scholarly journals Quantitative evaluation of dental bio-aerosols using particle count values. Part 1: the effect of High Volume Aspiration and natural ventilation.

2020 ◽  
Author(s):  
Andre Haigh ◽  
Ronuk Vasant ◽  
Dominic O'Hooley
Keyword(s):  
Time Series ◽  
Natural Ventilation ◽  
High Volume ◽  
Sample Standard Deviation ◽  
Particle Count ◽  
Aerosol Generation ◽  
Dependent Variables ◽  
The Mean ◽  
Post Hoc ◽  
Mean Time

Abstract AimRoutine dental treatments are frequently associated with aerosol generating procedures (AGP). Recently dental AGP have attracted significant attention as a possible vector for the transmission of SARS-CoV-2 and attempts have been made to establish when a surgery may be safely decontaminated following a dental AGP — the ‘fallow time’. There is a paucity of research in the dental literature regarding the near real time generation and dispersion of dental aerosol following a dental AGP. Study aims are to: (1) monitor dental aerosol generation and dispersal through semi-continuous particle count values (PCV), and (2) use this information to delineate a range of suitable fallow times.MethodFollowing baseline measurements, five identical dental AGP were conducted on a dental manikin for each of three groups: (SEO) saliva ejector only, (HVA) high volume aspiration, (WO) high volume aspiration with windows open. For each procedure PCV were recorded every 2.2 minutes with a Light Scattering Airborne Particle Counter (LSAPC) for 3.3 hours. Eleven dependent variables were analysed, including baseline PCV, total PCV, peak PCV, time taken to return to one sample standard deviation of baseline PCV, and a time series extending from 15 minutes to 3 hours after cessation of AGP. Due to heterogeneity, the data was analysed with Krushkall-Wallis test and Dunn-Bonferroni post hoc.ResultsBetween group mean baseline PCV were not statistically significant. Compared with SEO, WO had a statistically significant impact on peak PCV (p=.009) and HVA had a statistically significant impact on total PCV (p=.006). With the exception at 2 and 3 hours, PCV throughout the time series were statistically significantly lower for WO and HVA in comparison with SEO. WO PCV were influenced by outdoor aerosol levels.Four of the five SEO procedures failed to return to baseline PCV within 3.3 hours. Following AGP, the mean time for the HVA procedures to return to baseline PCV was 17.12 minutes, 95% CI [4.96 to 29.28]. The effect of HVA on the time taken to return to baseline PCV was very large (Glass’s Δ= -4.943, CLES=1.00).ConclusionThere is a significant benefit in opening windows during AGP. The effect of HVA on reducing fallow time is very large. Under the conditions of this study, PCV suggest that it might be safe to consider a fallow time of 29.28 minutes.

Abstract 98: Higher Volume Endovascular Stroke Centers Have Decreased Times to Treatment

Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Rishi Gupta ◽  
Anat Horev ◽  
Thanh N Nguyen ◽  
Raphael Y Gershon ◽  
Dheeraj Gandhi ◽  
...  
Keyword(s):  
Univariate Analysis ◽  
Binary Logistic Regression ◽  
High Volume ◽  
Arterial Puncture ◽  
Procedure Time ◽  
Total Procedure Time ◽  
Lower Volume ◽  
The Mean ◽  
Mean Time ◽  
Total Procedure

