Exploratory evaluation of negative-pressure operating modes for size- and position-specific aerosol containment during simulated cardiopulmonary resuscitation in a newly developed respiratory isolation chamber

ObjectiveTo compare negative-pressure operating modes for aerosol containment during simulated cardiopulmonary resuscitation (CPR) in a newly developed double-barrier respiratory isolation chamber, focusing on particle-size-and operator-position-specific particle-count patterns. MethodsIn this mannequin-based benchtop simulation, a standardized nebulized aerosol challenge was tested under four modes: 0 Pa, -10 Pa, nominal "Al Pa" adaptive pressure control, and -50 Pa.Particle counts across six size channels were measured at intubator and chest-compressor positions, with and without CPR.Each chamber-applied condition was assessed in 10 re-initialized runs.Analyses were descriptive and estimation-based, using absolute counts, percentage reductions relative to corresponding positive controls, and direct mode comparisons. Results DuringCPR, residual particle counts differed by particle size and operator position.Under 0 Pa at the chest-compressor position, mean counts were 199,724.3,79,870.1, and 12,580.0for 0.3, 0.5, and 1.0 μm particles; corresponding Al Pa counts were 17,539.3,1,826.1, and 222.3.Under Al Pa, mean reductions relative to corresponding positive controls ranged from 92.2% to >99.9% across CPR submicron comparisons.Compared with -50 Pa, Al Pa showed 11.1%-30.2%lower mean residual submicron counts.Conclusion During simulated CPR, aerosol containment varied by particle size and operator position.Thresholdbased adaptive pressure modulation maintained low residual submicron counts without continuous maximal suction and may offer a balanced strategy by applying additional suction only when needed.Patient-side safety and airflow effects require further evaluation.