A Negative-Pressure Face-Mounted System Reduces Aerosol Spread during Endonasal Endoscopic Surgery.

Purpose Due to the potential risk of COVID-19 transmission during endonasal surgery, we studied methods to reduce droplet and aerosol generation during these procedures. Methods Droplet spread was assessed using ultraviolet light and a camera that detected fluorescence in the operative field and surgeon's personal protective equipment. Density of aerosols sized <10 µm was measured using a photometric particle counter. We designed a face-mounted negative-pressure mask placed on the patients' face during endoscopic endonasal surgery. Sixteen patients were recruited between October 2020 and March 2021 and randomly assigned to the mask and no-mask groups. We compared droplet spread and aerosols generated in both groups, with copious irrigation and continuous suction during drilling forming the mainstay of surgical technique in all cases. Results Droplet contamination due to direct spillage of fluorescein from the syringe was noted in two patients. Aerosol density rose during sphenoid drilling in both groups, with no significant difference when continuous suction and irrigation were employed (1.27 times vs. 1.07 times the baseline, p = 0 .248 ). Aerosol density rose significantly when suction and irrigation were interrupted in the no-mask group (44.9 times vs. 1.2 times, p = 0 .028) , which was not seen when the mask was used. Conclusion Aerosol generation increases during drilling in endonasal procedures and is a concern during this pandemic. The use of a rigid suction close to the drill along with copious irrigation is effective in reducing aerosol spread. The use of a negative pressure mask provides additional safety when inadvertent blockage of suction and inadequate irrigation occur.

Aerosol Generation During Nasal Airway Instrumentation.

OBJECTIVE: Airborne aerosol transmission, an established mechanism of SARS-CoV-2 spread, has been successfully mitigated in the health care setting through the adoption of universal masking. Upper airway endoscopy, however, requires direct access to the face, thereby potentially exposing the clinic environment to infectious particles. This study quantifies aerosol production during rigid nasal endoscopy (RNE) and RNE with debridement (RNED) as compared with intubation, a posited gold standard aerosol-generating procedure. STUDY DESIGN: Prospective cross-sectional study. SETTING: Subspecialty single-center clinic and surgical study. METHOD: Three aerosol detectors (NANOSCAN-3910, OPS-3330, and APS-3321) with a particle size sensitivity of 10 to 20,000 nm were utilized to detect particulate production during the clinical care of 209 patients undergoing RNE/RNED and 25 patients undergoing intubation. RESULTS: RNE and RNED produced statistically significant particles over baseline in 29.3% and 51.0% of subjects (P = .003-.049 and .002-.047, respectively). Intubation produced statistically significant particles in 31.2% (P = .001-.015). The mean ± SD particle diameter in all tests was 69.9 ± 10.5 nm with 99.7% <300 nm. There were no statistical differences in particle production among RNE, RNED, and intubation. The presence of concomitant cough, sneeze, or prolonged speech similarly did not significantly affect particle production during any procedure. CONCLUSIONS: Instrumentation of nasal airway produces airborne aerosols to a similar degree of those seen during intubation, independent of reactive patient behaviors such as cough or sneeze. These data suggest that an improved understanding is necessary of both the definition of an aerosol-generating procedure and the functional consequences of procedural aerosol generation in clinical settings.

Operative Protocol for Testing the Efficacy of Nasal Filters in Preventing Airborne Transmission of SARS-CoV-2.

BACKGROUND: Standardized methods for testing Viral Filtration Efficiency (VFE) of tissues and devices are lacking and few studies are available on aerosolizing, sampling and assessing infectivity of SARS-CoV-2 in controlled laboratory settings. NanoAg-coated endonasal filters appear a promising aid for lowering viable virus inhalation in both adult and younger populations (e.g., adolescents). OBJECTIVE: to provide an adequate method for testing SARS-CoV-2 bioaerosol VFE of bio-gel Ag nanoparticles endonasal filters, by a model system, assessing residual infectivity as cytopathic effect and viral proliferation on in vitro cell cultures. METHODS: A SARS-CoV-2 aerosol transmission chamber fed by a BLAM aerosol generator produces challenges (from very high viral loads (105 PFU/mL) to lower ones) for endonasal filters positioned in a Y shape sampling port connected to a Biosampler. An aerosol generator, chamber and sampler are contained in a class II cabinet in a BSL3 facility. Residual infectivity is assessed from aliquots of liquid collecting bioaerosol, sampled without and with endonasal filters. Cytopathic effect as plaque formation and viral proliferation assessed by qRT-PCR on Vero E6 cells are determined up to 7 days post inoculum. RESULTS: Each experimental setting is replicated three times and basic statistics are calculated. Efficiency of aerosolization is determined as difference between viral load in the nebulizer and in the Biosampler at the first day of experiment. Efficiency of virus filtration is calculated as RNA viral load ratio in collected bioaerosol with and without endonasal filters at the day of the experiment. Presence of infectious virus is assessed by plaque forming unit assay and RNA viral load variations. CONCLUSIONS: A procedure and apparatus for assessing SARS-CoV-2 VFE for endonasal filters is proposed. The apparatus can be implemented for more sophisticated studies on contaminated aerosols.

