Quantifying Aerosol Generation in Maxillofacial Trauma Repair Techniques

Study Design Cadaveric simulation study. Objective The novel coronavirus (COVID-19), which can be transmitted via aerosolized viral particles, has directed focus on protection of healthcare workers during procedures involving the upper aerodigestive tract, including maxillofacial trauma repair. This study evaluates particle generation at different distances from open reduction and internal fixation (ORIF) of maxillofacial injuries in the intraoperative setting to reduce the risk of contracting airborne diseases such as COVID-19. Methods Two cadaveric specimens in a simulated operating room underwent ORIF of midface and mandible fractures via intraoral incisions as well as maxillomandibular fixation (MMF) using hybrid arch bars. ORIF was performed with both self-drilling screws and with the use of a power drill for creating guide holes. Real-time aerosol concentration was measured throughout each procedure using 3 particle counters placed 0.45, 1.68, and 3.81 m (1.5, 5.5, and 12.5 feet, respectively) from the operative site. Results There was a significant decrease in particle concentration in all procedures at 1.68 m compared to 0.45 m, but only 2 of the 5 procedures showed further significant decrease in particle concentration when going from 1.68 to 3.81 m from the operative site. There was significantly less particle concentration generated at all distances when using self-drilling techniques compared to power drilling for ORIF. Conclusion Consideration of using self-drilling screwing techniques as well as maintaining physical distancing protocols may decrease risk of transmission of airborne diseases such as COVID-19 while in the intraoperative setting.

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COVID-19: minimising contaminated aerosol spreading during CPAP treatment

Archives of Disease in Childhood - Fetal and Neonatal Edition ◽

10.1136/archdischild-2020-319431 ◽

2020 ◽

Vol 105 (6) ◽

pp. 669-671

Author(s):

Snorri Donaldsson ◽

Lars Naver ◽

Baldvin Jonsson ◽

Thomas Drevhammar

Keyword(s):

Healthcare Workers ◽

Work Of Breathing ◽

Lung Model ◽

Non Invasive ◽

Cpap Treatment ◽

Aerosol Generation ◽

Viral Particles ◽

A Minor ◽

Expiratory Limb ◽

Cpap Devices

BackgroundThe COVID-19 pandemic has raised concern for healthcare workers getting infected via aerosol from non-invasive respiratory support of infants. Attaching filters that remove viral particles in air from the expiratory limb of continuous positive airway pressure (CPAP) devices should theoretically decrease the risk. However, adding filters to the expiratory limb could add to expiratory resistance and thereby increase the imposed work of breathing (WOB).ObjectiveTo evaluate the effects on imposed WOB when attaching filters to the expiratory limb of CPAP devices.MethodsTwo filters were tested on three CPAP systems at two levels of CPAP in a mechanical lung model. Main outcome was imposed WOB.ResultsThere was a minor increase in imposed WOB when attaching the filters. The differences between the two filters were small.ConclusionTo minimise contaminated aerosol generation during CPAP treatment, filters can be attached to expiratory tubing with only a minimal increase in imposed WOB in a non-humidified environment. Care has to be taken to avoid filter obstruction and replace filters as recommended.

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Airway Management for Endoscopic Laryngotracheal Stenosis Surgery During COVID-19

Otolaryngology ◽

10.1177/0194599820927002 ◽

2020 ◽

Vol 163 (1) ◽

pp. 78-80 ◽

Cited By ~ 6

Author(s):

Andrew D. P. Prince ◽

Benjamin H. Cloyd ◽

Norman D. Hogikyan ◽

Samuel A. Schechtman ◽

Robbi A. Kupfer

Keyword(s):

Airway Management ◽

Surgical Management ◽

The Novel ◽

Laryngotracheal Stenosis ◽

Upper Aerodigestive Tract ◽

Operating Room Personnel ◽

Institutional Experience ◽

Novel Coronavirus ◽

High Risk Situation ◽

Airway Access

The novel coronavirus disease 2019 (COVID-19) pandemic presents unique challenges for surgical management of laryngotracheal stenosis. High viral concentrations in the upper aerodigestive tract, the ability of the virus to be transmitted by asymptomatic carriers and through aerosols, and the need for open airway access during laryngotracheal surgery create a high-risk situation for airway surgeons, anesthesiologists, and operating room personnel. While some surgical cases of laryngotracheal stenosis may be deferred, patients with significant airway obstruction or progressing symptoms often require urgent surgical intervention. We present best practices from our institutional experience for surgical management of laryngotracheal stenosis during this pandemic, including preoperative triage, intraoperative airway management, and personal protective measures.

