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Filtration
Since 1965 an awareness as to contaminated ventilating machines causing infections to subsequent patients has resulted in a universal acceptance to use filters to protect the patients, staff and machinery. Filters and Heat Moisture Exchangers (HME) have developed since then not only to prevent bacterial and viral contamination but to also compensate for bypassing the upper airway during anaesthesia or intubation.
The blood born virus advisory panel of the Association of Anaesthetists of Great Britain and Ireland recommended that an appropriate filter should be placed between the patient and the breathing system, with a new filter being used for each patient. This protection may be achieved by two different filtration methods, either by mechanical filtration, or by electrostatic charge filtration.
Mechanical filters, also known as pleated paper filters, have a tightly packed medium with a hydrophobic coating providing a small pore size membrane that physically stops the passage of organisms. Typically these filters have very high levels of efficiency and their hydrophobic properties also provide a degree of humidification for the patient.
Electrostatic filters use a medium that is loosely woven and given a charge that holds onto micro-organisms allowing filtration in a small, light casing.
Filtration Principles
The primary objective of breathing filters is to stop bacteria and viruses entering / leaving the patient. 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 passing through.
HME's use the patients own moisture and humidity from expiration to humidify anaesthetic gases during inspiration. When endotracheal tubes are used, the upper airway that usually warms inspired air is bypassed and for patients that are anticipated to be under anaesthesia for long periods or ventilated patients, it is recommended that an HME/HMEF be used as prolonged dry gas exposure can have adverse effects.
Properties of Filters and HMEF's
When considering filters a number of important properties should be taken in to account.
1 Filtration Efficiency
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 hospital deaths.
From this it is evident that filtration efficiency is paramount to protect the patients and ventilators from cross contamination. Flexicare filters provide protection against bacteria and viruses at a very high level of efficiency. This level of effectiveness is independently tested and verified by the Applied Centre for Microbiology and Research at Porton Down Salisbury, giving confidence in our filter properties. Flexicare filters will maintain the specified level of efficiency for the full recommended period of use.
2 Humidification Abilities
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 30C. 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).
3 Light Weight and Ergonomically Shaped
Flexicare Filters and HMEF's designs provide a rounded ergonomical 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.
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.
Since 1965 an awareness as to contaminated ventilating machines causing infections to subsequent patients has resulted in a universal acceptance to use filters to protect the patients, staff and machinery. Filters and Heat Moisture Exchangers (HME) have developed since then not only to prevent bacterial and viral contamination but to also compensate for bypassing the upper airway during anaesthesia or intubation.
The blood born virus advisory panel of the Association of Anaesthetists of Great Britain and Ireland recommended that an appropriate filter should be placed between the patient and the breathing system, with a new filter being used for each patient. This protection may be achieved by two different filtration methods, either by mechanical filtration, or by electrostatic charge filtration.
Mechanical filters, also known as pleated paper filters, have a tightly packed medium with a hydrophobic coating providing a small pore size membrane that physically stops the passage of organisms. Typically these filters have very high levels of efficiency and their hydrophobic properties also provide a degree of humidification for the patient.
Electrostatic filters use a medium that is loosely woven and given a charge that holds onto micro-organisms allowing filtration in a small, light casing.
Filtration Principles
The primary objective of breathing filters is to stop bacteria and viruses entering / leaving the patient. 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 passing through.
HME's use the patients own moisture and humidity from expiration to humidify anaesthetic gases during inspiration. When endotracheal tubes are used, the upper airway that usually warms inspired air is bypassed and for patients that are anticipated to be under anaesthesia for long periods or ventilated patients, it is recommended that an HME/HMEF be used as prolonged dry gas exposure can have adverse effects.
Properties of Filters and HMEF's
When considering filters a number of important properties should be taken in to account.
1 Filtration Efficiency
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 hospital deaths.
From this it is evident that filtration efficiency is paramount to protect the patients and ventilators from cross contamination. Flexicare filters provide protection against bacteria and viruses at a very high level of efficiency. This level of effectiveness is independently tested and verified by the Applied Centre for Microbiology and Research at Porton Down Salisbury, giving confidence in our filter properties. Flexicare filters will maintain the specified level of efficiency for the full recommended period of use.
2 Humidification Abilities
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 30C. 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).
3 Light Weight and Ergonomically Shaped
Flexicare Filters and HMEF's designs provide a rounded ergonomical 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.
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.
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Breathing Filters - Introduction
