Introduction to Breathing Filters
The primary objective of breathing filters is to stop bacteria
and viruses being transferred to and from the patient and
preventing cross infection. Electrostatic filters achieve this by
holding onto micro-organisms through the static electric charge in
the medium. The pleated paper filter also known as a mechanical
filter achieves this by tightly packed layers of mixed strands of
glass fibres physically preventing bacteria and viruses from
Properties of Filters and
When considering filters a number of important properties should
be taken into account and these are:
As many as 10-15% of intubated patients develop pneumonia at a
level of 1-3% per day of intubation. These pneumonia's may prolong
hospital stays by 4-9 days and contribute to as many as 15% of all
From this, it is evident that filtration efficiency is paramount
to protect the patients and ventilators from cross contamination.
Flexicare filters maintain protection against bacteria and viruses
at a very high level of efficiency. This level of effectiveness is
independently tested and verified by the Health Protection Agency
at Porton Down Salisbury, giving confidence in our filter
properties. Flexicare filters maintain there high level of
efficiency during the recommended period of use.
2. Light Weight and
Flexicare Filters and HMEF's designs provide a rounded ergonomic
shape to prevent pressure marking or discomfort for the patient.
They are of light weight design thus reducing drag on breathing
systems and are made of clear material allowing visual observation
in terms of potential obstructions.
To counteract the risk of actelectasis, epithelial damage and
reduction of mucocillary transport, adequate humidification should
be provided to long term intubated patients. HMEF's may not only
act against these factors by providing humidification, their use is
also thought to reduce the incidence of late onset Ventilator
Associated Pneumonia compared to heated wire systems.
It is recommended that HMEF humidification levels should be at
least 30mg/L H2O at an inspired air temperature of 30oC. All
Flexicare HMEF's exceed this minimum by providing a maximum
moisture output performance of 32.3mg/L H2O as independently tested
and verified by the Medical Device Agency (MDA). 4
4. Minimal Dead
Space and Minimal Pressure Drop
Design of the filter housing must provide the smallest dead space
possible whilst at the same time allowing a good gas flow with
minimal resistance (pressure drop) through the filter media. The
design of Flexicare Filters and HMEF's has incorporated a balance
of these critical requirements to create a filter with minimal
resistance to flow while maintaining a low dead space.
All the values stated in the product
specifications are supported by independent test results. The
efficiency of the Flexicare and HepaShield filter is tested by the
Health Protection Agency at Porton Down, Salisbury, UK. Testing was
done for bacterial and viral efficiency using Bacillus Subtillis
and MS-2 Coliphage. Moisture output and resistance were tested
independently by MeDEC, Wales College of Medicine.