What does a rising serum lactate level during resuscitation indicate?

• A. Decreasing lactate indicates improvement
• B. Lactate is not useful
• C. Ongoing tissue hypoperfusion or metabolic stress; worse prognosis if not decreasing
• D. Lactate rises with good perfusion

Answer: (C)

Rising serum lactate during resuscitation signals ongoing tissue hypoperfusion or metabolic stress. Lactate builds up when cells switch to anaerobic metabolism because oxygen delivery is still insufficient relative to demand, or when clearance is impaired. During resuscitation, you expect perfusion to improve and lactate to begin to fall as tissues receive adequate oxygen and metabolism returns toward aerobic pathways. If lactate continues to rise or fails to decrease, it suggests that tissues are still under stress despite resuscitation efforts, which is associated with a poorer prognosis and prompts a reassessment of volume status, perfusion pressures, and potential sources of ongoing hypoperfusion or metabolic demand.

Lactate is not simply a static marker of illness; its trend during resuscitation helps gauge the effectiveness of interventions. A decreasing lactate level is a favorable sign, whereas a rising level indicates ongoing hypoperfusion or stress. The statement that lactate rises with good perfusion is not correct, because improved perfusion should reduce lactate production and enhance clearance.