Respiratory rehabilitation during COVID-19
New guidance on the clinical management of COVID-19 patients has emerged thick and fast. On Twitter, there are frequent tweets from physiotherapists and intensive care unit (ICU) specialists sharing tips and promoting new information. Topics range from airway clearance techniques and the positioning of patients to different respiratory rehabilitation techniques to help those who have successfully recovered from acute COVID-19 pneumonia.
Inspiratory muscle training
Respiratory rehabilitation is often combined with inspiratory muscle training (IMT) to treat people with lung conditions. IMT is an activity which has the ability to strengthen the user’s inspiratory muscles or diaphragm muscle over time. It requires the user to breathe in through a device which has a valve set to a pressure threshold. A percentage of the user’s maximal inspiratory pressure (MIP) is used as the training load; this can range from 30% to 80% of MIP.
IMT has been used successfully in several ICUs in the United Kingdom and further afield to wean patients off their ventilators prior to and during the COVID-19 pandemic. Mechanical ventilation causes rapid wasting and weakness in the inspiratory muscles and IMT builds back their strength. The result is patients come off their ventilator faster and spend less time in intensive care.
Who can benefit from practising IMT?
A recent article has highlighted the link between respiratory muscle performance and COVID-19. Notably, patients with poor baseline health, such as those who are old or frail, smoke, have chronic disease, or are overweight, are more likely to have impaired respiratory muscle performance. It is these patients who have the highest risk of developing complications from COVID-19.
Although patients with impaired baseline respiratory muscle weakness tend to receive the greatest benefit from IMT, even healthy individuals without breathing difficulties show modest improvement in exercise performance.
So it is plausible that IMT may benefit a proportion of the population during a viral infection, but there is no evidence to date to support this hypothesis.
The INSPIRE study
The INSPIRE study is designed to determine whether IMT can reduce the risk of postoperative pulmonary complications (PPCs), including pneumonia, in patients undergoing major heart, chest, and abdominal surgery. The NIHR-funded  study aims to recruit 2,500 patients.
Study participants are asked to perform either IMT or other breathing exercises for a minimum of 2 weeks before their surgery. They are then followed up for 6 months after surgery to determine whether the incidence of PPCs differs between those who perform IMT and those who do not.
Interestingly, the same risk factors that increase the risk of severe complications from COVID-19 also increase the risk of developing a PPC after surgery.
COVID-19 has happened at a pivotal moment in the INSPIRE study. Although INSPIRE is not directly investigating the effects of IMT on participants with COVID-19, an amendment to the study protocol will enable capture of COVID-19 data from study participants.
Could participants who undergo elective surgery but are unfortunate enough to develop COVID-19 during their recovery benefit from the IMT they performed before surgery? INSPIRE is not designed to answer this question, but it may provide some important clues.
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