Diagnostic Performance and Clinical Utility of Conventional PCR Assay in Early Diagnosis of COVID-19 Associated Rhino-Orbito-Cerebral Mucormycosis.

Early diagnosis and treatment of rhino-orbital-cerebral mucormycosis (ROCM) are crucial. Potassium hydroxide with Calcofluorwhite (KOH + CFW) smears can demonstrate the fungal hyphae, but mixed infections caused by both mucorales and non-mucorales pose a diagnostic challenge. Polymerase chain reaction (PCR) can detect mixed infections and differentiate mucorales from non-mucorales. This study aimed to evaluate the utility of a single reaction PCR in the diagnosis of ROCM and the efficacy of nasal biopsy and endonasal swab in the detection of fungus. Sixty-six clinical samples were collected from 33 patients and were subjected to KOH + CFW smear, culture and PCR. PCR was performed using pan-fungal primers targeting the 28S large subunit rRNA gene, and the amplified products were further sequenced to identify the fungi. KOH + CFW smear, culture and PCR detected mucorales in 54.6%, 27.3% and 63.6% patients, respectively. PCR detected mixed infection in 51.5% patients compared to 9.1% by KOH + CFW smear. PCR detected fungus in 90% of nasal biopsies and 77.8% of endonasal swabs. Rhizopus spp. was the most common fungi identified in 43.2% of PCR-positive samples. PCR is effective in detecting mixed infection and in the diagnosis of ROCM. Nasal biopsies had better fungal detection rates than endonasal swabs.

Rapidly Progressive Pituitary Apoplexy in a Patient with COVID-19 Disease Treated with Endoscopic Endonasal Surgery.

This report describes a case of pituitary apoplexy with rapidly evolving hemorrhage in a 74-year-old female with coronavirus disease 2019 (COVID-19) disease. The patient presented with severe headache and mild respiratory symptoms, with laboratories concerning for pituitary hypofunction. Brain imaging demonstrated a sellar mass concerning for a pituitary adenoma with ischemic apoplexy. She subsequently developed visual deficits within 24 hours of presentation, and repeat imaging demonstrated evolving hemorrhage and new mass effect on the optic chiasm. She was successfully managed with urgent endoscopic endonasal surgery despite her COVID-19 positive status by taking special intraoperative precautions to mitigate SARS-CoV2 transmission risk. Only a handful of cases of pituitary apoplexy have been reported in association with COVID-19 disease, and even fewer reports exist of endonasal procedures in such cases. We discuss the potential implication of COVID-19 in the occurrence of pituitary apoplexy, in addition to the safety and success of endonasal surgery in this population.

Current Practices Surrounding Endonasal Skull Base and Pituitary Surgery during COVID-19 Pandemic: A Global Survey

