[The mixing index in the argon breath holding test for the demonstration of pharmacologically induced airways reactions. A comparison with other methods (author's transl)].
In 42 patients with obstructive airways diseases the behavior of the mixing index (delta argon %/1 during phase III of the argon-volume diagram) was studied after beta2 stimulation or after provocation by acetylcholine. Changes in airways resistance resp. conductance (GAW), FEV1.0 and residual volume (RV) were also determined for comparison. In an inhomogeneous subgroup with obstructive airways disease of various aetiology the mixing index (MI) and FEV1.0 indicated changes in the airways system with about equal frequency. Distinct discrepancies between the two tests, observed in a few cases, suggest that the two methods register different pathophysiological reactions. These differences could be confirmed statistically in a more homogeneous subgroup with extrinsic bronchial asthma. A correlation could be established between MI and RV on the one hand and between FEV1.0 or GAW and RV on the other hand. The results indicate that the mixing index as a test of distribution of ventilation reflects mainly the reactions of the small airways. Its use offers the possibility of a more differentiated pharmacodynamic evaluation.
D000109:Acetylcholine / Q000494:pharmacology; D000403:Airway Resistance; D001128:Argon / Q000378:metabolism*; D001944:Breath Tests / Q000592:standards*; D005541:Forced Expiratory Volume; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000175:diagnosis*; D012115:Residual Volume
D001128:Argon; D000109:Acetylcholine
Der Mischungsindex in der Argon-Breath-Holding-Methode zur Objektivierung pharmakologisch ausgelöster Atemwegsreaktionen im Vergleich mit anderen Untersuchungsmethoden.