Publications

Background & Aims: We studied the effects of diameter of covered, self-expandable, nitinol stents on survival times of patients with a transjugular intrahepatic portosystemic shunt (TIPS). Methods: We collected data from 185 patients (median age, 55 y; 30% female) who received a covered nitinol stent, from February 2006 through September 2010, using the online multicenter German TIPS registry. TIPS were given to 107 patients for refractory ascites and to 78 patients for variceal bleeding. Patients at risk of hepatic encephalopathy (owing to advanced age, prior episodes) or liver failure (bilirubin level, >3 mg/dL), and bleeding patients receiving variceal embolization at TIPS, received 8-mm stents (n = 53). The remaining patients received 10-mm stents (n = 132). Eighty-one of the 10-mm stents were underdilated using 8-mm dilation balloons. Clinical and biochemical data were collected after TIPS placement at 1 month, 3 months, 6 months, 9 months, 1 year, and thereafter every 3 to 6 months. Groups were compared using propensity score analysis. Results: Patients who received 8-mm stents survived significantly longer (34 ± 26 mo) than patients who received 10-mm stents (18 ± 19 mo), regardless of whether they were fully dilated or underdilated. When we compared 10-mm stents with or without underdilation, we found that a significantly higher proportion of patients who received underdilated stents survived for 1 month after TIPS placement (95% vs 84%; P = .03), but not for 3 months (P = .10). In multivariate analysis, 1-year mortality correlated with full dilation of the stent to 10 mm (hazard ratio [HR], 2.0; 95% CI, 1.1–3.5) and with serum creatinine concentration at baseline (HR, 1.5; 95% CI, 1.0–1.7). Five-year mortality was associated with use of the 10-mm stents (HR, 1.8; 95% CI, 1.4–2.7) and baseline concentration of creatinine (HR, 1.3; 95% CI, 1.1–1.6). Conclusions: A smaller stent (nominal diameter of 8 mm, but not underdilation of a 10-mm stent) is associated with a prolonged survival compared with 10-mm stents, independent of liver-specific prognostic criteria.

JTD Keywords: Cirrhosis, Comparison, Covered, Portal Hypertension

The performance of three different types of ion mobility spectrometer (IMS) devices: GDA2 with a radioactive ion source (Airsense, Germany), UV-IMS with a photo-ionization source (G.A.S. Germany) and VG-Test with a corona discharge source (3QBD, Israel) was studied. The gas-phase ion chemistry in the IMS devices affected the species formed and their measured reduced mobility values. The sensitivity and limit of detection for trimethylamine (TMA), putrescine and cadaverine were compared by continuous monitoring of a stream of air with a given concentration of the analyte and by measurement of headspace vapors of TMA in a sealed vial. Preprocessing of the mobility spectra and the effectiveness of multivariate curve resolution techniques (MCR-LASSO) improved the accuracy of the measurements by correcting baseline effects and adjusting for variations in drift time as well as enhancing the signal to noise ratio and deconvolution of the complex data matrix to their pure components. The limit of detection for measurement of the biogenic amines by the three IMS devices was between 0.1 and 1.2 ppm (for TMA with the VG-Test and GDA, respectively) and between 0.2 and 0.7 ppm for putrescine and cadaverine with all three devices. Considering the uncertainty in the LOD determination there is almost no statistically significant difference between the three devices although they differ in their operating temperature, ionization method, drift tube design and dopant chemistry. This finding may have general implications on the achievable performance of classic IMS devices.

JTD Keywords: Biogenic amines, Comparison of performance, Ion mobility spectrometry, Sensitivity, Signal processing, Vapor concentration