Initiation and Titration of NIV/BiPAP Settings

Initiating non-invasive ventilation is very similar to how you approach setting up PSV for a spontaneously breathing patient. There are three main settings that need to be adjusted as well as one additional “back-up” setting. First, you will set the oxygen delivery (FiO₂), a distending pressure to help recruit alveoli (EPAP), and a high pressure to augment the patient’s normal breath (IPAP). The back-up setting is a basic RR (remember, this setting does not replace the patient spontaneously breathing).

Therefore, the settings to be set for NIV are:

1. FiO₂
2. EPAP pressure (similar to PEEP)
3. IPAP pressure (delta Pressure, similar to pressure support)
4. RR

These settings will be discussed in detail below.

FiO₂

FiO₂ is mandatory to set and should be titrated based on what the patient needed before non-invasive application. If on high oxygen, start FiO₂ at 1.00 and then wean to SpO₂. If the patient does not require a lot of oxygen, starting at 0.50 and weaning within a few minutes to target SpO₂ >92% is ideal.

EPAP

EPAP pressure is similar to PEEP. It is the distending pressure that helps recruit alveoli and help with oxygenation. Where it differs from invasive ventilation is using an interface of a face mask instead of intubating and sealing the lungs to a ventilator. The normal pleural pressures that exist with spontaneously breathing patients are still present (see the discussion of lung pressures in Chapter 1). This means that the distending pressures of EPAP can be lower than the minimum PEEP you must set. EPAP settings are usually started from 4-8 cmH₂0.

IPAP

IPAP is the high pressure NIV will cycle up to when the patient initiates a breath. The difference between the EPAP and IPAP is the delta pressure or change in pressure. The change in pressure is the same as a pressure support or additional pressure given to help augment a person’s breath. Think of the change in pressure between the EPAP and the IPAP (delta pressure) as the push to get up to that high level. This is identical to the Pressure Support in PSV but described a slightly different way in NIV. Think back to the waveform and mountain analogy from Chapter 4:

If the difference between the EPAP and IPAP is bigger, that is a larger push of pressure to get to the higher level.

Example A:

EPAP 6 and IPAP 10 → Delta P/PS of 4 (difference between EPAP and IPAP)

This is a Pressure Support of 4 cmH₂0

Example B:

EPAP 6 and IPAP 12 → Delta P/PS of 6 (difference between EPAP and IPAP)

This is a Pressure Support of 6 cmH₂0.

In Example B, this is a higher support, or “push,” to give the patient a bigger assist for a larger tidal volume.

IPAP is usually set +4-10 cmH₂0 above the EPAP and then adjusted to make sure the patient is taking adequate tidal volumes. Increase the IPAP to help the patient take bigger breaths or if they need more support due to increased work of breathing (WOB).

RR

RR stands for Respiratory Rate. But, how can you set a respiratory rate for a non-invasive mode where the patient must have an intact drive to breathe? Though it is termed an “RR,” NIV does not use a true respiratory rate. As you have already learned, the patient must be triggering breaths on their own. Therefore, you can think of the RR as a mandatory breath cycle that can be used as a back-up to ensure the patient continues to trigger breaths at a certain rate. Usually, the RR is set much lower than the patient’s intrinsic RR. For NIV, it is normally set at 12-16 bpm, though most patients on NIV are usually tachypneic due to increased WOB or oxygenation issues.

When setting up a patient on NIV, the best guide for choosing your initial numbers originates in the reason the patient would benefit from NIV. As stated earlier, patients usually fall into two categories:

• difficulty oxygenating/requiring lung recruitment
  or
• high CO₂ or hypercapnia/increased WOB.

Patients needing lung recruitment or help with oxygenating will benefit from higher EPAPs and not as large of a delta P/PS—resulting in a lower IPAP setting. Patients with high CO₂/increased WOB do not need as much distending pressure (EPAP), but need their IPAPs set higher to ensure a larger delta P/PS to help augment their normal tidal volume.

Occasionally, you may have a patient that is a combination of the two situations. These patients will require a higher EPAP as well as a high IPAP with a large delta P.

Let’s break it down in this table, which shows recommended initial settings according to the type of patient you are dealing with: