The effects of different syringe volume, needle size and sample volume on blood gas analysis in syringes washed with heparin

Abstract

Introductıon: We evaluated the eff ect of diff erent syringe volume, needle size and sample volume on blood gas analysis in syringes washed with heparin. Materials and methods:In this multi-step experimental study, percent dilution ratios (PDRs) and fi nal heparin concentrations (FHCs) were calculated by gravimetric method for determining the eff ect of syringe volume (1, 2, 5 and 10 mL), needle size (20, 21, 22, 25 and 26 G) and sample volume (0.5, 1, 2, 5 and 10 mL). The eff ect of diff erent PDRs and FHCs on blood gas and electrolyte parameters were determined. The erroneous results from nonstandardized sampling were evaluated according to RiliBAK's TEa. Results: The increase of PDRs and FHCs was associated with the decrease of syringe volume, the increase of needle size and the decrease of sample volume: from 2.0% and 100 IU/mL in 10 mL-syringe to 7.0% and 351 IU/mL in 1 mL-syringe; from 4.9% and 245 IU/mL in 26G to 7.6% and 380 IU/mL in 20 G with combined 1 mL syringe; from 2.0% and 100 IU/mL in full-fi lled sample to 34% and 1675 IU/mL in 0.5 mL suctioned sample into 10 mLsyringe. There was no statistical diff erence in pH; but the percent decreasing in pCO 2 , K + , iCa 2+ , iMg 2+ ; the percent increasing in pO 2 and Na + were statistical signifi cance compared to samples full-fi lled in syringes. The all changes in pH and pO 2 were acceptable; but the changes in pCO 2 , Na + , K + and iCa 2+ were unacceptable according to TEa limits except fullfi lled-syringes. Conclusions:The changes in PDRs and FHCs due nonstandardized sampling in syringe washed with liquid heparin give rise to erroneous test results for pCO 2 and electrolytes.

Institutional practices and policies in acid-base testing: a self reported Croatian survey study on behalf of the Croatian society of medical biochemistry and laboratory medicine Working Group for acid-base balance

“…Many survey participants are not informed who exactly performs arterial blood collection. Highquality specimen which is not contaminated by air and clots depends on syringe type, anticoagulant and sampling procedure used by physician (19). High level of communication between ward and laboratory personnel is needed for avoiding problems with blood gas analysis caused by inappropriate arterial sampling and transport.…”

The effect of different forms of heparin on point-of-care blood gas analysis

“…[2][3][4] Even in the presence of these occasionally nonspecific guidelines, preparation of self-prepared heparinised syringes remains non-standardised among the majority of doctors, even within institutions. [5] The addition of liquid heparin to a blood sample can lead to error through dilution of the sample and binding of heparin to positive ions, resulting in a negative bias. The composition of the liquid heparin itself (e.g.…”

“…Electrolytes and partial pressure of carbon dioxide (pCO 2 ) appear to be the variables most susceptible to dilution, while pH and partial pressure of oxygen (pO 2 ) remain largely unaffected. [5][6][7] Ionised calcium is the ion most greatly affected by the binding of heparin salts, although sodium and potassium may also be affected. [7,8] These factors, in conjunction with the fact that the preparation of self-prepared heparinised syringes is nonstandardised, means that even repeated blood gas samples from the same patient may not necessarily be comparable or reliable, even if handled by the same operator.…”

“…The remainder of the analytes exhibited similar findings to those of the 1 000 IU/mL cohort, suggesting that any bias present is independent of heparin concentration and more likely due to dilution, as has been noted previously. [5][6][7] …”

“…It has been found (as would be expected) that the greater the added volume of liquid heparin, the greater the discrepancy in results. [5,18] In order to try to control for the effect of dilution, 1 mL of blood was used for all the methods. This 1 mL measurement was not performed with a pipette but with a regular syringe, which meant that there could have been small differences in the amounts.…”