Background: Currently, no metric exists for door to arterial puncture time for endovascular treatment in acute ischemic stroke. The aim of this study was to determine the timings of each step of endovascular stroke intervention stratified by the volume of procedures at each center. Methods: We retrospectively reviewed patients from seven institutions undergoing endovascular reperfusion therapies for acute ischemic stroke. Patients with anterior circulation strokes treated less than 8 hours from symptoms onset were included. Demographic, radiographic, angiographic and clinical outcomes were collected. The time interval at each milestone from CT acquisition to reperfusion was recorded. Successful reperfusion was defined as achieving a TICI 2B or 3 score as graded by the operator. Symptomatic hemorrhage was defined as a parenchymal hemorrhage type 2 as defined by ECASScriteria. Centers that performed more than 50 intra-arterial stroke interventions annually were considered high volume (HV) centers. A univariate analysis was performed with the Fisher’s exact test for categorical variables and students t-test for continuous variables to compare HV to lower volume (LV) centers. Variables with a p-value < 0.20 were placed in a binary logistic regression model to determine if there were differences in time to treatment between the two groups. Results: A total of 338 patients with a mean age of 67±14 years and mean NIHSS of 18±5 were included. The mean time from CT imaging to groin puncture was 108±73 minutes. The mean time from groin puncture to the placement of a microcatheter in the thrombus was 41±21 minutes and total procedure time 104±55 minutes. There were no differences in demographics, site of vascular occlusion and hemorrhage rates between high volume and lower volume centers. In univariate analysis, HV centers had a lower time from CT imaging to groin puncture (89±57 minutes vs. 154±84 minutes, p<0.001), procedure time (93±46 minutes vs. 129±65 minutes, p<0.001), final infarct volume (79±82 cm 3 vs. 94±106 cm 3 , p<0.03) and higher reperfusion rates (73% vs. 59%, p<0.01). In binary logistic regression modeling HV centers were found to have a shorter CT acquisition to arterial puncture time [OR 0.991, 95%CI (0.986-0.996), p<0.001] and higher reperfusion rates [OR 1.79, 95% CI (1.04-3.12), p<0.03]. Conclusions: Currently there is variability in the time from CT to arterial puncture and total procedure time across institutions, but HV centers appear to have lower times to treatment. Further study is required to determine how to reduce times to treatment and develop a metric for centers to target.

scholarly journals Fallow time determination in dentistry using aerosol measurement

2021 ◽  
Author(s):  
Shakeel Shahdad ◽  
Annika Hindocha ◽  
Tulsi Patel ◽  
Neil Cagney ◽  
Jens-Dominik Mueller ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Natural Ventilation ◽  
High Efficiency ◽  
High Volume ◽  
Mechanically Ventilated ◽  
Particle Count ◽  
Mitigating Factors ◽  
Particle Counts ◽  
Particle Sizer

AbstractAimTo calculate fallow time (FT) required following dental aerosol generating procedures (AGPs) in both a dental hospital (mechanically ventilated) and primary care (non-mechanically ventilated). Secondary outcomes were to identify spread and persistence of aerosol in open clinics compared to closed surgeries (mechanically ventilated environment), and identify if extra-oral scavenging (EOS) reduces production of aerosol and FT.MethodsIn vitro simulation of fast handpiece (FHP) cavity preparations using a manikin was conducted in a mechanically and non-mechanically ventilated environment using Optical Particle Sizer™ and NanoScan™ at baseline, during the procedure and fallow period.ResultsAGPs carried out in the non-mechanically, non-ventilated environment failed to achieve baseline particle levels after one hour. In contrast, when windows were opened after AGP, there was an immediate reduction in all particle sizes.In mechanically ventilated environments the baseline levels of particles were very low and particle count returned to baseline within 10 minutes following AGP. There was no detectable difference between particles in mechanically ventilated open bays and closed surgeries.The effect of the EOS was greater in non-mechanically ventilated environment on reducing the particle count; additionally, it also reduced the spikes in particle counts in mechanically ventilated environments.ConclusionHigh-efficiency particulate air filtered mechanical ventilation along with mitigating factors (high-volume suction) resulted in reduction of FT (10 minutes). Non-ventilated rooms failed to reach baseline level even after one hour of FT. There was no difference in particle counts in open bay or closed surgeries in mechanically ventilated settings. The use of an EOS device can reduce the particulate spikes during procedures in both mechanical and non-mechanical environments.This study confirms that AGPs are not recommended in dental surgeries where no ventilation is possible. No difference was demonstrated in FT required in open bays and closed surgeries in mechanically ventilated settings.Clinical significanceAGPs should not be carried out in surgeries where ventilation is not possible. Mechanical ventilation for AGPs should be gold standard; where not available or practical then the use of natural ventilation with EOS helps reduce FT. AGPs can be carried out in open bay environment with a minimum of 6 air changes per hour of mechanical ventilation. Four-handed dentistry with high-volume suction and saliva ejector are essential mitigating factors during AGPs.

