What is the best indicator of adequate resuscitation in septic shock?

From the Guidelines

The best indicator of adequate resuscitation in septic shock is E. Decreased lactate level. When treating septic shock, monitoring lactate clearance provides the most reliable evidence that tissue perfusion is improving and that resuscitation efforts are effective. During septic shock, tissues experience hypoperfusion and switch to anaerobic metabolism, producing lactate. As resuscitation improves oxygen delivery to tissues, lactate levels decrease, indicating restoration of aerobic metabolism. While normal blood pressure, pulse, urine output, and improved mental status are important clinical parameters to monitor, they may normalize before tissue perfusion is fully restored. Lactate clearance directly reflects cellular metabolism improvement and has been shown to correlate with better outcomes, as demonstrated by a significant reduction in mortality in lactate-guided resuscitation compared to resuscitation without lactate monitoring (RR 0.67; 95% CI 0.53–0.84; low quality) 1. Typically, a reduction in lactate levels by at least 10-20% within the first few hours of resuscitation suggests adequate treatment response. Persistent elevation of lactate despite normalization of other vital signs should prompt reassessment of resuscitation strategies and consideration of additional interventions. Some key points to consider in the management of septic shock include:

• Initial fluid resuscitation with at least 30 mL/kg of IV crystalloid fluid within the first 3 hours 1
• Frequent reassessment of hemodynamic status to guide additional fluid administration 1
• Use of dynamic variables over static variables to predict fluid responsiveness, where available 1
• Targeting a mean arterial pressure of 65 mm Hg in patients with septic shock requiring vasopressors 1
• Guiding resuscitation to normalize lactate in patients with elevated lactate levels as a marker of tissue hypoperfusion 1

From the Research

Indicators of Adequate Resuscitation in Septic Shock

• The best indicator of adequate resuscitation in septic shock is a topic of ongoing research and debate 2, 3, 4, 5, 6.
• According to the study by 2, parameters of peripheral perfusion could be used to guide the individualization of patients with septic shock.
• However, the study by 3 suggests that lactate is an unreliable indicator of tissue hypoxia in injury or sepsis, and that increased blood lactate often reflects increased aerobic glycolysis in skeletal muscle secondary to epinephrine-stimulated Na+,K+-ATPase activity.
• The study by 4 outlines the metabolism of lactate and etiology of lactic acidosis, and discusses the clinical implications of serum lactate measurement in diagnosis, monitoring, and prognostication in acute and intensive care settings.
• The study by 5 reviews the rationale for fluid resuscitation and vasopressor therapy and the importance of both mean and diastolic blood pressure during the initial resuscitation of the septic shock.
• The study by 6 demonstrates that elevated lactate levels are highly associated with in-hospital mortality, and that only patients who presented with lactate values greater than 4 mmol/L, with and without hypotension, are significantly associated with in-hospital mortality.

Lactate Levels as an Indicator

• Lactate levels greater than 4 mmol/L are associated with increased mortality in septic shock patients 6.
• The Surviving Sepsis Campaign guidelines recommend obtaining a serum lactate measurement within 6 hours of presentation for all patients with suspected severe sepsis or septic shock 6.
• However, the study by 3 suggests that lactate is not a reliable indicator of tissue hypoxia, and that other factors such as epinephrine-stimulated Na+,K+-ATPase activity may contribute to increased lactate levels.

Other Indicators

• Normal blood pressure is not necessarily an indicator of adequate resuscitation in septic shock, as patients may still have impaired tissue perfusion despite normal blood pressure 2, 5.
• Urine output and mental status may also be used as indicators of adequate resuscitation, but their reliability and sensitivity are not well established 2, 5.
• The study by 2 suggests that parameters of peripheral perfusion, such as decreased lactate levels, may be a more reliable indicator of adequate resuscitation in septic shock.