Peripheral venous and arterial blood gas analysis in adults: are they comparable? A systematic review and meta‐analysis

Peripheral venous blood gas ( PVBG ) analysis is increasingly being used as a substitute for arterial blood sampling; however, comparability has not been clearly established. To determine if the pH , PCO 2 and PO 2 obtained from PVBG analysis is comparable with arterial blood gas ( ABG ) analysis. A search was conducted of electronic databases as well as hand‐searching of journals and reference lists through D ecember 2012 to identify studies comparing PVBG with ABG analysis in adult subjects. A systematic review was conducted in accordance with the P referred R eporting I tems for S ystematic R eviews and M eta‐ A nalyses statement. A meta‐analysis using a random effects model was used to calculate the average difference (bias) and the limits of agreement for the venous and arterial pH , PCO 2 and PO 2 . A total of 18 studies comprising 1768 subjects were included in the meta‐analysis. There was considerable heterogeneity between studies with I 2 approaching 100%. There was little difference between the pH obtained from the PVBG and the ABG , with the arterial pH typically 0.03 higher than the venous pH (95% confidence interval 0.029–0.038). The venous and arterial PCO 2 were not comparable because the 95% prediction interval of the bias for venous PCO 2 was unacceptably wide, extending from −10.7 mm Hg to +2.4 mm Hg. The PO 2 values compared poorly, the arterial PO 2 typically 36.9 mm Hg greater than the venous with significant variability (95% confidence interval from 27.2 to 46.6 mm  H g). PVBG analysis compares well with ABG analysis for pH estimations in adults but not to the PCO 2 or PO 2 . These differences are sufficiently large to be of clinical significance.