This is Jeff Gott and this is surgery, ICU rounds.

This is a continuation of our talks on issues of mechanical ventilation.

Our last discussion was issues on peep and the effects of oxygenation,

as well as some of the issues on ventilation.

I'd like to pick up on that and talk about some more of the extra pulmonary effects of positive end

extratory pressure, namely looking at issues in the cardiovascular system, the bronchial

circulation, and going back to some issues on the nervous system.

In addition, I'd like to talk about what is prophylactic peep and a brief discussion on optimal peep.

In the last episode, you remember that we talked to that,

peep will actually decrease the cardiac output, so though we actually may improve the auctionation in patients,

we actually may decrease the auction delivery if we impair the cardiac output.

And this is largely due to an increase in the thoracic pressure.

The intratheracic pressure, as you remember, will reduce the venous return and decrease venous return.

We'll subsequently decrease cardiac output.

But there are some other factors that will play into the effect of peep on the cardiovascular system.

These are things such as lung and chest wall compliance, previous matricular loading conditions,

previous matricular contractile function, as well as the sympathetic memetic compensatory response.

Let's look first at the role of lung and chest wall compliance

and the impact of positive and extratory pressure on the cardiovascular system.

Remember, as we increase the peak pressure,

we can basically fill the thorax with positive pressure, and that positive

pressure impairs the venous return. When you have a situation with a decreased lung compliance,

...