Abstract
ABSTRACTBackgroundThe effects of non-invasive ventilation (NIV) on the breathing pattern and thoracoabdominal motion of patients with amyotrophic lateral sclerosis (ALS) are unknown.Objectives1) To analyze the influence of NIV on chest wall volumes and motion assessed by optoelectronic plethysmography in ALS patients and 2) to compare these parameters in the supine and sitting positions to those of healthy individuals (without NIV).MethodNine ALS patients were evaluated in the supine position using NIV. In addition, the ALS patients and nine healthy individuals were evaluated in both sitting and supine positions. Statistical analysis was performed using the paired Student t-test or Wilcoxon test and the Student t-test for independent samples or Mann-Whitney U test.ResultsChest wall volume increased significantly with NIV, mean volume=0.43 (SD=0.16)L versus 0.57 (SD=0.19)L (p=0.04). No significant changes were observed for the pulmonary rib cage, abdominal rib cage, or abdominal contribution. The index of the shortening velocity of the diaphragmatic muscle, mean=0.15 (SD=0.05)L/s versus 0.21 (SD=0.05)L/s (p<0.01), and abdominal muscles, mean=0.09 (SD=0.02)L/s versus 0.14 (SD=0.06)L/s (p<0.01), increased during NIV. Comparisons between the supine and sitting positions showed similar changes in chest wall motion in both groups. However, the ALS patients presented a significantly lower contribution of the abdomen in the supine position compared with the controls, mean=56 (SD=13) versus 69 (SD=10) (p=0.02).ConclusionsNIV improved chest wall volumes without changing the contribution of the chest wall compartment in ALS patients. In the supine position, ALS patients had a lower contribution of the abdomen, which may indicate early diaphragmatic dysfunction.
Highlights
The reduction in lung volumes combined with respiratory muscle weakness in patients with amyotrophic lateral sclerosis (ALS) is responsible for chronic hypoventilation, which can cause major disorders, those related to sleep[1], and can contribute to respiratory insufficiency, the major cause of death in ALS patients[2]
Optoelectronic plethysmography (OEP) enables the assessment of the contribution of the three compartments of the chest wall and the assessment of different intervention methods using a range of respiratory rehabilitation techniques
The main findings of this study were that Non-invasive ventilation (NIV) promoted a significant increase in the operating volumes, tidal volume of the chest wall, minute ventilation, and in the index of the shortening velocity of the diaphragm and abdominal muscles in patients with ALS without bulbar dysfunction
Summary
The reduction in lung volumes combined with respiratory muscle weakness in patients with amyotrophic lateral sclerosis (ALS) is responsible for chronic hypoventilation, which can cause major disorders, those related to sleep[1], and can contribute to respiratory insufficiency, the major cause of death in ALS patients[2]. The possible physiological responses that this treatment can produce in terms of respiratory muscle action and chest wall mechanics have not yet been identified. Different measures have been proposed for the assessment of diaphragmatic dysfunction in this population, including comparisons of the forced vital capacity in the supine and standing positions, changes in blood gases, symptoms and respiratory muscle strength[5]. Optoelectronic plethysmography (OEP) is a method recently proposed to measure chest wall volumes. OEP enables the assessment of the contribution of the three compartments of the chest wall (pulmonary rib cage, abdominal rib cage, and abdomen) and the assessment of different intervention methods using a range of respiratory rehabilitation techniques. It can be used to calculate its shortening velocity[7] and to assess the effect that positioning has on the performance of this muscle[8]
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