Inspiratory Muscle Training (IMT)

What is an Inspiratory Muscle Trainer (IMT)?

• A device that strengthens the diaphragm and external intercostal muscles (muscles of inspiration)
• Provides controlled, graded resistance to inspiration

Patients who can benefit from IMT use:

1. COPD
2. Respiratory Failure
3. Recent Mechanical Ventilation
4. Pneumonia
5. Cystic Fibrosis  
6. Congestive Heart Failure
7. Pre/Post CABG    
8. Pre/Post Lung Transplant
9. ALS/GB/SCI
10. Frailty/Debility

COVID-19

Patients who have or have recently had COVID-19 have probably experienced more than one or two things on this list. The typical progression is cold-like symptoms followed by onset of viral and/or bacterial pneumonia OR a COPD exacerbation if they already have COPD. This is then followed by Acute Respiratory Distress Syndrome (ARDS) and/or Acute Respiratory Failure (ARF) at which point the patient is then intubated and ventilated. Because the ventilator is doing the work of breathing for the patient, their diaphragm takes a break. Think of it as more like PROM for the diaphragm.

This is usually not a problem because the diaphragm really needs a break in these patients. However, they are being ventilated for several days, up to weeks. Many hospitals don’t have early mobility programs so these patients are not getting any activity at all during this time. Post-Intensive Care Syndrome (PICS) can set in quickly and the diaphragm begins to weaken just like every other muscle.

Therapists who have been utilizing IMTs for patients with COVID-19 have been having good results and are seeing quantitative improvements!

Why use an IMT device (like the Threshold pictured)?

• Improve strength of cough for improved airway clearance (17.8 cmH2O improvement on average) –> This number is HUGE!!!
• Improved diaphragm strength resulting in deeper inspiration for pneumonia prevention, especially in pre-CABG pts, with reduced hospitalization time after surgery
• Functional improvements on 6 Minute Walk Test, QOL, and decreased difficulty with ADL for severe COPD patients

How to Use an IMT:

Two protocols have been found effective:

Repetitions to fatigue at 80% max of max effort once per day

OR

30 minutes of training at 60% effort twice per day

I’m going to say this one time so listen up: Just like ANY OTHER strengthening activity we prescribe, inspiratory muscle training intensities lower than 40% of maximal effort do not translate into quantitative functional outcomes.

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I love to tell my patients that this is “lifting weights for your lungs!” Have you used any IMT techniques or tools in athletes or higher level patients? The evidence is growing in this, so let me know in the comments!

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References:

Valkenet, K, et al. (2016) Effects of a pre-operative home-based inspiratory muscle training programme on perceived health-related quality of life in patients undergoing coronary artery bypass graft surgery. Physiotherapy. In proof. https://doi.org/10.1016/j.physio.2016.02.007

Hang-Yu, C. et al. (2017) The effects of threshold inspiratory muscle training in patients with chronic obstructive pulmonary (COPD) disease: A randomized experimental study. J Clin Nurse. In proof. DOI: 10.1111/jocn.13841

Bisset, B. et al. (2016) Inspiratory muscle training to enhance recovery from mechanical ventilation: a randomised trial. Critical Care. In print. http://dx.doi.org/10.1136/thoraxjnl-2016-208279

Enright S, et al. (2011) Effect of inspiratory muscle training intensities on pulmonary function and work capacity in people who are healthy: a randomized controlled trial Phys Ther. 91(6):894-905

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