Related Experiment Videos
Blood distribution adaptations in paraplegics during posture changes: peripheral and central reflex responses
D Theisen1, Y Vanlandewijck, X Sturbois
1Unité d'Education Physique, Institut d'Education Physique et de Réadaptation, Faculté de Médecine, Université Catholique de Louvain, Louvain-la-Neuve, Belgium. daniel.theisen@edph.ucl.ac.be
European Journal of Applied Physiology
|April 25, 2000
Summary
Spinal cord injury (SCI) patients exhibit a veno-arteriolar reflex (VAR) in their paralyzed limbs, aiding blood redistribution. This peripheral reflex contributes to cardiovascular stability during posture changes.
Area of Science:
- Physiology
- Cardiovascular Research
- Neuroscience
Background:
- The veno-arteriolar reflex (VAR), a peripheral axon reflex, reduces limb blood flow with increased venous pressure.
- Its role in spinal cord injury (SCI) and blood redistribution remains understudied.
Purpose of the Study:
- To assess peripheral and central cardiovascular adaptations in paraplegics (high and low lesions) versus able-bodied individuals during passive postural changes.
- To compare these adaptations during leg dependency and upright sitting.
Main Methods:
- Evaluated lower-limb cutaneous vascular conductance (CVC) via laser Doppler flowmetry and ankle blood pressure.
- Assessed central hemodynamics (stroke volume, heart rate, myocardial performance) using impedance cardiography and brachial blood pressure.
Main Results:
- All groups showed vasoconstriction during leg dependency; the decrease in CVC was most pronounced in high lesion (HP) SCI subjects.
- No significant differences in central hemodynamics were observed between groups during leg dependency.
- During upright sitting, CVC remained low, stroke volume decreased, heart rate and blood pressure increased, with no group differences.
Conclusions:
- Paraplegics possess a functional peripheral veno-arteriolar reflex in their paralyzed lower limbs.
- This VAR contributes significantly to maintaining cardiovascular stability in individuals with SCI.