Nondispersive Infrared Spectrometry Research Articles

Variability of the 13C‐Acetate Breath Test for Gastric Emptying of Liquids in Healthy Children

Scintigraphy is considered as the "gold standard" for measuring gastric emptying (GE). The C-acetate breath test (C-ABT) offers an attractive alternative to measure GE of liquids as it is nonradioactive. The aim of this study was to assess the variability of the C-ABT for GE of liquids in healthy children using nondispersive infrared spectrometry (NDIRS). The C-ABT was repeated at least 2 times in 21 healthy children (6 girls and 15 boys), aged between 6.2 and 16.4 years, 2 to 7 days apart. After an overnight fast, a standardized milk drink, labeled with 50 or 100 mg C-acetate according to weight, was administered. Breath samples were taken before feeding, at 5-minute intervals for the first 40 minutes and at 10-minute intervals for the following 140 minutes after feeding. Breath samples were analyzed using NDIRS, and C recovery was used to calculate values for gastric half-emptying time (t1/2), time of peak C exhalation, or gastric lag phase (tlag) and gastric emptying coefficient (GEC). Intraindividual variabilities of the parameters t1/2, tlag, and GEC were expressed as coefficient of intrasubject variation (CV). The median CV of t1/2 was 8.3% (CV range, 1.6%-16.2%; t1/2 interindividual range, 65-112 minutes; and t1/2 intraindividual range, 4-33 minutes). The median CV of tlag was 16.6% (CV range, 2.0%-26.6%; tlag interindividual range, 31-76 minutes; and tlag intraindividual range, 1-35 minutes). The median CV of GEC was 4.3% (CV range, 0.8%-15.7%; GEC interindividual range, 3.81-4.89; GEC intraindividual range, 0.08-1.31). The CVs of t1/2, tlag, and GEC were independent of age, sex, weight, height, and measured values of t1/2, tlag, and GEC. The C-ABT using NDIRS is an easy, noninvasive, and nonradioactive procedure with a large intraindividual variation for measuring GE of liquids in healthy children, but comparable to the variation reported with other techniques.

Teste respiratório da 13C-metacetina na doença hepática crônica pelo vírus C

RACIONAL: O teste respiratório da metacetina marcada com carbono 13 (13C-metacetina) é método não-invasivo que permite examinar a função hepática microssomal, permitindo avaliação quantitativa da massa hepática funcional. OBJETIVO: Avaliar a utilidade clinica do teste respiratório da 13C-metacetina na avaliação de pacientes com doença crônica do fígado pelo vírus da hepatite C. CASUÍSTICA E MÉTODOS: Setenta e oito pacientes com hepatite crônica C e 13 indivíduos saudáveis pareados por sexo e idade foram estudados. Pacientes infectados cronicamente pelo vírus C foram classificados como portadores de hepatite crônica (n = 51) ou cirrose hepática (n = 27, sendo 7 deles classificados como descompensados pela presença de ascite, icterícia e/ou encefalopatia). Pacientes co-infectados HbsAg/HIV, em uso crônico de álcool, com outras doenças crônicas ou em uso de medicamentos que pudessem interferir com a atividade do citocromo P450, foram excluídos. O estádio e a atividade da doença nos fragmentos de biopsia foram determinados de acordo com os critérios da Sociedade Brasileira de Hepatologia. O teste respiratório da 13C-metacetina foi realizado com 75 mg de 13C-metacetina e a concentração de 13CO2 no ar expirado foi medido através de espectrometria infravermelha não dispersiva. Foram calculados o "delta over baseline" e o percentual de recuperação cumulativo do 13CO2 aos 40 (teste respiratório da 13C-metacetina 40 min) e aos 120 minutos (teste respiratório da 13C-metacetina 120 min). RESULTADOS: Os parâmetros do teste respiratório da 13C-metacetina se correlacionaram com avaliação estrutural histológica, mas não com a atividade necroinflamatória no tecido hepático, sendo que a melhor correlação foi obtida entre o grau de estádio e o teste respiratório da 13C-metacetina 120 min. Os valores médios do teste respiratório da 13C-metacetina 120 min foram significantemente mais reduzidos nos grupos cirróticos (19,2 ± 7,1% para cirróticos compensados e 14,7 ± 4,0% para os cirróticos descompensados) que nos grupos controle (29,9 ± 4,5%) e com hepatite crônica (27,8 ± 6,1%). A melhor acurácia no diagnóstico de cirrose entre os portadores de hepatite crônica C foi encontrada para o teste respiratório da 13C-metacetina 120 min com 81% de sensibilidade e 77% de especificidade. CONCLUSÃO: O teste respiratório da 13C-metacetina se correlaciona com alterações estruturais encontradas na hepatite crônica pelo vírus C e o percentual de recuperação de 13CO2 aos 120 minutos é um sensível parâmetro para identificar a presença de cirrose nesses pacientes.

