Continuous Airflow Research Articles

Biophotonic ring resonator for ultrasensitive detection of DMMP as a simulant for organophosphorus agents.

Combining photonic integrated circuits with a biologically based sensing approach has the ability to provide a new generation of portable and low-cost sensor devices with a high specificity and sensitivity for a number of applications in environmental monitoring, defense, and homeland security. We report herein on the specific biosensing under continuous air flow of DMMP, which is commonly used as a simulant and a precursor for the synthesis of Sarin. The proposed technology is based on the selective recognition of the targeted DMMP molecule by specifically modified proteins immobilized on photonic structures. The response of the biophotonic structures shows a high stability and accuracy over 3 months, allowing for the detection in diluted air of DMMP at concentration as low as 35 μg/m(3) (6.8 ppb) in less than 15 min. The performance of the developed technology satisfies most current homeland and military security requirements.

Association between serum lipoprotein lipase level and dyslipidemia in patients with obstructive sleep apnea syndrome

To explore the association between serum lipoprotein lipase (LPL) level and dyslipidemia in patients with obstructive sleep apnea syndromes (OSAS). Overnight polysomnography (PSG) was performed for 158 patients with snoring at our Sleep Center from June 2011 to April 2013. Based on the results of apnea-hypopnea index (AHI) assessment, they were divided into 4 groups: primary snoring (AHI<5/h, n = 26), mild (5/h ≤ AHI ≤ 15/h, n = 23), moderate (15/h < AHI ≤ 30/h, n = 31) and severe (AHI>30/h, n = 78) OSAS. According to body mass index (BMI), primary snoring group was further divided into normal BMI and overweight (obese) groups. The level of LPL was determined by enzyme-linked immunosorbent assay (ELISA) and the correlations were observed with OSAS, blood total cholesterol (TC), triglyceride (TG), high density lipoprotein (HDL), low density lipoprotein (LDL) and very low density lipoprotein (VLDL).In normal weight OSAS patients, the relationship was analyzed between different conditions, plasma lipid and serum LPL.In 49 OSAS groups, the level of LPL was observed after 6-month continuous positive airflow pressure (CPAP). From a comparison of four groups, it was found that AHI, night blood lowest oxygen saturation (L-SaO2) and time ratio of lowest SaO2<90% (TS90%) had statistical significance (all P < 0.01). The serum LPL gradually decreased in four groups. Compared with primary snoring group, there was a significant increase of serum LPL level in severe OSAS group ((37 ± 15) vs (45 ± 17) µg/L, P = 0.022). And severe OSAS group had significantly higher serum levels of TC, TG and LDL (P = 0.025,0.001,0.049).HDL of OSAS group was significantly lower than that of primary snoring group (all P < 0.05). Additionally, after adjustment for BMI and age, serum LPL levels showed significant negative correlations with TC and LDL (r = 0.221,0.199) .Serum LPL level was negative correlated with AHI and TS90 % and oxygen decrease index (ODI) (r = 0.231,0.228,0.184). Compared with normal BMI patients, there was a significant increase of VLDL ((0.77 ± 0.30) vs (0.46 ± 0.23) mmol/L, P = 0.034) and decrease of LPL ((37 ± 10) vs (523 ± 23) µg/L, P = 0.047) in weight (obesity) in primary snoring group. Compared with primary snoring group in normal BMI groups, there was a significant increase of TG,VLDL and decrease of LPL, HDL in OSAS group (all P < 0.05). The level of LPL significantly increased after 6-month CPAP ((60 ± 6) vs (38 ± 3) µg/L, P = 0.001). Serum LPL and plasma lipid decrease in OSAS patients. And serum LPL level is correlated significantly with the severity of OSAS and nocturnal hypoxia. Thus LPL may play some roles in dyslipidemia of OSAS patients.

Ammonia volatilization in Chinese double rice-cropping systems: a 3-year field measurement in long-term fertilizer experiments

