What does this research mean for the field?

The difference in blood pressure between baseline and the end of phase 2 of the Valsalva maneuver (SI3) is the optimal sympathetic index for quantifying the full spectrum of sympathetic failure. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

June 6, 2011Open Access

Assessment of sympathetic index from the Valsalva maneuver

PNPéter NovákInformation Technology Institute

Structured PICO

Does SI3 derived from the Valsalva maneuver accurately assess the degree of sympathetic failure compared to other indices?

Population

145 patients with sympathetic failure (20 mild, 65 moderate, 60 severe) and 23 healthy controls (total n=168).

Intervention

Evaluation of six sympathetic indexes (SIs) derived from blood pressure changes during the Valsalva maneuver.

Comparator

Comparison among the six different sympathetic indexes and across patient groups with varying degrees of sympathetic failure.

Outcome

Ability of the sympathetic indexes to differentiate between subject groups and correlate with orthostatic hypotension during tilt test.surrogate

SI3 (the difference in blood pressure between baseline and the end of phase 2 of the Valsalva maneuver) is an optimal index for quantifying sympathetic failure and correlates well with orthostatic hypotension.

Abstract

OBJECTIVE: Blood pressure (BP) decline and recovery during the Valsalva maneuver (VM) are used to evaluate the degree of sympathetic failure (SF) but a reliable sympathetic index (SI) derived from VM is lacking. METHODS: Patients with mild (n=20), moderate (n=65), and severe (n=60) SF and 23 healthy controls were evaluated using a standardized battery of autonomic tests. SF was defined as mild (associated with reduced sudomotor volumes at distal leg); moderate (associated with a fall in systolic BP ≥10< 30 mm Hg during the tilt test); and severe (associated with a fall in systolic BP ≥30 mm Hg during the tilt test). Six SIs were compared: SI1 (BP fall during phase 2), SI2 (BP recovery during phase 2), SI3 (the difference in BP between baseline and the end of phase 2), SI4 (the magnitude of phase 4), SI5 (BP recovery time), and SI6 (baroreflex sensitivity index). RESULTS: All indexes showed overall significant differences among tested groups (p<0.05). Only SI3 differentiated all subject groups. Compared to other SIs, SI3 correlated the most with orthostatic hypotension (OH; r=0.62, p < 0.05) during the tilt. CONCLUSIONS: SI3 is the optimal method for calculation of SI since it 1) easily differentiates between healthy controls and those with SF; 2) correlates with the OH, a proxy for a sympathetic failure; 3) tracks the full spectrum of SF (mild-moderate-severe). SI3 expands the utility of quantitative autonomic testing.

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