scholarly journals Tracheotomy in a High-Volume Center During the COVID-19 Pandemic: Evaluating the Surgeon’s Risk

2020 ◽  
pp. 019459982095517 ◽  
Author(s):  
Arielle G Thal ◽  
Bradley A. Schiff ◽  
Yasmina Ahmed ◽  
Angela Cao ◽  
Allen Mo ◽  
...  
Keyword(s):  
Personal Protective Equipment ◽  
Transmission Rate ◽  
High Volume ◽  
Protective Equipment ◽  
Minimal Risk ◽  
Surgical Team ◽  
Positive Antibody ◽  
Control And Prevention ◽  
The Mean ◽  
Mean Time

Objective Performing tracheotomy in patients with COVID-19 carries a risk of transmission to the surgical team due to potential viral particle aerosolization. Few studies have reported transmission rates to tracheotomy surgeons. We describe our safety practices and the transmission rate to our surgical team after performing tracheotomy on patients with COVID-19 during the peak of the pandemic at a US epicenter. Study Design Retrospective cohort study. Setting Tertiary academic hospital. Methods Tracheotomy procedures for patients with COVID-19 that were performed April 15 to May 28, 2020, were reviewed, with a focus on the surgical providers involved. Methods of provider protection were recorded. Provider health status was the main outcome measure. Results Thirty-six open tracheotomies were performed, amounting to 65 surgical provider exposures, and 30 (83.3%) procedures were performed at bedside. The mean time to tracheotomy from hospital admission for SARS-CoV-2 symptoms was 31 days, and the mean time to intubation was 24 days. Standard personal protective equipment, according to Centers for Disease Control and Prevention, was worn for each case. Powered air-purifying respirators were not used. None of the surgical providers involved in tracheotomy for patients with COVID-19 demonstrated positive antibody seroconversion or developed SARS-CoV-2–related symptoms to date. Conclusion Tracheotomy for patients with COVID-19 can be done with minimal risk to the surgical providers when standard personal protective equipment is used (surgical gown, gloves, eye protection, hair cap, and N95 mask). Whether timing of tracheotomy following onset of symptoms affects the risk of transmission needs further study.

scholarly journals The critical warning research of the mean time series mutations based on Logistic model

2012 ◽  
Vol 61 (18) ◽  
pp. 189202
Author(s):  
Yan Peng-Cheng ◽  
Hou Wei ◽  
Hu Jing-Guo
Keyword(s):  
Time Series ◽  
Logistic Model ◽  
The Mean ◽  
Mean Time

Predicting Daily Maintenance Dose of Fluindione, an Oral Anticoagulant Drug

1996 ◽  
Vol 75 (05) ◽  
pp. 731-733 ◽  
Author(s):  
V Cazaux ◽  
B Gauthier ◽  
A Elias ◽  
D Lefebvre ◽  
J Tredez ◽  
...  
Keyword(s):  
Effective Dose ◽  
Maintenance Dose ◽  
Successive Approximations ◽  
Hemorrhagic Complication ◽  
Simple Method ◽  
Individual Variations ◽  
Anticoagulant Drug ◽  
The Mean ◽  
Mean Time ◽  
Daily Maintenance Dose