INTRODUCTION: During the Sars-CoV-2 pandemic, Endoscopic Endonasal Surgery (EES) is feared to be a high-risk procedure for transmission of the COVID-19 virus. Nonetheless, data are lacking regarding the management of EES during this pandemic. METHODS: A web-based survey of skull base surgeons worldwide was conducted.Different practices by geographical regions and COVID-19 prevalence were analyzed. RESULTS: 135 unique responses were collected. Regarding the use of personal protection equipment (PPE), North America reported using more powered air-purifying respirators (PAPR) and Asia/Europe using more standard precautions. North America and Europe resorted more to reverse transcriptase polymerase chain reaction (RT-PCR) for screening asymptomatic patients. High prevalence countries showed a higher use of PAPR. The medium prevalence group reported lower RT-PCR testing for symptomatic cases and the high prevalence group used it significantly more in asymptomatic cases. 19 respondents reported healthcare personnel transmission of COVID-19 from EES, with a higher rate of transmission among countries classified as having a medium prevalence of COVID-19. These specific respondents (medium prevalence) also reported a lower use of airborne PPE. In the cases of healthcare transmission, the patient was reportedly asymptomatic 32% of the time. CONCLUSION: This survey gives an overview of EES practices during the Sars-CoV-2 pandemic. Intensified preoperative screening, even in asymptomatic patients, RT-PCR for all symptomatic cases, and an increased use of airborne PPE is associated with decreased reports of COVID-19 transmission during EES.

Suction mask device: a simple, inexpensive, and effective method of reducing spread of aerosolized particles during endoscopic endonasal surgery in the era of COVID-19.

OBJECTIVE: Aerosol-generating procedures, including endoscopic endonasal surgery (EES), are a major risk for physicians during the COVID-19 pandemic. Techniques for reducing aerosolization and risk of transmission of COVID-19 during these procedures would be valuable to the neurosurgical community. The authors aimed to simulate the generation of small-particle aerosols during EES and craniectomy in order to develop methods to reduce the spread of aerosolized particles, and to test the effectiveness of these methods. METHODS: This study was performed at the Anatomical Laboratory for Visuospatial Innovations in Otolaryngology and Neurosurgery at The Ohio State University. The following two scenarios were used to measure three different particle sizes (0.3, 2.5, and 10 µm) generated: 1) drilling frontotemporal bone, simulating a craniectomy; and 2) drilling sphenoid bone, simulating an endonasal approach. A suction mask device was created with the aim of reducing particle release. The presence of particles was measured without suction, with a single Frazier tip suction in the field, and with the suction mask device in addition to the Frazier suction tip. Particles were measured 12 cm from the craniectomy or endonasal drilling region. RESULTS: In the absence of any aerosol-reducing devices, the number of particles measured during craniectomy was significantly higher than that generated by endonasal drilling. This was true regardless of the particle size measured (0.3 µm, p < 0.001; 2.5 µm, p < 0.001; and 10 µm, p < 0.001). The suction mask device reduced the release of particles of all sizes measured in the craniectomy simulation (0.3 µm, p < 0.001; 2.5 µm, p < 0.001; and 10 µm, p < 0.001) and particles of 0.3 µm and 2.5 µm in the single Frazier suction simulation (0.3 µm, p = 0.031; and 2.5 µm, p = 0.026). The suction mask device further reduced the release of particles of all sizes during EES simulation (0.3 µm, p < 0.001; and 2.5 µm, p < 0.001) and particles of 0.3 µm and 2.5 µm in the single Frazier suction simulation (0.3 µm, p = 0.033; and 2.5 µm, p = 0.048). Large particles (10 µm) were not detected during EES. CONCLUSIONS: The suction mask device is a simple and effective means of reducing aerosol release during EES, and it could potentially be used during mastoidectomies. This could be a valuable tool to reduce the risk of procedure-associated viral transmission during the COVID-19 pandemic.

[The role of local antiseptics in the prevention of coronavirus infection during endonasal interventions on the lacrimal ducts]. / Rol' mestnykh antiseptikov v profilaktike koronavirusnoi infektsii pri endonazal'nykh vmeshatel'stvakh na sleznykh putyakh.

