Droplet and Aerosol Generation With Mastoidectomy During the COVID-19 Pandemic: Assessment of Baseline Risk and Mitigation Measures With a High-performance Cascade Impactor.

HYPOTHESIS: Aerosols are generated during mastoidectomy and mitigation strategies may effectively reduce aerosol spread. BACKGROUND: An objective understanding of aerosol generation and the effectiveness of mitigation strategies can inform interventions to reduce aerosol risk from mastoidectomy and other open surgeries involving drilling. METHODS: Cadaveric and fluorescent three-dimensional printed temporal bone models were drilled under variable conditions and mitigation methods. Aerosol production was measured with a cascade impactor set to detect particle sizes under 14.1 µm. Field contamination was determined with examination under UV light. RESULTS: Drilling of cadaveric bones and three-dimensional models resulted in strongly positive aerosol production, measuring positive in all eight impactor stages for the cadaver trials. This occurred regardless of using coarse or cutting burs, irrigation, a handheld suction, or an additional parked suction. The only mitigation factor that led to a completely negative aerosol result in all eight stages was placing an additional microscope drape to surround the field. Bone dust was scattered in all directions from the drill, including on the microscope, the surgeon, and visually suspended in the air for all but the drape trial. CONCLUSIONS: Aerosols are generated with drilling the mastoid. Using an additional microscope drape to cover the surgical field was an effective mitigation strategy to prevent fine aerosol dispersion while drilling.

Heads-up Surgery: Endoscopes and Exoscopes for Otology and Neurotology in the Era of the COVID-19 Pandemic.

A new era of surgical visualization and magnification is poised to disrupt the field of otology and neurotology. The once revolutionary benefits of the binocular microscope now are shared with rigid endoscopes and exoscopes. These 2 modalities are complementary. The endoscope improves visualization of the hidden recesses through the external auditory canal or canal-up mastoidectomy. The exoscope provides an immersive visual experience and superior ergonomics compared with binocular microscopy. Endoscopes and exoscopes are poised to disrupt the standard of care for surgical visualization and magnification in otology and neurotology.

Exoscope-assisted Otologic Surgery During the COVID-19 Pandemic.

OBJECTIVE: The recent COVID-19 pandemic has required careful reconsideration of safe operating room practices. We describe our initial experiences performing otologic surgery with the exoscope during the COVID-19 pandemic. METHOD: The exoscope was used for several semiurgent otologic surgeries in combination with complete eye protection, a "tent" drape, a smoke evacuator with ultra-low particulate air filter, and betadine irrigation. These techniques are demonstrated in the accompanying video. This was compared with our experiences using the microscope. RESULTS: The described modified goggles allowed complete eye protection while providing a fully three-dimensional view of the surgical site. The other safety measures described are simple and efficient techniques which can easily be adopted for otologic surgery using the microscope. CONCLUSION: Use of the exoscope for otologic surgery during the COVID-19 pandemic allows full three-dimensional visualization of the surgical field while simultaneously providing complete eye protection. Use of the "tent" drape, ultra-low particulate air filter, and betadine irrigation are also options that otologic surgeons may consider for additional safety.

Droplet and bone dust contamination from high-speed drilling during mastoidectomy.

OBJECTIVES: The aim of this study was to examine contamination from otolaryngologic procedures involving high-speed drilling, specifically mastoid surgery, and to assess the adequacy of PPE in such procedures. DESIGN AND SETTING: Mastoid surgery was simulated in a dry laboratory using a plastic temporal bone, microscope and handheld drill with irrigation and suction. Comparisons of distance of droplet and bone dust contamination and surgeon contamination were made under differing conditions. Irrigation speed, use of microscope and drill burr size and type were compared. MAIN OUTCOME MEASURES: Measurement of the distance of field contamination while performing simulated mastoidectomy and location of surgeon contamination. RESULTS: There was a greater distance field contamination and surgeon contamination without the use of the microscope. Contamination was reduced by using a smaller drill burr and by using a diamond burr when compared to a cutting burr. The use of goggles and a face mask provided good protection for the surgeon. However, the microscope alone may provide sufficient protection to negate the need for goggles. CONCLUSIONS: While the risks of performing mastoid surgery during the coronavirus pandemic cannot be completely removed, they can be mitigated. Such factors include using the microscope for all drilling, using smaller size drill burrs and creating a safe zone around the operating table.

