From the classroom to the emergency room, O.R. and beyond. You're joining Trauma ICU Rounds with your host, Dr. Dennis Kim.

Thanks for joining me on trauma ICU rounds. I'm your host, Dr. Dennis Kim. I'm an associate professor of clinical surgery at the David Geffen School of Medicine at UCLA,

and the medical director of the trauma surgical ICU at Harbor UCLA Medical Center in

South Los Angeles. In this our inaugural episode, we're going to review the mechanisms and

pathophysiology underlying acute respiratory failure. And whether you primarily work in the ER, wards, PACU, or ICU,

it's really critical that you have an organized approach

to the recognition and management of this common and potentially life-threatening condition.

There's a lot of reasons we're starting rounds with this particular topic.

First, acute respiratory failure is one of these final common pathways for a diverse range of clinical disease processes.

And as such, it's frequently encountered both in the trauma bay and ICU.

Second, and this is really important, having a strong grasp on the core physiologic concepts underlying both oxygenation and ventilation, as well as the relationships to one another, provides the foundation for understanding other core topics in trauma and critical care, including hemorrhagic shock, mechanical ventilation, resuscitation

endpoints, just to name a few. But before we delve into the clinical management side of things,

I wanted to spend the next 35 minutes reviewing the mechanisms of both acute hypoxemia and

hypercarbia. So there are four key objectives for today's episode, and by the end

of rounds, you should be able to, number one, discuss the key equations and concepts used to

describe oxygenation and ventilation. This includes the DO2 or oxygen delivery equation.

You should also understand the relationship between the partial pressure of oxygen

and oxygen saturation, or the oxygen hemoglobin dissociation curve, the AAO2 difference, as well as

the determinants of alveolar ventilation. Number two, you should be able to describe the differences

between hypoxia on the one hand and hypoxemia on the other.

Number three, you should understand the six pathophysiologic causes of hypoxemia, with the two

most relevant and commonly encounter mechanisms being VQ mismatch and shunts.

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