-labeled carbon dioxide in the exhaled air. Thus, for example, the bacterium Helicobacter pylori can be detected in the stomach, which is responsible for stomach diseases and stomach ulcers.