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Evaluation of the pulse wave arrival time as a marker for blood pressure changes in critically ill infants and
C F Wippermann1, D Schranz, R G Huth
1University Children's Hospital, Johannes Gutenberg University Mainz, Germany.
Insights
Pulse arrival time (PAT) does not reliably track blood pressure changes in critically ill infants and children. The correlation between 1/PAT and systolic blood pressure was insufficient for clinical use in this population.
Area of Science:
- Biomedical Engineering
- Pediatric Critical Care
Background:
- Pulse arrival time (PAT) is the interval between the electrocardiogram (ECG) R wave and peripheral pulse wave arrival.
- PAT has been explored as an indirect indicator of blood pressure fluctuations.
Purpose of the Study:
- To assess the correlation between 1/PAT and blood pressure (systolic, diastolic, mean) and heart rate in critically ill infants and children.
Main Methods:
- A laboratory device calculated PAT in real-time using ECG and pulse oximetry data.
- Data from 15 critically ill patients (6 days to 16 years) were analyzed.
Main Results:
- Mean correlation coefficients were highest for systolic blood pressure (r=0.73), followed by mean (r=0.68), diastolic (r=0.61), and heart rate (r=0.52).
- Individual patient correlations for systolic blood pressure varied significantly (r>0.9 in 7, r<0.5 in 4).
Conclusions:
- The correlation between 1/PAT and systolic blood pressure is not robust enough for monitoring blood pressure in critically ill pediatric patients.
- Variations in the pre-ejection period, a component of PAT, may explain the weak correlation.
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.