Good start settings for BiPAP

Your question: What are good start-up BiPAP settings?

My humble answer: Noninvasive Positive Pressure Ventilation, such as BiPAP, is generally indicated for patients who aren't taking in adequate tidal volumes to blow off CO2, or are poorly oxygenating. It may also be indicated to decrease cardiac output for patients suffering from heart failure to relieve the feeling of dyspnea until other medicines start to work.

A BiPAP is essentially used for the same reasons as a ventilator, only with BiPAP you have a spontaneously breathing patient.  That said, the settings should be adjusted to maintain the desired SpO2, PaCO2 and PaO2.  However, considering the patient is awake and alert, the settings must also be adjusted for patient comfort as well.  

That said, most experts recommend initial start settings as follows:

• IPAP 10
• EPAP 4

These settings supply a low pressures to the patient's airway, and are generally comfortable for the patient. Then they should be adjusted to maintain a desired tidal volume as tolerated by the patient. The tidal volume should be determined by the following formula:

• 5-8cc/kg ideal body weight

If these minimum settings obtain the goal tidal volumes and SpO2, then you are adequately ventilating and oxygenating this patient, and no further increase is needed.  

There are those who will argue with what I just wrote, however.  Many of my peers insist that the settings of 10/4 are non-therapeutic and, once a patient only needs 10/4, BiPAP is no longer indicated.  However, such number watching assumes that every patient is the same.

For example, consider the 98 pound lady who is suffering from a bout of heart failure.  Her lungs are full of fluid, and she is struggling to breathe.  You set up the BiPAP on the basic settings, and her tidal volume is adequate for this patient and her oxygenation improves.  In this case, all that was needed was the basic settings.

For another example, consider the patient with end stage COPD who is having a flare-up and not taking in deep enough breaths to blow off CO2. Or, say this patient isn't even having a flare-up, but when he is very relaxed or is sleeping he doesn't take in an ideal tidal volume.  This patient would benefit from BiPAP even at the lowest setting, if that setting gave just enough boost to maintain an adequate tidal volume to blow off CO2.  

I have seen 10/4 work many times to obtain an adequate SpO2 and tidal volume.  If these settings work, then great.  If they don't, then it's time to increase the settings.  Yet, regardless of what you do, it's important that you do not focus so much on the numbers, but on the patient.  Look at the patient. What does the patient need?

Now, if you're goal is to blow off CO2, then you'll want a larger gap between IPAP and EPAP.  For instance, if 10/4 is not enough to blow off CO2, then increase the IPAP.  If your goal is to oxygenate and a CPAP of four isn't cutting it, then you should increase IPAP and EPAP slightly.

Still, it is a good idea not to exceed 20 of IPAP, as this pressure might block the esophagus, thus preventing the patient from swallowing.  If you need to exceed this pressure, a nasal gastric tube should be in place.  

In my humble opinion, BiPAP should always be ordered "RT to titrate. Then it's up to the RT to use common sense.

This post originally published at respiratorytherapycave.blogspot.com on 4/3/12; it has been edited and updated for accuracy and improved wisdom by Rick Frea