Investigation of ventilation conditions associated with CO2 concentration changes in ultrasonographic exam room from the perspective of COVID-19 infection control

Objectives Ventilation is an important factor in preventing COVID-19 infection. To clarify the state of ventilation in ultrasonic exam rooms, as an index of ventilation rate, the carbon dioxide (CO2) concentration in our exam rooms was measured. Methods We measured the CO 2 concentration in each exam room before the examination and 0–15 minutes after end of the exam. The subjects were 70 cases (abdomen: 24, breast: 16, neck: 16, and musculoskeletal: 14). In infant cases, one parent accompanied the patient during the examination. Results The highest CO 2 concentration was 2261 ppm, observed after the breast examination. In all cases, the CO 2 concentration in the exam room was highest immediately after the examination or two minutes after. Almost all cases had recovered to within 120% of the pre-examination CO 2 concentrations within 15 minutes after the examination. The average CO 2 concentration after ultrasonography was significantly higher for breast examinations than others. Conclusions Even in a hospital with modern ventilation equipment, the CO 2 concentration in the ultrasound room was high after the exam and it takes 15 minutes to recover to the pre-exam state. Care must be taken to ensure adequate ventilation in ultrasonographic facilities.