This is the podcast Surgery I see rounds. My name is Jeff Guy. I'm an associate professor of surgery at Vanderbilt University Medical Center and director of the regional Burns Center. We've had a small hiatus from some of our podcasts. I do most later in the summertime. I've been pretty active. I have five kids. So a lot of times life happens and I'm not able to produce podcasts on a regular

basis, but hopefully as summer winds down, we'll get back into the swing of things.

One of the things that I would like to talk about starting today are some of the newer

ideas or perhaps some controversial issues regarding ventilator strategies, particularly lung ventilation strategies, and things that come up frequently on rounds this time of year.

And that is what is positive pressure ventilation and lung protective strategies.

As we've mentioned before in other podcasts, that positive pressure ventilation is

really a pretty significant alteration, normal physiology in the way that we typically breathe.

We breathe by negative inspiratory respirations in a normal setting. We lower the pressure

inside our thorax and air is drawn from an ambient pressure environment to a lower pressure environment in our thorax.

When we place somebody on a ventilator, we are pushing air into their lungs, and this really represents a 180-degree alteration in the normal physiology.

And in doing so with just absolute disregard to what we're doing,

we can actually injure the patient through our attempt to treat the patient.

And in some cases, the treatment may be worse than the disease.

And the lung may be injured by the positive pressure ventilation through a variety of different

mechanisms.

This type of injury is known as ventilator-induced lung injury,

which you may see sometimes abbreviated as VILI.

One mechanism by which over-distension is over-distension of the lung

when the lung units or ovular are physically stretched beyond their normal maximums.

We typically see this described as when the end-dispatory pressures or trans-pulmonary

pressures exceed the maximum of 30 to 35 sonometers of water.

Now this requires some thought on part of the clinician in that just because the display on the ventilator says 30 to 35

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