Effects of syringe material and temperature and duration of storage on the stability of equine arterial blood gas variables.
OBJECTIVE
To evaluate the consistency of partial pressures (P) of arterial oxygen (aO(2)), arterial carbon dioxide (aCO(2)) and pH measurements in equine carotid arterial blood samples taken into syringes made from three different materials and stored at room temperature or placed in iced water for measurement at three different times.


METHODS
Prospective observational study over 19 days.


METHODS
Four clinically normal Thoroughbred or Thoroughbred-cross horses (three geldings, one mare, mean age 6.25 years, range 5-7 years).


METHODS
Identical blood samples were taken on two separate occasions from the carotid arteries of the four horses into syringes made of glass, plastic and polypropylene. PaO(2), PaCO(2) and pH determinations were performed on blood from each syringe type at 10, 60 and 120 minutes post-sampling with samples stored at room temperature (approximately 20 degrees C) or in iced water (approximately 0 degrees C). Data were analysed by anova and a split plot model fitting syringe within horse X pair and time within temperature within syringe.


RESULTS
Syringe material, storage temperature and time before analysis all had significant effects on PaO(2) (p < 0.001). PaCO(2) was unaffected by syringe material or storage temperature. However, over 120 minutes, storage duration significantly (p = 0.002) affected values. Temperature of storage and duration prior to analysis both significantly affected pH values (p = 0.005 and p < 0.001, respectively), but syringe material did not. Several significant interactions between these variables were noted.


CONCLUSIONS
Equine arterial blood gas determination has a different sensitivity to storage conditions compared to other veterinary species.


CONCLUSIONS
For accurate equine arterial blood analysis, PaO(2) samples need to be analysed within 10 minutes or taken into glass syringes, stored on ice and analysed at 2 hours post-sampling. PaCO(2) and pH measurements can be performed on samples stored in glass, plastic or polypropylene syringes at room temperature for up to 1 hour post-sampling.
Deane
Joanne C
JC
Institute of Rural Studies, Llanbadarn Campus, University of Wales, Aberystwyth, Ceredigion SY23 3AL, UK.
Dagleish
Mark P
MP
Benamou
Agnes E M
AE
Wolf
Basil T
BT
Marlin
David
D
D000818:Animals; D001784:Blood Gas Analysis / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D001793:Blood Preservation / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006736:Horses; D006863:Hydrogen-Ion Concentration; D008297:Male; D010100:Oxygen / Q000097:blood*; D011446:Prospective Studies; D013594:Syringes / Q000662:veterinary; D013696:Temperature
D002245:Carbon Dioxide; D010100:Oxygen