It is known that respiratory filters are a necessary expendable material for ensuring work of a rebreathing system. Being located on the way of respiratory mix to the patient, respiratory filters can perform the following functions:
- to detain on the way of a stream of air mixture from the patient to the fan water and heat, allowing to maintain thus the necessary temperature and humidity of respiratory mix (heatmoisture exchange filters);
- to serve as a barrier to various microorganisms (bacteria and viruses), protecting the patient from their hit in his respiratory tracts (bacterial and virus filters).
Combined use of the respiratory filters located on the distal end of a rebreathing system (after the Y-shaped connector) with humidifiers of respiratory mix is inadmissible as it leads to accumulation of damp and warm respiratory mix in space between a humidifier and the filter.
During an era of a koronavirusny infection it is possible to expect increase in volumes of use of respiratory filters both bacterial and virus, and heatmoisture exchange. It is connected with sharply increased need for IVL and the equipment for its carrying out and also with the fact that at a large number of the patients who are at the same time in intensive care units and an intensive care it is simpler to provide moistening and warming of respiratory mix by means of respiratory filters, than use of humidifiers. The last demand additional expenses of the electric power and also constant observation of them in the course of work. Along with it, use during an era of a pandemic of virus and bacterial filters will also increase as during this period, on the one hand, it is extremely important to provide environment protection and medical personnel from virus loading, and with another — protection of the patient against secondary infection with its hospital strains of microorganisms.
The typical scheme of use of respiratory filters when carrying out artificial ventilation of the lungs to the patient with a koronavirusny infection looks as follows. If virus and bacterial respiratory filters with heatmoisture exchange function are available concrete medical institution, then it is the most preferable option. Such filter at its placement between a contour and the patient allows to solve three problems at once: to provide moistening and heating of respiratory mix, to protect the patient from hit in his respiratory tracts of hospital flora and to protect surrounding personnel and other patients from virus loading. At the same time there is no need to use a humidifier for the medical ventilator that saves the electric power and reduces load of medical personnel. If only virus and bacterial filters are available establishment, then it makes sense to install them on branch pipes of a breath and an exhalation. At such arrangement the filter which is on a breath branch pipe protects the patient from intrahospital flora, and the filter which is on an exhalation branch pipe — from contamination by an environment virus. Moistening and heating of respiratory mix in this case is carried out by means of a humidifier.
Special attention should be paid to timely replacement of respiratory filters. In addition to planned replacement through a certain period, the respiratory filter it is necessary to change for new at its pollution, for example, at once the patient's phlegm as resistance of such filter increases, and its functionality falls. When using the scheme from two virus and bacterial filters on branch pipes of a breath and an exhalation the filter located on an exhalation branch pipe usually demands more frequent replacement because on it water vapor from a contour is condensed.
When choosing the heatmoisture exchange respiratory filter it must be kept in mind age category of the patient as filters differ among themselves by the size and, respectively, size of so-called dead space. Considering that the heatmoisture exchange filter is placed in close proximity to the patient, angular respiratory filters and also filters with the corrugated adapter can be convenient. Many respiratory filters are supplied with Lyuera port that allows to use it for connection of the line of gas monitoring.