Tag: respiratory muscle dysfunction

Sonographic Diaphragm Abnormalities are an Unexpectedly Frequent Feature of Long COVID Outpatients with Unexplained Dyspnea and Fatigue

Abstract:

Purpose: The primary aim of this study is to define the sonographic diaphragm phenotype of Long COVID rehabilitation outpatients with non-specific dyspnea and fatigue. We analyzed patients referred from a pulmonary post-COVID clinic that were lacking a specific cardiopulmonary diagnosis for their symptoms. Additionally, we report the functional outcomes of subset of patients who completed an outpatient cardiopulmonary physical therapy program.

Methods: This was a retrospective cohort study (n = 58) of consecutive patients referred for neuromuscular ultrasound assessment of diaphragm muscle using B-mode technique. Patients were recruited from a single academic hospital between February 25, 2021 and November 22, 2022.

Results: Sonographic abnormalities were identified in 57% (33/58) of patients, and in the vast majority of cases (33/33) was defined by a low diaphragm muscle thickness. Thinner diaphragm muscles are correlated with lower serum creatinine and creatine kinase values, but there was no association with markers of systemic inflammation. Thirty three patients participated in outpatient cardiopulmonary physical therapy that included respiratory muscle training, and 75.8% (25/33) had documented improvement.

Conclusion: In the outpatient rehabilitation setting, patients with Long COVID display low diaphragm muscle thickness, but intact muscle contractility, with surprising frequency on neuromuscular ultrasound. We speculate this represents a form of disuse atrophy. Also, these patients appear to have a favorable response to cardiopulmonary physical therapy that includes respiratory muscle training.

Source: Prabhav P. Deo, Joseph I. Bailey, Alexandra S. Jensen, Ellen Farr, Meghan Fahey, Matthew Isherwood, Keerthana Chakka, Lisa F. Wolfe, Ishan Roy, Marc A. Sala, Colin K. Franz. Sonographic Diaphragm Abnormalities are an Unexpectedly Frequent Feature of Long COVID Outpatients with Unexplained Dyspnea and Fatigue. medRxiv 2022.06.29.22277054; doi: https://doi.org/10.1101/2022.06.29.22277054 (Full text)

Respiratory muscle dysfunction in long-COVID patients

Abstract:

Purpose: Symptoms often persistent for more than 4 weeks after COVID-19-now commonly referred to as ‘Long COVID’. Independent of initial disease severity or pathological pulmonary functions tests, fatigue, exertional intolerance and dyspnea are among the most common COVID-19 sequelae. We hypothesized that respiratory muscle dysfunction might be prevalent in persistently symptomatic patients after COVID-19 with self-reported exercise intolerance.

Methods: In a small cross-sectional pilot study (n = 67) of mild-to-moderate (nonhospitalized) and moderate-to-critical convalescent (formerly hospitalized) patients presenting to our outpatient clinic approx. 5 months after acute infection, we measured neuroventilatory activity P0.1, inspiratory muscle strength (PImax) and total respiratory muscle strain (P0.1/PImax) in addition to standard pulmonary functions tests, capillary blood gas analysis, 6 min walking tests and functional questionnaires.

Results: Pathological P0.1/PImax was found in 88% of symptomatic patients. Mean PImax was reduced in hospitalized patients, but reduced PImax was also found in 65% of nonhospitalized patients. Mean P0.1 was pathologically increased in both groups. Increased P0.1 was associated with exercise-induced deoxygenation, impaired exercise tolerance, decreased activity and productivity and worse Post-COVID-19 functional status scale. Pathological changes in P0.1, PImax or P0.1/PImax were not associated with pre-existing conditions.

Conclusions: Our findings point towards respiratory muscle dysfunction as a novel aspect of COVID-19 sequelae. Thus, we strongly advocate for systematic respiratory muscle testing during the diagnostic workup of persistently symptomatic, convalescent COVID-19 patients.

Source: Hennigs JK, Huwe M, Hennigs A, Oqueka T, Simon M, Harbaum L, Körbelin J, Schmiedel S, Schulze Zur Wiesch J, Addo MM, Kluge S, Klose H. Respiratory muscle dysfunction in long-COVID patients. Infection. 2022 May 16:1–7. doi: 10.1007/s15010-022-01840-9. Epub ahead of print. PMID: 35570238; PMCID: PMC9108020. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9108020/ (Full text)