Aerosol and droplet generation from mandible and midface fixation: Surgical risk in the pandemic era

Aerosol generation during pediatric otolaryngological procedures

OBJECTIVES

To assess the extent of staff exposure to aerosol generation in common pediatric otorhinolaryngological procedures (tonsillotomies, adenoidectomies, and tympanostomies) and determine the surgical phases responsible for most aerosol generation in these procedures.

METHODS

Aerosol generation was measured during 35 pediatric otolaryngological procedures using an Optical Particle Sizer that measures aerosol concentrations for particle sizes between 0.3 and 10.0 μm. The different phases of and instruments used in each procedure were logged. Operating room background aerosol levels and coughing were used as references.

RESULTS

Total aerosol concentrations were significantly higher during tonsillotomies and adenoidectomies when compared to tympanostomies (p = 0.011 and p = 0.042) and to empty room background aerosol concentrations (p = 0.0057 and p < 0.001). Aerosol concentration during tonsillotomies did not differ from coughing, which is considered as standard for high-risk aerosol procedures. During tympanostomies, aerosol concentrations were even lower than during perioperative concentrations. No statistically significant difference in aerosol generation comparing suction, electrocautery, cold instruments, and paracentesis was found.

CONCLUSION

According to the results of this study, tympanostomies are low-risk aerosol-generating procedures. On the other hand, pediatric tonsillotomies produced aerosols comparable to coughing, pointing to them being significantly aerosol-producing procedures and viral transmission is theoretically possible intraoperatively.

Aerosol and Droplet Generation from Open Rhinoplasty: Surgical Risk in the Pandemic Era

Introduction: The coronavirus disease 2019 pandemic has led to concerns over transmission risk from head and neck operations including facial cosmetic surgeries. Objectives: To quantify droplet and aerosol generation from rhinoplasty techniques in a human anatomic specimen model using fluorescein staining and an optical particle sizer. Methods: Noses of human anatomic specimens were infiltrated using 0.1% fluorescein. Droplets and aerosols were measured during rhinoplasty techniques including opening the skin-soft tissue envelope, monopolar electrocautery, endonasal rasping, endonasal osteotomy, and percutaneous osteotomy. Results: No visible droplet contamination was observed for any rhinoplasty techniques investigated. Compared with the negative control of anterior rhinoscopy, total 0.300-10.000 μm aerosols were increased after monopolar electrocautery (p < 0.001) and endonasal rasp (p = 0.003). Opening the skin-soft tissue envelope, endonasal osteotomies, and percutaneous osteotomies did not generate a detectable increase in aerosols (p > 0.15). Discussion and Conclusions: In this investigation, droplets were not observed under ultraviolet light, and aerosol generation was noted only with cautery and endonasal rasping.

Quantifying strategies to minimize aerosol dispersion in dental clinics

Many dental procedures are aerosol-generating and pose a risk for the spread of airborne diseases, including COVID-19. Several aerosol mitigation strategies are available to reduce aerosol dispersion in dental clinics, such as increasing room ventilation and using extra-oral suction devices and high-efficiency particulate air (HEPA) filtration units. However, many questions remain unanswered, including what the optimal device flow rate is and how long after a patient exits the room it is safe to start treatment of the next patient. This study used computational fluid dynamics (CFD) to quantify the effectiveness of room ventilation, an HEPA filtration unit, and two extra-oral suction devices to reduce aerosols in a dental clinic. Aerosol concentration was quantified as the particulate matter under 10 µm (PM10) using the particle size distribution generated during dental drilling. The simulations considered a 15 min procedure followed by a 30 min resting period. The efficiency of aerosol mitigation strategies was quantified by the scrubbing time, defined as the amount of time required to remove 95% of the aerosol released during the dental procedure. When no aerosol mitigation strategy was applied, PM10 reached 30 µg/m3 after 15 min of dental drilling, and then declined gradually to 0.2 µg/m3 at the end of the resting period. The scrubbing time decreased from 20 to 5 min when the room ventilation increased from 6.3 to 18 air changes per hour (ACH), and decreased from 10 to 1 min when the flow rate of the HEPA filtration unit increased from 8 to 20 ACH. The CFD simulations also predicted that the extra-oral suction devices would capture 100% of the particles emanating from the patient's mouth for device flow rates above 400 L/min. In summary, this study demonstrates that aerosol mitigation strategies can effectively reduce aerosol concentrations in dental clinics, which is expected to reduce the risk of spreading COVID-19 and other airborne diseases.

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.

Conclusions

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.

Inanimate surface contamination of SARS-CoV-2 during midfacial fracture repair in asymptomatic COVID-19 patients

Purposes

To evaluate inanimate surface contamination of SARS-CoV-2 during midfacial fracture repair (MFR) and to identify relevant aggregating factors.