In connection with the pandemic of coronavirus infection, it is urgent to develop measures to prevent the intraoperative spread of coronavirus particles and infection of the operating room staff. OBJECTIVE: Generalization and analysis of available data concerning local antiseptic therapy for the prevention of coronavirus infection during endonasal interventions on the lacrimal tract. MATERIAL AND METHODS: The search for literature sources was carried out using MEDLINE search engines and the Russian Science Citation Index for queries with the keywords "COVID-19", "coronavirus infection", "antiseptics", "protocol for otorhinolaryngological operations", "dacryosurgical operations" and similar in various combinations. RESULTS: It has been shown that during endonasal operations on the lacrimal tract, the number of risk factors for infection increases, since these procedures are aerosol-generating, and contact occurs not only with the nasal mucosa, but also with the lacrimal fluid, in which the coronavirus is also replicated. The data on the effectiveness of various antiseptics are summarized, the analysis of the possibility of their use in preoperative preparation for endonasal interventions on the lacrimal tract from the point of view of efficacy and safety is carried out. Information is provided on the proprietary protocol for the use of antiseptics to prevent the spread of coronavirus infection during endonasal dacryocystorhinostomy. It is shown that the preventive use of local disinfectants reduces the number of viral particles on the nasal mucosa, which leads to a decrease in contamination of the surrounding space. Among the available and studied antiseptics, the most suitable is povidone-iodine, which can be used in concentrations up to 1.25% to irrigate the nasal mucosa before surgery with an exposure of 30-60 sec. When performing operations on the lacrimal pathways, it is also advisable to carry out antiseptic treatment of the conjunctival cavity with a 5% solution of povidone-iodine and rinse the lacrimal pathways before the operation with povidone-iodine in a concentration of 0.4%. CONCLUSION: To date, information has been obtained that makes it advisable to use antiseptics before performing endonasal aerosol-generating interventions, in particular endonasal dacryocystorhinostomies and recanalization of the tear ducts.

Adapting management strategies for sellar-suprasellar lesions during the COVID-19 pandemic: a pragmatic approach from the frontline.

PURPOSE: During the ongoing COVID-19 pandemic, endonasal surgeries for sellar-suprasellar lesions were discouraged due to the risk of transmission of the disease. We reviewed the changes in our management protocol for these lesions as our disease understanding and preparedness evolved. MATERIALS AND METHODS: This was a retrospective observational study including patients with sellar-suprasellar and clival lesions presenting to us between March and October 2020. Management protocols were divided into three phases based on the prevalence of the disease and the number of mandatory preoperative COVID-19 tests being conducted. The surgical approach used was analyzed in relation to the preferred approach during pre-COVID times, and surgical outcomes and complications were noted. RESULTS: A total of 31 cases were operated during this period. During Phase I (low prevalence; no preoperative COVID testing) endonasal surgeries were largely abandoned in favor of transcranial approaches. In Phase II (medium prevalence; one preoperative COVID test) we gradually resumed endonasal surgeries for 'emergent' and 'essential' cases, and subsequently in Phase III (high prevalence; two preoperative COVID tests), we had no hesitation in performing 'elective' endonasal surgeries with additional barriers for prevention of aerosol transmission. No patient developed COVID-19 infection postoperatively. Eight HCWs in our department acquired the disease during this period, none of whom were directly involved in the surgeries for the above cohort of patients. CONCLUSIONS: With a strict preoperative COVID testing protocol, adherence to proper drilling techniques and using additional barriers to prevent droplet and aerosol spread, endonasal surgeries for sellar-suprasellar lesions are safe during this COVID-19 pandemic.

COVID-19 Testing in the Era of Modern Neurosurgery: Mitigating Risk in Our Vulnerable Patient Populations.

BACKGROUND: The respiratory illness identified as coronavirus disease 2019 (COVID-19) has resulted in a pandemic illness that has changed the face of healthcare. As the COVID-19 pandemic continues, patients have continued to require neurosurgical interventions, and the endoscopic endonasal approach for surgery has continued to be a mainstay treatment of pituitary tumors and anterior skull base lesions. METHODS: We sought to highlight the current lack of recommendations regarding testing protocols for neurosurgical patients. RESULTS: We implemented a novel testing protocol for our patient populations at increased risk and have proposed a model that can be used at other institutions to mitigate the risk of complications associated with some forms of COVID-19 testing. CONCLUSION: Patients with anterior skull base defects may be at risk with current COVID-19 testing protocols, and may benefit from alternative specimen collection strategies.

A Novel Negative Pressure, Face-Mounted Antechamber to Minimize Aerosolization of Particles During Endoscopic Skull Base Surgery.

