Ventilator Graphics: Are Pressure Volume Loops interesting?

If you buy a new ventilator today for your preterm infants, you cannot avoid having ‘sophisticated graphics’. These ‘sophisticated graphics’ are supposed to help you ventilate the babies appropriately. I have always been very skeptical about ‘sophisticated graphics’ as they never look like the pretty curves in the books and review articles with clear inflection points, that, supposedly, allow you to tell whether a patient is over-distended or under-inflated.

So I thought I would get the readers of this blog to help me with a little project. I took some photos of real-life pressure volume loops on ventilators in my NICU, either EvitaXL or VN500. I have created a survey monkey survey that will take you about 3 minutes to complete. I will give you some info about each baby, and I would like you to look at each loop, and tell me whether you think the lung is overdistended, or underinflated, and what change in ventilation you think should be made as a result of seeing the loops. The first thing that I have to admit is that to get clean loops like these is not very easy, often you have to freeze the screen multiple times to choose a loop that looks like something, and is not, for example, a double figure of 8 loop that crosses over itself multiple times. Which immediately introduces an element of subjectivity.

So the idea of this little survey is to see if people can agree to what the loops actually show.

The survey is at the following link

About Keith Barrington

I am a neonatologist and clinical researcher at Sainte Justine University Health Center in Montréal
This entry was posted in Neonatal Research and tagged , . Bookmark the permalink.

2 Responses to Ventilator Graphics: Are Pressure Volume Loops interesting?

  1. annie janvier says:

    Keith, to answer your question:
    “Ventilator Graphics: Are Pressure Volume Loops interesting?”
    My answer is: no (!)

    Your forgot some items in your multiple choice questionnaire:
    -I look at the baby
    -I ask the nurse’s baby how she finds her patient (is he uncomfortable, how stable is he)
    -I ask the baby’s parents how they find their baby

  2. Chris Prince, RRT says:

    Neonatal loops don’t tell me much. They change rapidly breath to breath. I also believe that some clinicians pay too much attention to how pretty the loops and waveforms look, without treating the patient. We’ve all had sick patients with nice loops and stable patients with bad loops. It all depends on what the patient looks like.

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