SummaryDue to large inter-individual variations, the dose of vitamin K antagonist required to target the desired hypocoagulability is hardly predictible for a given patient, and the time needed to reach therapeutic equilibrium may be excessively long. This work reports on a simple method for predicting the daily maintenance dose of fluindione after the third intake. In a first step, 37 patients were delivered 20 mg of fluindione once a day, at 6 p.m. for 3 consecutive days. On the morning of the 4th day an INR was performed. During the following days the dose was adjusted to target an INR between 2 and 3. There was a good correlation (r = 0.83, p<0.001) between the INR performed on the morning of day 4 and the daily maintenance dose determined later by successive approximations. This allowed us to write a decisional algorithm to predict the effective maintenance dose of fluindione from the INR performed on day 4. The usefulness and the safety of this approach was tested in a second prospective study on 46 patients receiving fluindione according to the same initial scheme. The predicted dose was compared to the effective dose soon after having reached the equilibrium, then 30 and 90 days after. To within 5 mg (one quarter of a tablet), the predicted dose was the effective dose in 98%, 86% and 81% of the patients at the 3 times respectively. The mean time needed to reach the therapeutic equilibrium was reduced from 13 days in the first study to 6 days in the second study. No hemorrhagic complication occurred. Thus the strategy formerly developed to predict the daily maintenance dose of warfarin from the prothrombin time ratio or the thrombotest performed 3 days after starting the treatment may also be applied to fluindione and the INR measurement.

Der Sommer und Herbst 2003 aus phänologischer Sicht | Summer and autumn 2003 from a phenological point of view

2004 ◽  
Vol 155 (5) ◽  
pp. 142-145 ◽  
Author(s):  
Claudio Defila
Keyword(s):  
Time Series ◽  
New Record ◽  
Point Of View ◽  
Late Spring ◽  
Mean Deviation ◽  
Leaf Shedding ◽  
The Mean ◽  
Very High ◽  
Selection Of

The record-breaking heatwave of 2003 also had an impact on the vegetation in Switzerland. To examine its influences seven phenological late spring and summer phases were evaluated together with six phases in the autumn from a selection of stations. 30% of the 122 chosen phenological time series in late spring and summer phases set a new record (earliest arrival). The proportion of very early arrivals is very high and the mean deviation from the norm is between 10 and 20 days. The situation was less extreme in autumn, where 20% of the 103 time series chosen set a new record. The majority of the phenological arrivals were found in the class «normal» but the class«very early» is still well represented. The mean precocity lies between five and twenty days. As far as the leaf shedding of the beech is concerned, there was even a slight delay of around six days. The evaluation serves to show that the heatwave of 2003 strongly influenced the phenological events of summer and spring.

scholarly journals The influence of solar wind on extratropical cyclones – Part 1: Wilcox effect revisited

2009 ◽  
Vol 27 (1) ◽  
pp. 1-30 ◽  
Author(s):  
P. Prikryl ◽  
V. Rušin ◽  
M. Rybanský
Keyword(s):  
Time Series ◽  
Solar Wind ◽  
Northern Hemisphere ◽  
High Speed ◽  
Coronal Holes ◽  
Extratropical Cyclones ◽  
Sector Boundary ◽  
Speed Solar Wind ◽  
The Mean ◽  
High Speed Solar Wind

