Lungenbasis (plural: Lungenbasen) = base of the lung(s)
atemverschieblich = Veränderung der Position beim Ein- und Ausatmen
respiratory excursion = movement (of organs or anatomical structures) during respiration
diaphragmatic excursion = movement of the thoracic diaphragm during respiration

The German term seems to pertain to the base of the lungs. However, in the US, I have always only heard of the assessment of respiratory excursion in general. It usually means how far the chest expands during respiration and refers to the thoracic expansion (expansion of the chest) but the term 'respiratory excursion' may not only pertain to the chest expansion and lungs only but also to the liver, spleen, etc., as these organs move during respiration. You would then refer to that as the 'respiratory excursion of the liver or spleen'. So, it doesn't necessarily only refer to the outward movement of the chest and I don't think in the US they distinguish between the base of the lungs and the respiratory excursion in itself but I suppose you could write something along the lines of the 'respiratory excursion of the lungs' or the 'respiratory excursion at the base of the lungs'.

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Note added at 7 hrs (2008-05-09 02:16:49 GMT)
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since 'verschieblich' is a good thing, it should say *normal* respiratory excursion (of the lungs/ at the base of the lungs)

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Note added at 13 hrs (2008-05-09 08:03:16 GMT)
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Physical diagnosis
The Respiratory Excursion of the Lung. - In determining the respiratory excursion of the lung the lower borders of both lungs should be defined by percussion in the mid-clavicular, midaxillary, and scapular lines, first during quiet respiration and then during forced inspiration, the difference being noted. Usually measuring approximately one inch, in certain diseases of the thorax or abdomen it may be diminished markedly.
http://books.google.com/books?id=KJW5VE0PpwQC&pg=PA74&lpg=PA...