[Reliability and survival of arterial catheters: optimal dynamic response]

Blood pressure is one of the most critical haemodynamic parameter in the intensive care unit (ICU). The measurement relies mainly on invasive methods (arterial lines) but also on noninvasive methods (Oscillometric and Manual). It is crucial to be instantaneous and accurate to adapt any decision making plan. The aim of this study is to evaluate the reliability of this measure given by an arterial catheter over time. This can determine the maintenance of catheter patency before clinical total occlusion.

Observational prospective study.

Damping coefficient (xi) and natural frequency (Fn) of the arterial catheter system are studied in vivo each 12 hours by a fast flush test (FFT) in 61 patients. The measurements of the arterial blood pressure invasively (arterial catheter method) and non invasively (oscillometric method) are compared each 12 hours until the catheter is removed.

All over the study period for each catheter (till 240 hours), the mean arterial blood pressure measurements given by either the catheter method or the oscillometric method were very concordant (coefficient > 0.7). Only 3.39% of the catheters had their physical characteristics (xi and Fn) in the optimal zone at T0; reaching 66.67% at T19. The maximal inserted time was highly correlated with a good operating catheter (R = 0.739; P < 10(-4)).

The measure of the arterial blood pressure invasively can still be reliable for a long period of time (10 days), as long as the catheter is inserted, especially when the mean arterial pressure is considered. Each time the distance of the catheter insertion site moves away 1 cm from the radiocarpal joint or the groin, the risk of troubleshooting is doubled; on each blood sample from the catheter, this risk is reduced by 20%.