Abstract. A sun-weather correlation, namely the link between solar magnetic sector boundary passage (SBP) by the Earth and upper-level tropospheric vorticity area index (VAI), that was found by Wilcox et al. (1974) and shown to be statistically significant by Hines and Halevy (1977) is revisited. A minimum in the VAI one day after SBP followed by an increase a few days later was observed. Using the ECMWF ERA-40 re-analysis dataset for the original period from 1963 to 1973 and extending it to 2002, we have verified what has become known as the "Wilcox effect" for the Northern as well as the Southern Hemisphere winters. The effect persists through years of high and low volcanic aerosol loading except for the Northern Hemisphere at 500 mb, when the VAI minimum is weak during the low aerosol years after 1973, particularly for sector boundaries associated with south-to-north reversals of the interplanetary magnetic field (IMF) BZ component. The "disappearance" of the Wilcox effect was found previously by Tinsley et al. (1994) who suggested that enhanced stratospheric volcanic aerosols and changes in air-earth current density are necessary conditions for the effect. The present results indicate that the Wilcox effect does not require high aerosol loading to be detected. The results are corroborated by a correlation with coronal holes where the fast solar wind originates. Ground-based measurements of the green coronal emission line (Fe XIV, 530.3 nm) are used in the superposed epoch analysis keyed by the times of sector boundary passage to show a one-to-one correspondence between the mean VAI variations and coronal holes. The VAI is modulated by high-speed solar wind streams with a delay of 1–2 days. The Fourier spectra of VAI time series show peaks at periods similar to those found in the solar corona and solar wind time series. In the modulation of VAI by solar wind the IMF BZ seems to control the phase of the Wilcox effect and the depth of the VAI minimum. The mean VAI response to SBP associated with the north-to-south reversal of BZ is leading by up to 2 days the mean VAI response to SBP associated with the south-to-north reversal of BZ. For the latter, less geoeffective events, the VAI minimum deepens (with the above exception of the Northern Hemisphere low-aerosol 500-mb VAI) and the VAI maximum is delayed. The phase shift between the mean VAI responses obtained for these two subsets of SBP events may explain the reduced amplitude of the overall Wilcox effect. In a companion paper, Prikryl et al. (2009) propose a new mechanism to explain the Wilcox effect, namely that solar-wind-generated auroral atmospheric gravity waves (AGWs) influence the growth of extratropical cyclones. It is also observed that severe extratropical storms, explosive cyclogenesis and significant sea level pressure deepenings of extratropical storms tend to occur within a few days of the arrival of high-speed solar wind. These observations are discussed in the context of the proposed AGW mechanism as well as the previously suggested atmospheric electrical current (AEC) model (Tinsley et al., 1994), which requires the presence of stratospheric aerosols for a significant (Wilcox) effect.

scholarly journals Technical note: Inherent benchmark or not? Comparing Nash–Sutcliffe and Kling–Gupta efficiency scores

2019 ◽  
Vol 23 (10) ◽  
pp. 4323-4331 ◽  
Author(s):  
Wouter J. M. Knoben ◽  
Jim E. Freer ◽  
Ross A. Woods
Keyword(s):  
Time Series ◽  
Coefficient Of Variation ◽  
Ad Hoc ◽  
Model Performance ◽  
Technical Note ◽  
Mean Flow ◽  
Model Adequacy ◽  
Robust Model ◽  
The Mean ◽  
Adequacy Assessment

Abstract. A traditional metric used in hydrology to summarize model performance is the Nash–Sutcliffe efficiency (NSE). Increasingly an alternative metric, the Kling–Gupta efficiency (KGE), is used instead. When NSE is used, NSE = 0 corresponds to using the mean flow as a benchmark predictor. The same reasoning is applied in various studies that use KGE as a metric: negative KGE values are viewed as bad model performance, and only positive values are seen as good model performance. Here we show that using the mean flow as a predictor does not result in KGE = 0, but instead KGE =1-√2≈-0.41. Thus, KGE values greater than −0.41 indicate that a model improves upon the mean flow benchmark – even if the model's KGE value is negative. NSE and KGE values cannot be directly compared, because their relationship is non-unique and depends in part on the coefficient of variation of the observed time series. Therefore, modellers who use the KGE metric should not let their understanding of NSE values guide them in interpreting KGE values and instead develop new understanding based on the constitutive parts of the KGE metric and the explicit use of benchmark values to compare KGE scores against. More generally, a strong case can be made for moving away from ad hoc use of aggregated efficiency metrics and towards a framework based on purpose-dependent evaluation metrics and benchmarks that allows for more robust model adequacy assessment.

scholarly journals Digit Variability in Carotenoid Scores Obtained with the Veggie Meter: A Pilot Study (P02-001-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Velarie Ansu ◽  
Stephanie Dickinson ◽  
Alyce Fly
Keyword(s):  
Indiana University ◽  
Left Hand ◽  
Funding Sources ◽  
Right Hand ◽  
Period Data ◽  
The Mean ◽  
The Right ◽  
Post Hoc ◽  
Main Effects ◽  
Mean Square Errors