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Isolated Tympanic Plate Fracture Frequency and Its Relationship to Mandibular Trauma

Canadian Association of Radiologists Journal ◽

10.1016/j.carj.2014.02.004 ◽

2014 ◽

Vol 65 (4) ◽

pp. 360-365 ◽

Cited By ~ 4

Author(s):

Canan Altay ◽

Nezahat Erdoğan ◽

Ozan Batkı ◽

Erdem Eren ◽

Sedat Altay ◽

...

Keyword(s):

Ct Images ◽

Maxillofacial Trauma ◽

Mandibular Fractures ◽

Condylar Process ◽

Plate Fracture ◽

Maxillofacial Fractures ◽

Significant Difference ◽

Mandible Fractures ◽

The Right ◽

Communications System

PurposeThis study evaluated the prevalence of isolated tympanic fractures and their correlation with mandibular fractures by using maxillofacial computed tomography (CT).Materials and MethodsWe retrospectively evaluated the maxillofacial CT of 1590 patients who presented to our emergency department with maxillofacial trauma between December 2010 and December 2012. Maxillofacial CT was used as the criterion standard for evaluating patients with maxillofacial fractures. The CT images were evaluated by using an electronic picture archiving and communications system and interpreted independently by 2 radiologists.ResultsThe maxillofacial CT images revealed mandibular fractures in 167 of the patients and isolated tympanic plate fractures in 35 of these 167 patients. Four patients (11%) had a bilateral tympanic plate fracture, and 31 patients (89%) had unilateral tympanic plate fracture. Of all the tympanic plate fractures, 19 (54%) were on the right side and 16 (46%) were on the left side ( P > .05). In our results, a significant correlation between the presence of a right-sided tympanic plate fracture and fracture of the ipsilateral condylar process was found ( P = .036). However, a statistically significant difference between the presence of a tympanic plate fracture and other mandible fractures, additional soft-tissue findings, or the number of fractures was not determined ( P > .05). Sex had no impact on the presence of tympanic plate fracture ( P > .05).ConclusionThe frequency of isolated tympanic plate fractures in maxillofacial trauma is low, but it is an important anatomic location. Condyle fractures are significantly associated with isolated tympanic plate fractures. The presence of these injuries should raise suspicion of a concomitant isolated tympanic plate fracture.

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Microdebrider is less aerosol-generating than CO2 laser and cold instruments in microlaryngoscopy

European Archives of Oto-Rhino-Laryngology ◽

10.1007/s00405-021-07105-9 ◽

2021 ◽

Author(s):

Enni Sanmark ◽

Lotta-Maria A. H. Oksanen ◽

Noora Rantanen ◽

Mari Lahelma ◽

Veli-Jukka Anttila ◽

...

Keyword(s):

High Risk ◽

Surgical Procedures ◽

Particle Concentration ◽

Aerosol Particles ◽

Aerosol Generation ◽

Laryngeal Surgery ◽

Step Down ◽

Particle Sizer ◽

Measured Particle ◽

Cold Dissection

Abstract Objective COVID-19 spreads through aerosols produced in coughing, talking, exhalation, and also in some surgical procedures. Use of CO2 laser in laryngeal surgery has been observed to generate aerosols, however, other techniques, such cold dissection and microdebrider, have not been sufficiently investigated. We aimed to assess whether aerosol generation occurs during laryngeal operations and the effect of different instruments on aerosol production. Methods We measured particle concentration generated during surgeries with an Optical Particle Sizer. Cough data collected from volunteers and aerosol concentration of an empty operating room served as references. Aerosol concentrations when using different techniques and equipment were compared with references as well as with each other. Results Thirteen laryngological surgeries were evaluated. The highest total aerosol concentrations were observed when using CO2 laser and these were significantly higher than the concentrations when using microdebrider or cold dissection (p < 0.0001, p < 0.0001) or in the background or during coughing (p < 0.0001, p < 0.0001). In contrast, neither microdebrider nor cold dissection produced significant concentrations of aerosol compared with coughing (p = 0.146, p = 0.753). In comparing all three techniques, microdebrider produced the least aerosol particles. Conclusions Microdebrider and cold dissection can be regarded as aerosol-generating relative to background reference concentrations, but they should not be considered as high-risk aerosol-generating procedures, as the concentrations are low and do not exceed those of coughing. A step-down algorithm from CO2 laser to cold instruments and microdebrider is recommended to lower the risk of airborne infections among medical staff.

