The use and impact of prehospital blood lactate measurements in acute non-traumatic patients: a systematic review.

Background: The prehospital use of blood lactate measurements is increasing. However, the test's benefits have not been methodically evaluated in non-trauma patients. This study had three aims: (1) To assess the evidence of prehospital blood lactate measurements' prognostic value in non-trauma patients, (2) to investigate to what extent the test changed early patient treatment, and (3) to evaluate the healthcare personnel's attitude towards the test.

Methods: MEDLINE, Embase, and Cochrane Central Register of Controlled Trials were systematically searched until Aug 26, 2023. Cohort and randomized controlled trials assessing ≥ 20 acute non-trauma patients with prehospital lactate measurements were included if they reported (1) prognostic outcomes such as short-term mortality or (2) changes in early patient treatments. All study designs were included to assess (3) the healthcare personnel's opinion on prehospital lactate measurements. The risks of bias were assessed using the QUIPS tool, the Newcastle-Ottawa Scale, and the RoB-2. Study registration number CRD42020167169 (PROSPERO).

Results: We screened 6028 study reports. We included 15 studies on (1) the prognostic value of prehospital lactate measurements. Elevated blood lactate levels were correlated to a higher short-term mortality risk in most of the studies but not in studies with out-of-hospital cardiac arrest (OHCA) patients. The 15 prognostic studies were all cohort studies with moderate or high risks of bias. Four studies investigated (2) early treatment changes. They found that the prehospital lactate measurement may have changed early treatment in sepsis patients. However, all four studies on treatment changes were at high risk of bias. Four studies were included on (3) the healthcare personnel's attitude towards the lactate measurement. Evidence of the healthcare personnel's opinion on prehospital lactate measurements was scarce.

Conclusion: Most acute non-trauma patients with elevated prehospital lactate levels had increased risks of short-term mortality, except OHCA patients. Few studies suggested that measuring prehospital lactate levels could change early patient care, particularly in patients with suspected sepsis. The certainty of the evidence is low in this systematic review. The included studies were heterogeneous, and many had high risks of bias. Further studies are needed to investigate the impact of prehospital lactate measurements on patient care.