1. Thrombosis (10-20%) related to duration of use (5-10% after 2/7), size of cannulae (18G>20G), wrist size (=arterial diameter), female > male, catheter material (Teflon best), flush system, prolonged systemic hypotension, number of insertion attempts.
2. Haematoma (>50%), haemorrhage
3. Sepsis risk after 4-5 days: local site (0.7%), bacteraemia (0.13%)
4. Distal emboli (2-4%), thumb (below) or hand ischaemia (transient in 10%), proximal forearm ischaemia.
5. Aneurysm (0.1%), AV fistulae.
6. Inadvertent arterial drug administration.
1. Equipment factors which optimise signal fidelity include: a high-frequency response transducer, short stiff non-compliant tubing, bubble free, slow continuous flush device (1-3ml/hr results in <2% error), transducer zero, and calibration against a mercury column.
2. Small air bubbles <0.25ml produce under-damping; larger air bubbles over damp.
3. Patient factors which reduce signal fidelity = rapid heart rate (resonance), high-frequencies reflected (elderly, high SVR, arteriosclerosis), site of catheter (radial vs femoral, axillary vs aorta).
Scheer, et al Crit Care. 2002; 6(3): 199–204.
1. Low pressure: check manual BP, check transducer is not above heart level, look for large air bubbles in transducer (damping), check cannula for kinks, check arm position for compression of brachial or subclavian artery.
2. High (systolic) pressure: check manual BP, check transducer is not below heart level, look for small air bubbles in transducer (resonance).