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Appendicitis with concurrent COVID-19 infection in a patient during the third trimester of pregnancy

BMJ Case Reports ◽

10.1136/bcr-2021-242651 ◽

2021 ◽

Vol 14 (6) ◽

pp. e242651

Author(s):

Laura Jane Sanders-Davis ◽

Joanne Ritchie

Keyword(s):

Unusual Case ◽

Fetal Loss ◽

Anaesthetic Techniques ◽

General Anaesthetic ◽

The Novel ◽

Third Trimester ◽

Aerosol Generation ◽

Maternal Morbidity And Mortality ◽

Novel Coronavirus ◽

In Pregnancy

This article presents an unusual case of appendicitis in pregnancy complicated by the novel coronavirus (SARS-CoV-2). The novel coronavirus has affected the way medicine is practised across most parts of the world with over 160 000 000 global cases to date. Tackling management of these cases is more complex when other pathological processes are ongoing. Appendicitis is a common occurrence in pregnancy, with most obstetric centres seeing about one or two cases a year. Though maternal morbidity and mortality are relatively unimpacted by this event, fetal loss and preterm labour are common sequelae. This case involves a 35-year-old woman presenting in her third trimester with abdominal pain and who went on to be diagnosed with concurrent appendicitis and SARS-CoV-2 infection. Although spinal anaesthesia would be most appropriate as it avoids aerosol generation, general anaesthetic techniques were indicated due to thrombocytopenia in this case. She underwent a successful appendicectomy, although preterm delivery was indicated as a result of maternal and fetal concerns.

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Aerosol emission from the respiratory tract: an analysis of aerosol generation from oxygen delivery systems

Thorax ◽

10.1136/thoraxjnl-2021-217577 ◽

2021 ◽

pp. thoraxjnl-2021-217577

Author(s):

Fergus W Hamilton ◽

Florence K A Gregson ◽

David T Arnold ◽

Sadiyah Sheikh ◽

Kirsty Ward ◽

...

Keyword(s):

Respiratory Tract ◽

Healthy Volunteers ◽

Oxygen Delivery ◽

Face Mask ◽

Aerosol Generation ◽

Aerosol Emission ◽

Viral Particles ◽

Hospitalised Patients ◽

Recorded Activity ◽

Aerosol Emissions

Introductioncontinuous positive airway pressure (CPAP) and high-flow nasal oxygen (HFNO) provide enhanced oxygen delivery and respiratory support for patients with severe COVID-19. CPAP and HFNO are currently designated as aerosol-generating procedures despite limited high-quality experimental data. We aimed to characterise aerosol emission from HFNO and CPAP and compare with breathing, speaking and coughing.Materials and methodsHealthy volunteers were recruited to breathe, speak and cough in ultra-clean, laminar flow theatres followed by using CPAP and HFNO. Aerosol emission was measured using two discrete methodologies, simultaneously. Hospitalised patients with COVID-19 had cough recorded using the same methodology on the infectious diseases ward.ResultsIn healthy volunteers (n=25 subjects; 531 measures), CPAP (with exhalation port filter) produced less aerosol than breathing, speaking and coughing (even with large >50 L/min face mask leaks). Coughing was associated with the highest aerosol emissions of any recorded activity. HFNO was associated with aerosol emission, however, this was from the machine. Generated particles were small (<1 µm), passing from the machine through the patient and to the detector without coalescence with respiratory aerosol, thereby unlikely to carry viral particles. More aerosol was generated in cough from patients with COVID-19 (n=8) than volunteers.ConclusionsIn healthy volunteers, standard non-humidified CPAP is associated with less aerosol emission than breathing, speaking or coughing. Aerosol emission from the respiratory tract does not appear to be increased by HFNO. Although direct comparisons are complex, cough appears to be the main aerosol-generating risk out of all measured activities.