The impact of long-term fertilizer on ammonia (NH3) volatilization in a double rice-cropping system is not well documented. A long-term fertilizer experiment in Chinese double rice-cropping systems initiated in 1990 was used in this study to evaluate the NH3 volatilization. Six fertilizer treatments were designed, including inorganic fertilizer [nitrogen and phosphorus fertilizer (NP), nitrogen and potassium fertilizer (NK), and balanced mineral fertilizer (NPK)], combined inorganic/organic fertilizers at full and reduced rate (FOM and ROM), and no fertilizer application (served as control). Ammonia volatilization fluxes were measured using a continuous airflow enclosure method during double rice growing seasons from 2007 to 2009. Results showed that the cumulative NH3 volatilizations in the fertilizer plots ranged from 12.8 to 27.3 kg N ha−1 for the early rice season and from 17.3 to 32.7 kg N ha−1 for the late rice season, which accounted for 9.2–33.6 % and 17.8–32.2 % of the applied N, respectively. The NH4 + concentration in floodwater is a predominant factor to NH3 losses in the double rice-cropping systems. Compared with the NPK, the cumulative NH3 volatilizations during double rice growing seasons were respectively increased by 9.7, 50.6, and 37.6 % for the NP, NK, and FOM plots, respectively, while they were decreased by 24.6 % for the ROM plots. Compared with the NPK, N uptakes by rice were decreased by 7.2–49.7 % with imbalanced fertilizer application (NP and NK), while they were increased by 9.6–41.0 % with combined inorganic/organic fertilizers application (ROM and FOM). Grain yields were comparable among the NPK, ROM, and FOM treatments, but they were declined by the treatments with imbalanced fertilizer application. These results suggested that agricultural economic viability and NH3 volatilization mitigation can be simultaneously achieved by balanced inorganic and organic fertilizers application.

Crop optimization and pre-steps standardization to get a Bipolaris euphorbiae-based bioherbicide

Making bioproducts available to the market requires finding appropriate processes for mass production and formulation of biological agents. This study aimed at evaluating the Bipolaris euphorbiae production in a solid medium (fermentation in solid substrate) and in a biphasic system (growth in a liquid medium followed by growth in a solid medium), as well as determining the processes for collecting and drying conidia, under laboratory conditions. The influence of the incubation period and inoculum quantity were also investigated. The conidia were dried by using an oven (30ºC, 35ºC, 40ºC, 45ºC, 50ºC, 55ºC and 60ºC), and laminar flow, continuous air flow and aseptic chamber at room temperature. Dry conidia were obtained by sieving and grinding in a ball mill, hammer mill or grain grinder. The conidia viability and sporulation efficiency were evaluated in the solid medium and in the biphasic system. For growth period, the best sporulation on solid medium was obtained after 10 days of incubation, reaching 8.3 x 10(7) conidia g-1 of substrate. The biphasic system did not increase the B. euphorbiae sporulation (4.5 x 10(7) conidia g-1 of substrate), after 14 days, and the amount of liquid inoculum used in this system was not an important factor for increasing its production. The continuous air flow and laminar flow preserved the conidial viability (94.6% and 99.1%, respectively), while promoting a great moisture loss (62.6% and 54.0%, respectively). All the grinding processes reduced the conidia germination (86.2%, 10.5% and 12%, respectively), while sieving allowed the collecting of powdered conidia with high viability (94.8%).

Tobacco exposure increased airway limitation in dogs with chronic cough

In the field of veterinary medicine, there are few reports regarding the incidence of respiratory diseases, including cancer of the nose and lung among pet animals with passive tobacco smoke...

Kinetics of short-term carbon mineralization in roots of biofuel crops in soils

Various crops have been used for energy production while striving to maintain C storage derived from roots in soils. To better understand and document the rates of root decomposition in biofuel cropping systems, we compared the evolution of CO2 from roots incubated with samples of two Iowa Mollisols (Clarion and Nicollet). Root samples were collected from experimental plots for four cropping systems: a multispecies reconstructed prairie, grown with and without N fertilization, and continuous corn, grown with and without a ryegrass cover crop. Major structural components of the root samples (lignin, cellulose, and hemicellulose) as well as chemical composition (total C and N) were assessed. The root materials were incubated for 30 days at room temperature (22 °C) by using an incubation apparatus with continuous airflow. The decomposition rates and half-lives of rapidly and slowly decomposable C fractions were calculated by fitting a two-component first-order kinetic model to the data. Mineralizable C ranged from 7 to 13 % of the added C. When the data for the two soils were combined, the CO2-C evolved was positively correlated with both the C/N ratio (r = 0.88**, p < 0.01) and the lignin/N ratio (r = 0.89**, p < 0.01) of the roots. For the Clarion soil, first-order decomposition rate constants for the rapid fraction ranged from 0.07 to 0.69 day−1, whereas for the Nicollet soil they ranged from 0.09 to 0.66 day−1. For both soils, the half-lives of the rapidly decomposable fraction ranged from 1 to 10 days, and half-lives of 204 to 770 days were observed for the slowly decomposable fractions. Among the cropping systems studied, the rapidly decomposable fraction of roots derived from the unfertilized prairie treatment was the largest. Those root residues also had the highest hemicellulose index and higher concentrations of arabinose, galactose, glucose, and xylose sugars than did roots of the other crops. Other decomposition parameters, such as the decomposition rates and half-lives obtained from the two-component model, were not correlated with the root composition parameters studied. Our results suggest that lignin did not inhibit the early rate of root C mineralization in mixed perennial crops. That information could be useful in refining models of root C dynamics in daily time steps or at the scale of a single growing season.

