Study Objective
Nebulizer treatments for ill patients with chronic lung disease, reactive airways and other respiratory emergencies have been implicated in aerosolized spread of highly contagious airborne viruses, including COVID-19. Considering the increased risk of aerosolized spread of viruses within confined ambulance compartments, this study specifically evaluated a specially designed nebulizer mask modified with expiratory-port filters and sealing faceplates to minimize bio-aerosol spread.
Methods
Recognizing that fugitive aerosol emissions (such as those that would possibly carry COVID-19) typically range from 0.5 to1.5 micron (μ), a six-port (0.3–10μ) Kanomax 3889 R particle measurement (PM) counter was placed 78 cm from each of 15 rotating adult volunteers (non-patient, beardless) including 7 women and 8 men, ages 18-59 with a mean age of 39 years. The subjects were each sitting upright on a stretcher within a closed standard ambulance compartment. Assigned to one of three rotating fleet ambulances, subjects used the EMS agency’s usual jet-nebulizers with a conventional mask (CM) and then returned on another day to receive jet-nebulization with the aerosol-controlling mask (ACM) or vice versa (ACM first day, CM next day). After documenting baseline ambient PMs (PM amb) within the compartment, the Kanomax operator quickly brought in a subject, closed the door, and waited 5 minutes before making a pre-nebulization PM (preNeb-PM). Jet-nebulizers (using H 2 0 solutions) were then applied (either by CM or ACM as described) for 5 min with immediate post-nebulization measurements (Post1) and two successive measurements (Post2/Post 3), all five minutes apart.
Results
Following the 5-min nebulization, mean CM PMs (Post1 cm) were 152.2-fold larger than mean ACM PMs (Post1 ACM) measurements (p=0.001) and respectively remained 49.6-fold (p=0.005) and 7.2-fold (p=0.006) larger at Post2 and Post3 readings. PM amb and preNeb-PM were all similar (NSD) for both ACM and CM approaches when examining all studied particle sizes (0.5, 1.0, and 3.0 μ) including 1μ preNeb-PMs, measuring 6,977 for ACM approaches and 5,683 for CM use, respectively (NSD). While mean Post1 ACM 1μ PMs decreased (-31.7%) from pre-Neb-PM readings (6,977 to 4,662; p=0.002), counterpart Post1 CM 1μ measurements rose 14,500.09% (from 5,683 to 709,549.93; p=0.002) with corresponding significant elevations for 0.5μ (p=0.001) and 3μ (p=0.002) particle sizes using conventional masks. Of additional note, though applied for just five minutes, ACMs were uniformly well tolerated.
Conclusion
Compared to conventional methods, a modified mask system designed specifically to limit aerosolization of inhaled solutions did provide profound control of fugitive aerosolized particle emissions during nebulizer applications. The findings indicate a much safer approach to treating COVID-19 patients and all others requiring nebulization.