van Tienhoven AJ, et al. - Given the utility of lactate measurement as a tool to risk-stratify critically ill patients in the Emergency Department, researchers examined if arterial or peripheral venous lactate levels can be used interchangeably for this purpose via performing a systematic review. For this purpose, they assessed studies investigating the agreement between arterial and peripheral venous lactate levels in the Emergency Department via searching PubMed, Embase, the Cochrane Central Register of Controlled Trials/Wiley, Web of Science/Clarivate Analytics, and references of selected articles. Findings revealed higher peripheral venous lactate levels than arterial lactate levels. Importantly, in hyperlactatemia, they observed poorer agreement between arterial and peripheral venous lactate. These findings suggest peripheral venous lactate as an unreliable parameter to use interchangeably in the Emergency Department. They suggest a possible utility of peripheral venous lactate as a screening tool to rule out arterial hyperlactatemia in clinical practice at a cut-off value of 2 mmol/l. However, in case of a peripheral venous lactate level > 2 mmol/l, confirmation of hyperlactatemia is recommended using arterial sampling.