Long-Term Facilitation of Ventilation in Humans with Chronic Spinal Cord Injury

American Journal of Respiratory and Critical Care Medicine, 2014 · DOI: 10.1164/rccm.201305-0848OC · Published: January 1, 2014

Spinal Cord Injury Physiology Neuroplasticity

Simple Explanation

The study investigates whether intermittent hypoxia (IH), where the body is briefly exposed to low oxygen levels, can improve breathing in people with long-term spinal cord injuries. Researchers exposed participants to short periods of low oxygen, while maintaining slightly elevated carbon dioxide levels, and then measured their breathing afterwards. The results showed that intermittent hypoxia could indeed lead to a sustained increase in breathing, suggesting that it could be a useful therapy for improving respiratory function after spinal cord injury.

Study Duration

10 days

Participants

8 individuals with incomplete spinal cord injury

Evidence Level

Level 2: Experimental study

Key Findings

1
Minute ventilation significantly increased for 30 minutes after acute exposure to intermittent hypoxia in individuals with chronic spinal cord injury.
2
The magnitude of ventilatory long-term facilitation was not enhanced over 10 days of intermittent hypoxia exposures.
3
The increase in minute ventilation during LTF was associated with increases in tidal volume and breathing frequency during the ER period

Research Summary

This study demonstrates that ventilatory long-term facilitation can be evoked in humans with chronic, incomplete spinal cord injury. Single sessions of intermittent hypoxia induced increases in minute ventilation that lasted at least 30 minutes beyond the hypoxia stimulation. This study provides the first evidence that intermittent hypoxia may induce respiratory neuroplasticity in humans with chronic spinal cord injury.

Practical Implications

Respiratory Rehabilitation Strategy

Intermittent hypoxia may represent a strategy for inducing respiratory neuroplasticity after declines in respiratory function that are related to neurological impairment.

Potential Therapeutic Intervention

IH could be used to improve breathing function in individuals with SCI, particularly those with cervical injuries.

Further Research Needed

Further investigation is needed to determine the optimal IH dosing and to understand the effects of IH on other neural systems and behaviors.

Study Limitations

1
The heterogeneity and limited size of our sample preclude any conclusions about the inﬂuence of these factors on the magnitude of LTF.
2
The effect of factors such as age, sex, injury chronicity, and comorbidities on the magnitude of LTF must also be taken into account.
3
Whether the outcomes observed resulted from (1) a training effect on the respiratory system due to IH or (2) direct or indirect changes in physiological parameters (e.g., neurotransmitter levels) remains speculative.

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