Real-time imaging of airflow patterns and impact of infection control measures in ophthalmic practice: a pandemic perspective

Abstract

Purpose: 

To analyze exhaled airflow patterns in a clinical scenario and the impact of infection control practices and room air circulation in context of the COVID-19 pandemic.

Setting: 

Raghudeep Eye Hospital, India.

Design: 

Experimental study.

Methods: 

Ten patients attending ophthalmic outpatient clinic (OPD) and operating room (OR) were included. Using Schlieren imaging, exhaled airflow patterns were documented with/without an N95 mask or face shield during respiratory activities. Recordings were performed with and without room air conditioning turned on. Exhaled airflow patterns in OPD and OR when using vs not using these infection control measures and the impact of room air circulation on these were compared.

Results: 

Five patients each in OPD and OR were included. There was a forward stream of exhaled air from the patient's mouth/nose during all respiratory activities. An N95 mask dampened its intensity and forward transmission. Taping the mask around the nasal bridge further reduced airflow leakage. A mechanical barrier in front of the patient's face blocked forward propagation of the exhaled airflow. Turning on a forceful and direct draft of air over the surgeon's working area dampened and diverted the exhaled airflow away from the surgeons' breathing area. This effect was particularly pronounced in the OR, with the overhead laminar airflow.

Conclusions: 

Using high force airflow with the draft facing downward can dampen and divert the exhaled airflow away from healthcare providers. Using masks/mechanical barriers and taping the mask reduces potential dissemination of aerosols and, thereby, human and surface contamination.

In Brief

This study use a noninvasive optical imaging technique to analyze patterns of airflow from patients and room air conditioning in context of the COVID-19 pandemic.