Dispersive liquid-liquid microextraction based on solidification of floating organic droplet for the determination of triazine and triazoles in mineral water samples.

A simple, rapid, and sensitive method for the determination of atrazine, simazine, cyproconazole, tebuconazole, and epoxiconazole in mineral water employing the dispersive liquid-liquid microextraction with solidification of a floating organic drop with determination by liquid chromatography tandem mass spectrometry has been developed. A mixed solution of 250 µL 1-dodecanol and 1250 µL methanol was injected rapidly into 10 mL aqueous solution (pH 7.0) with 2% w/v NaCl. After centrifugation for 5 min at 2000 rpm, the organic solvent droplets floated on the surface of the aqueous solution and the floating solvent solidified. The method limits of detection were between 3.75 and 37.5 ng/L and limits of quantification were between 12.5 and 125 ng/L. The recoveries ranged from 70 to 118% for repeatability and between 76 and 95% for intermediate precision with a relative standard deviation from 2 to 18% for all compounds. Low matrix effect was observed. The proposed method can be successfully applied in routine analysis for determination of pesticide residues in mineral water samples, allowing for monitoring of triazine and triazoles at levels below the regulatory limits set by international and national legislations.

Alveolar recruitment maneuver in patients with subarachnoid hemorrhage and acute respiratory distress syndrome: a comparison of 2 approaches.

PURPOSE: The purpose of the study was to compare 2 alveolar recruitment maneuvers (ARMs) approaches in patients with subarachnoid hemorrhage (SAH) and acute respiratory distress syndrome (ARDS). MATERIAL AND METHODS: Sixteen SAH patients with ARDS were randomized in 2 similar groups. One received ARM with continuous positive airway pressure (CPAP) of 35 cm H(2)O for 40 seconds (CPAP recruitment), whereas the other received pressure control ventilation with positive-end expiratory pressure of 15 cm H(2)O and pressure control above positive end-expiratory pressure of 35 cm H(2)O for 2 minutes (pressure control recruitment maneuver [PCRM]). Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were measured before and after ARM. The ratio of arterial oxygen tension to fraction of inspired oxygen was measured before and 1 hour after the ARM. RESULTS: After ARM, ICP was higher in CPAP recruitment (20.50 ± 4.75 vs 13.13 ± 3.56 mm Hg; P = .003); and CPP was lower in CPAP recruitment (62.38 ± 9.81 vs 79.60 ± 6.8 mm Hg; P = .001). One hour after the ARM, the ratio of arterial oxygen tension to fraction of inspired oxygen increased significantly only in PCRM (108.5 to 203.6; P = .0078). CONCLUSION: In SAH patients with ARDS, PCRM did not affect ICP and decreased CPP in safe levels, besides improving oxygenation.

A new integrative weaning index of discontinuation from mechanical ventilation.

INTRODUCTION: Indexes predicting weaning outcome are frequently inaccurate. We developed a new integrative weaning index aimed at improving the accuracy of the traditional indexes. METHODS: Three hundred and thirty-one patients mechanically-ventilated for more than 24 hours were evaluated. Initially, the threshold values of each index that best discriminate between a successful and an unsuccessful weaning outcome were determined in 115 patients. In the second phase, the predictive performance of these values was tested prospectively in the other 216 patients. Frequency/tidal volume ratio (f/Vt ratio), tidal volume (Vt), tracheal airway occlusion pressure 0.1 s (P 0.1), the product of P 0.1 and f/Vt (P 0.1 x f/Vt), respiratory rate (f), static compliance of the respiratory system (Cst,rs), ratio of arterial oxygen tension to fraction of inspired oxygen (PaO2/FiO2 ratio) and the new integrative weaning index IWI (Cst,rs x arterial oxygen saturation/f/Vt ratio) were evaluated in all patients. The readiness for weaning and the decision to return to mechanical ventilation was made by the physician in charge, based on the signs of poor tolerance. The receiver operating characteristic (ROC) curves were calculated in order to evaluate the predictive performance of each index. The Bayes' theorem was used to assess the probability of each test of predicting weaning. RESULTS: In the prospective-validation set, successful weaning was observed in 183 patients (84.7%) and weaning failure in 33 (15.27%). IWI presented the highest accuracy, with the area under the ROC curves larger than that under the curves for the f/Vt ratio (0.96 x 0.85 respectively; P = 0.003), and also larger than that under the curves for the other indexes. IWI presented a higher probability of successful weaning when the test was positive (0.99) and a lower probability when the test was negative (0.14). Measurement of Cst,rs during the weaning process was considered one of the study limitations. CONCLUSIONS: IWI was the best predictive performance index of weaning outcome and can be used in the intensive care unit setting. TRIAL REGISTRATION: controlled-trials.com ISRCTN92117906.