Objective:

To conduct a side-by-side comparison of blood pressure (BP) waveforms induced by the Valsalva maneuver (VM) using the two most commonly used beat-to-beat BP devices for clinical autonomic testing.

Background:

Anecdotal observations have suggested beat-to-beat BP changes, particularly rapid changes during and following the VM, may be captured with different fidelity by different non-invasive BP devices.  Such differences may have significant implications for the interpretation of autonomic reflexes.

Design/Methods:

We included randomly selected patients undergoing routine clinical autonomic testing at Mayo Clinic Rochester in January 2023. After obtaining informed consent, subjects were instrumented with two beat-to beat BP devices while responses to the VM were recorded. Devices studied were 1) NOVA with nanocore, Finapres Medical Systems (Enschede, Netherlands), and 2) CNAP HD monitor, CNSystems (Graz, Austria). BP responses were quantified using magnitude and latency of the different phases of the VM. Measurements were compared using paired t-tests, 2 sided, using SPSS version 28.

Results:

32 patients were included, average age was 60.9±15.1 years, 19 (59%) were female. Significant differences in the detection of BP changes between the devices were seen for the magnitude of the drop of BP during early phase II (Δ systolic BP, NOVA 36.9±18.0 vs CNAP 28.2±15.4mmHg, p<0.001) and phase IV overshoot (Δ systolic BP, NOVA 53.9±20.2 vs CNAP 39.4±18.0mmHg, p<0.001), while BP recovery during late phase II (Δ systolic BP, NOVA 8.9±7.1 vs CNAP 9.2±8.1mmHg, p=0.79) and BP recovery time (NOVA 5.5±5.5 vs CNAP 5.1±5.3sec, p=0.72) were measured comparably by the two devices.

Conclusions:

Findings confirm anecdotal observations of differences in the detection of rapid BP changes, resulting in an overall greater magnitude of BP swings reflected by NOVA compared to CNAP. However, the most important indices used to determine cardiovascular adrenergic failure were similar, suggesting both devices can be confidently used if the different appearance of waveforms is considered.