Original research
Exercise testing in patients with diaphragm paresis

https://doi.org/10.1016/j.resp.2017.11.006Get rights and content

Highlights

  • Exercise capacity is slightly reduced in patients with DP.

  • Dyspnea is the main factor limiting exertion.

  • Diaphragm function is correlated with exercise ventilation.

  • Overall inspiratory muscle function is correlated with both exercise capacity and ventilation suggesting the importance of the accessory inspiratory muscles during exercise in patients with DP.

Abstract

Purpose

Diaphragm paresis (DP) is characterized by abnormalities of respiratory muscle function. However, the impact of DP on exercise capacity is not well known.

This study was performed to assess exercise tolerance in patients with DP and to determine whether inspiratory muscle function was related to exercise capacity, ventilatory pattern and cardiovascular function during exercise.

Methods

This retrospective study included patients with DP who underwent both diaphragmatic force measurements, and cardiopulmonary exercise testing (CPET).

Results

Fourteen patients were included. Dyspnea was the main symptom limiting exertion (86%). Exercise capacity was slightly reduced (median VO2peak: 80% [74.5%–90.5%]), mostly due to ventilatory limitation. Diaphragm and overall inspiratory muscle function were correlated with exercise ventilation. Moreover, overall inspiratory muscle function was related with oxygen consumption (r = 0.61) and maximal workload (r = 0.68).

Conclusions

DP decreases aerobic capacity due to ventilatory limitation. Diaphragm function is correlated with exercise ventilation whereas overall inspiratory muscle function is correlated with both exercise capacity and ventilation suggesting the importance of the accessory inspiratory muscles during exercise for patients with DP. Further larger prospective studies are needed to confirm these results.

Introduction

Diaphragmatic paresis (DP) is characterized by abnormalities of pulmonary and respiratory muscle function. It may occur unilaterally or bilaterally although unilateral paresis is more frequent. Idiopathic DP is the most frequent etiology (50%) (Gibson, 1989, Higgs et al., 2002, Piehler et al., 1982, Riley, 1962). The condition is generally under-diagnosed and there are few epidemiologic data available, except for post-surgical traumatic injury (Deslauriers, 1998).

Studies of pulmonary function in patients with DP have shown little impairment in ventilation but a decrease in vital capacity (VC) (Eisele et al., 1972). The main symptom of DP is dyspnea (Chuang et al., 2005, Graham et al., 1990, Laroche et al., 1988a) and it intensity depends on the etiology, extent of the impairment of diaphragm function, comorbidities and the patient’s level of fitness (Le Pimpec-Barthes et al., 2014).

However, the impact of DP on exercise capacity is not well known. Hart et al. found exercise tolerance to be reduced, with no differences between patients with uni- or bilateral DP (Hart et al., 2002). Conversely, Chuang et al. found no effect on exercise capacity, despite a decrease in total lung capacity (TLC) (Chuang et al., 2005).

The aim of this study was to assess exercise tolerance in patients with unilateral and bilateral DP and to determine whether inspiratory muscle function was related to exercise capacity, ventilatory pattern and cardiovascular function during exercise.

Section snippets

Study design and patient selection

This retrospective study included all consecutive patients assessed for diaphragmatic dysfunction between 2004 and 2015 in Rouen University Hospital. For this type of study, ethical approval and formal consent was not required.

Inclusion criteria

Patients were included if they had uni- or bilateral DP relating to the phrenic nerve confirmed by diaphragmatic evoked motor potentials (EMP) and fluoroscopy. Patients had to be at least 18 years old and have undergone both pulmonary function testing and cardiopulmonary

Patients

Fourteen patients were included, ten of whom had unilateral DP (seven left and three right) and four had bilateral DP. No patients had complete diaphragmatic paralysis. Main etiologies were idiopathic (n = 4) and post traumatic (n = 4). Other etiologies included iatrogenic causes and post cervical oesoarthrosis DP. Patient characteristics are presented in Table 1. Briefly, median age was 66.5 [50–75] years and mean BMI was 29.3 (4.7) kg/m2, including five patients with obesity (BMI > 30 kg/m2) and one

Discussion

In this cohort of patients with uni and bilateral DP, exercise capacity was slightly decreased, limited by impaired ventilation. BR was abolished and ventilatory pattern was pathological (low tidal volume and excessive respiratory rate). Diaphragm and overall inspiratory muscle function were correlated with exercise capacity and ventilation.

Conclusion

Uni- or bilateral DP may lead to a decrease in aerobic capacity due to ventilatory limitation. Diaphragm function is correlated with exercise ventilation whereas overall inspiratory muscle function is correlated with both exercise capacity (oxygen consumption and maximal workload) and ventilation suggesting the importance of the accessory inspiratory muscles during exercise for patients with DP. Further prospective studies, with a larger sample of patients, are needed to confirm these results

Ethical approval

For this type of study, formal consent was not required.

Conflict of interest

The authors state that they have no conflicts of interest.

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