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Wednesday, August 7, 2013

Myth Buster: What BiPAP settings are best

So, what BiPAP settings are best?  Our doctors allow us to manage BiPAP (also known as NPPV) machines and titrate the settings as appropriate for the patient.  Many of my coworkers have fallen victims to the plague of myths that are associated with BiPAP numbers, while most assuredly failing to dial in adequate settings for their patients.

BiPAP (or NPPV) is an amazing tool that has significantly reduced the number of patients needing to be intubated.  It has benefited patients suffering from nearly every respirator ailment, such as heart failure, chronic bronchitis, emphysema, and asthma.  It is simply an amazing machine.  However, as with anything else in the medical profession, there are myths abounding about these machines, all of which I will try to dispel in this post.

The myths abounding are as follows:
  1. IPAP cannot exceed 20
  2. You cannot set a rate on BiAP
  3. You have to have IPAP set higher than 10 to be therapeutic
So, now to expel the myths so that sanity can prevail:

1.  IPAP cannot exceed 20.  Why not?  When a patient is on a ventilator a pressure of 20 or less is considered normal, so why would an IPAP of 20 on a BiPAP (which is essentially the same as a pressure support of 20) be too high.  This is another situation where you treat the patient, and not the number.  If 20 or greater of IPAP is necessary to maintain an adequate ventilation, then go with whatever IPAP is necessary.  

2. You cannot set a rate on BiPAP: Again, I ask, why not? If you set the back up rate at 6, and the patient rate is 0, will not the unit guarantee that rate of 6? I know it does, because I have seen it happen many times. So if this is true, then why can't you set the back up rate at 10, or even 20? I know you can, because I have done so successfully many times.  Of course depending on the machine, you can set the rate and it will guarantee that rate.

3. You have to have EPAP set higher than 10 to be therapeutic: Once again I ask, why not? It is not the number that you are concerned with, but the minute ventilation. You want the minimum settings necessary to maintain an adequate minute ventilation, even if this means setting the IPAP at 10, or even less.

Do not give in to the myths, because they are abounding.


Anonymous said...

The human esophageal opening pressure is about 20 cm H2O. It is recommended not to set the IPAP above this to prevent opening of the upper esophageal sphincter, which could result in gastric insuffluxation, gastric distension, emesis, and aspiration. If you do go above this, you might need to suction the stomach with an NG tube or OG tube. This isn't an issue with the ventilator because the ET tube bypasses the esophageal opening and the cuff prevents air from entering the esophagus. If it weren't for this issue, we would rarely need invasive mechanical ventilation.

K. Scott Richey said...


Thank you for the post.

I like myth number 1:
You will always get the argument that mask ventilating at pressures > 20-25 cmH2O is the opening pressure of the cardiac/pyloric sphincter and will lead to abdominal inflation, distention, gastric re-flux, vomiting, and aspiration.

This argument is based on the passively ventilated patient, with a good mask seal (from anesthesia literature during induction).

As you & many RT's have experienced NIV there are many leaks & that you should have a small leak to insure the interface is not too tight (leading to skin breakdown). So you may need higher pressures.

Patients requiring NIV are usually in the acute stage of Respiratory distress, so they have vigorous inspiratory drives, so you may need a higher pressure.

Additionally, look at home BiPap machines, I have a friend woes machine will auto-titrate pressures up to 30 cmH2O.

Basically, as you already stated "assess your patient" and adjust accordingly.

Rick Frea said...

True. However, it can be done, although as a short term fix only. I have done it, and usually with a doctor standing over my shoulder saying, "turn it up until the sat is at least 85%." You have to remember that the idea settings are unique to the patient. Note: if the ideal IPAP is equal or greater than 20, notify the physician if he is not already lurking over your back.

Anonymous said...

Scott, bipap machines will compensate for leaks, as long as they aren't excessive. If you set the pressure at 20 you will get a pressure of about 20 despite any leak you might have, as long as the leak isn't greater than 100L (at which point you will get a "disconnect" alarm).

Anonymous said...

My issue is with myth number 2. If the patient rate is 0, are they not apneic? And if that is the case my argument would be that they need the airway secured by more invasive means. Perhaps we operate differently, but here it would be unheard of to BiPAP a patient who has no respiratory drive.

Rick Frea said...

Newer BiPAP machines are more than capable of breathing for a patient with no rate. Now, whether or not to do this is up to the clinical caregivers. You should never say never in the medical profession, because you can always find a case that meets the exception, such as the end stage COPD patient who is a DNR.