NIV and COVID-19

COVID-19 INFORMATION & RESOURCES

Last Updated: Thursday, 9 April 2020, 6:37PM (NZDT)

International and national healthcare bodies have differing guidance for the use of Noninvasive ventilation (NIV) in the treatment of COVID-19 patients. 
Please refer to the guidance provided by the societies or governing body for your region (links to some of these can be found at the bottom of this page).


The key recommendations from the World Health Organization (WHO) when NIV is used for COVID-19 patients are:

  • NIV (generally used for hypercapnic respiratory failure) should only be used in selected patients with hypoxemic respiratory failure.
     
  • Patients treated with NIV should be closely monitored for clinical deterioration.
     
  • Due to uncertainty around the potential for aerosolization, NIV should be used with airborne precautions. 

NIV and potential for aerosolization

With any NIV mask there are two main places where gases and potential aerosols will leak. They are between the patient and the mask (patient leak) and, when venting is required, through the venting or exhalation port (intentional leak).
 
  • NIV therapy should be treated as an aerosol-generating therapy and appropriate PPE should be employed.
     
  • A well-sized and fitted mask should be used to reduce patient leak.
     
  • A non-vented mask should be used, and where venting is required an exhalation port and a filter to reduce exposure of exhaled aerosols from patients should also be used (refer to different setups below).

Filters

There are a number of considerations to take into account when selecting a filter to reduce aerosolization during NIV therapy. The use of a filter may reduce the amount of aerosol released into the environment. However, some aerosols may still be generated through patient leak and leak through connections. Subsequently, appropriate PPE should still be employed.

Filter selection considerations can include:

  • Viral-filtration efficiency when used dry.
     
  • Viral-filtration efficiency when conditioned with humidity.
     
  • Resistance to flow of the filter when both wet and dry. Typically, HEPA filters will have a higher filtration efficiency but also higher resistance to flow.


For more information, visit Viral & Bacterial Filtration Efficiency of Fisher & Paykel Healthcare Filters and F&P Evaqua™ 2 Circuits.

 

 

NIV setups


Dual-limb systems

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.

 

Recommended - Non-vented mask in a dual-limb system

 


 

Single-limb systems

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.

 

Recommended - Non-vented mask in a single-limb system exhalation port filter

 

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.

 

Not Recommended - Non-vented mask in a single-limb system in line filter