Q&A: A New Protocol to Evaluate Maximum Inspiratory Pressure in COPD

Photo Credit: stefanamer

Instead of a manovacuometer, researchers evaluated a one-repetition maximum test protocol for measuring maximum inspiratory pressure in patients with COPD.

Guidelines recommend using a manovacuometer to measure maximal respiratory pressure to gauge the impact of respiratory muscle weakness on breathing in patients with chronic obstructive pulmonary disease (COPD). Although highly effective, the expense of manovacuometers is a challenge, and, therefore, new methods that offer both a simple interface and a reduced cost are highly sought after.

Raúl Fabero-Garrido, MSc, and colleagues developed a study to evaluate an alternative to the manovacuometer-assessed maximum inspiratory pressure test protocol based on the foundational elements of the one-repetition maximum test (1RM). Fabero-Garrido and colleagues assessed this 1RM test protocol by evaluating its test-retest reliability and establishing a minimal detectable change in patients with COPD. The study’s results were published in the Physical Therapy and Rehabilitation Journal. Fabero-Garrido spoke with Physician’s Weekly (PW) about the findings of the work.

PW: What is the most important finding from your study?

Fabero-Garrido: This study’s most important finding is that the 1RM method of assessing PIMax [maximal inspiratory mouth pressure] in people with COPD appears to generate similar results to those directly evaluated by a manovacuometer (the gold standard method for this measurement). Although it generates some overestimation of the PIMax values, the difference is so small that the error is carried over when calculating percentages for training loads, which is completely acceptable.

How can physicians incorporate these findings into practice?

The study includes a detailed description of the protocol for calculating the 1RM, indicating the exact intensities for each attempt. It is designed to be as time-efficient as possible for the clinician, allowing more time dedicated to the therapeutic act. Knowing the patients’ maximal strength on inspiration is key, but knowing this calculation is less important than ensuring they are willing to train and can improve their health.  In addition, the 1RM protocol only requires the IMT [inspiratory muscle training] device and no other devices. Considering that the manovacuometers on the market are above 1500 euros, we think this protocol could be applied more widely, bringing the use and therapeutic benefits of IMT to more clinics and, thus, to many more patients.

What makes this issue particularly urgent in physiotherapy?

IMT using threshold devices improves inspiratory muscle strength, exercise capacity, and quality of life while decreasing dyspnea. That is the conclusion of one of the most up-to-date meta-analyses regarding IMT and COPD. However, IMT is not often implemented in physiotherapy practice. We believe that this study helps to overcome one of the main barriers to implementing IMT: the high costs of manovacuometers (usually higher than the monthly salary of a physiotherapist). Thanks to a quick, simple, inexpensive, and accessible PIMax assessment protocol such as the one validated in this study, we believe that implementing this training modality could now be expanded, even more so in developing countries where resources are still more limited.

What would you like future research to be focused on? What still needs to be explored? 

This study opens a new paradigm. Although this validation occurs in the context of COPD, the benefits of IMT are already evident in other respiratory, cardiological, and neurological pathologies. IMT even has positive effects on athletes’ performance. Further research is needed to see if this protocol is equally valid in these other health conditions or if it needs to be modified.