Practical Strategies for Stable Operation of HFF-QCM in Continuous Air Flow

Currently there are a few fields of application using quartz crystal microbalances (QCM). Because of environmental conditions and insufficient resolution of the microbalance, chemical sensing of volatile organic compounds in an open system was as yet not possible. In this study we present strategies on how to use 195 MHz fundamental quartz resonators for a mobile sensor platform to detect airborne analytes. Commonly the use of devices with a resonant frequency of about 10 MHz is standard. By increasing the frequency to 195 MHz the frequency shift increases by a factor of almost 400. Unfortunately, such kinds of quartz crystals tend to exhibit some challenges to obtain a reasonable signal-to-noise ratio. It was possible to reduce the noise in frequency in a continuous air flow of 7.5 m/s to 0.4 Hz [i.e., σ(τ) = 2 × 10−9] by elucidating the major source of noise. The air flow in the vicinity of the quartz was analyzed to reduce turbulences. Furthermore, we found a dependency between the acceleration sensitivity and mechanical stress induced by an internal thermal gradient. By reducing this gradient, we achieved reduction of the sensitivity to acceleration by more than one decade. Hence, the resulting sensor is more robust to environmental conditions such as temperature, acceleration and air flow.

BIRDS STOCK UP AS PRESSURE DROPS

If the weather forecast predicts that a snowstorm is heading your way you'd probably wisely decide to stay snuggled up inside. Wild birds, however, don't have this luxury, and getting caught out in bad weather can have serious consequences. Take for example white crowned sparrows, which return to the snowy mountains of the Sierra Nevada each spring to feast on the insects that have died on the snow. ‘If a storm comes in and snow falls, food availability goes to zero and then the majority of animals will abandon their territories’, says Creagh Breuner, from the University of Montana, USA. But do these storms really take the sparrows by surprise or can they predict them? After being asked this question several times at conferences, Breuner decided to investigate (p. 1982). Breuner explains that it is widely known that birds can sense barometric pressure changes and so she suspected that sparrows could use pressure drops associated with storms as a signal to increase levels of glucocorticoid hormones – stress hormones that divert energy towards maintenance-orientated and preparatory behaviours like feeding.To begin her investigation, Breuner, who has been working out in the Sierra mountains since 1997, looked back over her meticulously kept field notebooks: ‘I know when storms start, I'm out there and I write it down in my notebook – it just started snowing – so I took six snow events and looked to see what happened to barometric pressure before them.’ Sure enough, when she cross-referenced the storms with a dataset from a nearby study of barometric pressure she found that in the 12 h preceding the storm there had been a steady decline in pressure. Having taken between 70 and 100 blood samples each year to measure birds' corticosterone (a glucocorticoid hormone) levels, she was then able to identify samples that had been taken during those 12 h of dropping pressure. However, to her surprise there was no change in corticosterone levels.Although Breuner admits that it was disappointing to see that stress hormone levels did not increase as pressures dropped, she remained undeterred. With the help of two PhD students, Rachel Sprague and Stephen Patterson, Breuner continued her investigation. Back in the lab the team first faced the challenge of how to mimic environmental pressure drops without buying an expensive purpose-built chamber. Breuner turned to her husband and fellow scientist Art Woods for inspiration: ‘Art loves figuring out how to manipulate things that others can't do in the lab, he's just so good electronically and mechanistically with different things’. Woods designed a small Plexiglas chamber with a continuous flow of air through it. He realised that as long as the outflow of air remained constant, he could gradually lower the pressure simply by slowly closing a valve to limit air intake.Just as in the wild, the team found that corticosterone levels didn't increase with declining pressure, but they did find that the birds pecked at their food more. Eating and stocking up on reserves was a clear sign that the birds thought bad weather was on its way. Breuner points out: ‘They can burn through their fat reserves with 24 h of cold weather, so even small increases in fat mass before a storm comes would be an ecologically relevant difference.’ So, whilst the stress hormones don't seem to be the driving force behind their increased appetite and grazing, it is clear that the birds are able to using barometric pressure to predict the weather and as a sign to stock up and prepare for stormy weather ahead.

