Up to now, only the police breathalyzed people. But soon physicians will be able to use a similar procedure. In contrast to the wardens they would not be out to detect rests of alcohol in the breathing air of their patient but cancer and infectious diseases. For this purpose, researchers at the Dortmund Institute for Analytical Science (ISAS) developed a measuring device checking patients’ breathing air for various substances.
The human breath contains about 400 to 600 chemical compounds produced by the metabolism. Diseases influence the metabolism and thus the composition of the chemical compounds in breathing air. For example increased concentrations of acetone indicate Diabetes.
Spectrometer separates the breath into molecular components
In order to be able to analyze the breath of a man in the so-called ionmobility-spectrometer, the researchers of ISAS just need 10 milliliters of air – it’s just a small blow into the tube for the test person. The air flows from the mouthpiece into a small box first. It contains a stack made of 1,000 parallel aligned capillaries each sized only 43 millimeters. Depending on size, shape and chemical properties, the substances of the breathing air now wander through the slim tubes at different speeds until they hit upon a grid opening and closing itself periodically every 100 milliseconds. Behind this there is another apparatus separating the single molecules of the substance mix even further.
At first all molecules which passed the grid are charged electrically by an ionization source. This puts the ionized molecules in a position to drift through an electric field. The more mobile a molecule is the faster it reaches the other end of the drift tube where a detector registers the “arrival”. Each substance has a characteristic invariant drift time it can be identified by. After the test persons have blown into the tube it takes only 10 minutes until results are available. A special software helps the researchers with the interpretation of the data.
Faster diagnosis of infectious diseases
The rapidness of the ionmobility-spectrometry (IMS) could improve the future treatment of infectious diseases considerably. “Until now it normally took several days to identify the exact pathogen”, explains the physicist Jörg Ingo Baumbach signing responsible for the ISAS project. “Until then, the physician can only use broad-spectrum antibiotics with all its disadvantages.”
IMS provides the physician with the metabolic products of the pathogens rapidly by means of the breath of the patient and he can react immediately with a targeted therapy. Baumbach also sees a potential application of the electronic nose in the field of early detection of lung cancer. A pilot study at the lung clinic in Hemer showed that 36 patients with lung cancer in their breathing air had a specific pattern of substances clearly distinguishing them from 54 healthy test persons. But the physicians at the hospital knew beforehand which test person suffered from a bronchial carcinoma and which did not. Currently the physicians in the team of Michael Westhoff, chief physician for pneumology at the Hemer clinical center, are checking the method on a larger collective of patients. “In order to reproduce our measures, we have to know exactly whether it influences the results if the patient smoked, still smokes or suffers from a chronic obstructive pulmonary disease (COPD)”, explains Westhoff.
Room air influences measuring result
The location where the measurement is taken can influence the results as well. According to the lung specialist, it makes a difference whether the measurement is taken in an intensive care unit where the floors are cleaned with disinfectants several times a day or in a room with a wall-to-wall carpet. Westhoff: “That is why for each measurement we have to take a control measuring of the room air.” In a further step, the physicians want to disclose the identity of substances causing the characteristic pattern of cancer patients. Only after all these questions are answered, Westhoff considers that a multicenter double blinded clinical study will finally demonstrate the efficiency of the new procedure. Westhoff does not believe that the method will be really that mature to comprehensively diagnose lung cancer earlier than before. To him, ionmobility-spectrometry is rather a supplement for the aftercare of lung cancer patients supporting physicians to detect relapses faster. “We would control the breathing air of patients whose bronchial carcinoma was extirpated after their surgery on a regular basis whether the characteristic pattern of cancer reappears,” the pneumologist explains the procedure.
Coma patients profit from the new method
Coma patients could be tested in a similar way. For them the risk of unnoticed bacteria settling in their bronchial system and causing pneumonia is extremely high. To prevent this scenario, physicians would have the chance to analyze their breathing air daily with the IMS. Thus they would be able to detect early patterns indicating a beginning colonization with pathogen germs.
Meanwhile, the researchers with Ingo Baumbach at the ISAS are developing two prototypes of the device for future use either in intensive care or in physicians’ offices. The Federal Ministry of Education and Research supports it providing one million Euro for the project. Until the end of the year, the prototypes will be presented to a larger audience. Baumbach expects the spectrometer to cost less than 40,000 Euro per piece once it is manufactured in larger numbers. According to Westhoff though, it will take another five years until the IMS will be used as a routine and applicable by any physician. But the blow into a spectrometer could establish rapidly as a supplement to blood- and urine tests as an additional source of information on the health status of the patient.