Exhaled breath analysis in adult patients with cystic fibrosis by real-time proton mass spectrometry.

BACKGROUND: Proton-transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) is a promising tool for a rapid online determination of exhaled volatile organic compounds (eVOCs) profiles in patients with cystic fibrosis (CF). OBJECTIVE: To detect VOC breath signatures specific to adult patients with CF compared with controls using PTR-TOF-MS. METHODS: 102 CF patients (54 M/48, mean age 25.6 ± 7.8 yrs) and 97 healthy controls (56 M/41F, mean age 25.8 ± 6.0 yrs) were examined. Samples from normal quiet breathing and forced expiratory maneuvers were analyzed with PTR-TOF-MS (Ionicon, Austria) to obtain VOC profiles listed as ions at various mass-to-charge ratios (m/z). RESULTS: PTR-TOF-MS analysis was able to detect 167 features in exhaled breath from CF patients and healthy controls. According to cluster analysis and LASSO regression, patients with CF and controls were separated. The most significant VOCs for CF were indole, phenol, dimethyl sulfide, and not indicated: m/z = 297.0720 ([C12H13N2O7 and C17H13O5]H + ), m/z = 281.0534 ([C19H7NO2, C12H11NO7 and C16H9O5]H + ) during five-fold cross-validation both in forced expiratory maneuver and in normal quiet breathing. CONCLUSION: PTR-TOF-MS is a promising method for determining the molecular composition of exhaled air specific to CF.

Noninvasive Assessment of the Fractional Flow Reserve with the CT FFRc 1D Method: Final Results of a Pilot Study.

Background: Until recently, Russia did not utilize noninvasive fractional flow reserve (FFR) assessment. We developed an automated algorithm for noninvasive assessment of FFR based on a one-dimensional (1D) mathematical modeling. Objective: The research aims to evaluate the diagnostic accuracy of this algorithm. Methods: The study enrolled 80 patients: 16 of them underwent 64-slice computed tomography - included retrospectively, 64 - prospectively, with a 640-slice CT scan. Specialists processed CT images and evaluated noninvasive FFR. Ischemia was confirmed if FFR < 0.80 and disproved if FFR ≥ 0.80. The prospective group of patients was hospitalized for invasive FFR assessment as a reference standard. If ischemic, patients underwent stent implantation. In the retrospective group, patients already had invasive FFR values.Statistical analysis was performed using GraphPad Prism 8. We compared two methods using a Bland-Altman plot and per-vessel ROC curve analysis. Considering the abnormality of distribution by the Kolmogorov-Smirnov test, we have used Spearman's rank correlation coefficient. Results: During data processing, three patients of the retrospective and 46 patients of the prospective group were excluded. The sensitivity of our method was 66.67% (95% CI: 46.71-82.03); the specificity was 78.95% (95% CI: 56.67-91.49), p = 0.0052, in the per-vessel analysis. In per-patient analysis, the sensitivity was 69.57% (95% CI: 49.13-84.40); the specificity was 87.50% (95% CI: 52.91-99.36), p = 0.0109. The area under the ROC curve in the per-vessel analysis was 77.52% (95% CI: 66.97-88.08), p < 0.0001. Conclusion: The obtained indices of sensitivity, specificity, PPV, and NPV are, in general, comparable to those in other studies. Moreover, the noninvasive values of FFR yielded a high correlation coefficient with the invasive values. However, the AUC was not high enough, 77.52 (95% CI: 66.97-88.08), p < 0.0001. The discrepancy is probably attributed to the initial data heterogeneity and low statistical power.

One-Dimensional Mathematical Model-Based Automated Assessment of Fractional Flow Reserve in a Patient with Silent Myocardial Ischemia.

BACKGROUND Noninvasive assessment of the fractional flow reserve (FFR) in patients with coronary artery disease plays an important role in determining the need for revascularization. It is particularly relevant for patients with a borderline stenoses and painless myocardial ischemia. Our article describes the first clinical experience in the Russian Federation of using an automated method of noninvasive assessment of the fractional flow reserve (FFRct) with a one-dimensional (1-D) mathematical model in a patient with painless myocardial ischemia. CASE REPORT A 58-year-old male patient who underwent stent implantation in the left circumflex coronary artery (LCX) due to an acute non-ST-elevation posterior myocardial infarction had borderline stenoses of the left anterior descending artery (LAD). After stent implantation, there were no relapse angina symptoms on drug treatment, and according to our examination guideline for patients with borderline stenoses, a treadmill test was performed. The test was positive; therefore, FFR assessment was recommended, with coronary multi-slice CT being performed. The following results were obtained: FFRct LAD - 0.57; FFRct LCX - 0.88. An invasive assessment of FFR was also performed as a reference standard and revealed: FFR LAD - 0.6; FFR LCX - 0.88, and simultaneously a LAD percutaneous coronary intervention (PCI) was performed. Three months later, the patient underwent a stress test, which revealed no evidence of induced ischemia. CONCLUSIONS Our method of noninvasive assessment of FFR has shown encouraging results, but we believe that larger-scale studies are needed to establish it as common clinical practice.