In Vitro Delivery of Aerosolized Treprostinil via Modern Mechanical Ventilation

The Tyvaso Inhalation System is a hand-held nebulizer system used to administer treprostinil, an approved therapy for pulmonary arterial hypertension. Our goal was to establish an in vitro method for delivering a standard dose of treprostinil through a ventilator circuit and artificial airway. An AeroTech II jet nebulizer (continuous air flow at 10 L/min; Biodex Medical Systems) was placed in the ventilator circuit with a test lung. Two ventilators were tested, the Dräger Evita 2 Dura (Dräger Medical GmbH) and Avea (CareFusion), without humidity. Delivered dose was defined by capturing radiolabeled particles exiting the endotracheal tube with a filter (Pari) and measuring radioactivity. Particle distributions were measured distal to the endotracheal tube by cascade impaction. We hypothesized that drug delivery would be determined by the number of breaths needed, such that the complete time of inspiration totaled 29 sec (e.g., number of breaths needed=29 sec/TI, where TI is the inspiratory time of an average breath read from the ventilator display). Nebulizer output was linear for 6 min, and the standard prescribed target dose of 54 μg (3.1% of full ampule) was delivered in 29 sec. Using our TI algorithm to control delivery, the mean inhaled dose±SD was 72.2±16.5 μg (range 47.2-98.6; n=23). Dräger delivered higher doses than Avea. Effects of mode, breathing pattern, and positive-end expiratory pressures were not significant. The mass median aerodynamic diameter and fine particle fraction were 0.71±0.015 and 0.997±0.0006, respectively. Using the algorithm, it was possible to deliver aerosolized treprostinil, at controlled doses, via mechanical ventilation over a wide range of controlled breathing patterns. The conditions of nebulization must be precisely followed (one full ampule per treatment, use of the AeroTech II nebulizer, continuous nebulization using an external flow of 10 L/min, bypass of the humidifier or removal of in-line heat and moisture exchanger, and treatment completed in 6 min or less).

Multinight Recording and Analysis of Continuous Positive Airway Pressure Airflow in the Home for Titration and Management of Sleep Disordered Breathing

The authors examined magnitude/variability of residual sleep disordered breathing (SDB) at pressures around the therapeutic continuous positive airway pressure (CPAP), and described a multinight approach to CPAP titration/retitration consisting of recording airflow and summarizing SDB over multiple nights at multiple pressures and choosing an optimal pressure from these summarized data. Prospective, single-center nonblinded study. Ten female/18 male patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) (respiratory disturbance index [RDI] 67/h), 17 newly-initiated, 11 chronic CPAP users. A custom CPAP device (Fisher & Paykel Healthcare) recording airflow and pre-programmed to vary CPAP between 2-3 cm H2O below and 1-2 cm H2O above prescription pressure as determined by a full laboratory titration. Airflow and pressure continuously recorded for multiple nights (15.9 ± 5.1 nights) at four to seven different pressures in each patient. SDB events manually scored from the airflow as apnea (airflow reduction > 90%), hypopnea (airflow reduction > 30% lasting 10 to 120 sec with inspira-tory flow limitation [IFL]) and runs of sustained IFL > 2 min identified. RDI = (apnea + hypopnea)/total sleep time calculated for each night and an obstruction index, including sustained IFL, also was calculated. PressureMultinight was obtained for each patient from multiple nights of data using two mathematical techniques. Night-to-night variability of SDB indices was low in some patients and significant in others. PressureMultinight could be determined in 17 of 28 patients and was similar to the in-laboratory pressure. This study showed that recording multiple nights of CPAP airflow in the home and analyzing these data for residual SDB provided useful information, including the possibility of determining a therapeutic prescription for fixed CPAP in most patients and identification of others with significant physiologic variability of SDB.

