title: Effects of Pressure Support Ventilation May Be Lost at High Exercise Intensities in People with COPD.
abstract: Pressure support ventilation (PSV) may be used for exercise training in chronic obstructive pulmonary disease (COPD), but its acute effect on maximum exercise capacity is not fully known. The objective of this study was to evaluate the effect of 10 cm H2O PSV and a fixed PSV level titrated to patient comfort at rest on maximum exercise workload (WLmax), breathing pattern and metabolic parameters during a symptom-limited incremental bicycle test in individuals with COPD. Eleven individuals with COPD (forced expiratory volume in one second: 49 ± 16%; age: 64 ± 7 years) performed three exercise tests: without a ventilator, with 10 cm H2O of PSV and with a fixed level titrated to comfort at rest, using a SERVO-i ventilator. Tests were performed in randomized order and at least 48 hours apart. The WLmax, breathing pattern, metabolic parameters, and mouth pressure (Pmo) were compared using repeated measures analysis of variance. Mean PSV during titration was 8.2 ± 4.5 cm H2O. There was no difference in the WLmax achieved during the three tests. At rest, PSV increased the tidal volume, minute ventilation, and mean inspiratory flow with a lower end-tidal CO2; this was not sustained at peak exercise. Pmo decreased progressively (decreased unloading) with PSV at workloads close to peak, suggesting the ventilator was unable to keep up with the increased ventilatory demand at high workloads. In conclusion, with a Servo-i ventilator, 10 cm H2O of PSV and a fixed level of PSV established by titration to comfort at rest, is ineffective for the purpose of achieving higher exercise workloads as the acute physiological effects may not be sustained at peak exercise.
authors.affiliation: a School of Physical and Occupational Therapy , McGill University , Montreal , Quebec , Canada.|b Research Center , Sacré-Coeur Hospital , Montreal , Quebec , Canada.|c Center for Interdisciplinary Research in Rehabilitation in Montreal , Jewish Rehabilitation Hospital , Laval , Quebec , Canada.
authors.forename: David
authors.initials: D
authors.lastname: Anekwe
authors.affiliation: d Department of Adult Critical Care , Jewish General Hospital , Montreal , Quebec , Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: de Marchie
authors.affiliation: a School of Physical and Occupational Therapy , McGill University , Montreal , Quebec , Canada.|b Research Center , Sacré-Coeur Hospital , Montreal , Quebec , Canada.|c Center for Interdisciplinary Research in Rehabilitation in Montreal , Jewish Rehabilitation Hospital , Laval , Quebec , Canada.
authors.forename: Jadranka
authors.initials: J
authors.lastname: Spahija
mesh_terms: D000368:Aged; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005541:Forced Expiratory Volume; D006801:Humans; D008875:Middle Aged; D005082:Physical Exertion / Q000502:physiology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000628:therapy; D012123:Pulmonary Ventilation; D012121:Respiration, Artificial / Q000379:methods*; D012146:Rest / Q000502:physiology; D013990:Tidal Volume
keywords: Adjuncts to exercise; NIMV; bicycle exercise; dynamic hyperinflation; maximum exercise capacity; patient–ventilator interaction