In the time of pandemic, many people have lots of doubts like which filter should be used, HME or HEPA? How to use them, next to the patient or next to the exhalation valve?
Among the several solutions for the treatment and prevention of Covid19, the ventilatory management of patients undergoing orotracheal intubation requires special attention, mainly the functionality and usability of respiratory filters to answer health professionals doubts.
Consensually, respiratory filters prevent that respiratory pathogens spreads through droplets and aerosols by patients submitted to mechanical ventilation, provided that they have a minimum pore of 0.2 µm and a minimum effectiveness of 99.5% filtration for bacteria (BFE) and viruses (VFE).
Respiratory filters, also known as HME (Heat and moisture exchanger), are defined by the American Society for Testing and Materials, as passive humidifiers, however HME filters, according to the world medical literature, are grouped into three major categories.
- Humidifiers with hygroscopic condensers without antimicrobial filtration properties, only exchange heat and humidity;
- Hydrophobic humidifiers that act as a barrier, but with poor humidification production power;
- Mixed humidifiers or hygroscopic and hydrophobic, they have adequate moisture and heat production properties and excellent microbiological barrier action exerted by electrostatic membrane. This category is called by some authors by HMEF, that is, heat and humidity exchanger with filtering power.
The HEPA filter, that is High Efficiency Particulate Air and it fits the category of hydrophobic filters, since in general they are made of fiberglass or ceramic membranes acting as a mechanical barrier, being intended protection of ventilatory equipment in order to ensure that it is not contaminated and its components function properly.
Considering these definitions and respecting the clinical indications for the use of HME filters, let's see when and how to use each model.
BeCare HME Filters, in all their versions (adult, pediatric and neonatal), are MIXED, bidirectional filters, their filtering membrane is electrostatic, with 0.02µm pore, thus guaranteeing aerosol blocking, they can be used in a quiet and safe in suspected and / or confirmed patients with coronavirus, its BFE filtering efficacy is 99.9999% and VFE 99.9998%.
The BeCare HEPA Filter has a wide volume (150 to 1500 ml), thus serving the pediatric and adult audiences in a vast way. Its filtering membrane consists of pleated glass fiber with 0.02 µm pore, which mechanically blocks the passage of aerosols, the BFE is 99.9999% and the VFE 99.9998%.
The associated use of the HME BeCare Filter, in connection Y, with the HEPA Filter, in the exhalation outlet, further increases the protection against the spread of aerosols, the use of which is recommended, in accordance with several worldwide recommendations.
Thus, in ventilatory management, institutions will be able to count on BeCare Filters to protect the patient, equipment and health professionals.
Fontes: Esquinas A., 2012 - Humidicication in the Intensive Care Unit - The essentials. Springer. Galvão A. M. et al 2006 - Comparative study between the heated aqueous humidification systems and heat and humidity exchanger in the artificial airway of patients on invasive mechanical ventilation. Brazilian Journal of Physical Therapy, São Carlos, v. 10, n. 3, p. 303-308, jul./set. 2006. Gatiboni S. et al, - Humidification of gases inspired by mechanical ventilation in children. - Scientia Medica, Porto Alegre, Vol. 18, n. 2, p. 87-91, Apr./Jun. 2008. Lucato J., 2005 – Avaliação e comparação dos diferentes tipos de trocadores de calor e umidade. – Tese de Doutorado, Faculdade de Medicina de Universidade de São Paulo. / Sociedade Argentina de Terapia Intensiva / Sociedade Chilena de Medicina Intensiva / Federação Mundial das Sociedades de Anestesiologistas
