The effects of ice‐water storage on blood gas and acid–base measurements

Abstract

Objective: To determine the effects of storage of arterial and venous blood samples in ice water on blood gas and acid–base measurements. Design: Prospective, in vitro, laboratory study. Setting: School of veterinary medicine. Subjects: Six healthy dogs. Measurements and main results: Baseline measurements of partial pressure of oxygen (PO2), partial pressure of carbon dioxide (PCO2), pH, hemoglobin concentration (tHb), oxyhemoglobin saturation, and oxygen content (ContO2) were made. Bicarbonate (HCO3) and standard base excess (SBE) were calculated. Arterial and venous blood samples were separated into 1 and 3 mL samples, anaerobically transferred into 3 mL plastic syringes, and stored in ice water for 6 hours. Measurements were repeated at 15, 30 minutes, and 1, 2, 4, and 6 hours after baseline measurements. Arterial (a) PO2 increased significantly from baseline after 30 minutes of storage in the 1 mL samples and after 2 hours in the 3 mL samples. Venous (v) PO2 was significantly increased from baseline after 4 hours in the 1 mL samples and after 6 hours in the 3 mL samples. The pHa significantly decreased after 2 hours of storage in the 1 mL samples and after 4 hours in the 3 mL samples. In both the 1 and 3 mL samples, pHv decreased significantly only after 6 hours. Neither the arterial nor the venous PCO2 values changed significantly in the 1 mL samples and increased only after 6 hours in the 3 mL samples. No significant changes in tHb, ContO2, SBE, or HCO3 were detected. Conclusions: The PO2 of arterial and venous blood increased significantly when samples were stored in plastic syringes in ice water. These increases are attributable to the diffusion of oxygen from and through the plastic of the syringe into the blood, which occurred at a rate that exceeded metabolic consumption of oxygen by the nucleated cells.

Cardiopulmonary and isoflurane-sparing effects of epidural or intravenous infusion of dexmedetomidine in cats undergoing surgery with epidural lidocaine

“…Arterial blood samples (3 mL) were collected at the beginning and end of the evaluation period (20 and 80 minutes) directly from the arterial catheter, in syringes containing heparin. Samples were kept refrigerated on ice and water (Rezende et al. 2007) for a maximum of 3 hours prior to analysis (ABL‐5, Radiometer, Copenhagen, Denmark); data were corrected to the cat’s RT.…”

“…Arterial blood samples (3 mL) were collected at the beginning and end of the evaluation period (20 and 80 minutes) directly from the arterial catheter, in syringes containing heparin. Samples were kept refrigerated on ice and water (Rezende et al 2007) for a maximum of 3 hours prior to analysis (ABL-5, Radiometer, Copenhagen, Denmark); data were corrected to the cat's RT. Fifteen minutes prior to termination of inhalational anesthetic delivery, cats were given 1 mg kg )1 Table 2 Mean values (±SD) of E 0 ISO in cats pre-medicated with dexmedetomidine (4 lg kg )1 , IM) and receiving epidural lidocaine (1 mg kg )1 ) (GI), epidural lidocaine and dexmedetomidine (4 lg g )1 , GII), or epidural lidocaine and constant rate infusion of dexmedetomidine (0.25 lg kg )1 minute )1 ) (GIII)…”

Effects of collecting blood into plastic heparinised Vacutainer®tubes and storage conditions on blood gas analysis values in horses

“…Extensive research has been conducted on the use of plastic syringes for collection and storage of blood for gas analysis (Mahoney et al 1991;Muller-Plathe and Heyduck 1992;Wu et al 1997;Deane et al 2004;Knowles et al 2006;Picandet et al 2007;Piccione et al 2007;Rezende et al 2007). The results of these studies have led to recommendations that plastic syringes with low gas permeability can be used for blood gas analysis as long as blood samples are stored at room temperature and analysed within 30 min of collection.…”

“…The results of these studies have led to recommendations that plastic syringes with low gas permeability can be used for blood gas analysis as long as blood samples are stored at room temperature and analysed within 30 min of collection. Blood gas analysis should not be performed on blood samples collected in plastic syringes and stored in iced water because such storage facilitates oxygen diffusion from the atmosphere across the semi-permeable plastic barrel of the syringe into the blood sample, thereby increasing PO 2 (Mahoney et al 1991;Piccione et al 2007;Rezende et al 2007;Anon 2009).…”

Traditional Acid-Base Analysis

“…If a delay of greater than 15 minutes between sample collection and analysis is anticipated, the sample should be maintained under airtight conditions and immersed in ice water. 12,13 …”