Distribution of lung tissue hysteresis during free breathing

To characterize and quantify free breathing lung tissue motion distributions. Forty seven patient data sets were acquired using a 4DCT protocol consisting of 25 ciné scans at abutting couch positions on a 16-slice scanner. The tidal volume of each scan was measured by simultaneously acquiring spirometry and an abdominal pneumatic bellows. The concept of a characteristic breath was developed to manage otherwise natural breathing pattern variations. The characteristic breath was found by first dividing the breathing traces into individual breaths, from maximum exhalation to maximum exhalation. A linear breathing drift model was assumed and the drift removed for each breath. Breaths that exceeded one standard deviation in period or amplitude were removed from further analysis. A characteristic breath was defined by normalizing each breath to a common amplitude, aligning the peak inhalation times for all of the breaths, and determining the average time at each tidal volume, keeping inhalation and exhalation separate. Breathing motion trajectories were computed using a previously published five-dimensional lung tissue trajectory model which expresses the position of internal lung tissue, X, as: X(v,f:X0)=X0+α(X0)v+β(X0)f, where X0 is the internal lung tissue position at zero tidal volume and zero airflow, the scalar values v and f are the measured tidal volume and airflow, respectively, and the vectors α and β are fitted free parameters. In order to characterize the motion patterns, the trajectory elongations were examined throughout the subject's lungs. Elongation was defined here by generating a rectangular bounding box with one side parallel to the α vector and the box oriented in the plane defined by the α and β motion vectors. Hysteresis motion was defined as the ratio of the box dimensions aligned orthogonal to and parallel to the α vector. The 15th and 85th percentile of the elongation were used to characterize tissue trajectory hysteresis. The 15th and 85th percentile bounding box elongations were 0.090 ± 0.005 and 0.083 ± 0.013 in the upper left lung and 0.187 ± 0.037 and 0.203 ± 0.053, in the lower left lung. The 15th and 85th percentiles for the upper right lung were 0.092 ± 0.006 and 0.085 ± 0.013, and 0.184 ± 0.038, and 0.196 ± 0.043 in the lower right lung. Both percentiles were calculated for tidal volume displacements between 5 and 15 mm. In the left lung, the average elongations in the upper and lower lung were ζ=0.120 ± 0.064 and ζ=0.090 ± 0.055, respectively. The average elongations in the upper and lower right lung were ζ=0.107 ± 0.060 and ζ=0.082 ± 0.048, respectively. The elongation varied smoothly throughout the lungs. The hysteresis motion was relatively small compared to the volume-filling motion, contributing between 8% and 20% of the overall motion. Statistically significant differences were observed in the range of hysteresis contribution for upper and lower lung regions. The characteristic breath process provided an excellent method for defining an average breath. The characteristic breath had continuous tidal volume and airflow characteristics when the breath was continuously repeated,useful for generating patterns representative of realistic motion for breathing motion studies.

A Compact and Portable Deposition Chamber to Study Nanoparticles in Air-Exposed Tissue

Epidemiological studies show that elevated levels of particulate matter in ambient air are highly correlated with respiratory and cardiovascular diseases. Atmospheric particles originate from a large number of sources and have a highly complex and variable composition. An assessment of their potential health risks and the identification of the most toxic particle sources would require a large number of investigations. Due to ethical and economic reasons, it is desirable to reduce the number of in vivo studies and to develop suitable in vitro systems for the investigation of cell-particle interactions. We present the design of a new particle deposition chamber in which aerosol particles are deposited onto cell cultures out of a continuous air flow. The chamber allows for a simultaneous exposure of 12 cell cultures. Physiological conditions within the deposition chamber can be sustained constantly at 36-37°C and 90-95% relative humidity. Particle deposition within the chamber and especially on the cell cultures was determined in detail, showing that during a deposition time of 2 hr 8.4% (24% relative standard deviation) of particles with a mean diameter of 50 nm [mass median diameter of 100 nm (geometric standard deviation 1.7)] are deposited on the cell cultures, which is equal to 24-34% of all charged particles. The average well-to-well variability of particles deposited simultaneously in the 12 cell cultures during an experiment is 15.6% (24.7% relative standard deviation). This particle deposition chamber is a new in vitro system to investigate realistic cell-particle interactions at physiological conditions, minimizing stress on the cell cultures other than from deposited particles. A detailed knowledge of particle deposition characteristics on the cell cultures allows evaluating reliable dose-response relationships. The compact and portable design of the deposition chamber allows for measurements at any particle sources of interest.

Experimental study on hydrodynamic characteristics of gas–solid pulsed fluidized bed

Abstract The purpose of this study is to investigate the hydrodynamic characteristics of pulsed fluidized bed experimentally. Three different particles, silica with 196 μm mean diameter, alumina with 95 μm mean diameter and alumina with 10 μm mean diameter were introduced into the fluidized bed. Experiments were performed in 0.11 m ID and 0.5 m height fluidized bed. Pulsed airflow was introduced using square waves at 1 to 10 Hz pulsation frequency, which were generated using a solenoid valve connected to an electronic circuit. A high speed camera recorded the bed behavior to measure the bubble size and velocity. Results indicate that for alumina 95 μm the bed surface oscillation increases with decrease of pulsation frequency. Increasing the pulsation frequency decreases the bed expansion ratio and the bubble's diameter and velocity. In addition, the mean bed pressure drop becomes closer to the continuous airflow by increasing the pulsation frequency. This study indicates that the pulsating airflow decreases the minimum fluidization velocity and enhances fluidization of fine cohesive particles.

