Study objectives: The Pulmonary Embolism Rule-out Criteria (PERC) score has shown excellent negative predictive value; however, its use in the European population with high prevalence of PE is controversial. In Europe, PERC is not part of routine practice. For low-risk patients, guidelines recommend D-dimer testing, followed if positive by imaging study. We aimed to study the rate of diagnosis of PE after D-dimer testing in PERC-negative patients that could have been discharged if PERC was applied.Method: This was a multicenter retrospective study in Paris, France. We included all patients with a suspicion of PE who had D-dimer testing in the emergency department, low pre-test probability, and a negative PERC score (that was retrospectively calculated). Patients with insufficient record to calculate PERC score were excluded. The primary end point was the rate of PE diagnosis before discharge in this population. Secondary end points included rate of invasive imaging studies and subsequent adverse events.Results: We screened 4301 patients who had D-dimer testing, 1070 of whom were PERC negative and could be analyzed. The mean age was 35 years and 46% were men. D-dimer was positive (>500 ng/L) in 167 (16%) of them; CTPA or V/Q scan was performed in 153 (14%) cases. PE was confirmed in 5 cases (total rate 0.5%, 95% confidence interval 0.1%-1.1%). Fifteen patients (1%) experienced non-severe adverse events.Conclusion: D-dimer testing in PERC-negative patients led to a diagnosis of PE in 0.5% of them, with 15% of patients undergoing unnecessary irradiative imaging studies. (C) 2014 Elsevier Inc. All rights reserved.

La majorite des reseaux d'eau potable actuels etant exploites au chlore, il est imperatif pour Veolia Eau d'avoir une vision exhaustive de l'etat du parc de branchements afin d'anticiper leur renouvellement. A partir de l'analyse de prelevements terrain en conditions particulieres d'exploitation et d'echantillons vieillis en mode accelere, une methodologie de diagnostic de l'etat de sante d'un tube a ete etablie en laboratoire et deployee en routine. Title : Chemical interaction of pipes with chlorine in drinking water distribution systems Abstract : As chlorine remains the most common disinfectant for French drinking water distribution systems, Veolia Eau focuses on getting accurate data about structural state of connection pipes in service in order to anticipate their renewal. Lab-scale analyses of operated pipes and samples aged under accelerated ageing conditions were comprehensively carried out to define a methodology of polyethylene pipe's health diagnosis, which is currently available in routine.

De nombreux examens complémentaires sont prescrits inutilement aux urgences médicochirurgicales adultes. Nous avons testé l’hypothèse que la seniorisation de la prescription et le rappel des bonnes indications permettent de réduire la prescription des examens d’hémostase.

The presence of chlorine in drinking water supplies in many countries creates the undesirable side effect causing a relatively under investigated degree of polymer degradation in the polyethylene pipes used transport. In order to predict pipe lifetimes and ensure safe water supplies, a kinetic model using data for the degradation rates of polyethylenes immersed in chlorine solutions, was developed. In order to replicate phenomena that normally occur very slowly at low concentrations of chlorine, accelerated ageing studies were necessary. These were carried out at high chlorine concentrations under well-defined experimental conditions (70, 400 and 4000 ppm). Results showed that, for the chlorine concentrations studied, a chain scission process associated with carbonyl formation is occurring. It was also shown that the rate of this degradation does not depend on the presence of stabilizer. A kinetic model, taking into account the chlorine concentration, is proposed in order to simulate the molar mass changes occurring. This will facilitate the prediction of the degree of polyethylene embrittlement and ultimately the lifetime. (C) 2011 Elsevier Ltd. All rights reserved.

HDPE pipes are used for the transport of drinking water. However, disinfectants in water seem to have a strong impact on their mechanical behaviour, limiting their lifetime in operation. Indeed, oxidation occurs when they are in contact with disinfectants leading to the formation of a thin oxidised layer coupled to the cracks initiation of cracks of different lengths from the inner wall surface. An original method is proposed here to characterise the ageing effect of the pipe mechanical behaviour. Inspired from the ASTM D 2290-04 standard, Nol Ring tests have been performed under tensile and creep loadings on smooth rings. A constitutive equation has been determined from these tests using a finite element (FE) modelling. FE simulations have been performed to study the influence of the thin oxidised PE layer. Precracked specimens with different crack depth ratio have also been modelled. The crack depth ratio is an important parameter to quantify pipe ageing.

In order to characterize the mechanical behavior of HDPE pipes, the ASTM D 2290-04 standard recommends carrying out tensile tests on notched rings, cut out from the pipe. This very simple test is also utilized to investigate the aging effect of the pipe by determining the strain at failure. Comparison between full ring and notched ring mechanical responses are discussed. Constitutive modeling including strain rate effects was performed by finite element analysis. This allowed a better understanding of the stress state in the cross section perpendicular to the loading direction. Additionally, the influence of a thin layer of oxidized HDPE in the inner wall of the ring was studied in the light of the finite element results.

