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DOI: 10.1055/s-2006-953309
Comparison of beat-to-beat blood pressure and pulse-wave-latency during valsalva manoeuvre for the evaluation of autonomic function
Impairment of the autonomic nervous system is common in neurological diseases. Various tests to quantify autonomic dysfunction have been implemented, one is the Valsalva manoeuvre (VM). It consists of four phases. Phase 2 and Phase 4 are thought to reflect autonomic function. Since phase 2 is variable on a time basis, we focussed on phase 4, the blood pressure overshoot after VM. The aim of our study was to compare different methods of blood pressure estimation during VM.
We used the direct beat-to-beat blood pressure recording (Finapres®) as the standard method and compared the results to the calculation of the pulse-wave-latency (PWL). PWL is the time between R-peak in ECG and pulsewave recording at the earlobe using a photopleth. Reduction of PWL might be a surrogate of blood pressure increase. For this purpose we examined 25 healthy volunteers (36±10 years, 5 females, 20 males). During the Valsalva manoeuvre subjects had to maintain a pressure of 40mmHg. Data are expressed as mean±SD. For statistical evaluation students paired t-test and pearsons correlation were used. P<0.05 was considered as statistically significant.
As expected Finapres® recording revealed blood pressure increase (mean blood pressure increase: 17.9±11.8mmHg, p<0.001). On an individual basis, blood pressure increase could be detected in 24 of 25 subjects. Accordingly, PWL significantly decreased (mean PWL decrease: 9.4±11.3 ms, p<0.001). Individual analysis revealed in PWL decrease in 21/25 subjects. Quantitative comparison, however, showed that both tests did not correlate.
Our results indicate that although PWL almost regularly allows an estimation of the activation of the vasoconstrictor sympathetic nervous system, these results cannot be easily translated into blood pressure values. Nevertheless, PWL might be a cheap alternative for screening patients with suspected autonomic nervous system failure.
Supported by DFG Bi 579–1/1–3