Our chronic NPPV therapy compliance rate of 65% occurred in a comprehensive outpatient program that was geared toward maximizing patient comfort and the efficacy of NPPV application with frequent face mask changes or ventilator settings to optimize patient comfort and gas exchange. In the patients who were compliant with NPPV, they underestimated their use of noninvasive ventilation at least 45% of the time as compared with objective meter logs. This highlights the problems of prior studies that have commented on the efficacy of NPPV. Some patients who were previously reported not to have benefited from NPPV may have failed not because of lack of clinical efficacy, but rather because of noncompliance with prescribed NPPV therapy. ventolin inhaler
Future studies must address the issue of efficacy vs compliance and ensure that objective parameters of NPPV use are measured.
It should also be recognized that patients with COPD developed a set of complications when they used NPPV that differed from those developed by patients with restrictive ventilatory disorders. The development of tracheobronchitis, with an increase in airway secretions, dynamic development of worsened airways obstruction, and the need for additional medications such as bronchodilators, poses problems in the application of NPPV therapy to this group. Obviously, worsening secretions or bronchospasm affect gas exchange and require an alteration in the application of NPPV. Furthermore, the development of worsening hyperinflation or the need for concomitant use of other medications may negatively influence patient compliance with NPPV, such that only the most motivated patient who perceives benefit will continue with therapy.
Our data are strengthened by the fact that they were collected prospectively in a comprehensive inpatient and outpatient program that was optimized to provide maximal medical therapy (including pulmonary rehabilitation) and compliance with NPPV treatment (ie, adjustments of face mask and ventilator settings to maximize ventilatory support). Nonetheless, even in such a comprehensive program, we found that only approximately 50% of our patients with COPD could tolerate NPPV, in contrast to 75% of patients with restrictive ventilatory disorders.
In summary, our data corroborate prior studies that show an important beneficial effect of NPPV on gas exchange and functional status in patients with chronic respiratory failure secondary to COPD or restrictive ventilatory disorders. However, in our study, only 75% of patients with restrictive ventilatory disorders and 50% of patients with COPD continued to use NPPV during prolonged follow-up of approximately 6 months, despite enrollment in a comprehensive inpatient and outpatient program. Future studies, preferably conducted in a prospective, randomized, and controlled fashion, are required to determine the subgroups of COPD patients who may best benefit from NPPV therapy.
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