Evaluation of face shields used during aerosol generating procedures

Area of Science:

• Medical Devices
• Infectious Disease Control
• Respiratory Medicine

Background:

• Transnasal flexible laryngoscopy is an aerosol-generating procedure, posing infection risks.
• Standard disposable plastic face shields may not adequately contain patient-generated aerosols.
• A novel negative pressure face shield (NPFS) was developed to mitigate aerosol spread during laryngoscopy.

Purpose of the Study:

• To evaluate the efficacy of the NPFS in controlling virus aerosols compared to a standard plastic face shield.
• To assess aerosol reduction across various particle sizes.

Main Methods:

• Utilized a simulated patient coughing machine to aerosolize MS2 bacteriophage as a SARS-CoV-2 surrogate.
• Tested both a standard plastic face shield and an NPFS under simulated coughing conditions.
• Measured virus and particle concentrations inside and outside the face shields at different NPFS flow rates (38.6 LPM and 10 LPM).

Main Results:

• The standard face shield showed no significant difference in virus aerosol concentration inside versus outside.
• The NPFS significantly decreased virus and particle concentrations outside when operated at 38.6 LPM (p < 0.01).
• At 10 LPM, the NPFS did not significantly reduce virus concentrations but did reduce particle counts (p < 0.05).

Conclusions:

• The NPFS demonstrates significant potential for reducing virus aerosol transmission during flexible laryngoscopy.
• Optimal performance of the NPFS for aerosol control is flow rate-dependent.
• Further research may validate NPFS effectiveness in clinical settings for enhanced patient and healthcare worker safety.