Improving detection of respiratory insufficiency for patients with ALS

Nov. 04, 2022

Mayo Clinic researchers have found that overnight pulse oximetry and maximum inspiratory pressure are valuable parameters for detecting early respiratory insufficiency in people with amyotrophic lateral sclerosis (ALS). As described in a Mayo Clinic study published online in Neurology, both tests performed better than forced vital capacity criteria.

All three approaches are used to identify patients who would benefit from noninvasive ventilation. That respiratory therapy has been reported to improve quality of life and to extend survival time in individuals with ALS.

The Mayo Clinic researchers compared the performance of overnight pulse oximetry, maximum respiratory pressure and forced vital capacity in routine care in the multidisciplinary ALS clinic at Mayo Clinic in Rochester, Minnesota. The records of 476 patients who attended the clinic between 2008 and 2016 were evaluated.

For each patient, the times from disease onset to abnormal overnight pulse oximetry, maximum inspiratory pressure and forced vital capacity testing results were compared to determine the relative performance of each test. Comparisons also were made in subgroups of patients with spinal- and bulbar-onset ALS.

Key findings:

  • The median times from disease onset to abnormal maximum inspiratory pressure and overnight pulse oximetry results were 1.5 and 1.6 years, respectively — significantly shorter than the median time of 3.8 years for forced vital capacity testing.
  • Maximum inspiratory pressure and overnight pulse oximetry abnormalities occurred earlier, approximately 1.8 and 2.0 years after disease manifestation in patients with spinal-onset ALS — whereas forced vital capacity abnormality among those patients developed 4.2 years after disease onset.
  • Maximum inspiratory pressure and overnight pulse oximetry detected abnormalities earlier than forced vital capacity in both the spinal- and bulbar-onset ALS subgroups — although the time gap was greater in the spinal-onset subgroup.

Mailing system for in-home overnight pulse oximetry

The researchers also evaluated the effectiveness of new efforts aimed at reducing the need for patients and caregivers to travel to the ALS clinic.

Historically, patients were typically seen in person in the ALS clinic every three months. In the months before the coronavirus disease 2019 (COVID-19) pandemic, the ALS clinic team began regular telemedicine visits. As a result, the clinic could quickly transition to all-telemedicine care in March 2020. Although in-person visits have resumed, telemedicine visits remain an option.

To continue monitoring respiratory status of patients with ALS during the pandemic, the ALS clinic developed a system for mailing overnight pulse oximetry testing machines to patients' homes. The machines can be returned to the ALS clinic in person or by mail before a telemedicine visit.

A questionnaire administered to 31 patients before and after the transition to mail-out overnight pulse oximetry found the system to be so popular that it has become the standard in the ALS clinic.

"It is critical that we try to provide care for people with ALS that goes beyond the walls of the clinic. Technology is helping us provide that care to people wherever they are," says Nathan P. Staff, M.D., Ph.D., a neurologist at Mayo Clinic in Rochester, Minnesota. "Our quick adoption of telemedicine and mail-out home overnight oximetry approaches have clearly been a huge benefit."

Telehealth visits and remote monitoring continue to be an important part of care for patients with ALS enterprisewide. Remote monitoring of respiratory status is available at Mayo Clinic in Phoenix/Scottsdale, Arizona. At Mayo Clinic in Jacksonville, Florida, respiratory therapy service is provided by a vendor directly in patients' homes.

"Members of our ALS clinic team are always striving to provide new ways to care for our patients," Dr. Staff says.

For more information

Kelly CR, et al. Comparative performance of different respiratory test parameters for detection of early respiratory insufficiency in patients with ALS. Neurology. 2022;99:e743.

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