Assessing pulmonary function in ALS using electrical impedance tomography.

Area of Science:

• Pulmonary Medicine
• Biomedical Engineering
• Neurology

Background:

• Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons, leading to respiratory muscle weakness.
• Accurate and noninvasive assessment of pulmonary function is crucial for managing ALS patients.
• Current pulmonary function tests (PFTs) can be challenging for some ALS patients, especially those with bulbar or facial weakness.

Purpose of the Study:

• To evaluate the utility of thoracic electrical impedance tomography (EIT) in characterizing pulmonary function in ALS patients.
• To compare EIT measurements with standard PFTs, including spirometry and respiratory pressures.
• To assess EIT's performance in ALS patients with and without facial weakness.

Main Methods:

• 32 ALS patients and 32 healthy controls (HCs) underwent simultaneous EIT and PFT measurements.
• PFTs included slow and forced vital capacity (SVC, FVC) in upright and supine positions, and maximal inspiratory and expiratory pressures (MIPs, MEPs).
• Reproducibility of EIT measurements was assessed using intraclass correlation coefficients (ICCs), and correlations with PFTs were analyzed using Pearson's correlation.

Main Results:

• EIT demonstrated very high reproducibility for upright SVC measurements (ICC 0.98).
• Strong correlations were observed between EIT and spirometry measures in the ALS cohort (R values 0.64–0.82, p < 0.001).
• Correlations between EIT and MIPs/MEPs were less robust (R values 0.33–0.44), with no significant differences noted for patients with facial weakness.

Conclusions:

• Thoracic EIT offers a promising noninvasive method for assessing pulmonary function in ALS patients.
• EIT measurements correlate well with standard spirometry, suggesting its potential as an alternative or complementary tool.
• Further research and development of EIT are warranted for its clinical application in ALS management.