Dina Brooks

Obstructive sleep apnea as a cause of systemic hypertension. Evidence from a canine model.

Several epidemiological studies have identified obstructive sleep apnea (OSA) as a risk factor for systemic hypertension, but a direct etiologic link between the two disorders has not been established definitively. Furthermore, the specific physiological mechanisms underlying the association between OSA and systemic hypertension have not been identified. The purpose of this study was to systematically examine the effects of OSA on daytime and nighttime blood pressure (BP). We induced OSA in four dogs by intermittent airway occlusion during nocturnal sleep. Daytime and nighttime BP were measured before, during, and after a 1-3-mo long period of OSA. OSA resulted in acute transient increases in nighttime BP to a maximum of 13.0+/-2.0 mmHg (mean+/-SEM), and eventually produced sustained daytime hypertension to a maximum of 15.7+/-4.3 mmHg. In a subsequent protocol, recurrent arousal from sleep without airway occlusion did not result in daytime hypertension. The demonstration that OSA can lead to the development of sustained hypertension has considerable importance, given the high prevalence of both disorders in the population.

Evaluation of gait symmetry after stroke: a comparison of current methods and recommendations for standardization.

Symmetry is a gait characteristic that is increasingly measured and reported, particularly in the stroke patient population. However, there is no accepted standard for assessing symmetry making it difficult to compare across studies and establish criteria to guide clinical decision making. This study compares the most common expressions of spatiotemporal gait symmetry to describe post-stroke gait and makes recommendations regarding the most suitable measure for standardization. The following symmetry equations were compared: symmetry ratio, symmetry index, gait asymmetry and symmetry angle using step length, swing time, stance time, double support time and an intra-limb ratio of swing: stance time. Comparisons were made within a group of 161 community-dwelling, ambulatory individuals with stroke and 81 healthy adults as a reference group. Our analysis supports the recommendations of the symmetry ratio as the equation for standardization and step length, swing time and stance time as the gait parameters to be used in the equation. Future work should focus on establishing the intra-individual variability of these measures and linking them to mechanisms of gait dysfunction.

The effect of postrehabilitation programmes among individuals with chronic obstructive pulmonary disease

The purpose of this study was to examine the effects of two postrehabilitation programmes on functional exercise tolerance and health-related quality of life in patients with chronic obstructive pulmonary disease (COPD). Subjects with COPD (n=109) were randomised to receive either enhanced follow-up (EF) or conventional follow-up (CF). Subjects in the EF group attended a monthly support group and received a telephone call from a staff member at the midpoint (2 weeks) between their visits. Both groups had scheduled appointments with a physical therapist and physician at 3‐monthly intervals after discharge. Longitudinal data were recorded in 85 subjects (37 EF and 48 CF). Over the course of the study, there was no difference in distance walked in 6 min between the two groups but a significant difference for time and a group-time interaction. There was no difference in total chronic respiratory disease questionnaire score between groups at baseline or at any time interval despite a significant difference with time. There was a clear deterioration in functional exercise capacity and health-related quality of life after completion of respiratory rehabilitation but no difference between the groups.

Characterization of pulmonary rehabilitation programs in Canada in 2005

BACKGROUND Pulmonary rehabilitation (PR) is recognized as the prevailing standard of care for patients with chronic respiratory conditions. National surveys of PR programs provide important information regarding the structure, content and organization of these programs. OBJECTIVE To conduct a national survey to characterize adult PR across Canada, in terms of program distribution, utilization, content and outcome measures. METHODS A cross-sectional descriptive study in which questionnaires were mailed to PR programs connected with hospitals or identified through the Canadian Lung Association was performed. RESULTS Of the 98 PR programs identified, over 90% of patients in the programs had chronic obstructive pulmonary disease (COPD) and 57% of the programs were outpatient. Inpatient programs accounted for only 10% of the total. The main program components included supervised lower extremity strength (77%), cycle (72%) and treadmill (70%) training, education (75%) and breathing retraining (68%). Over 80% of patients completed their programs and 90% of patients were enrolled in a follow-up component. Physical therapists, dieticians, respiratory therapists and respirologists were the most commonly identified health care providers. The most commonly used outcome measures were the 6 min walk test and disease-specific quality of life questionnaires. CONCLUSION There were similarities in program format, content, staffing, follow-up and funding among Canadian PR programs. The marked shortfall between the national PR capacity and the prevalence of COPD meant that only 1.2% of the COPD population had access to PR.

