Noninvasive ventilation (NIV) delivered using a ventilator and a full-face mask during exercise reduced dynamic hyperinflation (DH) and improved exercise duration compared with no NIV in patients with severe and very severe chronic obstructive pulmonary disease (COPD), a small, randomized, crossover trial has indicated.
Moreover, endurance time was increased whether NIV was used with standardized expiratory positive airway pressure (S-EPAP) or the more complex, individually titrated (T-EPAP), the same study showed.
“DH [happens when] a patient is unable to fully exhale before they need to breathe in again and during exercise — where they need to breathe in more — patients end up with a slowly increasing end expiratory volume, so it’s like trying to breathe in with a full lung,” Clancy Dennis, a student at the University of Sydney, Sydney, Australia, and colleagues told Medscape Medical News in an email.
“Once breathing volumes reach a critical threshold, breathlessness increases exponentially and exercise usually stops quite quickly so by using NIV to help people with COPD breathe bigger breaths and with less energy expended, they were less hyperinflated at [test time] and ultimately did more exercise,” he added.
The study was published online December 1, 2021, in Chest.
Endurance Cycle Tests
A total of 19 patients were enrolled in the study. Patients were attending an outpatient pulmonary rehabilitation center in Australia or an inpatient rehabilitation hospital in Germany. Patients had a diagnosis of COPD with an FEV1/FVC <0.7, FEV1 <50% predicted and were asked to perform three endurance cycle exercise tests in random order at 75% of the maximum work rate achieved during the incremental cycle test.
Patients exercised with no NIV, NIV with S-EPAP, and NIV with T-EPAP, as investigators explain. NIV with S-EPAP delivered EPAP 5 cm H2O for all participants while NIV with T-EPAP delivered an individualized EPAP that maximized inspiratory capacity (IC) at rest for each participant. “IC was used as a surrogate measure of DH and was measured by instructing the patient to breathe in completely without hesitation from the current end-expiratory lung volume (EELV) each minute throughout exercise,” Dennis and colleagues elaborate.
Results With NIV
The mean difference in seconds of exercise time with NIV & S-EPAP vs without was 152 seconds (P = .003). Similarly, the mean difference in seconds of exercise time with NIV & T-EPAP vs without was 145 seconds (P < .0001), both in favor of NIV. “There was no [significant] difference between NIV with S-EPAP and NIV with T-PAP,” the authors observe.
Asked if it’s difficult to use NIV when COPD patients need to exercise, Dennis noted that normally with a skilled clinician and a patient familiar with NIV, it isn’t that complicated. “It’s akin to starting CPAP [for sleep apnea],” he noted, although in this particular trial, no one had used NIV before, so it turned out to be a learning experience.
However, “people use CPAP and NIV every night and people are very capable of using all of the equipment,” he said, “and participants with more hyperinflation said they felt that NIV made breathing easier; so for those who do use it, they can get a real reduction in breathlessness, which is, I think, the most important point for the patient,” Dennis emphasized.
Limitations of the study include the fact that no sham NIV was used.
Small but Important Effect?
Commenting on the findings in an editorial, Kylie Hill, PhD, Curtin School of Allied Health, Perth, Australia, and Thomas Dolmage, MSc, West Park Healthcare Centre, Toronto, Ontario, felt that the current study adds to the community’s understanding of the way NIV can improve exercise tolerance in patients with COPD. Although the editorialists weren’t convinced that NIV was totally responsible for the reduction in DH observed in this study, “the clinical implications of the study…and others of its kind is the role NIV may have to enhance exercise training,” they suggest.
As Hill and Dolmage explain, up to 40% of patients with COPD have little improvement in exercise tolerance when exposed to conventional exercise training. “It is here that we must put into context the use of high-intensity exercise and the change in endurance time that was achieved with NIV in this study,” they observe. While a 1.5-minute difference in median tolerance does not seem like much, “an effect of this magnitude at very high intensity would translate to an important effect at lower intensities that are used in a training session,” Hill and Dolmage point out.
For example, exercise that could be tolerated for 10 minutes without NIV would be tolerated for in excess of 15 minutes with NIV, while 20 minutes without NIV would be tolerated indefinitely with NIV, they explain. The editorialists therefore felt it was reasonable that specialty pulmonary rehab programs could offer specific adjuncts such as NIV to patients on a case-by-case basis.
“In people who are willing, knowledgeable clinicians can manage ventilator set up and titration of pressures during exercise,” Kill and Dolmage suggest, although they caution that the longevity of the use of NIV to optimize training adaptation after completion of training remains unknown.
The authors and editorialists have disclosed no relevant financial relationships.
Chest. Published online December 1, 2012. Abstract
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