A Rapid, Handheld Device to Assess Respiratory Resistance: Clinical and Normative Evidence

Introduction: Following reports of respiratory symptoms among service members returning from deployment to South West Asia (SWA), an expert panel recommended pre-deployment spirometry be used to assess disease burden. Unfortunately, testing with spirometry is high cost and time-consuming. The airflow perturbation device (APD) is a handheld monitor that rapidly measures respiratory resistance (APD-Rr) and has promising but limited clinical data. Its speed and portability make it ideally suited for large volume pre-deployment screening. We conducted a pilot study to assess APD performance characteristics and develop normative values. Materials and Methods: We prospectively enrolled subjects and derived reference equations for the APD from those without respiratory symptoms, pulmonary disease, or tobacco exposure. APD testing was conducted by medical technicians who received a 10-min in-service on its use. A subset of subjects performed spirometry and impulse oscillometry (iOS), administered by trained respiratory therapists. APD measures were compared with spirometry and iOS. Results: The total study population included 199 subjects (55.8% males, body mass index 27.7 ± 6.0 kg/m2, age 49.9 ± 18.7 yr). Across the three APD trials, mean inspiratory (APD-Ri), expiratory (APD-Re), and average (APD-Ravg) resistances were 3.30 ± 1.0, 3.69 ± 1.2, and 3.50 ± 1.1 cm H2O/L/s. Reference equations were derived from 142 clinically normal volunteers. Height, weight, and body mass index were independently associated with APD-Ri, APD-Re, and APD-Ravg and were combined with age and gender in linear regression models. APD-Ri, APD-Re, and APD-Ravg were significantly inversely correlated with FEV1 (r = −0.39 to −0.42), FVC (r = −0.37 to −0.40), and FEF25–75 (r = −0.31 to −0.35) and positively correlated with R5 (r = 0.61–0.62), R20 (r = 0.50–0.52), X5 (r = −0.57 to −0.59), and FRES (r = 0.42–0.43). Bland–Altman plots showed that the APD-Rr closely approximates iOS when resistance is normal. Conclusion: Rapid testing was achieved with minimal training required, and reference equations were constructed. APD-Rr correlated moderately with iOS and weakly with spirometry. More testing is required to determine whether the APD has value for pre- and post-deployment respiratory assessment

Assessment of Chemical Inhibitor Addition to Improve the Gas Production from Biowaste

The coexistence of sulphate-reducing bacteria and methanogenic archaea in the reactors during the anaerobic digestion from sulphate-containing waste could favor the accumulation of sulfide on the biogas, and therefore reduce its quality. In this study, the effect of sulphate-reducing bacteria inhibitor (MoO−2 4 ) addition in a two phase system from sulphate-containing municipal solid waste to improve the quality of the biogas has been investigated. The results showed that although SRB and sulphide production decreased, the use of inhibitor was not effective to improve the anaerobic digestion in a two phase system from sulphate-containing waste, since a significant decrease on biogas and organic matter removal were observed. Before MoO−2 4 addition the average values of volatile solid were around 12 g/kg, after 5 days of inhibitor use, those values did exceed to 28 g/kg. Molybdate caused acidification in the reactor and it was according to decrease in the pH values. In relation to microbial consortia, the effect of inhibitor was a decrease in Bacteria (44%; 60% in sulphate-reducing bacteria) and Archaea (38%) population