Inspiratory muscle training in adults with chronic obstructive pulmonary disease: An update of a systematic review

The purpose was to update an original systematic review to determine the effect of inspiratory muscle training (IMT) on inspiratory muscle strength and endurance, exercise capacity, dyspnea and quality of life for adults with chronic obstructive pulmonary disease (COPD). The original MEDLINE and CINAHL search to August 2003 was updated to January 2007 and EMBASE was searched from inception to January 2007. Randomized controlled trials, published in English, with adults with stable COPD, comparing IMT to sham IMT or no intervention, low versus high intensity IMT, and different modes of IMT were included. Nineteen of 274 articles in the original search met the inclusion criteria. The updated search revealed 17 additional articles; 6 met the inclusion criteria, all of which compared targeted, threshold or normocapneic hyperventilation IMT to sham IMT. An update of the sub-group analysis comparing IMT versus sham IMT was performed with 10 studies from original review and 6 from the update. Sixteen meta-analyses are reported. Results demonstrated significant improvements in inspiratory muscle strength (PI(max), PI(max) % predicted, peak inspiratory flow rate), inspiratory muscle endurance (RMET, inspiratory threshold loading, MVV), exercise capacity (Ve(max), Borg Score for Respiratory Effort, 6MWT), Transitional Dyspnea Index (focal score, functional impairment, magnitude of task, magnitude of effort), and the Chronic Respiratory Disease Questionnaire (quality of life). Results suggest that targeted, threshold or normocapneic hyperventilation IMT significantly increases inspiratory muscle strength and endurance, improves outcomes of exercise capacity and one measure of quality of life, and decreases dyspnea for adults with stable COPD.

Cellular Markers of Muscle Atrophy in Chronic Obstructive Pulmonary Disease

Skeletal muscle atrophy in individuals with advanced chronic obstructive pulmonary disease (COPD) is associated with diminished quality of life, increased health resource use, and worsened survival. Muscle wasting results from an imbalance between protein degradation and synthesis, and is enhanced by decreased regenerative repair. We investigated the activation of cellular signaling networks known to mediate muscle atrophy and regulate muscle regenerative capacity in rodent models, in individuals with COPD (FEV(1) < 50% predicted). Nine patients with COPD and nine control individuals were studied. Quadriceps femoris muscle isometric contractile force and cross-sectional area were confirmed to be significantly smaller in the patients with COPD compared with control subjects. The vastus lateralis muscle was biopsied and muscle transcript and/or protein levels of key components of ubiquitin-mediated proteolytic systems (MuRF1, atrogin-1, Nedd4), inflammatory mediators (IkappaBalpha, NF-kappaBp65/p50), AKT network (AKT, GSK3beta, p70S6 kinase), mediators of autophagy (beclin-1, LC3), and myogenesis (myogenin, MyoD, Myf5, myostatin) were determined. Atrogin-1 and Nedd4, two ligases regulating ubiquitin-mediated protein degradation and myostatin, a negative regulator of muscle growth, were significantly increased in the muscle of patients with COPD. MuRF1, Myf5, myogenin, and MyoD were not differentially expressed. There were no differences in the level of phosphorylation of AKT, GSK3beta, p70S6kinase, or IkappaBalpha, activation of NF-kappaBp65 or NF-kappaBp50, or level of expression of beclin-1 or LC3, suggesting that AKT signaling was not down-regulated and the NF-kappaB inflammatory pathway and autophagy were not activated in the COPD muscle. We conclude that muscle atrophy associated with COPD results from the recruitment of specific regulators of ubiquitin-mediated proteolytic pathways and inhibition of muscle growth.