Ventilation patterns of the songbird lung/air sac system during different behaviors

Unidirectional, continuous airflow through the avian lung is achieved through an elaborate air sac system with a sequential, posterior to anterior ventilation pattern. This classical model was established through various approaches spanning passively ventilated systems to mass spectrometry analysis of tracer gas flow into various air sacs during spontaneous breathing in restrained ducks. Information on flow patterns in other bird taxa is missing, and these techniques do not permit direct tests of whether the basic flow pattern can change during different behaviors. Here we use thermistors implanted into various locations of the respiratory system to detect small pulses of tracer gas (helium) to reconstruct airflow patterns in quietly breathing and behaving (calling, wing flapping) songbirds (zebra finch and yellow-headed blackbird). The results illustrate that the basic pattern of airflow in these two species is largely consistent with the model. However, two notable differences emerged. First, some tracer gas arrived in the anterior set of air sacs during the inspiration during which it was inhaled, suggesting a more rapid throughput through the lung than previously assumed. Second, differences in ventilation between the two anterior air sacs emerged during calling and wing flapping, indicating that adjustments in the flow pattern occur during dynamic behaviors. It is unclear whether this modulation in ventilation pattern is passive or active. This technique for studying ventilation patterns during dynamic behaviors proves useful for establishing detailed timing of airflow and modulation of ventilation in the avian respiratory system.

フードと持続送気用チャンネルを併備したビデオ下咽頭スコープによる鉗子チャンネル経由日帰り局麻喉頭手術

フードと持続送気用チャンネルを併備したビデオ下咽頭スコープによる鉗子チャンネル経由日帰り局麻喉頭手術

671: Prevalence of obstructive sleep apnea (OSA) in pregnancy

(OSA) in pregnancy Kathleen Antony, Alpna Agrawal, Melanie Arndt, Adrienne Murphy, Philip Alapat, Kay Guntupalli, Kjersti Aagaard Baylor College of Medicine, Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Houston, TX, Baylor College of Medicine, Department of Pulmonary-Critical Care, Houston, TX, University of Texas Health Science Center, Department of Medical Education, Houston, TX OBJECTIVE: While polysomnography (PSG) is the gold standard for diagnosisofOSA, it is cumbersomeandexpensive toperform.Severalquestionnaire-based scales for diagnosis have been developed and validated in non-pregnant subjects, namely the Berlin (BQ) and Epworth sleepiness scale (ESS). We sought to ascertain the validity of these scales in pregnancy in order to establish the true prevalence of OSA in pregnancy. STUDY DESIGN: Following sample sized estimation based on pilot data, the BQ and ESS were administered to low and high-risk gravidae at initial presentation. Screen positive subjects were referred to a certified sleep lab for PSG, and incentivization reimbursement was provided. All subjects were tracked and, if admitted for antepartum care, underwent a modified sleep study (ResMed ApneaLin (AL) recording continuous pulse oximetry and nasal airflow). RESULTS: 1507 subjects were enrolled (results summarized in Fig.). The prevalence of subjects who screened positive varied by method (15.1% BQ, 19.0% ESS, and 30.1% by either BQ or ESS); screening positive on the BQ was significantly associated with screening positive on the ESS (p 0.05). Neither the BQ nor ESS were reliable diagnositic measures for OSA by either AL or PSG (ROC 0.45 for BQ, ROC 0.55 for ESS). Despite incentivization, written and verbal contact, and flexbile scheduling, 86.8% of subjects did not undergo diagnostic testing. Among 13.2% received PSG or AL, neither the BQ nor ESS were predictive of OSA and a higher than expected AL-negative rate was observed (92.6%). Among those screen positive subjects undergoing PSG or AL testing, 14.5% ultimately met OSA diagnostic criteria for an estimated point prevalence of 4.35%. CONCLUSION: In the largest reported prospective trial on OSA to date, we have observed that while screening by either Berlin or Epworth scales may be validated measures in non-pregnant subjects, it is poorly predictive among gravidae. These findings raise concern for studies which report OSA-linked outcomes without corroborating PSG diagnostic criteria having been met. 672 General anesthesia at cesarean delivery portends worse maternal and neonatal outcomes Kathleen Brookfield, Sarah Osmundson, Mariam Naqvi, Alexander Butwick, Dierdre Lyell Stanford University, Obstetrics & Gynecology, Stanford, CA, Stanford University, Anesthesia, Stanford, CA OBJECTIVE: The cesarean delivery rate is more than 34% in the U.S., and is expected to continue to rise. Women undergo cesarean delivery under general anesthesia (GA) for several reasons, some of which may increase maternal and neonatal morbidities. We compared maternal and neonatal outcomes for women undergoing cesarean delivery under GA vs. other types of anesthesia (spinal, epidural, narcotics, and local) to assess the effect of anesthetic on outcome. STUDY DESIGN: A subset of women who underwent primary or repeat cesarean delivery were identified from the NICHHD MFMU Network registry, which collected data on pregnancy outcomes from patients at 19 centers from 1999-2002. We compared outcomes including time to delivery, birthweight, Apgars, need for prolonged ventilation, and maternal/neonatal death among patients receiving GA vs. other anesthesia. RESULTS: 54,632 patients underwent cesarean, of whom 4,172 underwent GA and 50,460 underwent another type of anesthesia. Women who received GA were more likely to have an abruption, chorioamnionitis, pulmonary edema, emergency cesarean, abnormal placentation, maternal ICU admission and death, stillbirth, neonatal hypotension, prolonged hypotonicity, and respiratory morbidity (p 0.01). Although mean incision to delivery time was faster for women undergoing GA (6.2 mins vs. 10.7 mins; p 0.001), mean neonatal umbilical cord pH was lower (7.21 vs. 7.24; p 0.001). When emergent cesareans were excluded (n 365), a multilogistic regression model demonstrated that exposure to GA vs. other types of anesthesia was an independent predictor of 5 minute Apgar score 5 (p 0.01), as was delivery at 32 weeks. In a second model including only women who received GA for non-emergent cesarean deliveries, prolonged incision-to-delivery time ( 18 mins) was an independent predictor of 5 minute Apgar scores of 5 (p 0.037). CONCLUSION: Multiple maternal and neonatal effects exist from the use of general anesthesia. Shortening the incision to delivery time may improve neonatal outcomes.

