Hypokinetic circulation in persons with paraplegia

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Abstract

Introduction

It is well established that hemodynamic dysfunction, resulting in diminished upper-extremity work capacity, occurs in persons with spinal cord injury (SCI) as compared with those who are nondisabled (ND). Although it has been shown that persons with paraplegia display higher values of heart rate (HR) with lower values of stroke volume (SV) during exercise, it is not resolved whether there is adequate compensation to produce similar values of cardiac output (𝑄̇) as in ND.

Purpose

This study examined central cardiovascular responses (HR, SV, and 𝑄̇) of 20 subjects with complete thoracic level SCI (T4–T11) and 20 sedentary ND subjects during matched levels of arm-crank (AC) exercise.

Methods

All subjects performed an incremental peak AC test to volitional exhaustion with continuous metabolic analysis and HR measurement via open circuit spirometry and 12-lead electrocardiography, respectively. Stroke volume was assessed using transthoracic impedance.

Results

Heart rate was higher for SCI (P < 0.05) with significantly lower values for SV and 𝑄̇ at rest (∼25%). Peak responses were significantly higher for ND in all factors except HR. Although subpeak HRs at matched absolute workloads were significantly higher for SCI (12–20 beats·min−1), SV and 𝑄̇ were significantly lower (P < 0.05).

Conclusions

The results of this study indicate that 𝑄̇ is significantly lower in SCI than in ND during AC, despite significantly greater values of HR. These findings also suggest that the disparity in exercise values of 𝑄̇ is related to differences exhibited at rest.

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