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“The Conditions Are Different from Study to Study“

Airway Research: “The conditions are different from study to study“


Photo: Norbert Krug

Professor Norbert Krug; © Fraunhofer-Institut

Take a deep breath – for some people that is easier said than done. Why we are “out of breath“ can have many different reasons: If you are allergic to house dust, even dispersed dust from the carpet can do you in. But industry pollutants can also take your breath away – and be harmful to your health. That is why there are studies that closely examine the air for these pollutants. spoke with Professor Norbert Krug, Medical Director at the Fraunhofer Institute of Toxicology and Experimental Medicine and Director of the Department of Clinical Airway Research. Professor Krug, your Institute conducts research studies on airways, among them some that investigate the risk potential of air pollutants. In which areas are people in particular exposed to these pollutants?

Norbert Krug: Basically, we differentiate between air pollutants outdoors, for example on a street, and indoors, especially in certain specific places of work. Indoors for the most part only certain people, which work in these areas, are exposed to pollutants. Outdoors virtually everyone is exposed, because everybody spends time outside. There in particular we come across those pollutants, which are often discussed in the press, like for example ozone, nitrogen oxides or respirable dust. These are pollutants which are very strongly affected by industry and road traffic. If you plan to investigate pollutants – for instance respirable dust – on their effect: How do you develop your study?

Krug: At the outset of our study is the formulation of a question, related to the airways. For example: In what concentration is the pollutant actually harmful? What are parameters that indicate damage? These could perhaps be inflammatory cells in the lungs. Then we consider what concentrations we want to use in an experiment. After that we look for the damage we can readout, meaning, which inflammation values are measurable. It is also important to have a control group to blind the study. Can you give as a study example?

Krug: We did a study on “particles“ for example, which is a core area of our Institute. It was about superfine particles or rather nano particles. They are present in exhaust emissions in the form of small carbon particles. We have artificially generated nano particles in our provocation room and then placed test subjects with asthma in the room for two hours. Afterwards, we conducted measurements to check whether the particles have an effect on lung function or whether readings appear in the blood or can be measured in the airways. We were able to clarify by this study that an allergic inflammation can worsen through prior inhalation of particles. Can you always find enough test persons for a study?

Krug: Before we start a research study and develop a trial protocol, we consider how many test persons we need to demonstrate an effect. For this purpose, we deliberate on how big the possible effect is and what variability it has. This gives us the chance to estimate how many test persons are necessary. If we have those numbers, we search our data base and see whether we can find that many patients. In our case that’s usually about 20 people. We only conduct a study if we can actually find the number of test persons we need, because it is unethical to begin a study if you are not sure whether you will be able to reach your goal. In pharmaceutical studies this is certainly different. There you cannot predict when and if you can come up with the number of necessary test persons. Some of these pharmaceutical studies require very large groups, sometimes thousands of patients. Which occupational groups are crosslinked in a team for an airway study?

Krug: In the Institute we provide an interdisciplinary team. For the airway studies where the test persons come to the Institute, we have physicians and nurses, so-called study nurses for starters. The latter are specialized in taking care of the study participants. Moreover, there are always statisticians and documentation officers participating, who collect the data, process and analyze it. Then we have physicists and process technicians, who set up exposure for the study rooms, monitor and simultaneously make sure that things occur in the room that we want to research. In the background we have quality assurance which ensures that the measurement instruments are in order, and that we comply with the study guidelines. In addition, the ethics committee needs to be involved to check the study protocol. For some studies you also need to consult government agencies, which check the study and authorize it. How should we picture these provocation rooms, also called Environmental Challenge Chambers?

Krug: These are so-called clean rooms, each ranging in size between 20 and 30 square meters. Up to 20 people can stay in these rooms at the same time. The atmosphere in the room – meaning the consistency of the air, the temperature and air humidity – can be accurately regulated. This way over many hours, we can create an air quality that is well delineable and does not randomly change. For example, we can keep a set pollen concentration – we regularly conduct studies, where allergens are being inhaled – constant for everybody in this room. This means, exposure rooms are rooms where patients breathe in a controlled atmosphere. What are the test persons doing during the investigation periods?

Krug: The test persons have to perform lung function tests or enter the symptoms they experience at that moment into a computer. In some studies, the test persons have to sit on bicycles from time to time and physically exert themselves, so they inhale more air and we can analyze what effect the air has on a stress situation. There are studies where concentration tests are conducted to see whether the air has an influence on brain function. The conditions are different from study to study.

The interview was conducted by Simone Ernst and translated by Elena O’Meara


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