You are here:
A NON-INVASIVE DIAGNOSIS OF INTESTINAL ISCHEMIA BY EXHALED BREATH ANALYSIS USING GAS CHROMATOGRAPHY AND MASS SPECTROMETRY-PRELIMINARY RESULTS
Citation:
Holterman, A. L. AND J D. Pleil. A NON-INVASIVE DIAGNOSIS OF INTESTINAL ISCHEMIA BY EXHALED BREATH ANALYSIS USING GAS CHROMATOGRAPHY AND MASS SPECTROMETRY-PRELIMINARY RESULTS. Presented at American Pediatric Surgical Association Meeting, Naples, FL, May 20-23, 2001.
Impact/Purpose:
The objective of this task is to develop state-of-the-art methods for measuring xenobiotic compounds, to include the isolation of the analyte from the appropriate matrix (extraction), preconcentration (typically sorbent-based), and analysis via GC/MS and/or LC/MS. Once established, these methods will be applied in small scale pilot studies or demonstration projects. Particular emphasis will be placed on methods which are readily transferable to other laboratories, including those within the Human Exposure and Atmospheric Sciences Division (HEASD), the National Exposure Research Laboratory (NERL), other EPA Laboratories, Program Offices, Regions, and academic institutions.
Specific objectives of this task include the following:
1) Development of GC/MS and LC/MS methods for the measurement of key xenobiotic compounds and their metabolites (to include the pyrethroid pesticides, perfluorinated organic compounds, and the BFRs) in relevant environmental and biological matrices.
2) Development of efficient low cost methods for the extraction and clean up of these compounds collected from relevant matrices.
3) Determination of xenobiotic compound and metabolite concentrations in samples derived from laboratory and field monitoring studies to help assess exposures and evaluate associated risks.
Description:
To explore the potential of exhaled breath analysis by Column Chromatography-Mass Spectrometry (GC-MS) as a non invasive and sensitive approach to evaluate mesenteric ischemia in pigs.
Domestic pigs (n=3) were anesthetized with Guaifenesin/ Fentanyl/ Ketamine/ Xylazine drip and ventilated with compressed air. Intestinal ischemia was induced by ligation of the proximal superior mesentery artery. Mean arterial pressure (MAP), body temperature, heart rate (HR), arterial blood gas, urine output were monitored. Markers for ischemia were assessed with serum Phosphate, Creatine Kinase (CK) enzymes, base excess (BE) and full thickness intestinal biopsies. A sampling device triggered by exhaled breath temperature is used to collect primarily exhaled alveolar breath. Breath samples were harvested into SUMMA stainless steel canisters (1 Liter) at 0 and 3 hours of arterial occlusion and after reperfusion for analysis. Polar and non-polar volatile organic compounds (VOCs) in the breath were analyzed with cryogenic preconcentration followed by GC-MS detection. Quantification of relative amounts of VOCs was achieved with normalization to breath CO2 content. Data were tested for statistical significance using the two-tailed t test.
Biopsies samples confirmed mucosal necrosis at 3 hours of arterial occlusion. There were no significant differences in MAP ( 83+/-8 and 70+/- 32), HR ( 83+/- 2 and 76+/-30), base deficit ( -1 +/- 5 and ?2 +/- 5), serum phosphate ( 6 +/-2 and 6.5 +/- 1) or CK levels ( 737+/- 79 and 804 +/- 91) between the 0 and 3 hours time points. Canister breath samples indicated marked increases following ischemia in the levels of 2-methyl propanal ( 26 fold increase at 3 hours, and 190 fold after reperfusion), 2-methyl-butanal ( 28 and 102) and benzaldehyde ( 5 and 11). These polar-VOCs are known organic metabolites of lipid peroxidation indicative of oxidative injury. Conclusion: Biochemical markers for ischemia can be identified in exhaled breath early in the course of injury using non invasive breath analysis by GC-MS. The clinical applicability of breath measurement in the diagnosis of extensive mucosal injury (necrotizing enterocolitis, intestinal ischemia) should be further explored.
This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.