What are the barriers and enablers of referral, uptake, attendance and completion of pulmonary rehabilitation for people with chronic obstructive pulmonary disease (COPD)? Systematic review of qualitative or quantitative studies reporting data relating to referral, uptake, attendance and/or completion in pulmonary rehabilitation. People aged >18years with a diagnosis of COPD and/or their healthcare professionals. Data were extracted regarding the nature of barriers and enablers of pulmonary rehabilitation referral and participation. Extracted data items were mapped to the Theoretical Domains Framework (TDF). A total of 6969 references were screened, with 48 studies included and 369 relevant items mapped to the TDF. The most frequently represented domain was 'Environment' (33/48 included studies, 37% of mapped items), which included items such as waiting time, burden of illness, travel, transport and health system resources. Other frequently represented domains were 'Knowledge' (18/48 studies, including items such as clinician knowledge of referral processes, patient understanding of rehabilitation content) and 'Beliefs about consequences' (15/48 studies, including items such as beliefs regarding role and safety of exercise, expectations of rehabilitation outcomes). Barriers to referral, uptake, attendance or completion represented 71% (n=183) of items mapped to the TDF. All domains of the TDF were represented; however, items were least frequently coded to the domains of 'Optimism' and 'Memory'. The methodological quality of included studies was fair (mean quality score 9/12, SD 2). Many factors - particularly those related to environment, knowledge, attitudes and behaviours - interact to influence referral, uptake, attendance and completion of pulmonary rehabilitation. Overcoming the challenges associated with the personal and/or healthcare system environment will be imperative to improving access and uptake of pulmonary rehabilitation. PROSPERO CRD42015015976. [Cox NS, Oliveira CC, Lahham A, Holland AE (2017) Pulmonary rehabilitation referral and participation are commonly influenced by environment, knowledge, and beliefs about consequences: a systematic review using the Theoretical Domains Framework. Journal of Physiotherapy 63: 84-93].

Background: Respiratory muscle unloading during exercise could improve locomotor muscle oxygenation by increasing oxygen delivery (higher cardiac output and/or arterial oxygen content) in patients with chronic obstructive pulmonary disease (COPD). Methods: Sixteen non-hypoxaemic men (forced expiratory volume in 1 s 42.2 (13.9)% predicted) undertook, on different days, two constant work rate (70–80% peak) exercise tests receiving proportional assisted ventilation (PAV) or sham ventilation. Relative changes (Δ%) in deoxyhaemoglobin (HHb), oxyhaemoglobin (O₂Hb), tissue oxygenation index (TOI) and total haemoglobin (Hb_tot) in the vastus lateralis muscle were measured by near-infrared spectroscopy. In order to estimate oxygen delivery (Do₂est, l/min), cardiac output and oxygen saturation (Spo₂) were continuously monitored by impedance cardiography and pulse oximetry, respectively. Results: Exercise tolerance (Tlim) and oxygen uptake were increased with PAV compared with sham ventilation. In contrast, end-exercise blood lactate/Tlim and leg effort/Tlim ratios were lower with PAV (p<0.05). There were no between-treatment differences in cardiac output and Spo₂ either at submaximal exercise or at Tlim (ie, Do₂est remained unchanged with PAV; p>0.05). Leg muscle oxygenation, however, was significantly enhanced with PAV as the exercise-related decrease in Δ(O₂Hb)% was lessened and TOI was improved; moreover, Δ(Hb_tot)%, an index of local blood volume, was increased compared with sham ventilation (p<0.01). Conclusions: Respiratory muscle unloading during high-intensity exercise can improve peripheral muscle oxygenation despite unaltered systemic Do₂ in patients with advanced COPD. These findings might indicate that a fraction of the available cardiac output had been redirected from ventilatory to appendicular muscles as a consequence of respiratory muscle unloading.

