The effect of syringe volume on blood gas analysis

Iatrogenic anaemia is an important problem for patients at the intensive care
unit and in neonatal care. To moderate negative impact of anaemia on the
recovery in this group of patients, red blood cell transfusions or
erythropoiesis stimulating agents are often used. As both treatments come with
extra risks for the patients, it is important to work on less invasive methods
preventing iatrogenic anaemia. One of the ways which proved to be successful is
to minimize the blood lost upon blood sampling.

The ultimate goal of our study is to reduce the amount of blood withdrawn for
blood gas analysis, especially in the intensive care unit and in neonatal care
by replacing regularly used 3 ml blood gas syringes with 1 ml blood gas
syringes. The main objective is to test whether a 1 ml blood gas syringe can be
used in a clinical setting compared to a regularly used 3 ml blood gas syringe.
Secondary objective is to establish the minimal blood volume to what 1 ml blood
gas syringe has to be filled and whether the blood is mixed well in the 1 ml
blood gas syringe.

From patients of the Adult Intensive Care Unit who have an arterial catheter,
1500**l of arterial blood will be collected in a 3 ml blood gas syringe for the
regular blood gas analysis, and an additional 3600**l for the blood gas syringe
study. For the blood gas syringe study 1800 *l (200 + 300 + 500 + 800) of blood
will be collected in 4 independent 3 ml blood gas syringes and another 1800 *l
(200 + 300 + 500 + 800) in 4 independent 1 ml blood gas syringes. Blood gas
analysis will be performed on one designated Rapidlab 1265 blood gas analyser
(Siemens, USA) according to manufacturer protocol. Results from 3 ml blood gas
syringes and 1 ml blood gas syringes will be compared to evaluate whether 1 ml
blood gas syringes perform equally good as regularly used 3 ml blood gas
syringes. Results obtained with different fill volumes will be compared in
order to check if the fill volume influences the results and to establish the
minimal fill volume that gives reliable results. If results from 1 ml blood gas
syringes are 1. agreeing with results from the regularly used 3 ml blood gas
syringes, 2. minimal fill volume for the 1 ml blood gas syringes is lower than
the volume currently withdrawn for the 3ml blood gas syringes (500 *l) and 3.
the blood can be mixed well in the 1 ml blood gas syringes, the verification by
means of patient comparison will be performed in 20 children and 20 neonates
from the Paediatric Intensive Care Department and Department of Neonatology
respectively. This verification in minors is necessary to eliminate possible
variations related to differences in hematologic and rheologic properties of
the blood between adults and children/neonates. For that from children/neonates
one additional 1 ml blood gas syringe will be collected. The blood gas syringe
will be filled with the minimum fill volume that has been established by
testing different fill volumes in adults (see above). Results of the 1 ml blood
syringe will be compared to the results of 3 ml blood gaseous syringe of
regular blood gas analysis. Collected blood will not exceed 3% of the total
circulating blood volume and no blood will be collected in the first week of
life.

Patients will have an additional blood drawn from the arterial catheter (in
children and neonates no more than 3 % of the total circulating blood volume)
performed during the routine sampling in patient care.
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