371 EVALUATION OF THE PULSE ARRIVAL TIME AS A MARKER FOR BLOOD PRESSURE CHANGES IN INFANTS AND CHILDREN AFTER CARDIAC SURGERY

Abstract

The arterial blood pressure (BP) is an important parameter in patients (pts) after cardiac surgery. It would be desirable to monitor BP non-invasively and continuously. Pulse arrival time (PAT), which is the interval between the R wave of the ECG and the arrival of the pulse wave peripherally, has been reported to be suitable for use as an indirect measure of blood pressure changes.

Objective: The purpose of this research was to evaluate, in critically ill infants and children after open heart surgery, the degree to which 1/PAT covaries with systolic, diastolic and mean blood pressure as well as heart rate.

Methods: A laboratory device (Vectron GmbH) was used to calculate PAT in real time from the ECG and the plethysmographic curve of pulse oximetry used for routine monitoring. Calculated PAT and corresponding blood pressures and heart rate were stored on harddisk. Patients: Fifteen critically ill pts aged 6 days to 16 years with a weight of 3 to 80 kg were studied.

Results: In all patients one period of 11- to 36-thousand beats could be evaluated. Mean correlation coefficients were best for systolic (r=0,73), followed by mean (r=0,68) and diastolic (r=0,61) blood pressure and finally heart rate (r=0,52). In 7 patients the correlation coefficient for systolic blood pressure was r > 0,9, but in 4 patients it was, r < 0,4.

Conclusion: Although there is a significant correlation between 1/PAT and systolic blood pressure, it is not strong enough to use it as a marker for blood pressure changes in critically ill pts. This is most likely due to changes of the pree-jection period, which is part of the PAT.

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