Evaluation of high flow local extraction for controlling aerosol plumes in operating theaters

Abstract

SARS-CoV-2 can be transmitted through contact with fomite, respiratory droplets, and aerosolized viruses. Recent evidence suggests that aerosol transmission represents a significant route of infection. In relation to healthcare workers (HCWs), much attention has been focused on personal protective equipment, yet this is the lowest level of the Centers for Disease Control and Prevention hierarchy of controls. Although engineering controls are prominent in the hierarchy, little attention has been given to developing effective interventions. This study aims to evaluate the performance of a simple extraction device in a clinical setting. This was accomplished by using a high flow local extraction (HFLE) that was connected to the existing ventilation system of the hospital on one end and to an intake nozzle near the patient's airway on the other end. Propylene glycol was aerosolized through a physiological test apparatus to simulate the breath of a patient. The field of interest was illuminated using a laser sheet in two planes from the model, namely, the sagittal plane and the transverse plane, and the movement of the simulated aerosol was recorded using a video camera to assess the dispersion of the aerosol qualitatively. In the meantime, the concentration of the aerosol particles was measured using a particle meter to evaluate the effectiveness of the extraction quantitatively. It was found that the HFLE device could effectively reduce the dispersion of the exhaled aerosols to undetectable levels when it was positioned within 250 mm from the mouth. This result has significance in the safety of HCWs involved in the management of patients with infectious diseases and may also have potential applications in other clinical areas with high airflow in the ventilation systems.