Noninvasive Ventilation and Posture Influence Respiratory Ability in ALS Patients

Researchers who studied noninvasive ventilation (NIV) in patients with amyotrophic lateral sclerosis (ALS) found that respiratory muscles may work more efficiently during NIV. They also believe their measurement technique can be useful for detecting changes in breathing patterns even in early-stage ALS patients.

The research paper, “Effects of non-invasive ventilation and posture on chest wall volumes and motion in patients with amyotrophic lateral sclerosis: a case series,” was published in the Brazilian Journal of Physical Therapy.

Respiratory muscle weakness and reduction of lung volume in ALS patients leads to chronic hypoventilation and respiratory failure, the main cause of death in these patients. Noninvasive ventilation (NIV), widely used in people with ALS, is a therapeutic procedure that improves the ventilation and perfusion rates, which refers to the air and blood that reach the alveoli in the lungs, respectively.

Despite its common use, the physiological responses to NIV, in terms of respiratory muscle function and chest wall function, remain unknown.

The primary objective of the study was to assess the effects of NIV on the volumes and function of the chest wall and its compartments in patients with ALS. The second objective was to determine respiratory dysfunction by assessing forced vital capacity in the supine (lying on their backs) and standing positions of ALS patients and matched controls.

Measurement instruments included optoelectronic plethysmography (OEP), which assesses breath-by-breath changes in the total volume of the chest wall and the contributions of its three compartments (pulmonary rib cage, abdominal rib cage, and abdomen). Oxygen saturation and heart rate were also measured.

Nine patients were evaluated using NIV. The same patients and nine healthy controls were evaluated in laying down and sitting up. According to the results, chest wall volume increased significantly with NIV, which may indicate that the respiratory muscles might work more efficiently due to this noninvasive procedure. However, no significant changes were observed regarding ventilation/perfusion.

In the supine position, ALS patients presented a significantly lower percentage of contribution of the abdomen compared to controls. The results suggest that diaphragm involvement could be considered an early stage of dysfunction. The OEP technique was shown to be an accurate and precise tool for detection of these early modifications in breathing patterns in ALS.

“OEP can be used as a new strategy to evaluate this patient population,” the researchers said.