My humble answer: Noninvasive Positive Pressure Ventilation, such as BiPAP, is generally indicated when for patients who aren't taking in adequate tidal volumes to blow off CO2, or are poorly oxygenating. Common disease conditions that might do this are heart failure, chronic obstructive disease, and asthma.
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. 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.
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?
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