Unilateral pleural effusion mars diaphragmatic function, causes hyperactivity
10 Oct 2022
Unilateral pleural effusion impairs the ipsilateral hemidiaphragm function and sets off compensatory hyperactivity of the contralateral hemidiaphragm, which resolves postdrainage, suggest the results of the second PLeural Effusion And Symptom Evaluation (PLEASE-2) study.
“In the PLEASE-1 study, abnormal ipsilateral hemidiaphragm shape and movement, assessed qualitatively, were independently associated with breathlessness relief after pleural drainage,” the researchers said.
PLEASE-2 is a prospective exploratory pilot study assessing the effects of unilateral effusion and drainage on both hemidiaphragms using advanced quantitative bedside ultrasonography. The researchers included individuals with symptomatic unilateral pleural effusion undergoing therapeutic drainage.
In addition to shape and movement, measurements during pre- and postdrainage included severity of breathlessness (visual analogue scale) and ultrasound measurements of diaphragm excursion and thickness. The researchers compared diaphragm measurements to published reference values.
Twenty individuals (mean age 68.9 years, 12 females) participated in the study. Contralateral hemidiaphragm excursion went above the ipsilateral excursion and reference values (p≤0.001 for all) during tidal breathing.
Participants with abnormal ipsilateral hemidiaphragm movement had the greatest contralateral excursion, which was inversely associated with ipsilateral tidal excursion (r, ‒0.676; p=0.001).
Abnormal shape (n=12) and paradoxical movement (n=9) of the ipsilateral hemidiaphragm resolved in all participants, while tidal excursion of the contralateral hemidiaphragm normalized, after drainage (mean volume 2,121 ml). Relief of breathlessness following drainage was associated with improvement in ipsilateral hemidiaphragm excursion (r, 0.556; p=0.031).
“These findings provide a basis for detailed studies of diaphragmatic function and ventilatory drive in patients with symptomatic pleural effusion,” the researchers said.