I work in a large pediatric institution. I have been working on getting the physicians to utilize APRV ventilation more in my institution (we primarily use HFOV.) I had started to have some success, but recently have run into a road block. One of the physicians that I work with closely will no longer use this mode of ventilation. His reasoning was that he went to a conference about a year ago and he saw a presentation put on by Gary Neiman.
Gary is a PHD out of New York. He has done some studies about alveolar instability in which he does experiments on rats. He cuts away the thoracic cage over a lung segment. He then places a high powered microscope over the lung field. In Resp Care. 2005;50:1520 an abstract was presented that looked into alveolar instability with APRV. Even with the shortest exhalation time, it showed alveolar instability.
I explained to the physician that APRV has some beneficial aspects over HFOV- primarily the way the patient can spontaneously breath. I am still having problems convincing him to once again use this mode of ventilation.

There have been a few studies out there that demonstrate alveolar closure with even short expiratory times; somewhere around 6 seconds. However these studies were done utilizing a pig model which has no collateral ventilation. Collateral ventilation plays a significant role in the preservation of lung recruitment when implementing APRV. How does a rat model compare to the human model? Sounds like a silly question, but may hold the answer to your question.

Try going to intensivecareonline.com. This is a Drager website/forum with a wealth of knowledge.

GJ

If he is going to use this ONE abstract to define his practice I would ask him to reveal the in vivo study that supports his practice.

I would also show him that the rat lung model that they used at sunny side did not have the rat spontaneous breathing.

I would then also ask why it is that patients CXR, and PF ratio all improved on APRV if it does not provide stable alveoli.

The Abstract that you mentioned did not tell that much about the settings or anything else, and I would wonder why no one else has mentioned anything along these lines. One abstract should not define your practice, I will match 10 to 1 on the benifits of APRV.