Permeability reduction in porous materials by in situ

The effect of in situ formed silica gel on the permeability of a porous material was investigated experimentally. Gelling solutions of tetra-methyl-ortho-silicate (TMOS) and methanol in water were imbibed into dry sandstone plates and cured for several days. The permeability of the untreated sandstone is on the order of 1 µm^2, whereas the intrinsic permeability of the silica alcogel is 5–6 orders of magnitude lower. The method of beam bending was employed to measure concurrently the permeability D and Young’s modulus Ep of cylindrical gel rods, prepared from the TMOS-based sol-gel solutions. Second, the permeabilities and moduli of the treated sandstones were measured. For both types of samples the gel structure was varied by varying the concentration of the TMOS in a solution and the pH of the water used. The parameters D and Ep follow from a detailed analysis of the measured relaxation of the load that is applied to the sample under constant deflection. In case of the gels, the relaxation was interpreted using common expressions for hydrodynamic relaxation and viscoelastic (VE) relaxation. It was found that the permeability of the gels decreases with increasing silica content and that acid-catalyzed gels exhibit a significantly lower permeability than base-catalyzed gels. The modulus Ep increases with increasing silica content and aging time. The relaxation data of the sandstone—treated with gel—exhibited a more complex behavior. The normalized load curves showed hydrodynamic relaxation as well as strong and fast VE relaxation. The relaxation data for the rock samples treated with the lowest concentration gel was fitted successfully with the predictions. For higher concentrations the fit was less accurate, but the permeability estimates were within an order of magnitude. The overall permeability of the treated rock is higher than the intrinsic permeability of the gels; this indicates that the gel does not completely fill the pore space. Nevertheless, the permeability is reduced by a factor 10^4 with respect to untreated sandstone, and therefore the gel adequately blocks the pores

Pathogen reduction/inactivation of products for the treatment of bleeding disorders:what are the processes and what should we say to patients?

Patients with blood disorders (including leukaemia, platelet function disorders and coagulation factor deficiencies) or acute bleeding receive blood-derived products, such as red blood cells, platelet concentrates and plasma-derived products. Although the risk of pathogen contamination of blood products has fallen considerably over the past three decades, contamination is still a topic of concern. In order to counsel patients and obtain informed consent before transfusion, physicians are required to keep up to date with current knowledge on residual risk of pathogen transmission and methods of pathogen removal/inactivation. Here, we describe pathogens relevant to transfusion of blood products and discuss contemporary pathogen removal/inactivation procedures, as well as the potential risks associated with these products: the risk of contamination by infectious agents varies according to blood product/region, and there is a fine line between adequate inactivation and functional impairment of the product. The cost implications of implementing pathogen inactivation technology are also considered

A Rapid, Handheld Device to Assess Respiratory Resistance: Clinical and Normative Evidence

Introduction: Following reports of respiratory symptoms among service members returning from deployment to South West Asia (SWA), an expert panel recommended pre-deployment spirometry be used to assess disease burden. Unfortunately, testing with spirometry is high cost and time-consuming. The airflow perturbation device (APD) is a handheld monitor that rapidly measures respiratory resistance (APD-Rr) and has promising but limited clinical data. Its speed and portability make it ideally suited for large volume pre-deployment screening. We conducted a pilot study to assess APD performance characteristics and develop normative values. Materials and Methods: We prospectively enrolled subjects and derived reference equations for the APD from those without respiratory symptoms, pulmonary disease, or tobacco exposure. APD testing was conducted by medical technicians who received a 10-min in-service on its use. A subset of subjects performed spirometry and impulse oscillometry (iOS), administered by trained respiratory therapists. APD measures were compared with spirometry and iOS. Results: The total study population included 199 subjects (55.8% males, body mass index 27.7 ± 6.0 kg/m2, age 49.9 ± 18.7 yr). Across the three APD trials, mean inspiratory (APD-Ri), expiratory (APD-Re), and average (APD-Ravg) resistances were 3.30 ± 1.0, 3.69 ± 1.2, and 3.50 ± 1.1 cm H2O/L/s. Reference equations were derived from 142 clinically normal volunteers. Height, weight, and body mass index were independently associated with APD-Ri, APD-Re, and APD-Ravg and were combined with age and gender in linear regression models. APD-Ri, APD-Re, and APD-Ravg were significantly inversely correlated with FEV1 (r = −0.39 to −0.42), FVC (r = −0.37 to −0.40), and FEF25–75 (r = −0.31 to −0.35) and positively correlated with R5 (r = 0.61–0.62), R20 (r = 0.50–0.52), X5 (r = −0.57 to −0.59), and FRES (r = 0.42–0.43). Bland–Altman plots showed that the APD-Rr closely approximates iOS when resistance is normal. Conclusion: Rapid testing was achieved with minimal training required, and reference equations were constructed. APD-Rr correlated moderately with iOS and weakly with spirometry. More testing is required to determine whether the APD has value for pre- and post-deployment respiratory assessment