What is the clinical evidence from this study?

Study design: RCT. Population: Healthy (n=20). Intervention: Chest wall strapping (CWS) vs. Unrestricted control. Primary outcome: Sensory intensity of dyspnea at peak exercise (Borg 0-10 scale) (p=<0.05).

What question did this study set out to answer?

To determine whether neuromechanical uncoupling or elevated neural respiratory drive mediates dyspnea during exercise under acute thoracic restriction.

December 20, 2013Journal of Applied Physiology

Physiological mechanisms of dyspnea during exercise with external thoracic restriction: Role of increased neural respiratory drive

Q: What are the key findings of this study?

Chest wall strapping during exercise increased the intensity and unpleasantness of dyspnea, reflecting an awareness of increased neural respiratory drive rather than neuromechanical uncoupling.

Q: What question did this study set out to answer?

To determine whether neuromechanical uncoupling or elevated neural respiratory drive mediates dyspnea during exercise under acute thoracic restriction.

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Key result

Chest wall strapping during exercise increased the intensity and unpleasantness of dyspnea, reflecting an awareness of increased neural respiratory drive rather than neuromechanical uncoupling.

Why the study?

Does chest wall strapping alter neuromechanical coupling and increase dyspnea during exercise in healthy men?

Population

20 healthy men, mean age 25.7 ± 1.1 years

Comparison

Chest wall strapping to reduce vital capacity by… vs Unrestricted control during symptom-limited…

Design

RCT, randomized conditions

Authors

CMCassandra T. MendoncaUniversity of Ottawa MSMichele R. SchaefferKU Leuven PRPatrick RileyAkron Children's Hospital

Discussion

Member takes

Implication

Dyspnea in restrictive constraints warrants targeting neural drive; extends mechanistic models beyond neuromechanical uncoupling in exercise.

Key Points

To determine whether neuromechanical uncoupling or elevated neural respiratory drive mediates dyspnea during exercise under acute thoracic restriction.
Twenty healthy men (aged 25.7 ± 1.1 years) completed symptom-limited incremental cycle exercise tests under two randomized conditions: unrestricted control and chest wall strapping.
Chest wall strapping was applied to induce a mild restrictive deficit, reducing vital capacity by 21.6 ± 0.5%.
Esophageal electrode-balloon catheters measured diaphragm electromyogram activity, transdiaphragmatic pressure-time products, operating lung volumes, and sensory dyspnea ratings.
Chest wall strapping resulted in exaggerated diaphragm electromyogram and transdiaphragmatic pressure-time product responses alongside higher dyspnea intensity and unpleasantness ratings compared with control.
Neuromechanical coupling was preserved, as relationships between diaphragm electromyogram activity, tidal volume, inspiratory reserve volume, and dyspnea ratings did not change between conditions.

Study Design

Type

RCT (n=20)

Blinding

Open-label

Randomization

Randomized crossover

Multicenter

Structured PICO

Does chest wall strapping alter neuromechanical coupling and increase dyspnea during exercise in healthy men?

Population

20 healthy, nonsmoking, normal-weight men aged 20-40 years with normal spirometry underwent symptom-limited incremental cycle exercise tests.

Intervention

Chest wall strapping (CWS) to reduce vital capacity (VC) by 21.6 ± 0.5% during symptom-limited incremental cycle exercise tests

Comparator

Unrestricted control during symptom-limited incremental cycle exercise tests

Outcome

Interrelationships between ventilation, breathing pattern, dynamic operating lung volumes, diaphragm electromyogram (EMGdi), transdiaphragmatic pressure time product (PTPdi), and sensory intensity and unpleasantness ratings of dyspneasurrogate

Main Result

Absolute Event Rate: 7.6% vs 7%

p-value: p=<0.05

Increased dyspnea during exercise with restrictive lung constraints is likely driven by increased neural respiratory drive rather than neuromechanical uncoupling.

Limitations

Small sample size of only 20 participants
Study population restricted to healthy young men, limiting generalizability
Chest wall strapping may not perfectly replicate the pathophysiology of chronic restrictive lung disease
Lack of objective measures of diaphragm fatigue

Cite This Study

Mendonca et al. (2013) conducted an RCT in Healthy (n=20). Chest wall strapping (CWS) vs. Unrestricted control was evaluated on Sensory intensity of dyspnea at peak exercise (Borg 0-10 scale) (p=<0.05). Chest wall strapping during exercise increased the intensity and unpleasantness of dyspnea, reflecting an awareness of increased neural respiratory drive rather than neuromechanical uncoupling.

synapsesocial.com/papers/6a7a017902ab7a73dd02ab94 https://doi.org/10.1152/japplphysiol.00950.2013

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Implication

Dyspnea in restrictive constraints warrants targeting neural drive; extends mechanistic models beyond neuromechanical uncoupling in exercise.

Physiological mechanisms of dyspnea during exercise with external thoracic restriction: Role of increased neural respiratory drive

Discussion

Member takes

Implication

Key Points

Study Design

Structured PICO

Main Result

Limitations

Cite This Study

Physiological mechanisms of dyspnea during exercise with external thoracic restriction: Role of increased neural respiratory drive

Discussion

Member takes

Implication

Key Points

Study Design

Structured PICO

Main Result

Limitations

Cite This Study

Also Consider

Also Consider