Use of a novel drape 'tent' as an infection prevention control measure for mastoid surgery.

BACKGROUND: Mastoid surgery is an aerosol-generating procedure that involves the use of a high-speed drill, which produces a mixture of water, bone, blood and tissue that may contain the viable coronavirus disease 2019 pathogen. This potentially puts the surgeon and other operating theatre personnel at risk of acquiring the severe acute respiratory syndrome coronavirus-2 from contact with droplets or aerosols. The use of an additional drape designed to limit the spread of droplets and aerosols has been described; such drapes include the 'Southampton Tent' and 'OtoTent'. OBJECTIVES: To evaluate the use of a novel drape 'tent' that has advantages over established 'tent' designs in terms of having: (1) a CE marking; (2) no requirement for modification during assembly; and (3) no obstruction to the surgical visual field. RESULTS AND CONCLUSION: During mastoid surgery, the dispersion of macroscopic droplets and other particulate matter was confined within the novel drape 'tent'. Use of this drape 'tent' had no adverse effects upon the surgeon's manual dexterity or efficiency, the view of the surgical field, or the sterility. Hence, our findings support its use during mastoid surgery in the coronavirus disease 2019 era.

Effect of Personal Protection Equipment (PPE) and the Distance From the Eye Piece of Surgical Microscope on the Field of Vision; An Experimental Study.

BACKGROUND: During the Covid-19 pandemic, otolaryngologists are at risk due to aerosol-generating procedures such as mastoidectomy and need enhanced personal protective equipment (PPE). Eye protection can interfere with the use of a microscope due to a reduction in the field of vision. We aimed to study the effect of PPE on the microsurgical field. METHODS: Five surgeons measured the visual field using digital calipers at different power settings. They were done with no PPE, a surgical mask, FFP3 mask (N99), and with the addition of small goggles, large vistamax goggles, vistamax plus a face shield, and only a face shield. The measurements were repeated with rings of 5 mm increments. We also measured the "eye relief" of the microscope which is the ideal distance for maximum field of view. RESULTS: There was no major reduction of the field with the surgical or FFP3 mask. But even simple goggles reduced the field up to 31.6% and there were progressive reductions of up to 75.7% with large goggles, 76.8% when a face shield was added, and 61.9% when only face shield was used. The distance rings more than 5 mm also affected the field of view.The eye relief of our eyepiece was found to be 15 mm. CONCLUSION: The current PPE eye protection is not compatible with the use of a microscope. There is scope for research into better eye protection. Mitigation strategies including barrier drapes and alternative techniques such as endoscopic surgery or use of exoscopes should also be considered.

Two-drape closed pocket technique: minimizing aerosolization in mastoid exploration during COVID-19 pandemic.

BACKGROUND: Mastoidectomy is associated with extensive bone-drilling which makes it a major aerosol generating procedure. Considering the ongoing COVID-19 global pandemic, it is essential to devise methods to minimize aerosolization and hence ensure safety of the healthcare workers during the operative procedure. METHODS: Two disposable surgical drapes are used to create a closed pocket prior to commencement of mastoid bone-drilling. This limits aerosolization of bone-dust in the external operating theatre environment. CONCLUSION: Two-drape closed pocket technique is an easy, cost-effective and safe method to limit aerosolization of tissue particles during mastoidectomy.

COVID-19 and ear endoscopy in otologic practices.

PURPOSE: Otolaryngologists have had to postpone the majority of surgical procedures in the current COVID-19 pandemic. Airborne transmission, beyond the projection of droplets from upper airways, expose healthcare workers to a risk of viral infection. Aerosol generating procedures (AGP) increase the risk of viral transmission to staff within the operating room. METHODS: Surgery of middle ear and mastoid is also considered an AGP, particularly mastoidectomy performed using a high-speed drill. The authors report their experience in endoscopic ear surgery as an alternative technique to reduce AGP in otologic procedures. RESULTS: Transcanal endoscopic ear surgery is a reliable technique used to manage many otologic conditions. CONCLUSION: The endoscopic approach may reduce the risk of viral transmission to operating room staff by reducing the need for mastoidectomy.

The challenge of performing mastoidectomy using the operating microscope with coronavirus disease 2019 personal protective equipment (PPE).

