Sources of error ina- aD O 2 calculated from blood stored in plastic and glass syringes

Abstract

We studied the effects of time delay on blood gases, pH, and base excess in blood stored in glass and plastic syringes on ice and the effects of resulting errors on calculated alveolar-to-arterial PO2 difference (A-aDO2). Matched samples of dog whole blood were tonometered with gas mixtures of 5% CO2-12% )2-83% N2 (mixture A), 10% CO2-5% O2-85% N2 (mixture B), and 2.88% CO2-4% O2-93.12% N2 (mixture C). Tonometered blood samples were transferred to 5-ml glass (5G), 5-ml plastic (5P), and 3-ml plastic (3P) syringes and stored on ice. Blood gases were measured every 1 h up to 6 h. In 5G, PO2 progressively decreased in blood tonometered with mixture A but rose in blood tonometered with mixtures B and C. O2 saturation progressively fell in all cases. In 5G, blood PCO2 progressively rose regardless of which gas mixture was used, and pH as well as base excess progressively fell. The rise in PO2 was faster in plastic than in glass syringes, and O2 saturation always rose in plastic syringes. Differences between storage in plastic and glass syringes on PO2 change were greatest when initial blood PO2 was highest (mixture A). At the highest PO2, O2 exchange was faster in 3P than in 5P. The rise of PCo2 was just as fast in plastic as in glass syringes, but in both the rise in PCO2 was faster at a higher initial PCO2 (mixture B) than in lower initial PCO2 (mixtures B and C). Rates of PO2 and PCO2 change in matched samples were significantly faster in 3P than in 5P. Errors due to rises in PCO2 and PO2 cause additive errors in calculated A-aDO2, and when blood is stored in plastic syringes for > 1 h significant errors result. Errors are greater in normoxic blood, in which estimated A-aDO2 decreased by > 10 Torr after 6 h on ice in plastic syringes, than in hypoxic blood.

A new device for the aspiration of follicular fluid for acid-base balance analysis in cattle

“…In Experiment 2G, when samples of cystic fluid were collected in glass, we obtained the same results as in Experiment 1 with absolute stability in the differences for all 12 triads of samples. Our results are supported by evidence that syringe material and conditions and length of sample storage, significantly influence acid-base balance values (Szenci and Besser 1990;Wu et al 1997;Beaulieu et al 1999;Knowles et al 2006;Cingi et al 2009). Despite the fact that we have not performed a direct comparison of the samples from the same source stored in glass and plastic syringes, we agree with the assertion that if a delay in acid-base balance analysis is expected, the samples should be drawn and stored in glass (Knowles et al 2006).…”

“…This procedure is much easier than the recovery of follicular fluid. Nevertheless, for this analysis, there are many potential pre-analytical errors in blood sampling-e.g., caused by the underfilling of the syringe (Bandi 1981;James et al 1997), the syringe material itself or conditions of sample storage (Szenci and Besser 1990;Wu et al 1997;Beaulieu et al 1999;Knowles et al 2006;Cingi et al 2009). Because similar errors should be expected during and after the collection of follicular fluid (Redding et al 2006), requirements for anaerobic follicular fluid collection have been reported (Berg et al 2005;Redding et al 2006).…”

Limitations of ultrasound guided follicular aspiration for analysis of ovarian follicular fluid in dairy cattle

“…The underfilling of blood collection tubes results in a false decrease of CO 2 concentration in serum and can result in a false diagnosis of metabolic acidosis in dogs and cats (James et al 1997). Acid-base indicators can also be changed by storage temperature or type of syringe (plastic or glass) (Wu et al 1997;Beaulieu et al 1999). Because similar errors should be expected during and after collection of follicular fluid (Redding et al 2006), the requirements for anaerobic follicular fluid collection have been reported (Berg et al 2005;Redding et al 2006).…”

“…Recovery of the follicular fluid for acid-base balance (ABB) analysis from live animals has been rarely described (Berg et al 2005;Cech et al 2007) and technical aspects of the procedure were not evaluated. Although peripheral blood collection for ABB analysis is performed routinely and this procedure is easier than the recovery of follicular fluid, many preanalytical errors in blood sampling for this analysis have been described (Bandi 1981;James et al 1997;Wu et al 1997;Beaulieu et al 1999).…”

Circumstances When Arterial Blood Gas Analysis Can Lead Us Astray

“…Several studies have sought to determine the effects of syringe material (plastic vs glass), storage time, and storage temperature on normal ABG and blood oxygen saturation values. 2,3 Results suggest that samples drawn into plastic syringes should be analyzed immediately, that on-ice storage of plastic syringes is ineffective, and that if analysis is going to be delayed, samples should be drawn and stored in glass containers. Although values can change with time in both glass and plastic syringes, errors are most prevalent and consequential when used to calculate the alveolar-to-arterial oxygen difference using the alveolar gas equation.…”