BACKGROUND: The COVID-19 pandemic has revealed deficiencies in the adequacy of personal protective equipment (PPE) for healthcare workers. Endoscopic endonasal skull base surgery is thought to be among the highest-risk aerosol-generating procedures for surgeons and operating room personnel. OBJECTIVE: To validate the efficacy and clinical feasibility of a novel surgical device. METHODS: A low-cost, modifiable, and easily producible negative pressure, face-mounted antechamber was developed utilizing 3D printing and silicone molding. Efficacy was evaluated using an optical particle sizer to quantify aerosols generated during both cadaver and intraoperative human use with high-speed drilling. RESULTS: Particle counts in the cadaver showed that drilling led to a 2.49-fold increase in particles 0.3 to 5 µm (P = .001) and that the chamber was effective at reducing particles to levels not significantly different than baseline. In humans, drilling led to a 37-fold increase in particles 0.3 to 5 µm (P < .001), and the chamber was effective at reducing particles to a level not significantly different than baseline. Use of the antechamber in 6 complex cases did not interfere with the ability to perform surgery. Patients did not report any facial discomfort after surgery related to antechamber use. CONCLUSION: The use of a negative pressure facial antechamber can effectively reduce aerosolization from endoscopic drilling without disturbing the flow of the operation. The antechamber, in conjunction with appropriate PPE, will be useful during the COVID-19 pandemic, as well as during flu season and any future viral outbreaks.

CSF Rhinorrhea After Endonasal Intervention to the Skull Base (CRANIAL) - Part 2: Impact of COVID-19.

BACKGROUND: During the coronavirus disease 2019 (COVID-19) pandemic, concerns have been raised regarding the increased risk of perioperative mortality for patients with COVID-19, and the transmission risk to healthcare workers, especially during endonasal neurosurgical operations. The Pituitary Society has produced recommendations to guide management during this era. We sought to assess contemporary neurosurgical practice and the effects of COVID-19. METHODS: A multicenter prospective observational cohort study was conducted at 12 tertiary neurosurgical units (United Kingdom and Ireland). Data were collected from March 23 to July 31, 2020, inclusive. The data points collected included patient demographics, preoperative COVID-19 test results, operative modifications, and 30-day COVID-19 infection rates. RESULTS: A total of 124 patients were included. Of the 124 patients, 116 (94%) had undergone COVID-19 testing preoperatively (transsphenoidal approach, 97 of 105 [92%]; expanded endoscopic endonasal approach, 19 of 19 [100%]). One patient (1 of 116 [0.9%]) had tested positive for COVID-19 preoperatively, requiring a delay in surgery until the infection had been confirmed as resolved. Other than transient diabetes insipidus, no other complications were reported for this patient. All operating room staff had worn at least level 2 personal protective equipment. Adaptations to surgical techniques included minimizing drilling, draping modifications, and the use of a nasal iodine wash. At 30 days postoperatively, no evidence of COVID-19 infection (symptoms or positive formal testing results) were found in our cohort and no mortality had occurred. CONCLUSIONS: Preoperative screening protocols and operative modifications have facilitated endonasal neurosurgery during the COVID-19 pandemic, with the Pituitary Society guidelines followed for most of these operations. We found no evidence of COVID-19 infection in our cohort and no mortality, supporting the use of risk mitigation strategies to continue endonasal neurosurgery in subsequent pandemic waves.

Droplet and Aerosol Generation With Endonasal Surgery: Methods to Mitigate Risk During the COVID-19 Pandemic.

OBJECTIVE: To define the aerosol and droplet risks associated with endonasal drilling and to identify mitigation strategies. STUDY DESIGN: Simulation series with fluorescent 3-dimensional (3D) printed sinonasal models and deidentified cadaveric heads. SETTINGS: Dedicated surgical laboratory. SUBJECTS AND METHODS: Cadaveric specimens irrigated with fluorescent tracer and fluorescent 3D-printed models were drilled. A cascade impactor was used to collect aerosols and small droplets of various aerodynamic diameters under 15 µm. Large droplet generation was measured by evaluating the field for fluorescent debris. Aerosol plumes through the nares were generated via nebulizer, and mitigation measures, including suction and SPIWay devices, nasal sheaths, were evaluated regarding reduction of aerosol escape from the nose. RESULTS: The drilling of cadaveric specimens without flexible suction generated aerosols ≤3.30 µm, and drilling of 3D sinonasal models consistently produced aerosols ≤14.1 µm. Mitigation with SPIWay or diameter-restricted SPIWay produced same results. There was minimal field contamination in the cadaveric models, 0% to 2.77% field tarp area, regardless of drill burr type or drilling location; cutting burr drilling without suction in the 3D model yielded the worst contamination field (36.1%), followed by coarse diamond drilling without suction (19.4%). The simple placement of a flexible suction instrument in the nasal cavity or nasopharynx led to complete elimination of all aerosols ≤14.1 µm, as evaluated by a cascade impactor positioned immediately at the nares. CONCLUSION: Given the findings regarding aerosol risk reduction, we strongly recommend that physicians use a suction instrument in the nasal cavity or nasopharynx during endonasal surgery in the COVID-19 era.

