gms | German Medical Science

The spontaneous baroreceptor sensitivity (BRS) is an important parameter for the characterisation of cardiovascular regulation. This study aims at investigating the accuracy of the spontaneous BRS estimated from continuous blood pressure recordings depending on different technical requirements.

In 20 male patients suffering from coronary heart disease the radial artery blood pressure were measured invasively 2 and 24 hours after coronary surgery (30 min, sampling frequency 1000 Hz). From the recorded signals, the beat-to-beat intervals of the heart rate as well as the systolic blood pressure values were extracted. The BRS was calculated for the original data as well as for 100, 200, and 500 Hz recordings artificially generated from the 1000 Hz series. Additionally, all BRS parameters were determined from the original signals for the time scales of 5, 15, and 30 minutes.

It could be shown that low sampled 30-minutes blood pressure signals are characterised by a significantly decreased BRS fluctuations and an increased average slope (BRS fluctuations: 1000 Hz: 111.74±16.75, 100 Hz: 46.21±8.58, p<10-4; average slope: 1000 Hz: 6.80±1.08, 100 Hz: 9.14±1.07, p<10-6).

Moreover, the accuracy in discriminating between peri- and post-operative BRS could be improved by using longer recording periods. The standard deviations and the respective p values showed a decrease [Tab. 1].

These results reveal the restricted applicability of low sampled blood pressure signals. To estimate the spontaneous BRS, the blood pressure should be recorded with 500Hz at least or a highly sampled electrocardiogram should be used synchronously to estimate the beat-to-beat intervals. Finally, recording periods of 15 minutes at least are recommended for a robust estimation of the BRS parameters.