Patients with chronic obstructive pulmonary disease (COPD) have slowed pulmonary O₂uptake (V̇o_2p) kinetics during exercise, which may stem from inadequate muscle O₂delivery. However, it is currently unknown how COPD impacts the dynamic relationship between systemic and microvascular O₂delivery to uptake during exercise. We tested the hypothesis that, along with slowed V̇o_2pkinetics, COPD patients have faster dynamics of muscle deoxygenation, but slower kinetics of cardiac output (Q̇t) following the onset of heavy-intensity exercise. We measured V̇o_2p, Q̇t (impedance cardiography), and muscle deoxygenation (near-infrared spectroscopy) during heavy-intensity exercise performed to the limit of tolerance by 10 patients with moderate-to-severe COPD and 11 age-matched sedentary controls. Variables were analyzed by standard nonlinear regression equations. Time to exercise intolerance was significantly ( P < 0.05) lower in patients and related to the kinetics of V̇o_2p( r = −0.70; P < 0.05). Compared with controls, COPD patients displayed slower kinetics of V̇o_2p(42 ± 13 vs. 73 ± 24 s) and Q̇t (67 ± 11 vs. 96 ± 32 s), and faster overall kinetics of muscle deoxy-Hb (19.9 ± 2.4 vs. 16.5 ± 3.4 s). Consequently, the time constant ratio of O₂uptake to mean response time of deoxy-Hb concentration was significantly greater in patients, suggesting a slower kinetics of microvascular O₂delivery. In conclusion, our data show that patients with moderate-to-severe COPD have impaired central and peripheral cardiovascular adjustments following the onset of heavy-intensity exercise. These cardiocirculatory disturbances negatively impact the dynamic matching of O₂delivery and utilization and may contribute to the slower V̇o_2pkinetics compared with age-matched controls.

The inspiratory-to-total lung capacity ratio or “inspiratory fraction” (inspiratory capacity(IC)/total lung capacity (TLC)) may be functionally more representative than traditional indices of resting airflow limitation and lung hyperinflation in patients with chronic obstructive pulmonary disease (COPD).In the present retrospective study, a comparison was made of the individual performance of post-bronchodilator IC, IC/TLC and forced expiratory volume in one second (FEV₁) in predicting a severely reduced peak oxygen uptake (V′O₂; <60% predicted) in 44 COPD patients Global Initiative for Chronic Obstructive Lung Disease stages II-III (post-bronchodilator FEV₁ranging from 31–79% pred).Patients with lower IC/TLC values (≤0.28) showed increased lung volumes and reduced exercise capacity as compared with other subjects. Following a multiple linear regression analysis, only IC/TLC and FEV₁remained as independent predictors ofV′O₂(r² = 0.33). A receiver operating characteristic (ROC) curve analysis revealed that an IC/TLC ≤0.28 had the highest specificity (89.6%), positive predictive value (80%) and overall accuracy (86.3%) in identifying patients withV′O₂<60% pred. In addition, the area under the ROC curve tended to be higher for IC/TLC than IC.In conclusion, post-bronchodilator total lung capacity-corrected inspiratory fraction provides useful information in addition to forced expiratory volume in one second and inspiratory capacity, to estimate the likelihood of chronic obstructive pulmonary disease patients to present with severely reduced maximal exercise capacity.

Blood flow requirements of the respiratory muscles (RM) increase markedly during exercise in chronic heart failure (CHF). We reasoned that if the RM could subtract a fraction of the limited cardiac output (Q_T) from the peripheral muscles, RM unloading would improve locomotor muscle perfusion. Nine patients with CHF (left ventricle ejection fraction = 26 ± 7%) undertook constant-work rate tests (70-80% peak) receiving proportional assisted ventilation (PAV) or sham ventilation. Relative changes (Δ%) in deoxy-hemoglobyn, oxi-Hb ([O₂Hb]), tissue oxygenation index, and total Hb ([Hb_TOT], an index of local blood volume) in the vastus lateralis were measured by near infrared spectroscopy. In addition, Q_T was monitored by impedance cardiography and arterial O₂ saturation by pulse oximetry (SpO₂). There were significant improvements in exercise tolerance (Tlim) with PAV. Blood lactate, leg effort/Tlim and dyspnea/Tlim were lower with PAV compared with sham ventilation ( P < 0.05). There were no significant effects of RM unloading on systemic O₂ delivery as Q_T and SpO₂ at submaximal exercise and at Tlim did not differ between PAV and sham ventilation ( P > 0.05). Unloaded breathing, however, was related to enhanced leg muscle oxygenation and local blood volume compared with sham, i.e., higher Δ[O₂Hb]% and Δ[Hb_TOT]%, respectively ( P < 0.05). We conclude that RM unloading had beneficial effects on the oxygenation status and blood volume of the exercising muscles at similar systemic O₂ delivery in patients with advanced CHF. These data suggest that blood flow was redistributed from respiratory to locomotor muscles during unloaded breathing.