To compare blood gas results obtained from 4 point-of-care (POC) blood gas analyzers under routine working conditions in order to determine their interchangeability.Design
University teaching hospital.Animals
Arterial blood samples from 34 dogs, 22 presented for cardiorespiratory disease and 12 healthy experimental Beagles.Measurements
Each sample was analyzed by 4 POC blood gas analyzers in a random order: Cobas b-123 POC system, IRMA TruPoint, Idexx VetStat, and ABL80 FLEX. Values obtained for pH, partial pressure of oxygen (PO2), and partial pressure of carbon dioxide (PCO2) were compared between analyzers using a statistical mixed linear model and the Bland–Altman method; P < 0.05 was set as the level of significance. One sample was also repeatedly measured 5 times on each machine to calculate and compare intra-analyzer variance for each measured variable using Fisher-statistics.Results
PO2 and PCO2 values were significantly higher when measured with the Idexx and IRMA machine than with Cobas and ABL80 (PO2: P < 0.001; PCO2: P < 0.05). pH values were significantly higher when measured with the Idexx instrument than with others' devices (P < 0.01). An interaction between health status and results delivered by devices was found only for PO2 values. There was no significant difference in intra-analyzer variance between the 4 machines, for any of the measured variables.Conclusions
PO2, PCO2, and pH differed significantly between the 4 analyzers. Differences in PO2 results were substantial and clinically relevant. All 4 analyzers displayed good intra-analyzer variance. Consequently, serial blood gas analysis should be performed on a single device and interpreted in accordance of the device's specific reference intervals.