APPENDIX E: LACTATE

Lactate can be measured with the CG4 i-STAT cartridge. This specific cartridge must be stored in a temperature-controlled environment. Lactate can also be measured using a lactate-specific device but many are not approved for medical management of critical patients.1

Adding lactate to other resuscitation endpoints is beneficial, however patients should be monitored using a “whole patient” approach. He or she could be doing well clinically with an adequate blood pressure and capillary refill, good urine output, and down-titrating vasopressors, but continues to have a persistently elevated lactate level. There are many reasons for this, some of which do not require a clinical response, only further monitoring. Lactate levels have a direct impact on a patient’s pH (acidosis), however the main adverse effects of acidosis are a) decreased cardiac output and vascular “tone,” which will be seen as persistent hypotension and b) impaired coagulation, which will be seen as bleeding despite adequate blood product resuscitation and source control. In general, these effects do not occur at a pH above 7.2 (which does not correlate directly to a specific lactate level).

If lactic acid levels are available, they should be integrated into patient monitoring as follows:

- Trend lactic acid levels at a frequency of every 4 – 6 hours. Lactate improvement will lag behind improvement in vital signs, mental status, and urine output.
- If patient is under-resuscitated, or resistant to resuscitation, vital signs and organ dysfunction assessments will continue to be abnormal, with no appreciable response, and lactate will remain elevated.
- If other markers of resuscitation are improving and the patient is clinically improving, but lactate is not decreasing or is increasing, it could be an indication of tissue reperfusion (flushing out vascular beds that have not been perfused due to shock). Keep trending lactate, and if it remains elevated or is increasing, this could be an indication of a source of infection that has not been adequately addressed and may require a change in antibiotic regimen, and/or surgical intervention. Obtain telemedicine consult.

1. Bonaventura JM, Sharpe K, Knight E, et al. Reliability and accuracy of six hand-held blood lactate analysers. J Sports Sci Med. 2015 Mar 1;14(1):203-14.