Monitoring of blood gas measurements is an important part of the assessment
of patients with chronic lung disease. Increasingly, this is being done in
the patients' homes by specialist nurses. This makes it important to know
the effect of time delay and storage temperature on the reliability of capi
llary blood gas analysis results.
In this study, the effect of a delay of 1 and 2 h and of storage at both ro
om temperature and in ice, on blood stored in glass capillary tubes was inv
estigated. Samples, initially taken from the earlobes, were transferred to
glass capillary tubes and used to provide duplicate initial samples for imm
ediate analysis, and then single samples at 1 and 2 h stored at room temper
ature or in ice.
The duplicate baseline measurements showed good reproducibility. There was
a small, but statistically significant, increase in PCO2 when samples were
stored in capillaries at room temperature, or in ice, both at 1 and 2 h. Sm
all changes in PO2 were not statistically significant, either in ice or at
room temperature. None of the changes was considered to be sufficient to be
of clinical significance, thus supporting the use of capillary blood sampl
ing even when there might be a delay of 1-2 h and transport is at room temp
erature, as might be the case when taking domiciliary samples. (C) 1999 HAR
COURT PUBLISHERS LTD.