Background
Measurements of lactate (lactic acid levels) in blood have been shown to correlate with the severity of illness in many groups of acutely ill patients. The test is commonly used in acute patient assessments in the hospital, but rarely in pre-hospital settings.
Objectives
We aimed to investigate the use and benefits of measuring lactate levels in patients when they were assessed acutely outside the hospital. This was done in four subprojects.
Methods
Subproject 1:
Testing the accuracy of a small lactate device when used during the acute treatment of patients seen by the Medical Emergency Care Unit in Odense.
Subproject 2:
A systematic review of the use and findings of lactate measurements in acute patients worldwide until August 2023.
Subproject 3:
A study of the significance of lactate levels for the prognosis of patients treated by the Medical Emergency Care Unit in Odense from 2015 to 2018. The importance of pH and carbon dioxide levels for prognosis was also investigated.
Subproject 4:
A large study on the prognostic value of lactate levels measured in patients treated in ambulances in the Region of Southern Denmark from February to July 2020.
Results
Subproject 1:
The StatStrip Lactate Xpress device was compared to a larger, highly accurate lactate device in 111 patients. StatStrip's lactate measurements showed good agreement with the larger device. The StatStrip was robust for use in the pre-hospital setting.
Subproject 2:
6028 abstracts from studies conducted until August 2023 were reviewed to identify 15 studies focusing on the prognostic value of pre-hospital lactate measurements. The studies showed that the higher a patient's lactate level, the higher their short-term mortality risk (within 30 days). This was true for all patient groups, except for patients with out-of-hospital cardiac arrest, where we found no correlation between lactate levels and survival rate.
Subproject 3:
745 patients were included. The higher the patients' lactate levels, the greater their risk of being admitted to an Intensive Care Unit, requiring mechanical ventilation, needing circulatory support, or dying within 7 days. This was also true for low pH levels and both high and low carbon dioxide levels.
Subproject 4:
15,515 patients were included while treated in the Region of Southern Denmark’s ambulances, and their lactate levels were measured during their treatment. Again, we found that the higher the lactate levels, the greater the risk for these patients to be admitted to an Intensive Care Unit, require mechanical ventilation, need circulatory support, or die within 7 days. These correlations were found in all patient groups except for patients with seizures, where no relationship between elevated lactate levels and prognosis was found.
Collaboration
The studies were conducted in collaboration between researchers from the Region of Southern Denmark and the Region of Northern Jutland, with significant contributions from pre-hospital actors in the Region of Southern Denmark.