ABSTRACT
Background: Droplets and aerosol cloud generating procedures in dentistry can increase the risk of airborne transmission of diseases such as COVID-19. To gain insight into the diffusion of spatters and possible preventive measures, we measured the particle spatial-temporal distribution characteristic and evaluated the effectiveness of the control measures.Methods: We conducted an experiment to observe the emitted spatters obtained during the simulated dental preparation by using high-speed videography. We measured the particle size distributions by laser diffraction and preliminarily estimated its velocity. We qualitatively and quantitatively described the spatial-temporal distributions of spatters and their control measure effects. Results: Majority of the dental spatters were small droplets (diameter less than 50 μm). A large number of smallest droplets (diameter less than 10 μm) were generated by high-speed air turbine handpiece. At the oral outlet, the speed of large droplets could exceed 2.63 m/s, and the speed of aerosol clouds ranged from 0.31–2.37 m/s. The evolution of the spatters showed that the more fully developed the state, the greater the number of spatters and the wider the contamination range. When the operation mode was moved from the central incisor to the first molar, the spatter direction became increasingly concentrated, and the velocities were enhanced. Larger droplets randomly moved along trajectories and rapidly settled. The aerosol cloud tended to float as a mass that interacted with the surrounding air. The high-volume evacuation could effectively clear away most of the dental spatters. The suction air purifier could change the diffusion direction of the spatters, compress the contamination range, and control aerosol escape into surrounding air. Conclusions: Our view is that we should combine the ‘point’ control measure (high-volume evacuation) and ‘area’ control measure (suction air purifier) to reduce the scope of pollution and prevent the aerosol escape into the surroundings. The study contributes to devising more accurate infection control guidelines, establishing appropriate interventions for different oral treatments, and minimizing the spread of respiratory diseases so that we can reduce cost and achieve the best results when medical resources are limited.
Subject(s)
COVID-19 , Respiratory Tract DiseasesABSTRACT
Background: COVID-19 is a serious respiratory disease currently causing a global pandemic. However, few studies have evaluated the prognosis of chronic kidney disease (CKD) patients infected with COVID-19. Given the comorbidities evident in CKD patients, we speculate that they are more likely to be susceptible to COVID-19 infection relative to healthy individuals. However, a systematic study is necessary to confirm the relationship between these two conditions.Methods: The Wanfang, China Science Journal Citation Report (VIP database), EMBASE, CNKI, Web of Science, PubMed, and Cochrane Library databases will be reviewed to identify relevant studies. The PRISMA-P and Cochrane Handbook guidelines were used to prepare a standardized table to extract data from all relevant studies in a uniform manner. Risk and quality assessment analyses will be conducted for all included studies, with Revman 5.3 and Stata 13.0 being used for all data analyses. The primary study outcome is the assessment of whether CKD is a risk factor associated with COVID-19 infection, and to establish whether CKD increases the risk of severe illness in those infected with COVID-19. Secondary outcomes include mortality rates in CKD patients with COVID-19.Results: This study approach will synthesize extant studies into a single systematic review and meta-analysis in order to establish whether or not CKD is a risk factor associated with the development of critical COVID-19 illness, and whether CKD patients are at a higher risk of being infected by COVID-19.Conclusion: These results will provide a basis for the clinical treatment of COVID-19 in those with CKD.Systematic Review registration: CRD42020216330（PRORPERO registration number）