Study objectives: In adults, arterial blood samples are
usually drawn using plastic syringes. In contrast to glass syringes,
plastic syringes let oxygen diffuse through their wall. This results in
Po2 changes during storage, especially when
Po2 is high. An alternative to glass syringes
is the Microsampler (Roche Diagnostics; Schaffhausen, Switzerland), a
commercially available device consisting of a heparinized glass
capillary fitted with a 26-gauge needle and used to collect arterial
blood in the same way as a plastic syringe fitted with a needle.
Design: We evaluated the performance of the Roche
Microsampler for storing arterial blood in view of
Po2 measurement, comparatively with glass and
plastic syringes. Five approximate initial Po2
levels (650, 400, 200, 130, and 80 mm Hg) and two storage temperatures
(ambient temperature and 4°C) were studied.
Settings: Bench study.
syringes allowed reliable measurement of Po2
values when initial Po2 was too low to ensure
complete hemoglobin oxygen saturation, but were associated with
time-dependent underestimation of Po2 at higher
initial Po2 values. No such underestimation
occurred with the Roche Microsampler stored at 4°C for up to 1 h
for all Po2 levels studied.
Conclusion: The Roche Microsamplers appeared to be reliable
devices in preventing oxygen diffusion.