BACKGROUND:Diagnosis of brain death usually requires an arterial carbon dioxide partial pressure (Paco2) of 60 mmHg during the apnea test, but the increase in Paco2 is unpredictable. The authors evaluated whether transcutaneous carbon dioxide partial pressure (Ptcco2) monitoring during apnea test can predict that a Paco2 of 60 mmHg has been reached.METHODS:The authors compared Ptcco2 measured with a transcutaneous ear sensor (V-Sign Sensor, Sentec Digital Monitoring System; SENTEC-AG, Therwil, Switzerland) and Paco2 obtained from arterial blood gas measurements in 32 clinically brain-dead patients.RESULTS:In the first 20 patients, the mean Paco2-Ptcco2 gradient was 0.7 +/- 3.6 mmHg at baseline and 8.7 +/- 7.1 mmHg after 20 min of apnea. Using receiver operating characteristic curve analysis (area under the curve: 0.983 +/- 0.013), the best threshold value of Ptcco2 to predict that a Paco2 of 60 mmHg had been reached was 60 mmHg (positive predictive value: 1.00 [0.93-1.00]). In the following 12 patients investigated with use of this Ptcco2 target value of 60 mmHg, the mean duration of the apnea test (11 +/- 4 vs. 20 +/- 0 min; P < 0.001), hypercapnia (74.0 +/- 4.9 vs. 98.3 +/- 20.0 mmHg; P < 0.001), acidosis (pH: 7.18 +/- 0.06 vs. 7.11 +/- 0.08; P < 0.001), and decrease in arterial oxygen partial pressure (-47 +/- 44 vs. -95 +/- 89; P < 0.05) at the end of the test were reduced as compared with the 20-min apnea test group.CONCLUSION:During the apnea test in brain-dead patients, a Ptcco2 of 60 mmHg accurately predicts that a Paco2 of 60 mmHg has been reached. This may allow a reduction in the duration of the apnea test and consecutively limit occurrence of complications.

The aim of this prospective study was to determine factors influencing effects of inhaled nitric oxide (NO) on the pulmonary circulation and on gas exchange in critically ill patients with acute lung injury. Twenty-one hypoxemic patients with acute respiratory failure (PaO2 = 127 +/- 69 mm Hg during intermittent positive pressure ventilation, FiO2 = 1), were mechanically ventilated with 2 ppm NO and pure oxygen. The effect of positive end-expiratory pressure (PEEP) on alveolar recruitment was assessed on an anatomic basis using a high-resolution and spiral thoracic computed tomographic (CT) scan. Four conditions were studied in random order: zero end-expiratory pressure (ZEEP), ZEEP + 2 ppm NO, 10 cm H2O PEEP, 10 cm H2O PEEP + 2 ppm NO. During ZEEP and PEEP, NO significantly decreased pulmonary vascular resistance index (PVRI), mean pulmonary arterial pressure (MPAP), true pulmonary shunt (Qs/QT), and alveolar dead space (VDA/VT) and significantly increased PaO2 (p < 0.01). During ZEEP, NO-induced decreases in PVRI (delta PVRI) and MPAP (delta MPAP) were significantly correlated to baseline PVRI and MPAP (delta PVRI = -0.5 PVRI + 125, r = 0.97, p < 0.01 and delta MPAP = -0.28 MPAP + 4.8, r = 0.69, p < 0.05). These changes were not potentiated by PEEP-induced alveolar recruitment. The NO-induced increase in PaO2 (delta PaO2) was not significantly correlated with baseline PaO2 but was correlated with baseline PVRI (delta PaO2 = 0.11 PVRI + 30, r = 0.67, p < 0.05). In patients in whom PEEP was associated with alveolar recruitment, NO increased PaO2 by 66 +/- 24 mm Hg during ZEEP and by 104 +/- 26 mm Hg during PEEP (p < 0.01). In patients in whom PEEP did not induce alveolar recruitment, the NO-induced increase in PaO2 was similar during ZEEP and PEEP conditions (+70 +/- 15 mm Hg versus +76 +/- 12 mm Hg, NS). In patients with adult respiratory distress syndrome, factors determining NO-induced improvement in arterial oxygenation and pulmonary vascular effects are PEEP-induced alveolar recruitment and the baseline level of pulmonary vascular resistance.

The mechanism of brain death-induced myocardial dysfunction remains debatable. Hypocalcemia is known to induce reversible myocardial dysfunction. However, the incidence of hypocalcemia and its effect on myocardial function during brain death is unknown.

