A quantitative evaluation of aerosol generation during supraglottic airway insertion and removal

Abstract

Many guidelines consider supraglottic airway use to be an aerosol-generating procedure. This status requires increased levels of personal protective equipment, fallow time between cases and results in reduced operating theatre efficiency. Aerosol generation has never been quantitated during supraglottic airway use. To address this evidence gap, we conducted real-time aerosol monitoring (0.3-10-µm diameter) in ultraclean operating theatres during supraglottic airway insertion and removal. This showed very low background particle concentrations (median (IQR [range]) 1.6 (0-3.1 [0-4.0]) particles.l À1 ) against which the patient's tidal breathing produced a higher concentration of aerosol (4.0 (1.3-11.0 [0-44]) particles.l À1 , p = 0.048). The average aerosol concentration detected during supraglottic airway insertion (1.3 (1.0-4.2 [0-6.2]) particles.l À1 , n = 11), and removal (2.1 (0-17.5 [0-26.2]) particles.l À1 , n = 12) was no different to tidal breathing (p = 0.31 and p = 0.84, respectively). Comparison of supraglottic airway insertion and removal with a volitional cough (104 (66-169 [33-326]), n = 27), demonstrated that supraglottic airway insertion/removal sequences produced <4% of the aerosol compared with a single cough (p < 0.001). A transient aerosol increase was recorded during one complicated supraglottic airway insertion (which initially failed to provide a patent airway). Detailed analysis of this event showed an atypical particle size distribution and we subsequently identified multiple sources of nonrespiratory aerosols that may be produced during airway management and can be considered as artefacts. These findings demonstrate supraglottic airway insertion/removal generates no more bio-aerosol than breathing and far less than a cough. This should inform the design of infection prevention strategies for anaesthetists and operating theatre staff caring for patients managed with supraglottic airways.

Quantitative evaluation of aerosol generation during manual facemask ventilation

“…Inter‐patient variation was considerable and ranged up to 50‐fold for tidal breathing and 36‐fold during coughing. This is in keeping with previous studies performed by the AERATOR group and others [ 6 , 8 , 11 , 12 , 16 ]. Therefore, using each participant as their own reference increases the power to generate meaningful comparisons from a relatively small sample.…”

“…In brief, a prospective environmental monitoring study was conducted in operating theatres in a UK hospital (Southmead Hospital, North Bristol NHS Trust). All recordings were made within operating theatres with an ultraclean ventilation system (EXFLOW 32, Howorth Air Technology, Farnworth, UK) placed in standby mode [ 11 , 12 ]. This provides an environment with: very low background aerosol concentrations; an air change rate of 25 changes.h ‐1 (in line with most other operating theatres in the UK); an air velocity of 0.25 m.s ‐1 at 1 m above the ground; an air temperature of 20˚C; and relative humidity of 40–60%.…”

Lessons from COVID‐19: A reflection on the strengths and weakness of early consensus recommendations for pediatric difficult airway management during a respiratory viral pandemic using a modified Delphi method

“…question in light of more recent evidence. 16,[19][20][21][22][23][24] The panel recommended that cases not be used for educational purposes and only be managed by very senior trainees or fully credentialed staff in the interest of minimizing the number of clinicians exposed to the risk transmission from patients. Some key principles hold for both prepandemic and patients with COVID-19 disease.…”

“…Recent evaluation of aerosol generation with SGA insertion and removal without neuromuscular blockade found that these events were associated with similar levels of aerosol generation as calm, tidal breathing and less than a volitional cough. 24 The clinician should chose the induction technique based on the clinical situation at hand and his or her own familiarity and comfort with the selected technique.…”

Pre‐operative SARS‐CoV‐2 testing, isolation, vaccination and remote prehabilitation – the road to ‘COVID‐19 secure’ elective surgery

“…Enforcing and adherence to isolation is also increasingly impractical. Moreover, nosocomial transmission is a hospital‐related problem, and organisations must think about other areas where gains can be made, such as: mandating the use of airborne precautions for those caring for COVID‐19 patients on wards; rethinking practices around ‘aerosol‐generating procedures’ in patients who do not have COVID‐19 [ 16 ]; and ensuring adequate ventilation in all indoor spaces. Offering elective surgery to a patient who has refused a vaccine, where it is free and available, will continue to present a moral dilemma for many.…”