Evaluation of the pulse wave arrival time as a marker for blood pressure changes in critically ill infants and children.

OBJECTIVE

Pulse arrival time (PAT), which is the interval between the R wave of the electrocardiogram (ECG) and the arrival of the pulse wave peripherally, has been reported to be suitable for use as an indirect measure of blood pressure change. The purpose of this study was to evaluate, in critically ill infants and children, the degree to which 1/PAT covaries with systolic, diastolic, and mean blood pressure, as well as heart rate.

METHODS

A laboratory device 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 hard disk. A total of 15 critically ill patients, aged 6 days to 16 years, weighing 3 to 80 kg, were studied.

RESULTS

In all patients, one period of 11,000 to 36,000 beats could be evaluated. Mean correlation coefficients were best for systolic blood pressure (r = 0.73), followed by mean blood pressure (r = 0.68) and diastolic blood pressure (r = 0.61), and, finally, heart rate (r = 0.52). In 7 patients, the correlation coefficient for systolic blood pressure was > 0.9; but, in 4 patients, it was < 0.5.

CONCLUSIONS

We conclude that the correlation between 1/PAT and systolic blood pressure is not strong enough to serve as a marker for blood pressure changes in critically ill infants and children. This may be due to changes of the preejection period, which is part of the PAT.