Abstract Details

Title Electrical Impedance Tomography as a Quantitative Measure of Pulmonary Function in ALS Patients

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P1 - Poster Session 1 (12:00 PM-1:00 PM)

Poster/Presentation
Number 1-007

Objective

To assess the potential of chest electrical impedance tomography (EIT) to serve as a non-invasive, easily applied technology for the assessment of pulmonary function in amyotrophic lateral sclerosis (ALS) patients.

Background

Pulmonary function tests (PFTs) are valuable in assessing ALS patients. However, concomitant bulbar dysfunction can result in spurious, unreliable data with an overestimation of pulmonary dysfunction. Chest EIT has potential to overcome these limitations. In chest EIT, a real-time low-resolution image of lungs is created via application and measurement of weak high frequency electrical currents passed through electrodes placed circumferentially around the chest.

Design/Methods

EIT images were obtained on 6 ALS patients (5 men and 1 woman, median age of 62 years) and 5 healthy volunteers (3 men and 2 women, median age of 46 years). EIT was performed simultaneously with standard PFTs. In addition to qualitative evaluation of the resulting images, the overall EIT value for the chest was obtained by averaging all of the impedance data yielding a single value. The EIT normalized ratio (EIT-NR) was calculated by taking the difference in impedance values at maximal inspiration versus maximal expiration and dividing it by the mean impedance during tidal breathing.

Results Qualitative differences were apparent between healthy volunteers and ALS patient EIT images, with the ALS cohort showing greater heterogeneity. Intraclass correlation coefficients of 0.99 confirmed high test-retest repeatability. The two groups of participants were easily distinguished by the EIT-NR value. Strong positive correlations between EIT-NR and PFTs was obtained, with R²=0.75 in ALS patients and 0.63 in healthy controls.

Conclusions

These findings suggest that EIT has excellent construct validity, supporting that it may serve as an easily applied alternative technology to standard PFTs. Future work will determine if EIT can serve as a better approach for measuring pulmonary function in ALS patients with bulbar weakness.

Authors/Disclosures
Badria Munir, MD PRESENTER	Dr. Munir has nothing to disclose.
Ethan Murphy	No disclosure on file
Akashleena Mallick, MD, MBBS (Massachusetts General Hospital- Harvard Medical School)	Dr. Mallick has nothing to disclose.
Hilda V. Gutierrez, MD (Beth Israel Deaconess Medical Center)	Ms. Gutierrez has nothing to disclose.
	No disclosure on file
Christy Smith	No disclosure on file
Sean Levy	No disclosure on file
Courtney E. McIlduff, MD (Beth Israel Deaconess Medical Center)	The institution of Dr. McIlduff has received research support from NIH - R21NSNS118434. The institution of Dr. McIlduff has received research support from NIH - R01MH111875. The institution of Dr. McIlduff has received research support from Blavatnik Family Fund. Dr. McIlduff has received publishing royalties from a publication relating to health care.
	No disclosure on file
Ryan Halter	No disclosure on file
Seward B. Rutkove, MD, FAAN	Dr. Rutkove has received personal compensation in the range of $50,000-$99,999 for serving as a Consultant for Myolex, Inc. Dr. Rutkove has received personal compensation in the range of $10,000-$49,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for American Academy of Neuorlogy . The institution of Dr. Rutkove has received research support from NIH. The institution of Dr. Rutkove has received research support from NASA. The institution of Dr. Rutkove has received research support from Blavatnik Family Foundation. Dr. Rutkove has received intellectual property interests from a discovery or technology relating to health care. Dr. Rutkove has received intellectual property interests from a discovery or technology relating to health care. Dr. Rutkove has received publishing royalties from a publication relating to health care. Dr. Rutkove has received publishing royalties from a publication relating to health care. Dr. Rutkove has received personal compensation in the range of $500-$4,999 for serving as a Grant Reviewer with NIH.