Comparison of lactate levels in venous blood gas versus in arterial blood gas in patients admitted to the intensive care unit - an observational study
Background
Measurement of lactate level is an essential tool in the clinical assessment of a patient – especially in patients suspected of having decreased perfusion caused by organ failure or internal bleeding. Aim of this study is to evaluate the agreement of venous lactate values with arterial lactate values in patients with either acidosis or alkalosis.
Method
Prospectively collected data was included in this study. 44 samples were collected from patients admitted to the ICU. The inclusion criteria was a deviating level of pH relative to pH-neutrality (reference interval 7.35-7.45.)
One arterial lactate sample was collected from arterial catheters and compared with venous lactate samples collected from central venous catheters or peripheral venous catheters. All samples were collected simultaneously and analyzed using ABL800 (Radiometer, Denmark). Vital parameters, need for inotropic drugs and occurrence of cyanosis was also registered. ABG and VBG samples were compared using Bland-Altman plot.
Results
The Bland-Altman plot showed narrow 95% limits of agreement and average difference in lactate of 0,07 between arterial and venous lactate. An average difference between arterial compared to central and peripheral venous was found to be 0,06 and -0,26 respectively. When analysing the samples according to the need for inotropic drugs similar results were found.
Conclusion
This small-scale study shows that venous lactate is a valid parameter when measuring the level of lactate and adds that venous lactate has a reliable diagnostic value in patients with deviating pH value.