REPRODUCIBILITY OF THE 13 C OCTANOIC ACID BREATH TEST FOR GASTRIC EMPTYING OF SOLIDS IN CHILDREN.

Introduction: The “gold standard” for measuring gastric emptying (GE) is scintigraphy. The 13 C octanoic acid breath test (13COBT) is an interesting alternative to measure GE of solids, as it is non radioactive. The 13COBT using mass spectrometry has been validated against scintigraphy and has a physiological day-to-day variability in adults as well as in children. There are no data in the literature concerning the use of Non Dispersive InfraRed Spectrometry (NDIRS) in the evaluation of GE of solids with octanoic acid in children. Aim: To assess the reproducibility of the 13COBT for GE of solids in children using NDIRS. Methods: GE for solids was tested in 19 healthy children (6 girls, 13 boys). After an overnight fastening, a solid test meal consisting of a pancake with a caloric content of 230 kcal, and labelled with 50 μl 13 C octanoic acid, was given. Breath samples were taken before feeding and at 15 minutes intervals after feeding for 4 hours. Samples were analysed using NDIRS, and 13 C recovery was used to calculate values for gastric half emptying time (t 1/2), time of peak 13 C exhalation or gastric lag phase (t lag) and gastric emptying coefficient (GEC). The 13COBT was then repeated ≥2 times 2 to 7 days apart. Intra-individual variability and reproducibility of the parameters t 1/2, t lag and GEC were expressed as coefficient of variation (CV). Results: The mean age was 12.83 years (range 6.75-17.08), the median CV of t 1/2 was 12.9% (range 2.5-29.6) for a t 1/2 with a range between 89 and 220 minutes, the median CV of t lag was 12.4% (range 0.8-27.8) for a t lag with a range between 61 and 163 minutes, the median CV of GEC was 10.9% (range 3.4-30.2) for a GEC with a range between 1.8 and 4.2. The median CV of t 1/2, t lag and GEC was independent of the values of t 1/2, t lag and GEC. Conclusions: The 13COBT using NDIRS is a non-radioactive, easy and less expensive procedure for measuring the gastric emptying of solids in children with very good reproducibility.

Feasibility of a breath test with a substrate of natural 13C‐abundance and isotope‐selective non‐dispersive infrared spectrometry: A preliminary study

Isotope-selective non-dispersive infrared spectrometry (NDIRS) is a cheaper alternative to isotope ratio mass spectrometry (IRMS). We checked on the efficiency of NDIRS to perform a breath test with naturally (13)C-enriched maize starch. Fifty-six healthy volunteers were examined. After a basal fasted sample of their expiratory air was collected, the subjects ate a test breakfast of 50 g (CF50 group, n = 9) or 100 g (CF100 group, n = 47) cornflakes with 175 g yoghurt. For 6 h thereafter, exhaled air was collected every 30 min for the NDIRS measurement of (13)CO(2) concentration. The time-course of the curves of (13)CO(2) concentration resembled those obtained previously with IRMS. A dose-response to the amount of ingested cornflakes was observed--the maximum postprandial net increment in (13)CO(2) was statistically significantly higher in the CF100 than CF50 group: 4.78 +/- 0.13 versus 3.12 +/- 0.17 per thousand (P < 0.001), whereas the time needed to reach the maximum did not differ after the intake of 50 g (233 +/- 13 min) or 100 g (248 +/- 9 min) cornflakes. The 5-h area-under-the-curve of cumulative (13)CO(2) net recovery (AUC(60-360)) was statistically significantly greater after ingestion of 100 g compared to 50 g cornflakes (97.6 +/- 2.2 versus 61.7 +/- 2.2 micromol, P < 0.001) and it also exhibited a stable between-subject variability. The obtained proof of technical feasibility of a breath test with the use of naturally (13)C-enriched starch and NDIRS provides background for future research on the clinical usefulness of this method for a non-invasive assessment of the pancreatic exocrine function.

