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Abstract
To test the hypothesis that measurements of peripheral venous lactate (V-LACT) can
be substituted for arterial lactate (A-LACT) in predicting arterial hyperlactacidemia.
We conducted a prospective comparison of paired A-LACT and V-LACT measurements obtained
from a convenience sample of 74 ED patients who presented to an urban, public teaching
hospital, 70% of whom had abnormal A-LACT.
Mean A-LACT and V-LACT were 2.8 mmol/L and 3.0 mmol/L, respectively. A-LACT and V-LACT
were strongly correlated (r2 = .89). Simultaneous multivariate adjustment for tourniquet
time and for time elapsed between drawing of A-LACT and V-LACT had no effect on this
correlation. Although the mean difference between V-LACT and A-LACT was only .22 mmol/L,
the range that included 95% of the disagreement between paired measurements in individual
patients was-1.3 mmol/L to 1.7 mmol/L. When A-LACT and V-LACT levels were each divided
into normal and abnormal (elevated) groups, V-LACT showed 94% sensitivity (95% confidence
interval [CI], 83% to 99%), 57% specificity (95% CI, 34% to 78%), a positive likelihood
ratio of 2.2, and a negative likelihood ratio of .1. A-LACT values were used as the
criterion standard for these calculations.
Correlation between A-LACT and V-LACT was high in this cohort of patients, but agreement
is imperfect. The odds of arterial hyperlactacidemia appear to be reduced substantially
by the finding of a normal V-LACT but are only marginally increased if the V-LACT
is increased. Caution should be used in the routine substitution of V-LACT for A-LACT.