How to distinguish an active air leak from a pleural space effect

We aimed to distinguish a pleural space effect from an active air leak, using a digital chest drain system that provided continuous air flow and pleural pressure checks. between March 2010 and October 2011, we employed 144 digital drains for 138 thoracic surgical procedures. We observed 18 (12.5%) active air leaks, among which 4 (2.8%) were prolonged air leaks characterized by high differential pleural pressure due to increased mean expiratory pressure (>1 cm H(2)O; p<0.0001), and 3 (2.1%) late air leaks, all long-lasting (p<0.0001), predicted by pressure curve divergence before the air flow appearance. We also reported 25 (17.4%) pleural space effects characterized by a high differential pleural pressure, but mainly due to a lower mean inspiratory pressure (<20 cm H(2)O; p<0.0001), and especially related to surgical pleurodesis procedures (p<0.0003) and wide lung resections (p<0.0002); there was no increasing pneumothorax after provocative clamping. A digital chest drain system, ensuring continuous air flow and pleural pressure measurement, could clearly identify a pleural space effect, avoiding the frequent misinterpretation of an active air leak, and allowing safe removal of the chest tube at the right time.

Vergleich von Antibeschlagmethoden in der Endoskopie

The use of a flexible or rigid fiberoptic bronchoscope belongs to the standard repertoire in anesthesiology. Besides a lack of training these procedures may be considerably compromised by endoscopic lens fogging. Several antifogging approaches are commercially available but to date no controlled studies regarding the efficacy of these devices in bronchoscopes exists. The aim of the present study was to compare the efficacy of different commercially available anti-fogging techniques for rigid and flexible bronchoscopes.The study was performed at the department of anesthesia in a university children's hospital. An artificial airway model was created to simulate in vivo conditions with respect to airflow, temperature and atmospheric moisture. A test picture was inserted into the artificial airway for assuring a standardized view through the bronchoscopes. Antifogging efficacy of two liquid antifog solutions (Ultrastop and Anti-Fog), two antifog wipes (Lina Clear and Reso Clear) and an induction endoscope preheater system (used after one and two induction preheating phases) was assessed by video taping of the bronchoscope view of the test picture. In addition the administration of continuous oxygen airflow of 2 l min⁻¹ through the suction channel of the flexible bronchoscope was tested as an alternative method to prevent lens fogging. All final pictures were rated by 10 staff anesthesiologists who were blinded to the antifog devices used. To assess the clinical relevance of the results, ratings were classified into a 5 grade rating scale (ranging from no visualization of any structure to excellent endoscopic view allowing safe endotracheal intubation). In addition, the failure rate of each anti-fog technique was calculated.A total of 300 endoscopic test pictures were taken and assessed. Using the flexible bronchoscope, the use of anti-fog solution (failure rate 3 %) and Lina Clear wipes (failure rate 4%) showed the best results. In the rigid bronchoscope group Ultrastop solution (failure rate 5 %) and Lina Clear wipes (failure rate 3.5 %) showed superior results. The two-time use of the endoscope preheater system was effective using flexible (failure rate 6 %) and rigid bronchoscopes (failure rate 10 %). The application of a continuous oxygen flow of 2 l/min failed to provide a clear endoscopic view (failure rate 93.5 %).All commercially available antifog liquids and wipes showed slightly different reduction of lens fogging. However, other factors such as frequency of usage, the type of endoscope, hygiene properties as well as cost-effectiveness might have a substantial impact on the comparison of all tested anti-fog devices. The use of an endoscope preheater system might be a conceivable alternative method to reduce lens fogging despite the higher initial cost. However, the multiple use of the preheater system cannot be recommended at present as additional handling procedures to ensure an appropriate but safe temperature of the endoscopic tip should be provided by the manufacturer. Application of a continuous oxygen flow was shown not to be effective in preventing lens fogging using a flexible fiberoptic bronchoscope.

