Bilevel Devices Converted to Ventilators

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Watch AARC’s video to learn about using a ventilator designed for NIV to provide invasive ventilation.

Why is this important?

The overwhelming demand for ventilators in the current pandemic requires that respiratory therapists ‘triage’ ventilators to the needs of the patient. ICU ventilators for the sickest patients. Followed by use of portable or transport devices which have capable performance but less monitoring capabilities. Anesthesia ventilators could also be used. Devices most commonly used for NIV are in fact ventilators. These devices can be used to provide invasive ventilation but this requires some nuance to apply safely and effectively.

Highlights:

CPAP Devices
  • Reiterate that devices for Obstructive Sleep Apnea (OSA) cannot be repurposed for invasive ventilation.
  • CPAP devices provide no ventilatory support.
  • Difficult to provide higher FiO2 concentrations.
Bilevel devices
  • Bilevel devices provide positive pressure ventilation (they are ventilators).
  • Some are FDA cleared for invasive ventilation.
  • Bilevel devices for home ventilation can be repurposed.
  • Some of the Bilevel devices have internal blenders, for those that do not:
    • Require oxygen titration from an external flowmeter.
    • High oxygen concentrations are difficult to deliver.
    • FiO2 varies with minute ventilation.
    • Clinicians will need to adjust flow to achieve a targeted SpO2.

Key Points

  • CPAP devices do not provide ventilation.
  • Bilevel devices are ventilators.
  • Bilevel devices can be used for invasive ventilation.
  • The same principles apply to bilevel ventilators for invasive ventilation as for ICU ventilators.

FAQs

Q1:
Let’s talk about best practice and the leak that is needed for NIV. How do we address this when using bilevel as an invasive ventilation?

A1:
A leak port is necessary for single limb circuit bilevel devices. The leak should be filtered to avoid contamination of the environment.

Q2:
Since these patients on bilevel are now intubated and receiving invasive ventilation, how do we address the best practice for the airways to receive humidified gas?

A2:
The gas must be humidified. An active humidifier can be used. Alternatively, a heat and moisture exchanger (HME) can be used. An HME with a filter (HMEF) provides humidification while also filtering the exhaled gas. If an HME or HMEF is used, it must be fitted between the leak port and the endotracheal tube.

Q3:
Since COVID-19 patients appear to have an ARDS-like pathology, how do we address the normal modes and settings we typically use for bilevel ventilators normally used as NIV devices?

A3:
Starting settings will be different than what is typically used for NIV:

  • IPAP (PIP): 25 cm H2O
  • EPAP (PEEP): 12 cm H2O
  • Rate: 25/min
  • Mode: S/T or PC (need to set rate); avoid volume targeting modes and modes for sleep disordered breathing
  • Ti: 0.8 cm H2O
  • FiO2: 1

Settings are adjusted per arterial blood gases and SpO2. Target tidal volume to 6 mL/kg predicted body weight (400 mL).

Q4:
What is best practice in monitoring these patients on bilevel devices?

A4:

  • Tidal volume; Target tidal volume to 6 mL/kg predicted tidal volume
  • SpO2: target 88% – 95%
  • Arterial blood gases
  • Capnography is not necessary unless needed as a disconnect alarm
  • Also important to set alarms – particularly disconnect alarm