Air bubbles and temperature effect on blood gas analysis.

Abstract

SUMMARY The effect of temperature, time of storage, and presence of air bubbles in specimens for blood gas analysis was studied. The results show that air bubbles in a 10 % proportion are undesirable because of significant elevation in the Po2, and the storage of anaerobic blood samples at room temperature (250C) is acceptable when measurements are done within the first 20 minutes.The presence of air bubbles in blood samples for blood gas analysis can cause significant error in such determinations.' 2Although the potential of sucherror has been recognised, the clinical significance is not clear since most of the available data have been obtained from theoretical and experimental models.1-4 In this study we have analysed the observable effects of air bubbles introduced into blood samples and the time-temperature effects of storage. The results of the study show some of the actual effects of air bubbles and storage on routine blood gas determination. Material and methodsBlood samples were obtained from patients in the intensive care unit and coronary care unit of Milwaukee County Hospital by arterial puncture in a 6 ml disposable plastic syringe (Monoject (R)) containing a lead washer and approximately 0-2 ml of sodium heparin (1000 IU/ml). The volume of blood obtained was approximately 4-5 ml. Any entrapped air bubbles were removed immediately and the initial blood gas analysis was performed within 45 seconds using a Radiometer ABL-1 blood gas analyser. The syringes were sealed with a rubber cup and divided into three groups. In the first group an air bubble corresponding to 10% of the blood volume was introduced into the syringe, which was manually inverted 10 times and placed in ice (40C) for 15-20 minutes; then blood gases were measured. The second and third groups were kept anaerobically, one at 4VC and the other at room temperature (250C). Blood gases were determined at different intervals up to 120 minutes after the initial measurement. Comparative analysis of these results Received for publication 22 February 1980 was then performed based on the difference observed between the initial result and subsequent results from each sample. The statistical significance of differences was determined with a paired t test and the comparison of differences in the precision of the respective method was used for clinical appraisal of the various treatments.

Multi Frequency Phase Fluorimetry (MFPF) for Oxygen Partial Pressure Measurement: Ex Vivo Validation by Polarographic Clark-Type Electrode

“…In general and as demonstrated by porcine results, temperature is obviously one major confounder on P O2 measurement [20], [21]. However, the present results of the artificial circulatory setup show that the MFPF technology accurately compensates for alterations in temperature if assessed strictly at the measurement site.…”

Instrumental variability of respiratory blood gases among different blood gas analysers in different laboratories

“…In addition, tonometered samples were kept in ice-water slush for a considerable time. Although PCO 2 and pH values hardly change within 4 h, theoretically PO 2 values could have changed more than 2% [16][17][18]. The PO 2 and PCO 2 values measured by the same BGA at the beginning and at the end of every round, however, did not differ by more than 0.09 and 0.07 kPa (0.7 and 0.5 mmHg), respectively.…”

“…This is different from the situation in clinical practice where pre-analytical errors play a major role, especially for PO 2 . In the preanalytical phase, the blood gas results may be influenced, for example, by: the ventilatory status of the patient before and during blood collection; the blood PO 2 level; the technique of specimen collection; the nature of the specimen container, preparation of the container with anticoagulant; sample handling; cooling of the sample; storage and transport of the specimen; and severe leucocytosis or thrombocytosis [16][17][18][19][20][21][22][23][24][25][26]. This study provides indirect support for the idea that standardization and quality control in the preanalytical phase represent the best strategy to optimize reproducibility of measurements of blood gas values in a clinical setting.…”

IFCC Section

“…Immediately after blood collection, the sample is checked for air bubbles, which have to be expelled at once (20)(21)(22). The needle is replaced by a tightly fitting cap.…”

“…For a sample remaining at room temperature for 30 min, the following alterations (SD) were found (12): pH pC0 2 cHCOf Base excess pO 2 normal range p0 2 high range -0,021± 0,008 +0,11 ± 0,14 kPa +0,86 ± 1,02 mm Hg -0,44 ± 0,50mmol/l -0,77 ± 0,41 mmol/1 -7,5 ± 3,7% of original value (8,0-16,0 kPa or 60-120 mm Hg) -30,1 ± 2,9% of original value (18,(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)7 kPa or 140-200 mm Hg) For a sample remaining at room temperature for 30 min, the following alterations (SD) were found (12): pH pC0 2 cHCOf Base excess pO 2 normal range p0 2 high range -0,021± 0,008 +0,11 ± 0,14 kPa +0,86 ± 1,02 mm Hg -0,44 ± 0,50mmol/l -0,77 ± 0,41 mmol/1 -7,5 ± 3,7% of original value (8,0-16,0 kPa or 60-120 mm Hg) -30,1 ± 2,9% of original value (18,(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)7 kPa or 140-200 mm Hg)…”