Effect of blood collection by the push-pull technique from an indwelling catheter versus direct venipuncture on venous blood gas values before and after administration of alfaxalone or propofol in dogs.

OBJECTIVE To compare the effect of blood collection by a push-pull technique from an indwelling IV catheter versus direct venipuncture on venous blood gas values before and after administration of alfaxalone or propofol to dogs. DESIGN Prospective randomized clinical study. ANIMALS 30 healthy client-owned dogs that weighed ≥ 10 kg (22 lb) and were anesthetized for elective surgical procedures. PROCEDURES All dogs were premedicated with methadone (0.5 mg/kg [0.2 mg/lb], IM), and 20 to 30 minutes later, anesthesia was induced with either alfaxalone (1 to 3 mg/kg [0.5 to 1.4 mg/lb], IV to effect; n = 15) or propofol (2 to 6 mg/kg [0.9 to 2.7 mg/lb], IV to effect; 15). Immediately prior to premedication and after anesthesia induction, paired blood samples were collected from the cephalic veins; 1 by direct venipuncture and 1 by use of a push-pull technique from a 20-gauge catheter. All blood samples underwent venous blood gas analysis immediately after collection. Results were compared between sample collection techniques before and after anesthesia induction and between anesthesia induction protocols. RESULTS All results were within established reference ranges. For many variables, statistically significant but clinically irrelevant differences were detected between samples collected by direct venipuncture and those collected by the push-pull technique but not between the 2 anesthesia induction protocols. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated the push-pull technique was an acceptable method for collection of blood samples from dogs for venous blood gas analysis that could be used instead of direct venipuncture for patients with patent IV catheters.