Influence of needle gauge and venepuncture difficulty on thromboelastography in healthy cats

Abstract

Objectives The aim of this study was to evaluate the effect of two differently sized butterfly catheter needles and the effect of venepuncture difficulty on thromboelastography (TEG) results in healthy cats. Methods Twenty-four healthy cats were included. Blood samples were collected from the jugular vein by syringe aspiration via direct venepuncture with 21 G and 22 G butterfly needles. The venepuncture difficulty score was classified into four categories. The first 1.5 ml blood drawn from each subject was discarded before collecting a sample for TEG analysis. TEG analyses were performed on citrated whole blood samples from 17 clinically healthy cats, using assays with kaolin as activators. Among the TEG parameters, reaction time (R), clot formation time (κ), alpha angle (α), maximum amplitude (MA) and global clot strength (G) were recorded from each tracing. Results Seven cats were excluded from the study; results were obtained for the remaining 17 cats. There were no statistically significant differences between the use of two different needles for R ( P = 0.72), κ ( P = 0.74), α ( P = 0.99), MA ( P = 0.08) and G ( P = 0.09). Samples with difficulty scores ⩾1 were not significantly different from samples with difficulty scores of 0 for R ( P = 0.24), κ ( P = 0.65), α ( P = 0.65), MA ( P = 0.72) and G ( P = 0.77). Conclusions and relevance The results of TEG in clinically healthy cats do not differ significantly when using two different gauge needles. There was no significant difference in the TEG results according to venepuncture difficulty scoring.

Comparison of viscoelastic test results from blood collected near simultaneously from the jugular and saphenous veins in cats

“…12 However, the large CV between paired samples for multiple parameters, particularly CT, suggest that the observed difference might be clinically relevant. Previous canine and feline studies using recalcified citrated samples have not identified effects of needle or catheter gauge on viscoelastic parameters, 10,13 and canine studies have not detected differences between jugular and saphenous samples. 9 The more hypercoagulable results for jugular venipuncture in the current study suggest immediate analysis of non-anticoagulated blood is more sensitive to factors such as the thicker skin overlying the jugular vein, and thus greater comparative trauma and potential for tissue factor contamination with jugular vs saphenous venipuncture.…”

“…Both sampling sites and needle gauges have been previously used in viscoelastic studies in cats. 10,11 Identification of statistical differences between the two sites suggest that the same site and needle gauge should be used consistently for serial monitoring or for research purposes. Our findings also suggest that different reference intervals (RIs) may be required for different venipuncture techniques.…”

“…Saphenous samples are often collected with smaller-diameter needles. A recent feline study reported no difference between results for 21 G or 22 G butterfly needles and syringe needles when citrated samples were collected after a discard sample from a jugular vein and analyzed using kaolin-activated TEG, 10 but the effect of needle gauge on viscoelastic testing of feline non-anticoagulated whole blood requires investigation.…”