Panel Discussion: Filtration of breathing gases during mechanical ventilation

Filtration of contaminated breathing gases is a necessary measure in mechanical ventilation. There are two types of filters available for filtration of breathing gases: mechanical filters and electrostatic filters. Filter efficiency can be established through a number of means, the most stringent being the High Efficiency Particulate Air (HEPA) test. While a variety of HEPA-grade filters are available, single-layer media and electrostatic filters are those commonly used in breathing circuits and heat and moisture exchange filters. Filters are generally used in equipment where bacterial contamination can occur, such as breathing tubes, mechanical ventilators and anesthesia circuits and nebulizers. Use of these filters can potentially minimize the risk of infection and cross-contamination to patients, caregivers and visitors in the critical care setting. For optimal filter function, attention must be paid to factors such as humidity, airflow rate, filter drying or obstruction, decreased performance with anesthetic gases, and the possible buildup of toxic gases in closed anesthesia circuits. The clinical benefits of filtering exhaled gases are many, the most important of which is the protection of patients, healthcare workers, and visitors from nosocomial infections. Effective filtering may also reduce or prevent asthma episodes in healthcare workers, although more data is needed. More studies need to be performed to demonstrate the effectiveness of filters, through bacteriological monitoring and epidemiological monitoring.