Skull Base Aerosol Generating Cases Amidst the COVID-19 Pandemic: An Experience from the Epicenter.

Soon after the World Health Organization declared the severe acute respiratory syndrome coronavirus 2 a global health emergency on January 30, 2020, New York City was plagued by the virus and its health system and economy pushed to their limits. The majority of the limited neurosurgical data in relation to COVID-19 is anecdotal and the higher theoretical risk of transmission of the virus among skull base aerosol generating (SBAG) cases has not been investigated or discussed in a neurosurgical population. We discuss a series of 13 patients who underwent 15 SBAG surgical procedures during the peak of COVID-19 in our hospital system and the protocols use perioperatively for their procedures. Our data support that with proper preoperative testing, a well-delineated surgical algorithm, and appropriate personal protective equipment, emergent/urgent cases can be done safely in hospitals that are currently experiencing high volumes of COVID-19 cases as we did in March to May of 2020.

Aerosolisation in endonasal endoscopic pituitary surgery.

PURPOSE: To determine the particle size, concentration, airborne duration and spread during endoscopic endonasal pituitary surgery in actual patients in a theatre setting. METHODS: This observational study recruited a convenience sample of three patients. Procedures were performed in a positive pressure operating room. Particle image velocimetry and spectrometry with air sampling were used for aerosol detection. RESULTS: Intubation and extubation generated small particles (< 5 µm) in mean concentrations 12 times greater than background noise (p < 0.001). The mean particle concentrations during endonasal access were 4.5 times greater than background (p = 0.01). Particles were typically large (> 75 µm), remained airborne for up to 10 s and travelled up to 1.1 m. Use of a microdebrider generated mean aerosol concentrations 18 times above baseline (p = 0.005). High-speed drilling did not produce aerosols greater than baseline. Pituitary tumour resection generated mean aerosol concentrations less than background (p = 0.18). Surgical drape removal generated small and large particles in mean concentrations 6.4 times greater than background (p < 0.001). CONCLUSION: Intubation and extubation generate large amounts of small particles that remain suspended in air for long durations and disperse through theatre. Endonasal access and pituitary tumour resection generate smaller concentrations of larger particles which are airborne for shorter periods and travel shorter distances.

Aerosol generation during routine rhinologic surgeries and in-office procedures.

OBJECTIVE: Cadaveric simulations have shown endonasal drilling and cautery generate aerosols, which is a significant concern for otolaryngologists during the COVID-19 era. This study quantifies aerosol generation during routine rhinologic surgeries and in-office procedures in live patients. METHODS: Aerosols ranging from 0.30 to 10.0 µm were measured in real-time using an optical particle sizer during surgeries and in-office procedures. Various mask conditions were tested during rigid nasal endoscopy (RNE) and postoperative debridement (POD). RESULTS: Higher aerosol concentrations (AC) ranging from 2.69 to 10.0 µm were measured during RNE (n = 9) with no mask vs two mask conditions (P = .002 and P = .017). Mean AC (0.30-10.0 µm) were significantly higher during POD (n = 9) for no mask vs a mask covering the patient's mouth condition (mean difference = 0.16 ± 0.03 particles/cm3, 95% CI 0.10-0.22, P < .001). There were no discernible spikes in aerosol levels during endoscopic septoplasty (n = 3). Aerosol spikes were measured in two of three functional endoscopic sinus surgeries (FESS) with microdebrider. Using suction mitigation, there were no discernible spikes during powered drilling in two anterior skull base surgeries (ASBS). CONCLUSION: Use of a surgical mask over the patient's mouth during in-office procedures or a mask with a slit for an endoscope during RNE significantly diminished aerosol generation. However, whether this reduction in aerosol generation is sufficient to prevent transmission of communicable diseases via aerosols was beyond the scope of this study. There were several spikes in aerosols during FESS and ASBS, though none were associated with endonasal drilling with the use of suction mitigation. LEVEL OF EVIDENCE: 4.