Abstract: A method and apparatus for measuring a blood alcohol content value by means of a breath alcohol concentration as well as for securing the reliability of this measured value. The apparatus comprises: sensor elements (1) for obtaining a measured alcohol concentration value from an incoming exhalation air stream; sensor elements (1) for obtaining a measured carbon dioxide concentration value from the same exhalation air stream (9); as well as first output elements (2) for producing, if necessary, a result proportional at least to a blood alcohol content.

Abstract: Provided herein is a novel breath test for assessing hepatic function. The test involves administration of a labeled methionine or methionine metabolite to a subject and measurement of the expired label.

Abstract: A breath test for diagnosing the presence of Chlamydia species, such as Chlamydia pneumoniae, in a subject is described. The method of diagnosing Chlamydia species in a subject is performed as follows. First, a safe and effective amount of a substrate, preferably appropriately labelled, is administered to the subject. Second, the exhaled breath of the subject is analyzed to detect the concentration of a cleavage product or products, produced when an enzyme from Chlamydia bacteria cleaves the substrate. The presence of the cleavage product or products indicates a positive diagnosis of Chlamydia species in the subject. A breath test kit is also described. Such a breath test kit would include an item or items necessary for performing at least one of the methods of diagnosing Chlamydia species in a subject. For example, such a breath test kit could include a substrate to be administered to the subject.

Abstract: To optimize the .sup.14 C-urea breath test for Helicobacter pylori (a) a collection method for alveolar breath samples, (b) varying the post-dosage breath collection time and (c) varying the concentrations of KOH in the liquid trap employed for the capture of .sup.14 CO.sub.2 are employed. Collection of alveolar breath samples in bags was convenient for user and patient. The test provided optimal sensitivity and specificity for the detection of H. pylori infection when breath collections were performed 10 min after dosage with .sup.14 C-urea, and when breath CO.sub.2 was captured in liquid traps containing 80 or 800 mM KOH.

Abstract: A non-invasive system and procedure for deriving the blood gas content for a patient. The system measures the carbon dioxide concentration of the expiratory breath relative to volume. This data is then processed to derive arterial blood gas levels of carbon dioxide. If data sampling is in the time domain, the processing shifts the data from the time domain to the volume domain. The processing also iteratively assesses the significance of numerous variables. The resulting relationship provides a fast and accurate measure of blood gas content for both healthy and diseased lung patients.