Breath testing

Fig. 9.1 (a) Block diagram of a gas chromatograph. (b) Typical chart record. Reproduced by permission from R. C. Denney, The Truth about Breath Tests, Nelson, London, 1970. 

A breath test, used to determine the presence of Helicobacter pylori, associated with stomach ulcers, is an example of a diagnostic product involving separate drug and device components. To perform the test, a patient swallows some isotopically (e.g. 

Non-endoscopic testing methods include the urea breath test, serologic testing, and the stool antigen assay. Compared to endoscopic procedures, these tests are more comfortable, less expensive, and do not require a special procedure. The urea breath test is usually the first-line test to detect active... 

Office-based serologic testing provides a quick assessment (within 15 minutes) of an exposure to HP, but patients can remain seropositive for up to 1 year after eradication, making the clinical utility of this test limited. Stool antigen assays can be useful for the initial diagnosis or to confirm HP eradication, and unlike the urea breath test, are less affected by concomitant medication use.9... 

Of the indirect tests the 13C or 14C-d-xylose or lactulose breath test and the glucose, lactose or lactulose hydrogen breath tests are available alternatives. These tests are in general developed to recognize Gram-negative bacilli rather than URT overgrowth. There are, however, pitfalls involved. 

Rapid intestinal transit may result in a false-positive breath test, in particular when hyperosmolar nonabsorbable substrates are used. A false-negative outcome in patients with culture-proven Gram-negative bacilli in the upper gut further query the sensitivity and usefulness of breath tests for clinical practice [10-13]. Positive microbial culture from small intestine is thus advantageous when major alterations of clinical management are considered. 

Furthermore, similar glucose hydrogen breath tests in the elderly with and without omeprazole [76] and normal 14C-r/-xylose breath test in healthy old people with acquired gastric hypochlorhydria (pH >6) [32] counterindi-cate that H2 blockers induce colonization with strict anaerobes of intestinal types (colonic flora) in the upper gut. 

Studies of small bowel transit time have demonstrated a great variability both within and between individuals. When the hydrogen breath test was performed under fasting conditions, using 10 ml of lactulose, the coefficient of variation amounted to 18%. Di Lorenzo et al. [129] showed that variations under fasting conditions are partly accounted for by the phase of the migrating motor complex at the intake of test solution. Moreover, when a lactose-containing meal was used, the coefficient of variation was reduced to 4% [130],... 

Breath tests are, therefore, less useful for testing of intestinal transit in the presence of bacterial overgrowth. 

Yantrappen et al. [23] for the first time showed the relevance of phase III of the migrating motor complex in the current context, when reporting its absence in 5 of 12 patients with bacterial overgrowth detected by the bile acid breath test and response to antibiotics. 

Rumessen JJ, Gudmand-Hoyer E, Bachmann E, Justesen T Diagnosis of bacterial overgrowth of the small intestine. Comparison of the 14C-D-xylose breath test and jejunal cultures in 60 patients. Scand J Gastroenterol 1985 20 1267-1275. 

Valdovinos MA, Camilleri M, Thomforde GM, Frie C Reduced accuracy of 14C- >-xylose breath test for detection of bacterial overgrowth in gastrointestinal motility disorders. Scand J Gastroenterol 1993 28 963-968. 

Hutchinson S, Fogan R The effect of long-term omeprazole on the glucose-hydrogen breath test in elderly patients. Age Ageing 1997 26 87-89. 

Di Lorenzo C, Dooley CP, Valenzula JE Role of fasting gastrointestinal motility in the variability of gastrointestinal transit time assessed by hydrogen breath test. Gut 1991 32 1127-1130. 

In addition to ANP where it is associated with GI dys-motility [198, 199], SIBO is present in a significant proportion of patients with chronic pancreatitis [200, 201], Short-term rifaximin therapy was able to normalize the hydrogen breath test and improve symptoms (i.e. diarrhea and fecal fat excretion) in all patients studied (fig. 9) [201]. Bowel decontamination via administration of this topical antibiotic could, therefore, be beneficial in both acute and chronic pancreatitis. Double-blind, placebo-controlled studies are to be performed to explore the rifaximin potential in this indication. 

Pimentel M, Chow EJ, Lin HC Normalization of lactulose breath testing correlates with symptom improvement in irritable bowel syndrome. A double-blind, randomized, placebo-controlled study. Am J Gastroenterol 2003 98 412-419. 

Casellas F, Guamer L, Vaquero E, Antolin M, de Gracia X, Malagelada JR I Iydrogen breath test with glucose in exocrine pancreatic insufficiency. Pancreas 1998 16 481 186. 

Hepatic Effects. Hepatic changes were observed in one chronic human exposure to mirex, as well as in a number of workers exposed to chlordecone for intermediate or chronic durations. In the mirex study, human subjects (sex and number not specified) from a chronically exposed cohort from southeast Ohio (route of exposure not specified, assumed to be oral) were assessed for cytochrome P- 4501A2 induction using a breath test that measures caffeine metabolism. The subjects exposed to mirex had elevated caffeine metabolism as compared to negative control individuals (subjects with no known exposure to polyhalogenated biphenyls or other related chemicals) in which the metabolism did not increase (Lambert et al. 1992). In the chlordecone study, liver function and structure in 32 men exposed to high levels of chlordecone while employed for 1-22 months (5.6... 

A spirometry test is a breathing test in which a person takes as deep a breath as possible and blows out quickly and completely into a tube cormected to a spirometry machine (Table 3.1). Lung measurements obtained from fhis fesf include forced expiratory volume in one second (FEVi), fhe amounf of air blown ouf in one second forced vifal capacify (FVC), fhe fofal amounf of air blown ouf fhe FEVi/FVC ratio and fhe... 

The structural feature of aminopyrine is similar to antipyrine except that aminopyrine has a substituent (dimethylamino group) at the C-4 position (Fig. 4). The exceptional efficacy of the aminopyrine breath test derives from the presence of multiple N-methyl groups that are readily removed by oxidative N-demethyla-tion. Hence, further oxidation of several formaldehyde molecules produced by demethylation of aminopyrine gives large volumes of labeled COj that is readily quantified. Some of the metabohtes of aminopyrine are given in Fig. 4 [30, 85, 87-90]. 

Hydrophobic (Aromatic) Amino Acid Breath Test... 

Gastrointestinal transit time by hydrogen breath test and radio-opaque markers Gastrointestinal motiUty agents... 

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