Figure 2. Depth-Duration Dose Plot from a Study Patient with Multiple Hypotensive Episodes.

Depth-Duration Dose = Total area of shaded region under 90 mmHg

When calculating the dose, if either the first or last (as in this case) recorded SBP is a hypotensive value, the shaded region is closed by a vertical line passing through this point

This case shows a patient with three separate hypotensive episodes where the total dose is the sum of the AUC from all of the shaded regions