Serum Lactate Measured
Corresponding Bundle Element
Serum lactate measured.
Background
Hyperlactatemia is typically present in patients with severe sepsis or septic shock and may be secondary to anaerobic metabolism due to hypoperfusion. The prognostic value of raised blood lactate levels has been well established in septic shock patients (1), particularly if the high levels persist. (2,3) In addition, blood lactate levels have been shown to have greater prognostic value than oxygen-derived variables. (4) Obtaining serum lactate is essential to identifying tissue hypoperfusion in patients who are not yet hypotensive but who are at risk for septic shock.
Limitations
However, the interpretation of blood lactate levels in septic patients is not always straightforward. A number of studies have suggested that elevated lactate levels may result from cellular metabolic failure in sepsis rather than from global hypoperfusion. Elevated lactate levels can also result from decreased clearance by the liver.
Implications
Given the high risk for septic shock, all patients with elevated lactate > 4 mmol/L (36 mg/dl) will enter the early goal-directed therapy portion of the Severe Sepsis Resuscitation Bundle, regardless of blood pressure.
This approach is consistent with the trial that established the value of early goal directed therapies, Rivers et al. (5)
Turnaround Time
Serum lactate must be available in your institution with rapid turnaround time (within minutes) to effectively treat severely septic patients. An arterial blood gas analyzer located in the clinical laboratories usually accomplishes this. However, any means of rapid turnaround time will be acceptable. It is essential for hospitals to invest in adequate equipment in order to meet present standards of care for septic patients.
The technique of obtaining serum lactate by venipuncture typically carries a 24- to 48-hour turnaround time and will not be suitable to care for septic patients. This technique also requires special collection conditions, such as without the use of tourniquet, hindering clinical care.
References
- Weil MH, Afifi AA. Experimental and clinical studies on lactate and pyruvate as indicators of the severity of acute circulatory failure (shock). Circulation. 1970;41:989–1001.
- Vincent JL, Dufaye P, Berre J, et al. Serial lactate determinations during circulatory shock. Critical Care Medicine. 1983;11:449–451.
- Friedman G, Berlot G, Kahn RJ, et al. Combined measurements of blood lactate concentrations and gastric intramucosal pH in patients with severe sepsis. Critical Care Medicine. 1995;23:1184–1193.
- Bakker J, Coffernils M, Leon M, et al. Blood lactate levels are superior to oxygen derived variables in predicting outcome in human septic shock. Chest. 1991;99:956–962.
- Rivers E, Nguyen B, Havstad S, et al. Early goal-directed therapy in the treatment of severe sepsis and septic shock. New England Journal of Medicine. 2001;345:1368–1377.
Content adapted extensively from:
- Vincent JL, Gerlach H. Fluid resuscitation in severe sepsis and septic shock: An evidence-based review. Critical Care Medicine. 2004;32(11):(Suppl.)S451-S454.
Tips
- If serum lactate is not rapidly available in your institution, invest in equipment to make rapid assessment possible. This should be presented to hospital and laboratory administration as a present standard of care.
- Create a standardized protocol to manage severe sepsis that includes measurement of serum lactate.
- Include a prompt on arterial blood gas requisitions or physician order entry to prompt users to order lactate for suspected severe sepsis.