O0117 REPRODUCIBILITY OF THE 13 C OCTANOIC ACID BREATH TEST FOR THE MEASUREMENT OF GASTRIC EMPTYING OF SOLIDS IN CHILDREN

Introduction: The “gold standard” for measuring gastric emptying is scintigraphy. The 13 C octanoic acid breath test is an interesting alternative to measure the gastric emptying of solids, as it is non radioactive. The 13 C octanoic acid breath test using mass spectrometry has been validated against scintigraphy in adults (Ghoos, Gastroenterology 1993;104:1640–7) and has a physiological day-to-day variability in adults (mean coefficient of variation: 26.71 % for gastric half emptying time, 44.93 % for gastric lag phase, 10.82 for gastric emptying coefficient )(Ghoos, Gastroenterology 1993;104:1640–7) as well as in premature infants (mean coefficient of variation: 23.9 % for gastric half emptying time, 12.2 % for gastric emptying coefficient) (Barnett, JPGN 1999; 29: 26–30). There are no data in the literature concerning the use of Non Dispersive InfraRed Spectrometry (NDIRS) in the evaluation of gastric emptying of solids with octanoic acid in children. This study was performed to assess the reproducibility of the 13 C octanoic acid breath test for gastric emptying of solids in children using NDIRS. Methods: Gastric emptying for solids was tested in 19 healthy children (6 girls, 13 boys). After an overnight fasting, a solid test meal consisting of a pancake with a caloric content of 230 kcal, and labelled with 50 microliter 13 C octanoic acid, was given. Breath samples were taken before feeding and at 15 minutes interval after feeding for 4 hours. Samples were analyzed using NDIRS (Wagner Analysen Technik, Worpswede, Germany), and 13 C recovery was used to calculate values for gastric half emptying time (t1/2), time of peak 13 C exhalation or gastric lag phase (tlag) and gastric emptying coefficient (GEC). The 13 C octanoic acid breath test was then repeated 2 or more times 2 to 7 days apart (2 patients 4 times, 7 patients 3 times, 10 patients 2 times). Intra-individual variability and reproducibility of the parameters t1/2, tlag and GEC were expressed as coefficient of variation (CV). Results: The median age was 12.83 years (range 6.75 –17.08), the median CV of t1/2 was 12.9 % (range 2.5 – 29.6) for a t1/2 with a range between 89 and 220 minutes, the median CV of tlag was 12.4 % (range 0.8 – 27.8) for a tlag with a range between 61 and 163 minutes, the median CV of GEC was 10.9 % (range 3.4 – 30.2) for a GEC with a range between 1.82 and 4.20. The CV’s of t1/2, tlag and GEC were independent of the values of t1/2, tlag and GEC. Conclusion: The 13 C octanoic acid breath test using NDIRS is an easy and non-radioactive procedure with very good reproducibility for measuring the gastric emptying of solids in children.

Infrared spectrometry based 13C-octanoic acid breath test in measuring human solid gastric emptying.