The course of arterial to end-tidal carbon dioxide tension difference [P(a-ET)CO2] was evaluated during general anesthesia in 25 patients scheduled for renal surgery performed in the "kidney position." The difference between arterial PCO2 (PaCO2) corrected to body temperature, and end-tidal PCO2 (PETCO2) measured by mass spectrometry was assessed after induction of anesthesia, after placement in the lateral decubitus position with back arched over a kidney bridge ("kidney position"), and every 20 min until the patients were replaced in the supine position at the end of the surgical procedure. Heart rate, arterial blood pressure, and esophageal temperature were simultaneously recorded. After induction of anesthesia, when the patients were lying supine (T1), P(a-ET)CO2 was 4.8 +/- 3.9 mm Hg (mean +/- SD). Placing the patients in the kidney position (T2) induced a significant increase in P(a-ET)CO2 (to 7.9 +/- 3.5 mm Hg; P less than 0.01). These alterations occurred without any significant change in mean arterial blood pressure or heart rate. A progressive increase in mean P(a-ET)CO2 occurred with maintenance of anesthesia; P(a-ET)CO2 reached 8.8 +/- 4.1 mm Hg (P less than 0.05 vs T2) and 8.9 +/- 4.4 mm Hg (P less than 0.05 vs T2) at 65 and 85 min, respectively, after lateral decubitus positioning. Large variations between and within patients were observed. Although stable mean arterial pressure was maintained, these changes were associated with a significant decrease in body temperature. These results demonstrate that P(a-ET)CO2 increases when patients are placed in the kidney position and may vary with the prolongation of anesthesia in this situation.(ABSTRACT TRUNCATED AT 250 WORDS)

Recovery from inhalation anesthesia is often marked by the occurrence of postoperative tremor that resembles shivering, which is known to be associated with an increase in oxygen uptake (VO2), CO2 output (VCO2), and minute ventilation (VE). This study determined the time course of the ventilatory changes observed during the first hour of recovery from isoflurane anesthesia. Ten patients (ASA PS 1) scheduled for minor orthopedic surgery (knee arthroscopy) were included in this study. Anesthesia was induced with thiopental (5 mg/kg) and maintained with 70% N2O and isoflurane (1-2%) in oxygen, allowing spontaneous ventilation. In the recovery room, after N2O had been discontinued, patients were connected to a Beckman Metabolic measurement cart, which allowed a continuous monitoring of VE, VO2, VCO2, and PETCO2. Postoperative tremor was observed in all patients within 7.1 +/- 1.2 min (mean +/- SEM) after isoflurane discontinuation and was associated with a marked increase in the following: VO2, from 173 +/- 26 ml/min at the end of anesthesia to 457 +/- 88 ml/min; VCO2, from 149 +/- 18 ml/min at the end of anesthesia to 573 +/- 98 ml/min; and VE, from 6.8 +/- 0.7 l/min at the end of anesthesia to 16.6 +/- 2.8 l/min (values obtained 20 min after isoflurane discontinuation). In three patients during intense shivering, VO2, VCO2, and VE reached peak values higher than 800 ml/min, 1,300 ml/min and 30 l/min, respectively. This study shows that postoperative tremor following isoflurane anesthesia may be associated with prolonged and large increases in oxygen uptake, CO2 output, and minute ventilation.

In five anesthetized patients with a Jarvik-7 artificial heart, pulmonary volume displacements generated by cardiogenic oscillations were measured using an indirect spirometric method. Consequences on gas exchange were also evaluated during a 15-min period of apnea by use of a tracheal insufflation of pure O2 at a constant flow rate of 20 l/min. The Jarvik-7 artificial heart generated a mean pulmonary volume displacement of 105 +/- 29 (SD) ml/heart beat. After 15 min of apnea, arterial PCO2 (PaCO2) significantly increased from 29 +/- 5 to 47 +/- 6 (SD) Torr. PaCO2 increased by 0.8 Torr/min from the 5th to the 15th min of apnea. Mean arterial PO2, mean pulmonary shunt, mean O2 consumption, and mean metabolic production of CO2 did not change significantly during the apnea period. Because cardiac output was kept constant during the study, O2 transport was adequately maintained throughout the apnea period. In patient 1, where the period of apnea was continued for 60 min, PaCO2 progressively increased until the 45th min and then remained stable at 61 Torr during the last 15 min of apnea. This "plateau" corresponded to an alveolar ventilation of 3,907 ml/min, representing 69% of the alveolar ventilation calculated during conventional mechanical ventilation. In conclusion, the Jarvik-7 artificial heart provides a potent respiratory support through the cardiogenic oscillations it generates.