The image is a page from a book titled "Chapter 13. Ventilatory strategies during anesthesia". The page is divided into three sections. 

The first section on the left side of the page has a graph that shows the flow of air pressure from the heart to the lungs. The graph is labeled "PEEP" and shows a downward trend in the air pressure. The x-axis of the graph represents the pressure level, while the y-axis represents the stress index.

There are also three lines on the page, each representing a different step in the process of ventilating the lungs during anesthesia. The first line shows the pressure of the lungs, the second line shows a decrease in the pressure, and the third line shows an increase in stress index, the fourth line shows that the pressure is higher than the rest of the body, and finally, the fifth line shows how the pressure increases. The text on the right side reads "Figure 13.9 Assessment of the Stress Index" and "Stress Index".

At the bottom of the image, there is a paragraph that explains that the image is related to the study of the study and provides further information about the study.