OBJECTIVE: Mastoidectomy is considered an aerosol-generating procedure. This study examined the effect of wearing personal protective equipment on the view achieved using the operating microscope. METHODS: ENT surgeons assessed the area of a calibrated target visible through an operating microscope whilst wearing a range of personal protective equipment, with prescription glasses when required. The distance between the surgeon's eye and the microscope was measured in each personal protective equipment condition. RESULTS: Eleven surgeons participated. The distance from the eye to the microscope inversely correlated with the diameter and area visible (p < 0.001). The median area visible while wearing the filtering facepiece code 3 mask and full-face visor was 4 per cent (range, 4-16 per cent). CONCLUSION: The full-face visor is incompatible with the operating microscope. Solutions offering adequate eye protection for aerosol-generating procedures that require the microscope, including mastoidectomy, are urgently needed. Low-profile safety goggles should have a working distance of less than 20 mm and be compatible with prescription lenses.

Aerosol Dispersion During Mastoidectomy and Custom Mitigation Strategies for Otologic Surgery in the COVID-19 Era.

OBJECTIVE: To investigate small-particle aerosolization from mastoidectomy relevant to potential viral transmission and to test source-control mitigation strategies. STUDY DESIGN: Cadaveric simulation. SETTING: Surgical simulation laboratory. METHODS: An optical particle size spectrometer was used to quantify 1- to 10-µm aerosols 30 cm from mastoid cortex drilling. Two barrier drapes were evaluated: OtoTent1, a drape sheet affixed to the microscope; OtoTent2, a custom-structured drape that enclosed the surgical field with specialized ports. RESULTS: Mastoid drilling without a barrier drape, with or without an aerosol-scavenging second suction, generated large amounts of 1- to 10-µm particulate. Drilling under OtoTent1 generated a high density of particles when compared with baseline environmental levels (P < .001, U = 107). By contrast, when drilling was conducted under OtoTent2, mean particle density remained at baseline. Adding a second suction inside OtoTent1 or OtoTent2 kept particle density at baseline levels. Significant aerosols were released upon removal of OtoTent1 or OtoTent2 despite a 60-second pause before drape removal after drilling (P < .001, U = 0, n = 10, 12; P < .001, U = 2, n = 12, 12, respectively). However, particle density did not increase above baseline when a second suction and a pause before removal were both employed. CONCLUSIONS: Mastoidectomy without a barrier, even when a second suction was added, generated substantial 1- to 10-µm aerosols. During drilling, large amounts of aerosols above baseline levels were detected with OtoTent1 but not OtoTent2. For both drapes, a second suction was an effective mitigation strategy during drilling. Last, the combination of a second suction and a pause before removal prevented aerosol escape during the removal of either drape.

Demonstration and Mitigation of Aerosol and Particle Dispersion During Mastoidectomy Relevant to the COVID-19 Era.

BACKGROUND: COVID-19 has become a global pandemic with a dramatic impact on healthcare systems. Concern for viral transmission necessitates the investigation of otologic procedures that use high-speed drilling instruments, including mastoidectomy, which we hypothesized to be an aerosol-generating procedure. METHODS: Mastoidectomy with a high-speed drill was simulated using fresh-frozen cadaveric heads with fluorescein solution injected into the mastoid air cells. Specimens were drilled for 1-minute durations in test conditions with and without a microscope. A barrier drape was fashioned from a commercially available drape (the OtoTent). Dispersed particulate matter was quantified in segments of an octagonal test grid measuring 60 cm in radius. RESULTS: Drilling without a microscope dispersed fluorescent particles 360 degrees, with the areas of highest density in quadrants near the surgeon and close to the surgical site. Using a microscope or varying irrigation rates did not significantly reduce particle density or percent surface area with particulate. Using the OtoTent significantly reduced particle density and percent surface area with particulate across the segments of the test grid beyond 30 cm (which marked the boundary of the OtoTent) compared with the microscope only and no microscope test conditions (Kruskall-Wallis test, p = 0.0066). CONCLUSIONS: Mastoidectomy with a high-speed drill is an aerosol-generating procedure, a designation that connotes the potential high risk of viral transmission and need for higher levels of personal protective equipment. A simple barrier drape significantly reduced particulate dispersion in this study and could be an effective mitigation strategy in addition to appropriate personal protective equipment.