These are for use with ICU ventilators that have the ability to provide NIV, and are commonly used to provide NIV in Europe.
Setup 1: Non-vented mask in a dual-limb system: Recommended
The majority of guidance where NIV is indicated in the treatment of COVID-19 patients recommends the use of a non-vented mask in a dual-limb system (where venting is not required) to reduce caregiver exposure to aerosolization. However, many regions will see these ventilators required for invasive ventilation, and the use of NIV on single-limb systems (dedicated NIV ventilators, Bi-level and CPAP devices) may be necessary.
Dedicated NIV ventilators, Bi-level and CPAP devices are generally single-limb systems. These single limb systems require venting of the patients exhaled breath to prevent the buildup of CO2 .
- A non-vented mask with an exhalation port should be used rather than a vented mask.
- Vented masks could worsen contamination of the environment.
- Ensure the employed ventilator mode supports the use of non-vented masks and exhalation ports.
Setup 2: Non-vented mask in a single-limb system exhalation port filter: Recommended
- Ideally an exhalation port with reduced jetting should be used. Typically, this has a shroud around the exhalation holes to reduce air entrainment and an array of small holes creating a diffuse flow.
- An exhalation port with the ability for the exhaust to go through a filter should be employed to reduce aerosol dispersion.
- A low resistance-to-flow filter is recommended to reduce CO2 rebreathing and maximize the percentage of gases being filtered.
Setup 3: Non-vented mask in a single-limb system in line filter: Not Recommended
Some guidance recommends the system uses a filter between the mask and exhalation port. There are some major drawbacks of this setup.
Fisher & Paykel Healthcare don’t recommend this setup if you already have an exhalation port which allows a filter to be attached to reduce aerosols being released into the environment.
Reasons we do not recommend this setup include:
- This will likely increase dead space, work of breathing and potentially reduce the efficacy of treatment.
- Triggering and pressure delivery may be affected due to the resistance to flow of the filter.
- Inspiratory flow may be exhausted out the port before reaching the patient due to the inline filter’s resistance to flow.
- Secretion accumulation may cause filter blockage.
- Frequent replacement of the filter is required, which in this setup involves breaking the circuit, increasing the risk of infection for caregivers.