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. 2018 Sep 29;37(1):22.
doi: 10.1186/s40101-018-0182-x.

Characteristics of cardiovascular responses to an orthostatic challenge in trained spinal cord-injured individuals

Masahiro Itoh  1 , Masako Yamaoka Endo  2   3 , Tatsuya Hojo  4 , Miho Yoshimura  4 , Yoshiyuki Fukuoka  3   5
Affiliations

Characteristics of cardiovascular responses to an orthostatic challenge in trained spinal cord-injured individuals

Masahiro Itoh et al. J Physiol Anthropol. .

Abstract

Background: We investigated cardiovascular responses to an orthostatic challenge in trained spinal cord-injured (SCI) individuals compared to able-bodied (AB) individuals.

Methods: A total of 23 subjects participated, divided into three groups: seven were trained as spinal cord-injured (Tr-SCI) individuals, seven were able-bodied individuals trained as runners (Tr-AB), and nine were untrained able-bodied individuals (UnTr-AB). We measured the cardiovascular autonomic responses in all three groups during each 5-min head-up tilt (HUT) of 0°, 40°, and 80°. Stroke volume (SV), heart rate (HR), and cardiac output (Qc) as cardiovascular responses were measured by impedance cardiography. Changes in deoxyhemoglobin (∆[HHb]) and total hemoglobin (∆[Hbtot]) concentrations of the right medial gastrocnemius muscle were measured using near-infrared spectroscopy (NIRS).

Results: As the HUT increased from 0° to 80°, Tr-SCI group showed less change in SV at all HUT levels even if HR increased significantly. Mean arterial pressure (MAP) also did not significantly increase as tilting increased from 0° to 80°. Regarding peripheral vascular responses, the alterations of ∆[Hbtot] from 0° to 80° were less in Tr-SCI group compared to AB individuals.

Conclusion: There is a specific mechanism whereby blood pressure is maintained during a HUT in Tr-SCI group with the elicitation of peripheral vasoconstriction and the atrophy of the vascular vessels in paraplegic lower limbs, which would be associated with less change in SV in response to an orthostatic challenge.

Keywords: Cardiovascular responses; Near-infrared spectroscopy; Orthostatic challenge; Spinal cord injury.

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Conflict of interest statement

Ethics approval and consent to participate

The experimental protocol was approved by the ethics committee of the Institutional Review Board of the Prefectural University of Kumamoto. All subjects provided written consent for their participation after they were fully informed about the study. The investigation was performed in compliance with the Declaration of Helsinki.

Consent for publication

We fully understand and agree to all the terms and conditions stated here by you. Thank you for your consideration of my submitted paper.

Competing interests

The authors declare that they have no competing interests.

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Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1
Fig. 1
Time progression of stroke volume (SV), heart rate (HR), and cardiac output (Qc) in three representative individuals of trained (Tr-) spinal cord-injured (SCI) individuals and Tr-/untrained (UnTr-) able-bodied (AB) individuals
Fig. 2
Fig. 2
Changes in SV, HR, and Qc with the difference of gradient degree (0°, 40°, and 80°) for each group (light gray, Tr-AB; white, UnTr-AB; black, Tr-SCI). Data are mean ± SE. +, ++ p < 0.05, 0.01 vs. Tr-AB in each degree
Fig. 3
Fig. 3
Time progression in peripheral circulatory responses estimated from ∆[HbO2] (gray), ∆[HHb] (dotted), and ∆[Hbtot] (solid) during an orthostatic challenge in four representative individuals of the Tr-SCI, Tr-AB, and UnTr-AB groups
Fig. 4
Fig. 4
Changes in peripheral circulatory responses, ∆[HbO2], ∆[HHb], and ∆[Hbtot] with the difference of gradient degree (0°, 40°, and 80°) for each group (white circle: Tr-AB, white square: UnTr-AB, black trianle: Tr-SCI). Data are mean ± SE. *, ** p < 0.05, 0.01 vs. 0 gradient degree at each group. +, ++ p < 0.05, 0.01 vs. Tr-AB
See this image and copyright information in PMC

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