The Effects of Abnormal Blood Pressure on Arterial Sampler Filling Times

Abstract

BACKGROUND: Sampler filling time begins with the initial flash of blood in the needle hub until the preset sampler volume is obtained. Previous studies have shown statistically significant differences between arterial and venous sampler filling times, but included only a few subjects with abnormal blood pressures. OBJECTIVE: To determine whether the time required to fill a vented arterial sampler is an accurate indication of a successful arterial blood sample in adults with abnormal blood pressure. We hypothesized that mean arterial pressure and arterial sampler filling time would have a negative correlation, and that venous sampler filling time would be significantly longer than arterial filling time. METHODS: We studied 40 subjects: 25 arterial subjects, and 15 venous subjects. The arterial subjects included 3 groups: hypertensive, hypotensive, or normal. During the arterial and venipuncture procedures, we measured sampler filling time and recorded blood volume. The P O 2 of the samples was measured. Additionally, blood pressure and S pO 2 were measured in the arterial group. RESULTS: The mean sampler filling time was 220.4 s/mL for the venous group, and 18.1 s/mL for all 3 arterial groups combined. There were significant differences between each mean arterial sampler filling rate and mean venous filling rate (P < .001). There were no significant differences in mean sampler filling rate between the arterial subgroups (P > .99). The correlation between mean arterial pressure and filling rates was 0.06 (P ‫؍‬ .38). CONCLUSIONS: There is a significant difference between arterial and venous filling rates. There was no relationship between filling time and abnormal mean arterial pressure. Regardless of the arterial pressure, the arterial sampler filling time can be used as an indicator of a successful arterial puncture at the bedside.

Comparison of Sampler Filling Times Among Selected Arterial Blood Samplers

“…Our study further supports previous studies conducted by Johnson et al, 1 Bender et al, 2 and Cortes et al, 3 who concluded that arterial sampler filling time can distinguish between arterial and venous punctures. Johnson et al 1 used an extracorporeal laboratory model and tested various needle sizes, whereas Bender et al 2 studied subjects with normal mean arterial pressures, and Cortes et al 3 studied subjects with abnormal blood pressures.…”

“…Bender et al 2 studied sampler filling times in human subjects with normal mean arterial pressures and concluded that arterial puncture filling time is significantly faster than venopuncture. Cortes et al 3 showed that there was no statistically significant difference in arterial filling times for subjects with abnormal blood pressures. Although these studies showed that sampler filling time is a useful indicator that the sample is arterial, all 3 studies used only the Portex Pro-Vent arterial sampler (Smiths Medical, Dublin, Ohio) in their comparisons.…”