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Human Kidney is a Target for Novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection

10.1101/2020.03.04.20031120 ◽

2020 ◽

Cited By ~ 126

Author(s):

Bo Diao ◽

Chenhui Wang ◽

Rongshuai Wang ◽

Zeqing Feng ◽

Yingjun Tan ◽

...

Keyword(s):

Renal Failure ◽

Acute Renal Failure ◽

Immune Cell ◽

Human Kidney ◽

Tubular Damage ◽

Kidney Tubules ◽

Tubular Necrosis ◽

Viral Particles ◽

Direct Cytotoxicity ◽

Novel Coronavirus

SummaryBACKGROUNDThe outbreak of a novel coronavirus (SARS-CoV-2, previously provisionally named 2019 novel coronavirus or 2019-nCoV) since December 2019 in Wuhan, China, has become an emergency of major international concern. Apart from the respiratory system, it is unclear whether SARS-CoV-2 can also directly infect other tissues such as the kidney or induce acute renal failure.METHODSWe conducted a retrospective analysis of estimated glomerular filtration rate (eGFR) along with other clinical parameters from 85 patients with laboratory-confirmed COVID-19 admitted to a hospital in Wuhan from January 17, 2020 to March 3, 2020. Kidney tissues from six patients with postmortem examinations were analyzed by Hematoxylin and Eosin (H&E) and in situ expression of viral nucleocaspid protein (NP) antigen, immune cell markers (CD8, CD68 and CD56) and the complement C5b-9 was detected by immunohistochemistry. Moreover, the viral particles in kidneys were also investigated by transmission electronic microscope (EM).RESULTS27.06% (23/85) patients exhibited acute renal failure (ARF). The eldery patients and cases with comorbidities such as hypertension and heart failure more easily developed ARF (65.22% vs 24.19%, p< 0.001; 69.57% vs 11.29%, p< 0.001, respectively). H&E staining demonstrated kidney tissues from postmortems have severe acute tubular necrosis and lymphocyte infiltration. Immunohistochemistry showed that SARS-CoV-2 NP antigen was accumulated in kidney tubules. EM observation also demonstrated that viruses-like particles are visible in the kidneys. Viral infection not only induces CD68+ macrophages infiltrated into tubulointerstitium, but also enhances complement C5b-9 deposition on tubules.CONCLUSIONSSARS-CoV-2 induces ARF in COVID-19 patients. Viruses directly infect human kidney tubules to induce acute tubular damage. The viruses not only have direct cytotoxicity, but also initiate CD68+ macrophage together with complement C5b-9 deposition to mediate tubular pathogenesis.

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A quantitative evaluation of aerosol generation during manual facemask ventilation

10.1101/2021.08.23.21262441 ◽

2021 ◽

Author(s):

A. J. Shrimpton ◽

J. M. Brown ◽

F. K. A. Gregson ◽

T. M. Cook ◽

D.A. Scott ◽

...

Keyword(s):

Particle Concentration ◽

Direct Evidence ◽

Tidal Breathing ◽

Core Component ◽

Emergency Airway ◽

Aerosol Generation ◽

Aerosol Monitoring ◽

Facemask Ventilation ◽

Background Particle ◽

Made In

SummaryManual facemask ventilation, a core component of elective and emergency airway management, is classified as an aerosol generating procedure. This designation is based on a single epidemiological study suggesting an association between facemask ventilation and transmission from the SARS 2003 outbreak. There is no direct evidence to indicate whether facemask ventilation is a high-risk procedure for aerosol generation. We conducted aerosol monitoring during routine facemask ventilation, and facemask ventilation with an intentionally generated leak, in anaesthetised patients with neuromuscular blockade. Recordings were made in ultraclean theatres and compared against the aerosol generated by the patient’s own tidal breathing and coughs. Respiratory aerosol from tidal breathing was reliably detected above the very low background particle concentrations (191 (77-486 [3.8-1313]) versus 2.1 (0.7-4.6 [0-12.9] particles.l-1 median(IQR)[range], n=11, p=0.002). The average aerosol concentration detected during facemask ventilation both without a leak (3.0 particles.l-1 (0 – 9 [0-43])) and with an intentional leak (11 particles.l-1 (7.0 – 26 [1-62])) was 64-fold and 17-fold lower than that of tidal breathing (p=0.001 and p=0.002 respectively). The peak particle concentration during facemask ventilation both without a leak (60 particles.l-1 (0 – 60 [0-120])) and with a leak (120 particles.l-1 (60 – 180 [60-480]) were respectively 20-fold and 10-fold lower than a cough (1260 particles (800 – 3242 [100-3682]), p=0.002 and p=0.001 respectively). This study demonstrates that facemask ventilation, even performed with an intentional leak, does not generate high levels of bioaerosol. On the basis of this evidence, facemask ventilation should not be considered an aerosol generating procedure.