Methods

Using a prospective non-randomised comparative study design, we enrolled a cohort of asymptomatic COVID-19 patients undergoing MFR. The predictor variables were osteofixation system (conventional titanium plates [CTiP] vs. ultrasound-assisted resorbable plates [USaRP]). The main outcomes were the presence of SARS-CoV-2 on four different surfaces. Other study variables were categorised into demographic, anatomical, and operative. Descriptive, bi- and multivariate statistics were computed.

Results

The sample consisted of 11 patients (27.3% females, 63.6% right side, 72.7% displaced fractures) with a mean age of 52.7 ± 20.1 years (range, 19–85). Viral spread was, on average, 1.9 ± 0.4 m. from the operative field, including most oral and orbital retractors’ tips (81.8% and 72.7%) and no virus was found at 3 m from the operative field, but no significant difference was found between 2 osteofixation types. On binary adjustments, significantly broader contamination was linked to centrolateral MFR (P = 0.034; 95% confidence interval [CI], 0.05 to 1.02), and displaced MFR > 45 min (P = 0.022; 95% CI, 0.1 to 1.03).

Conclusions

USaRP, albeit presumably heavily aerosol-producing, cause similar SARS-CoV-2 distribution to CTiP. Non-surgical operating room (OR) staff should stay ≥ 3 m from the operative field, if the patient is SARS-CoV-2-positive. Enoral and orbital instruments are a potential virus source, especially during displaced MFR > 45 min and/or centrolateral MFR, emphasising an importance of appropriate patient screening and OR organisation.

Aerosol Generation During Laryngology Procedures in the Operating Room

OBJECTIVE

Severe acute respiratory syndrome coronavirus-2 spreads through respiratory fluids. We aim to quantify aerosolized particles during laryngology procedures to understand their potential for transmission of infectious aerosol-based diseases.

STUDY DESIGN

Prospective quantification of aerosol generation.

METHODS

Airborne particles (0.3-25 μm in diameter) were measured during live-patient laryngology surgeries using an optical particle counter positioned 60 cm from the oral cavity to the surgeon's left. Measurements taken during the procedures were compared to baseline concentrations recorded immediately before each procedure. Procedures included direct laryngoscopy with general endotracheal anesthesia (GETA), direct laryngoscopy with jet ventilation, and carbon dioxide (CO₂ ) laser use with or without jet ventilation, all utilizing intermittent suction.

RESULTS

Greater than 99% of measured particles were 0.3 to 1.0 μm in diameter. Compared to baseline, direct laryngoscopy was associated with a significant 6.71% increase in cumulative particles, primarily 0.3 to 1.0 μm particles (P < .0001). 1.0 to 25 μm particles significantly decreased (P < .001). Jet ventilation was not associated with a significant change in cumulative particles; when analyzing differential particle sizes, only 10 to 25 μm particles exhibited a significant increase compared to baseline (+42.40%, P = .002). Significant increases in cumulative particles were recorded during CO₂ laser use (+14.70%, P < .0001), specifically in 0.3 to 2.5 μm particles. Overall, there was no difference when comparing CO₂ laser use during jet ventilation versus GETA.

CONCLUSIONS

CO₂ laser use during laryngology surgery is associated with significant increases in airborne particles. Although direct laryngoscopy with GETA is associated with slight increases in particles, jet ventilation overall does not increase particle aerosolization.

LEVEL OF EVIDENCE

III Laryngoscope, 2021.

Aerosol and droplet generation from orbital repair: Surgical risk in the pandemic era

INTRODUCTION

The highly contagious COVID-19 has resulted in millions of deaths worldwide. Physicians performing orbital procedures may be at increased risk of occupational exposure to the virus due to exposure to secretions. The goal of this study is to measure the droplet and aerosol production during repair of the inferior orbital rim and trial a smoke-evacuating electrocautery handpiece as a mitigation device.

MATERIAL AND METHODS

The inferior rim of 6 cadaveric orbits was approached transconjunctivally using either standard or smoke-evacuator electrocautery and plated using a high-speed drill. Following fluorescein inoculation, droplet generation was measured by counting under ultraviolet-A (UV-A) light against a blue background. Aerosol generation from 0.300-10.000 μm was measured using an optical particle sizer. Droplet and aerosol generation was compared against retraction of the orbital soft tissue as a negative control.

RESULTS

No droplets were observed following the orbital approach using electrocautery. Visible droplets were observed after plating with a high-speed drill for 3 of 6 orbits. Total aerosol generation was significantly higher than negative control following the use of standard electrocautery. Use of smoke-evacuator electrocautery was associated with significantly lower aerosol generation in 2 of 3 size groups and in total. There was no significant increase in total aerosols associated with high-speed drilling.

DISCUSSION AND CONCLUSIONS

Droplet generation for orbital repair was present only following plating with high-speed drill. Aerosol generation during standard electrocautery was significantly reduced using a smoke-evacuating electrocautery handpiece. Aerosols were not significantly increased by high-speed drilling.