Methacholine Challenge Test and COVID
A Methacholine Challenge Test is typically performed when asthma is suspected but traditional testing methods have not been conclusive. During the COVID-19 pandemic, many clinics and providers cancelled this kind of testing, as it increased the potential for transmission of the virus. The members of the 2020 Proficiency Standards for Pulmonary Function Testing Society recommended that “Pulmonary Function Testing be limited to tests that are only essential for immediate treatment decisions and that personal protective equipment for healthcare workers should be discussed with the local infection control teams.”(1) With the current downtrend in COVID cases, as reported by the Centers for Disease Control, procedures are being rescheduled, with new safety precautions in place.
A coordinated task force, made up of the directors of the Association of Pulmonary, Critical Care and Sleep Division and the American Thoracic Society, developed plans for resuming elective services, such as methacholine challenging testing, in light of a decreasing number of COVID cases in the U.S.(2)
The task force states that in order to resume elective services, the community (where the provider is located) should have a new case rate that is consistently low or in a downward trajectory for at least 14 days. Further, “institutions should have an operation strategy that consists of patient prioritization, screening, diagnostic testing, physical distancing, infection control, and follow-up surveillance.”(2) Defining the virus transmission as a dynamic process, the task force stressed that operating procedures should be “frequently reassessed and modified as needed.”(2)
Pulmonary Function Testing (PFT) “presents unique challenges during the COVID-19 pandemic,” the task force stated. The test results in high aerosol generation. Droplets could spread from an infected individual (even if the individual is asymptomatic) to a health care worker. There is also risk of cross contamination of testing rooms, equipment and waiting areas. The task force states that some institutions may want to test all patients undergoing PFT within 72 hours of their appointment.(2)
The task force continued that bronchial challenge testing should be performed in a negative-pressure room, if possible. “Patients should be instructed in cough etiquette and wear a surgical mask as much as possible to avoid aerosol dispersion, and the staff should wear appropriate PPE (N95 mask, face shield, gown, and gloves). Both patients and staff should maintain safe distance from one another and wash their hands before and after testing.”(2)
(1) Lombardi, C. M.D., Milanese, M. M.D., Annals of Allergy, Asthma & Immunology, Rethinking Respiratory Function Laboratories in the Era of Coronavirus Disease, https://www.annallergy.org/
(2) Wilson, K. M.D., Kaminsky, D. M.D., Workshop Report, The Association of Pulmonary, Critical Care, and Sleep Division Directors and American Thoracic Society, Coordinated Task Force, Restoring Pulmonary and Sleep Services as the COVID-19 Pandemic Lessons, https://www.atsjournals.org/