PubMed · 13398132
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1957. WHY RESPIRATORY function tests?. https://pubmed.ncbi.nlm.nih.gov/13398132/
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BACKGROUND: The 13C-galactose breath test has been reported to be an accurate, non-invasive method for the assessment of liver function. AIMS: To determine the optimal doses of labelled and unlabelled carrier galactose necessary to perform the 13C-galactose breath test, to assess the utility of the 13C-galactose breath test in distinguishing between normal subjects and those with liver cirrhosis and to determine whether the 13C-galactose breath test can stratify patients with cirrhosis based on their Child-Pugh score. METHODS: Twenty-three control subjects and 30 patients with liver cirrhosis received fixed doses of unlabelled carrier galactose and labelled 13C-galactose. Breath samples were collected just before and at 30-min intervals up to 4 h after the ingestion of unlabelled carrier galactose and labelled 13C-galactose. Each sample was analysed for its 13CO2 content. RESULTS: Doses of 25 g/m2 of unlabelled carrier galactose and 100 mg of 13C-galactose had the greatest sensitivity (93%; 95% confidence interval, 76-99%) and specificity (87%; 95% confidence interval, 65-97%) for distinguishing between normal subjects and cirrhotics when the test was performed 2 h after ingestion. The 13C-galactose breath test was also able to distinguish between class A and class B or C cirrhotics. CONCLUSION: The 13C-galactose breath test is a useful non-invasive tool for distinguishing between healthy subjects and patients with liver cirrhosis and between cirrhotics with well-compensated liver disease and those with decompensated liver disease.
BACKGROUND: A better substrate is needed for a hydrogen breath test to measure the orocaecal transit time. The currently used substrate, lactulose, accelerates the orocaecal transit time by increasing the osmolality of the gut contents. The recently developed lactose 13C-ureide breath test is reliable, but a hydrogen breath test is preferred, as it allows the simultaneous investigation of the digestion and absorption of nutrients by means of 13C-labelled compounds. METHODS: The usefulness of different types of inulin as a substrate for a hydrogen breath test was studied. Raftilin HP (>99% inulin with a degree of polymerization of between 5 and 60 and <0.5% glucose, fructose and sucrose) was further evaluated and compared with lactulose with regard to its effects on gastric emptying and the digestion of protein and lipids. RESULTS: A good correlation was found between the orocaecal transit times using Raftilin HP (338 min; interquartile range, 300-383 min) and lactose 13C-ureide (353 min; interquartile range, 285-375 min) (r=0.85; P<0.001). The administration of 5 or 10 g Raftilin HP had no influence on the orocaecal transit time, whereas lactulose significantly shortened the orocaecal transit time. Neither inulin nor lactulose had a significant influence on gastric emptying or protein or lipid assimilation. CONCLUSION: Raftilin HP is an ideal substrate for a hydrogen breath test to measure the orocaecal transit time.
Analysis of exhaled air is of particular interest as an indicator of health as well as a tool for the diagnosis of diseases. It is also a very attractive procedure for the biological control of the exposition to hazardous solvents. This kind of analysis presents numerous advantages over other methods, the most important being that it is not an invasive procedure and, therefore, it is well accepted and can be applied to a wide range of compounds. Furthermore, the analysis is simplified since the matrix is less complex that in the case of blood or urine. In spite of these obvious advantages and the good results obtained, analysis of exhaled air is not in daily use, probably due to the fact that there are no normalized systems of sampling, thus making the interpretation of the results difficult. In this paper, a method for the determination of tetrachloroethylene in exhaled air using solid-phase microextraction is presented. This method, which can be applied to other volatile organic compounds, was developed with special emphasis of end-exhaled breath sampling. The sample is collected in a glass tube whose ends are closed once the exhalation is finished. The tube has an orifice sealed with a septum through which the fiber is inserted. Then, the fiber is desorbed in the injector of a gas chromatograph and the analysis is accomplished using mass spectrometry for the identification and quantification of the components. The proposed system avoids the need of complex sampling equipment and allows analysis of the alveolar fraction. Additionally, the system is economical and easy to handle, thus facilitating the development of normalized methods and its routine use in field studies.