Arterial Blood Gases
Contraindications
Contraindications are relative and should be considered in terms of the
risks to the patient under the circumstances and the importance of
obtaining the sample. Areas of skin infection should be avoided because
of the risks of inoculating the blood with bacteria. Patients on
anticoagulants and those with coagulopathies are at risk for severe
bruising and hematoma formation so blood gases should only be done when
absolutely necessary and the operator should take extra care to apply
pressure to the area to reduce bruising. Anytime an arterial puncture
is made there is a risk of causing an obstructing thrombus in the
artery. Patients with poor collateral flow to an area, for example a
positive Allen test (discussed later) at the wrist, should not have an
arterial puncture to that site. Finally, if it seems likely that a
patient will require frequent arterial blood gas samples, consideration
should be given to starting an indwelling arterial line. Arterial lines
are beyond the scope of this module and will not be discussed further.