Table 3.

Efficacy – Quantitative results, review of particle counter studies

Study	Device & methods	Comparators/Interventions	Main results
Box
Lyaker, US83	Airway Management. Particle generator placed inside/outside enclosure.	1-wall suction vs. 2-wall suction vs. No Suction	Particle detection outside the chamber increased above the ambient level without suction. Suction reduced the counts.
Brar, UK23	Tracheostomy. Vaporizer generated particles with counters outside the enclosure.	Device vs. no device / Suction vs. no Suction	Decrease in particles detected at the position of the surgeon with the device and a reduction in the number of particles over time.
Hellman, US58	AGMPs. Particle generator and a particle counter inside enclosure.	Hospital suction / commercially available suction / none	Aerosol clearance was significantly hastened with suction vs. passive clearance and the commercial suction device was better than in-hospital system.
Perella, UK22	AGMPs. Simulated cough with normal breath measured through a particle generator.	Suction position /device openings/suction flow rate / device vs. no device	Device prevented particle escape. Optimal condition was when the suction was vertically next to the patient's head.
Le, US95	Airway Management. Atomizer used to simulate aerosol production with counter inside/outside enclosure.	None listed	Containment of greater than 90% of sub-micrometer particles across all particle sizes.
Plastic Sheet
Lang, US57	AGMPs. Humidifier generated particles with particle counters placed inside/outside enclosure.	Device vs. no device / Suction vs. no suction	Particle count detected outside hood significantly decreased with the system. Suction system reduced particle count inside the enclosure.
Shaw, US52	Respiratory Support. Humidifier generated particles with particle counters placed inside/outside enclosure. Nasal cannula used inside hood.	Smoke evacuator 60%/80%/100%/Off	Particle count outside and inside the hood decreased with the use of smoke evacuator.
Bryant, US96	Airway Management. Particle generator placed inside enclosure. Counter measured inside & outside enclosure.	Complete closure, arms inserted, enclosure with flaps open and closed. All vs. suction.	Greatest reduction in particles was with the enclosure closed using suction and highest concentrations when the flap was open. There was no change in particles concentrations with the front flap was open.
Bassin, US32	Canopy. AGMPs. Particle generator inside hood with counters placed inside/outside enclosure.	HFNC, Nebulizer, CPAP with / without particle generator	No detectable increase in room air particle counts.
Chari, US66	Surgical. Mastoidectomy performed on a cadaver. Spectrometer measured particles 30 cm from site.	2 barrier drape designs with/without suction	No drape, no barrier drape + suction, barrier drape without suction had high particle counts. Original drape with suction, modified barrier drape, and modified barrier drape with suction showed no increase.
Milne, Canada97	Airway Management. Flow rate testing completed with two suction sources.	Surgical suction sources vs. in-hospital wall suction	Theoretical times for airborne contaminant at 99% and 99.9% would be faster with the in-hospital suction system due to higher flow rates.
Adir, Israel30	Respiratory Support. Face velocity and smoke direction of air measured perpendicular to hood. Photometry used for particle leakage.	None listed	The average air flow velocity was 4.4 m·s − 1 with the smoke flowing into the back side of the canopy. Filtration efficiency was reported at 0.0006%.
Multiple Device Types
Simpson, Australia24	Box & Plastic Sheet. Airway Management. Nebulized saline through a simulated cough with particle counter outside enclosure.	Box / vertical drape / horizontal drape / sealed box with suction / sealed box without suction	The sealed intubation box with suction resulted in a decrease in almost all particle sizes across all time periods. The box had an increase in particle exposure. No difference using the plastic drapes.