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Background: In patients with COPD, exercise intensity is often limited by the ventilatory system. We hypothesized that by exercising with a smaller muscle mass, ventilatory-limited patients would perform more high-intensity, [...]

Study objective: Estimating lung volume using inspiratory capacity (IC) maneuvers is a useful way of tracking dynamic hyperinflation. An understanding of the repeatability of the IC in a clinical setting [...]

Study objective: This study determined whether proportional assist ventilation (PAV) applied during constant power submaximal exercise could enable individuals with severe but stable COPD to increase their exercise tolerance. Design: Prospective controlled study having a randomized order of intervention. Setting: Pulmonary function exercise laboratory. Participants: Ten subjects with severe stable COPD (mean [SD]: age=59 [6] years; [FEV.sub.1] = 29 [7]% predicted; [FEV.sub.1]/FVC = 33 [7]%; thoracic gas volume = 201 [47]% predicted; diffusion of carbon monoxide = 36 [10]% predicted; [PaO.sub.2] = 76 [8] mm Hg; and [PaCO.sub.2] = 41 [4] mm Hg). Intervention: Each subject completed five sessions of cycling at 60 to 70% of their maximum power. The sessions differed only in the type of inspiratory assist: (1) baseline (airway pressure [Paw] = 0 cm [H.sub.2]O); (2) proportional assist ventilation (PAV) (volume assist = 6 [3] cm [H.sub.2]O/L, flow assist = 3 [1] cm [H.sub.2]O/L/s); (3) continuous positive airway pressure (CPAP) (5 [2] cm [H.sub.2]O); (4) PAV+CPAP; and (5) sham (Paw = 0 cm [H.sub.2]O). Measurements and results: Dyspnea was measured using a modified Borg scale. Subjects reached the same level of dyspnea during all sessions but only PAV+CPAP significantly (p [is less than] 0.05) increased exercise tolerance (12.88 [8.74] min) vs the sham session (6.60 [3.12] min). Exercise time during the PAV and CPAP sessions was 7.10 [2.83] and 8.26 [5.54] min, respectively. Minute ventilation increased during exercise but only during PAV+CPAP was the end exercise minute ventilation greater than the unassisted baseline end exercise minute ventilation (36.2 [6.7] vs 26.6 [6.4] L/min, respectively; p [is less than] 0.05). Conclusions: In this study, PAV+CPAP provided ventilatory assistance during cycle exercise sufficient to increase the endurance time. It is now appropriate to evaluate whether PAV+CPAP will facilitate exercise training. (CHEST 1997;111:948-54) Key words: assisted ventilation; COPD; exercise; rehabilitation Abbreviations: ANOVA=analysis of variance; CPAP=continuous positive airway pressure; [FECO.sub.2]=fractional concentration of expired carbon dioxide; [FEO.sub.2]=fractional concentration of expired oxygen; PAV=proportional assist ventilation; Paw=airway pressure, It is becoming widely accepted that pulmonary rehabilitation has an important role in the management of chronic respiratory conditions, especially COPD. Several reports have shown that supervised exercise training for [...]

Study objective: The objective was to determine whether external chest wall oscillation (ECWO) during sleep (1) reduced spontaneous ventilation while maintaining adequate gas exchange over several hours, (2) influenced the [...]

Effective gas exchange can be maintained in animals without the need for endotracheal intubation using exteRNal chest wall oscillation (ECWO). The clinical application of this technique has been limited by [...]

Although arm activity is poorly tolerated by patients with COPD, the ventilatory response to arm elevation alone is not well understood. We therefore studied the ventilatory response to arm elevation [...]

Purpose: This study determined whether subjects undergoing cardiopulmonary exercise testing altered their breathing before making an inspiratory capacity (IC) manoeuvre and whether correcting IC to compensate for the change would [...]

Purpose: The concept of critical power is based upon the hyperbolic relationship between power (P) and endurance time (tlimit) and its parameters can be estimated by the transformation which linearly [...]