Abstract 281: Does Chest Compression-Only CPR Provide Meaningful Gas Exchange in Humans?

Background: During CPR in animals, chest compressions (CC) may produce passive volumes large enough to provide adequate ventilation. In humans, this mechanism may explain why continuous CCs have been associated with improved survival. We quantified the volume of passive ventilation during emergency department (ED) CCs to determine if compression-only CPR (COCPR) provides clinically significant gas exchange during resuscitation. Methods: In an urban ED, continuous flow and volume of air exhaled through an endotracheal tube were measured during the CC phase of manual CPR (between ventilations) with NICO monitors (Philip/Respironics) and recorded using LabView (National Instruments). Gas exchange with CC was quantified using Matlab (Mathworks) as the area under the flow curve (figure). CC quality was measured using accelerometer-based technology (R Series, ZOLL Medical). Results: Eight patients (6 male) aged 37-83 yrs [median age 51 yr (IQR 43-56)] who suffered out-of-hospital cardiac arrest (CA) and were transported and treated with CC in the ED were included. A total of 548 CCs [median depth 1.89 in (IQR=1.66, 2.29), median rate 128 CC/min (IQR=122-134) were analyzed over 30 min of CPR. Median tidal volume per CC was 17.3 mL (IQR=5.9-22.4). This was considerably less than measured dead space in all patients (median 118mL, IQR=93-143), regardless of CC depth. The figure illustrates a typical tracing in which ventilation volume dwarfs any passive ventilation occurring with CC. Conclusion: Late in CA, passive ventilation occurring during CCs appears to produce considerably less gas exchange than calculated dead space. The effectiveness of passive ventilation during early stages of CPR, when chest and lung compliance are greater, remains unknown. However, these findings suggest that the benefits of COCPR strategies may be related to reliably higher CC fraction and/or prevention of the negative effects of hyperventilation rather than from any passive ventilation.

Leaching of heavy metals under ambient resembling conditions from hydrotreating spent catalysts

Spent hydrotreating catalysts are not inert to air, humidity and temperature, as the combination of these factors may gradually leach metals from the catalyst causing contamination of land and groundwater. In order to investigate the combined effect of ambient variables on metals leaching, a spent hydrotreating catalyst is placed in a tin can heated at 40–50°C and then treated for 1000h under a continuous flow of wet air. Said spent catalyst contains 10.68wt.% V, 0.43wt.% Fe, 2.67wt.% Ni and 3.78wt.% Mo as well as 14.7wt.% coke and 19.4wt.% sulfur, the latter basically in the form of metallic sulfides. During the leaching experiment, samples of spent catalyst are taken at different times to track the evolution of metals and coke/sulfur content. At the end of the test, even though relatively low temperatures are used, Ni is fully removed, Mo and V are partially extracted (around 25% for each metal) while the Fe content increases. Practically no leaching of metals is observed on the sulfur/coke-free fresh catalyst subjected to an identical experimental procedure. The presence of sulfur and coke on the spent catalyst clearly enhances metals leaching. The sulfur oxides produced from the oxidation of metallic sulfides with air, in combination with water, results in the formation of acidic species, which have a strong positive influence in leaching metals from the spent catalyst.