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Cryogenic Aerosol Generation: Airborne Mist Particles Surrounding Liquid Nitrogen

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17031071 ◽

2020 ◽

Vol 17 (3) ◽

pp. 1071 ◽

Cited By ~ 1

Author(s):

Byung Uk Lee

Keyword(s):

Liquid Nitrogen ◽

Particle Concentration ◽

Fold Increase ◽

Particle Counter ◽

Aerosol Generation ◽

Optical Particle Counter ◽

Generation Mechanisms ◽

Surrounding Liquid

Aerosol mist particles generated near the surface of a liquid nitrogen container were measured and analyzed. The particles present at various distances from the boiling surface of liquid nitrogen were detected using an optical particle counter. In this experiment, 3 micrometer particles exhibited a more than 100-fold increase in concentration due to the liquid nitrogen surface. However, 0.3 micrometer and 10 micrometer particles showed smaller variations (2% to 79%) in their concentrations in the vicinity of liquid nitrogen. The distance from the boiling surface of the liquid nitrogen strongly affected the variations in particle concentration. The variations in aerosol concentrations were significant within 20 cm of the liquid nitrogen surface. These results can be considered as a useful quantitative environmental guideline in cryogenic studies that use liquid nitrogen, and this concept can be applied to cryogenic aerosol mist generation mechanisms.

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Identification of the source events for aerosol generation during oesophago-gastro-duodenoscopy

Gut ◽

10.1136/gutjnl-2021-324588 ◽

2021 ◽

pp. gutjnl-2021-324588

Author(s):

Florence K A Gregson ◽

Andrew J Shrimpton ◽

Fergus Hamilton ◽

Tim M Cook ◽

Jonathan P Reid ◽

...

Keyword(s):

Particle Concentration ◽

Particle Number ◽

Protective Equipment ◽

Average Particle ◽

Respiratory Pathogens ◽

Tidal Breathing ◽

Aerosol Generation ◽

Wide Range ◽

Monitoring Study ◽

Particle Sizer

ObjectiveTo determine if oesophago-gastro-duodenoscopy (OGD) generates increased levels of aerosol in conscious patients and identify the source events.DesignA prospective, environmental aerosol monitoring study, undertaken in an ultraclean environment, on patients undergoing OGD. Sampling was performed 20 cm away from the patient’s mouth using an optical particle sizer. Aerosol levels during OGD were compared with tidal breathing and voluntary coughs within subject.ResultsPatients undergoing bariatric surgical assessment were recruited (mean body mass index 44 and mean age 40 years, n=15). A low background particle concentration in theatres (3 L−1) enabled detection of aerosol generation by tidal breathing (mean particle concentration 118 L−1). Aerosol recording during OGD showed an average particle number concentration of 595 L−1 with a wide range (3–4320 L−1). Bioaerosol-generating events, namely, coughing or burping, were common. Coughing was evoked in 60% of the endoscopies, with a greater peak concentration and a greater total number of sampled particles than the patient’s reference voluntary coughs (11 710 vs 2320 L−1 and 780 vs 191 particles, n=9 and p=0.008). Endoscopies with coughs generated a higher level of aerosol than tidal breathing, whereas those without coughs were not different to the background. Burps also generated increased aerosol concentration, similar to those recorded during voluntary coughs. The insertion and removal of the endoscope were not aerosol generating unless a cough was triggered.ConclusionCoughing evoked during OGD is the main source of the increased aerosol levels, and therefore, OGD should be regarded as a procedure with high risk of producing respiratory aerosols. OGD should be conducted with airborne personal protective equipment and appropriate precautions in those patients who are at risk of having COVID-19 or other respiratory pathogens.

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