Comparison of two point of care lactate instruments in guinea pigs (Cavia porcellus)

Background

Lactate measurements have been utilized as diagnostic and prognostic tools for a variety of veterinary species. Reference intervals for lactate have not been published or validated in guinea pigs.

Methods

Whole blood from 48 anesthetized laboratory guinea pigs (46 Dunkin Hartley [38 males, eight females]; two Strain 13 [two males]) was analyzed using two point of care instruments (iSTAT and Lactate Plus). There were two consecutive timepoints on the iSTAT (iSTAT time 1 and time 2) and three consecutive timepoints on the Lactate Plus (Lactate Plus time 1, time 2, and time 3).

Results

There was agreement with no constant or proportional bias between the two instruments compared at equivalent timepoints (iSTAT time 1 and Lactate Plus time 3) as determined by Bland-Altman (bias: −0.19; 95% LoA: −0.55 to 0.16) and Deming linear regression analyses (slope: 1.092, 95% confidence intervals (CI): −0.9 to 1.29; y-intercept: 0.09, 95% CI: −0.12 to 0.30). Reference intervals for iSTAT time 1 were 0.49 to 1.83 mmol/L and Lactate Plus time 1 were 0.60 to. 2.2 mmol/L. There was a significant increase in lactate values from iSTAT time 1 to iSTAT time 2 and from Lactate Plus time 1 to Lactate Plus time 3.

Conclusions and Clinical Relevance

This study found strong agreement between the point of care instruments. Reference intervals for lactate for both the iSTAT and Lactate Plus instruments were similar to canine and feline intervals. Analysis should occur within 5 minutes of sample collection. Future work should assess lactate as a prognostic indicator in guinea pigs.