The main objective of this study is to examine the agreement between arterial, central venous, and peripheral venous lactate values in a population of medical Intensive Care Unit (ICU) patients.

This study is a single-center, prospective trial to assess the agreement between arterial, central venous, and peripheral venous lactate measurements. When an arterial lactate is deemed to be necessary as part of ICU management, a central venous and peripheral venous sample will also obtained within 5 minutes. All of the samples will be analyzed using the same analyzer as quickly as possible. A maximum of 10 paired arterial and venous lactate samples will be obtained per patient to prevent a single patient from dominating the data set. Additional data collected on a standardized data collection form will include primary diagnosis, intubation status, use of inotropic agents, hypotension (defined as a systolic blood pressure < 90 mm Hg), ICU length of stay and mortality. The Bland-Altman method will be used to assess agreement between arterial (A), central venous(CV), and peripheral venous (PV) lactate measurements. Approximately 50 patients will be enrolled in this study.

Inclusion Criteria:

• Adult patients 18 years or older
• Admitted to the Intensive Care Unit (ICU)
• Determined by their treating clinicians to require both a central venous line and arterial line

Exclusion Criteria:

• None