IMT fast-tracks COVID-19 recovery

Home-based inspiratory muscle training (IMT) – incorporated into COVID-19 rehabilitation programme – speeds up the recovery of patients in a UK study presented at ERS 2021.

IMT significantly improved fitness and fatigue, on top of breathing measures post-intervention, said study author Professor Melitta McNarry from Swansea University, Swansea, Wales, UK.

IMT “significantly accelerated” recovery from COVID-19, which makes it an “acceptable and feasible home-based rehabilitation tool,” she added. “Consequently, IMT should be considered as part of a wider COVID-19 recovery strategy.”

Therapeutic potential of IMT

People recovering from COVID-19 often experience breathlessness, and this debilitating experience persists even after a year of acute infection. This makes the potential rehabilitative role of IMT in COVID-19 patients of paramount interest.

To assess the role of IMT in COVID-19 recovery, McNarry and her team randomly assigned 250 adult patients (median age 48 years, 84 percent female) with COVID-19, whose primary symptom was breathlessness, to IMT for 8 weeks or a control arm. The intervention consisted of three sessions per week at 80 percent maximal capacity, delivered remotely through a video call. [ERS 2021, abstract 169]

The patients completed the KBILD* and the Chester Step Test at baseline and following the intervention to determine overall fitness. A device was worn to examine physical activity levels.

IMT improved all domains of the KBILD* in the first 87 participants studied. Breathlessness was reduced by a significant 33 percent (p<0.001), or twice the minimal clinically important difference.

IMT also improved maximal inspiratory pressure (MIP) from 75 cm H₂O at baseline to 117 cm H₂O at follow-up (p<0.001) so was sustained MIP from 420 pressure-time units (PTUs) to 575 PTUs (p<0.001).

The fatigue index increased significantly with IMT, from 17 au at baseline to 23 au at follow-up (p<0.001), while fitness rose from 36 mL/kg/min to 44 mL/kg/min (p<0.001).

Participants in both the intervention and control arms improved over time, with the magnitude of improvement with IMT two to 14 times greater than that seen with controls.

IMT though was not associated with changes in overall physical activity.

Caution warranted

Commenting on the study, Dr Daniel Langer, assistant professor at the Department of Rehabilitation Sciences, Respiratory Rehabilitation Group at KU Leuven, Belgium, said the initial findings were promising but clinicians should be cautious in making clinical assumptions with regard to the impact of IMT intervention in the absence of a proper control group.

He added that more data are needed to validate the initial findings and identify which COVID-19 patients would have respiratory muscle weakness as the most prevalent feature. He believes that in this group of patients, IMT might be a useful intervention.