Abstract Objectives To determine which digit and hand have the highest and lowest skin carotenoid scores, to compare inter-and-intra-hand variability of digits, and to determine if results are consistent with another subject. Methods Two subjects’ first(F1), second(F2), third(F3) and fifth(F5) digits on both hands were measured for skin carotenoids with a Veggie Meter, for 3 times on each of 18 days over a 37-day period. Data were subjected to ANOVA in a factorial treatment design to determine main effects for hand (2 levels), digits (4), and days (18) along with interactions. Differences between digits were determined by Tukey's post hoc test. Results There were significant hand x digit, hand x day, digit x day, and hand x digit x day interactions and significant simple main effects for hand, digit, and day (all P < 0.001). Mean square errors were 143.67 and 195.62 for subject A and B, respectively, which were smaller than mean squares for all main effects and interactions. The mean scores ± SD for F1, F2, F3, and F5 digits for the right vs left hands for subject A were F1:357.13 ± 45.97 vs 363.74 ± 46.94, F2:403.17 ± 44.77 vs. 353.20 ± 44.13, F3:406.76 ± 43.10 vs. 357.11 ± 45.13, and F5:374.95 ± 53.00 vs. 377.90 ± 47.38. For subject B, the mean scores ± SD for digits for the right vs left hands were F1:294.72 ± 61.63 vs 280.71 ± 52.48, F2:285.85 ± 66.92 vs 252.67 ± 67.56, F3:268.56 ± 57.03 vs 283.22 ± 45.87, and F5:288.18 ± 34.46 vs 307.54 ± 40.04. The digits on the right hand of both subjects had higher carotenoid scores than those on the left hands, even though subjects had different dominant hands. Subject A had higher skin carotenoid scores on the F3 and F2 digits for the right hand and F5 on the left hand. Subject B had higher skin carotenoid scores on F5 (right) and F1 (left) digits. Conclusions The variability due to hand, digit, and day were all greater than that of the 3 replicates within the digit-day for both volunteers. This indicates that data were not completely random across the readings when remeasuring the same finger. Different fingers displayed higher carotenoid scores for each volunteer. There is a need to conduct a larger study with more subjects and a range of skin tones to determine whether the reliability of measurements among digits of both hands is similar across the population. Funding Sources Indiana University.

Retrospective analysis of mortality within 30 days of systemic anticancer therapy and comparison with a previous audit at an Australian Regional Cancer Centre

2021 ◽  
pp. 107815522110160
Author(s):  
Bernadatte Zimbwa ◽  
Peter J Gilbar ◽  
Mark R Davis ◽  
Srinivas Kondalsamy-Chennakesavan
Keyword(s):  
Checkpoint Inhibitors ◽  
Anticancer Therapy ◽  
Mortality Rates ◽  
Feedback Process ◽  
Time To Death ◽  
Cancer Centre ◽  
Haematology Patients ◽  
The Mean ◽  
Regional Cancer Centre ◽  
Mean Time

Purpose To retrospectively determine the rate of death occurring within 14 and 30 days of systemic anticancer therapy (SACT), compare this against a previous audit and benchmark results against other cancer centres. Secondly, to determine if the introduction of immune checkpoint inhibitors (ICI), not available at the time of the initial audit, impacted mortality rates. Method All adult solid tumour and haematology patients receiving SACT at an Australian Regional Cancer Centre (RCC) between January 2016 and July 2020 were included. Results Over a 55-month period, 1709 patients received SACT. Patients dying within 14 and 30 days of SACT were 3.3% and 7.0% respectively and is slightly higher than our previous study which was 1.89% and 5.6%. Mean time to death was 15.5 days. Males accounted for 63.9% of patients and the mean age was 66.8 years. 46.2% of the 119 patients dying in the 30 days post SACT started a new line of treatment during that time. Of 98 patients receiving ICI, 22.5% died within 30 days of commencement. Disease progression was the most common cause of death (79%). The most common place of death was the RCC (38.7%). Conclusion The rate of death observed in our re-audit compares favourably with our previous audit and is still at the lower end of that seen in published studies in Australia and internationally. Cases of patients dying within 30 days of SACT should be regularly reviewed to maintain awareness of this benchmark of quality assurance and provide a feedback process for clinicians.

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