Which measurements are used to assess tissue perfusion after ROSC?

• A. Lactate concentration, venous oxygen saturation, and base deficit
• B. Blood glucose
• C. ECG
• D. Urine output

Answer: (A)

Post-ROSC tissue perfusion is best assessed with markers that show how well oxygen is getting to tissues and how effectively cells are clearing metabolic byproducts. Lactate rises when cells switch to anaerobic metabolism due to inadequate perfusion; after ROSC, lactate levels and their trajectory over time reveal how well perfusion and oxygen delivery are being restored. A decreasing lactate trend suggests improving tissue perfusion, while persistently high or rising lactate points to ongoing hypoperfusion or shock.

Venous oxygen saturation reflects the balance between oxygen delivery and consumption. If the central or mixed venous oxygen saturation is low, tissues are extracting more oxygen than is being delivered, indicating insufficient perfusion or high metabolic demand; when this value improves, it implies better delivery relative to demand.

Base deficit measures metabolic acidosis resulting from lactate buildup and anaerobic metabolism. A larger base deficit means more buffering is needed to correct acidosis, signaling worse perfusion; as perfusion improves and lactate clears, the base deficit tends to normalize.

Together, these markers give a dynamic picture of perfusion status after ROSC. While urine output or ECG and glucose levels provide useful information, they do not directly reflect tissue perfusion in the same way lactate, SvO2, and base deficit do.