Comparison of Arterial and Venous Blood Gases and the Effects of Analysis Delay and Air Contamination on Arterial Samples in Patients with Chronic Obstructive Pulmonary Disease and Healthy Controls

Abstract

Background: Arterial blood gases (ABGs) are often sampled incorrectly, leading to a ‘mixed’ or venous sample. Delays in analysis and air contamination are common. Objectives: We measured the effects of these errors in patients with chronic obstructive pulmonary disease (COPD) exacerbations and controls. Methods: Arterial and venous samples were analyzed from 30 patients with COPD exacerbation and 30 controls. Venous samples were analysed immediately and arterial samples separated into non-air-contaminated and air-contaminated specimens and analysed at 0, 30, 60, 90 and 180 min. Results: Mean venous pH was 7.371 and arterial pH was 7.407 (p < 0.0001). There was a correlation between venous and arterial pH (r = 0.5347, p < 0.0001). The regression equation to predict arterial pH was: arterial pH = 4.2289 + 0.43113 · venous pH. There were no clinically significant differences in arterial PO₂ associated with analysis delay. A statistically significant decline in pH was detected at 30 min in patients with COPD exacerbation (p = 0.0042) and 90 min in controls (p < 0.0001). A clinically significant decline in pH emerged at 73 min in patients with COPD exacerbation and 87 min in controls. Air contamination was associated with a clinically significant increase in PO₂ in all samples, including those that were immediately analyzed. Conclusions: Arterial and venous pH differ significantly. Venous pH cannot accurately replace arterial pH. Temporal delays in ABG analysis result in a significant decline in measured pH. ABGs should be analysed within 30 min. Air contamination leads to an immediate increase in measured PO₂, indicating that air-contaminated ABGs should be discarded.

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

“…, n.b. figure analysis excludes O'Connor, due to incomplete data). Heterogeneity was statistically significant; the I 2 of 99.6% showed that most variability was across studies.…”

“…, n.b. figure analysis excludes O'Connor). The difference between the venous and arterial PO 2 was very large.…”

“…For the assessment of pH, there were 1747 subjects from 15 studies (comprising 21 datasets) that compared PVBG with ABG. 1,4,5,13,[17][18][19][20][21][22][23][24][25][26][27][28] All studies provided details on sampling technique and the time between PVBG and ABG analysis (universally described as 'minimal'). The populations ranged from healthy control participants to those that were acutely ill. Statistical heterogeneity was considerable (I 2 = 85%, Chi 2 = 158, df = 20, P < 0.0001).…”

Impact of Partial Pressure of Oxygen in Blood Samples on the Performance of Systems for Self-Monitoring of Blood Glucose

“…12,13 Low pO 2 values can be found in patients with respiratory diseases or at high altitude (e.g., hiking, mountaineering, during air travel). [14][15][16][17][18][19] Increased pO 2 values can occur in patients requiring artificial respiration. 9,11,20 In this study, at ''high'' pO 2 values the GOD systems showed a negative bias for the measurement results compared with those at pO 2 values approximately 70 mm Hg.…”

Influence of Partial Pressure of Oxygen in Blood Samples on Measurement Performance in Glucose-Oxidase-Based Systems for Self-Monitoring of Blood Glucose

“…Decreased pO 2 levels can be expected, e.g., during long-distance flights or in patients with respiratory diseases. [9][10][11][12][13] In addition, for many GOx systems, detailed information, i.e., the pO 2 range in which the system operates well, is not provided in the manufacturers' labeling.…”