Because of the convenience of non-dispersive infrared spectrometry (NDIRS), we attempted to validate the usefulness of NDIRS compared with scintigraphy in human solid gastric emptying (GE) measurement, and tried to establish the normal range of solid GE based on NDIRS. Twelve healthy volunteers (three men, nine women) were recruited for simultaneous scintigraphy and 13C-octanoic acid breath test (13C-OABT) studies. Stomach half-emptying time (t1/2) and lag phase (tlag) were the two main GE parameters measured and correlated. The breath samples were analyzed using NDIRS every 10-15 min for a total of 6 h, while scintigraphy was taken minute by minute for the first 30 min, then hourly for 4 h. Another 32 healthy volunteers (19 men, 13 women) received only the 13C-OABT to measure their solid GE. A significant correlation for t1/2 was found between the breath test and scintigraphy (r = 0.85, P = 0.001), while tlag was also positively correlated (r = 0.73, P = 0.007). The reference range of t1/2B based on all 44 subjects was 89.4-185.1 min (135.9 +/- 21.1 min (mean +/- SD)), while the range for tlagB was 37.1-117.8 min (81.9 +/- 17.4 min). No demographic characteristics were found to influence the GE parameters. 13C-octanoic acid breath test determined by NDIRS is a simple, non-invasive and reliable measurement, which may provide an 'office-based' tool to detect solid GE.

Is the accuracy of isotope-selective non-dispersive infrared spectrometry (NDIRS) sufficient for determination of gastric emptying using the 13C-octanoic acid breath test ( 13C-OABT): Comparison with isotope-ratio mass spectrometry (IRMS)

Is the accuracy of isotope-selective non-dispersive infrared spectrometry (NDIRS) sufficient for determination of gastric emptying using the 13C-octanoic acid breath test ( 13C-OABT): Comparison with isotope-ratio mass spectrometry (IRMS)

Determination of 13CO2/12CO2 Ratio by IRMS and NDIRS

Breath tests using 13C-labelled substrates require the measurement of 13CO2/12CO2 ratio in breath gas samples. Next to isotope ratio mass spectrometry (IRMS), which is very sensitive but also complex and expensive, alternatively isotope selective nondispersive infrared spectrometry (NDIRS) can be used to determine the 13CO2/12CO2 ratio in expired breath. In this study we compared NDIRS- with IRMS-results to investigate whether the less expensive and very simply to operate NDIRS works as reliable as IRMS. For this purpose we applicated 1-13C-Phenylalanine to patients with advanced liver cirrhosis and healthy volunteers and took duplicated breath samples for IRMS and NDIRS at selected time points. Our data show a good correlation between these two methods for a small number of samples as required for simple breath tests. Longer series, where repeated measurements are required on the NDIRS instrument lead to a decreasing correlation. This indicates the superiority of IRMS concerning 13CO2-kinetics over longer time periods.

Nondispersive infrared spectrometry: a new method for the detection of Helicobacter pylori infection with the 13C-urea breath test.

Nondispersive infrared spectrometry (NDIRS) was used to detect Helicobacter pylori infection with the 13C-urea breath test. The results were compared with those of standard isotope ratio mass spectrometry (IRMS). Both methods accurately distinguished between H. pylori-positive and H. pylori-negative individuals. The results demonstrate that NDIRS technology is accurate and therefore of equal value to standard IRMS for detection of H. pylori infection. It can be recommended for routine clinical application. As NDIRS technology is much cheaper than current IRMS machines, we consider the new method extremely useful for clinical applications.

Collaborative testing of methods to measure air pollutants. II. The non-dispersive infrared method for carbon monoxide.

The Methods Standardization Branch of the Environmental Protection Agency, National Environmental Research Center, has undertaken a program to standardize methods used in measuring air pollutants covered by the national primary and secondary air quality standards. This paper presents the results of a collaborative test of the method specified for carbon monoxide. The test involved analysis of CO in air samples (in cylinders) by participating laboratories. Three concentrations, covering the range of the method which is, 0 to 58 mg/m3, were analyzed dry and humidified on each of three days by 15 collaborators. The method of analysis, nondispersive infrared spectrometry (NDIR), involved an NDIR instrument in combination with different procedures for eliminating water vapor interference. A statistical analysis of the data obtained produced the following results: 1. The checking limit for duplicates (replication error) is 0.5 mg/m3. 2. The repeatability (variation within a laboratory) is 1.6 mg/m3. 3. The repr...