Compression aids improve cardiovascular control during verticalization in patients after cervical spinal cord injury

Purpose: Patients after complete cervical spinal cord injury suffer from autonomic dysregulation. Impaired sympathetic control over cardiovascular system leads to the blood redistribution and in consequence to the hypotension during orthostatic challenge. Compression aids are used as a non-pharmacological therapy supporting venous return and thus preventing hypotension. The aim of the study was to evaluate the effect of CA on the baroreflex control over the cardiovascular system during verticalization. Methods: Blood pressure was continuously recorded by volume-clamp photoplethysmography in 10 subjects with cervical spinal cord injury in three situations: sitting, verticalization with and verticalization without compression aids. From the blood pressure record, sequences of beat-to-beat systolic, diastolic and pulse pressures, and inter-beat intervals were detected. Causal coherence from systolic blood pressure to inter-beat-intervals and baroreflex sensitivity were calculated by autoregressive bivariate model. Results: All assessed hemodynamic variables significantly decreased during verticalization and this decrease was attenuated by compression aids application. Coherence did not change during verticalization without compression aids, but increased with compression aids. Conclusion: The results indicate that application of compression aids supported venous return and consequently stroke volume (reflected by pulse pressure increase). Parasympathetic control related indices (baroreflex sensitivity and respiratory sinus arrhythmia magnitude) decreased during verticalization and this decrease was attenuated by compression aids indicating less prominent cardiac parasympathetic control decrease during verticalization preserving wider functional reserve in reflex baroreflex control to blood pressure perturbations.