Effectiveness of Acute Geriatric Unit Care Using Acute Care for Elders Components: A Systematic Review and Meta-Analysis

To compare the effectiveness of acute geriatric unit care, based on all or part of the Acute Care for Elders (ACE) model and introduced in the acute phase of illness or injury, with that of usual care.

Interval versus continuous training in individuals with chronic obstructive pulmonary disease--a systematic review.

Background In patients with chronic obstructive pulmonary disease (COPD), interval exercise has gained recent attention as a possible means of achieving greater physiological training effects compared with continuous exercise. The primary aim of this systematic review was to compare the effects of interval versus continuous training on peak oxygen uptake, peak power, 6 minute walk test (6MWT) distance and health-related quality of life in individuals with COPD. Methods Randomised controlled trials comparing the effects of interval versus continuous training in patients with COPD were identified after searches of six databases and reference lists of appropriate studies in May 2009. Two reviewers independently assessed study quality. Weighted mean differences (WMD) with 95% CIs were calculated using a random effects model for measures of exercise capacity and health-related quality of life. Results: Eight randomised controlled trials, with a total of 388 patients with COPD, met the inclusion criteria. No significant differences were found for peak power (WMD 1 W, 95% CI −1 to 3) or peak oxygen uptake (WMD −0.04 l/min, 95% CI −0.13 to 0.05) between interval and continuous training. The WMD for the Chronic Respiratory Questionnaire dyspnoea score was −0.2 units (95% CI −0.5 to 0.0). There was no difference in 6MWT distance between groups (WMD 4 m, 95% CI −15 to 23). Conclusions Interval and continuous training modalities did not differ in their effect on measures of exercise capacity or health-related quality of life. Interval training may be considered as an alternative to continuous training in patients with varying degrees of COPD severity.

Measurement properties of the SenseWear armband in adults with chronic obstructive pulmonary disease

Rationale The SenseWear armband (SAB) is designed to measure energy expenditure (EE). In people with chronic obstructive pulmonary disease (COPD), EE estimated using the SAB (EESAB) is a popular outcome measure. However, a detailed analysis of the measurement properties of the SAB in COPD is lacking. Objective To examine the sensitivity of EESAB, agreement between EESAB and EE measured via indirect calorimetry (EEIC), and its repeatability in COPD. Methods 26 people with COPD (forced expiratory volume in 1 s (FEV1)=49±18% predicted; 15 males) spent 6 min in five standardised tasks that comprised supine, sitting, standing and two walking speeds. A subgroup (n=12) walked using a rollator. Throughout each task, measurements of EESAB and EEIC were collected. The protocol was repeated on a second day. Results EESAB increased between standing and slow walking (2.4, metabolic equivalents (METs) 95% CI 2.2 to 2.7) as well as slow and fast walking (0.5 METs, 95% CI 0.3 to 0.7). Considering all tasks together, the difference between EESAB and EEIC was −0.2 METs (p=0.21) with a limit of agreement of 1.3 METs. The difference between days in EESAB was 0.0 METs with a coefficient of repeatability of 0.4 METs. Rollator use increased the variability in EESAB, compromising its repeatability and agreement with EEIC. Conclusions EESAB was sensitive to small but important changes. There was fair agreement between EESAB and EEIC, and measurements of EESAB were repeatable. These observations suggest that the SAB is useful for the evaluation of EE in patients with COPD who walk without a rollator.

Impairments in balance discriminate fallers from non-fallers in COPD

BACKGROUND Preliminary evidence suggests individuals with COPD exhibit deficits in balance. Further investigation of balance and risk of falls is warranted in these patients. The objective of this study was to determine the clinical measures that discriminate fallers from non-fallers among patients with COPD. METHODS A cross-sectional study design was used. Subjects>60 years with COPD attended a single assessment session. A one-year incidence of falls was collected via self-report questionnaire. Risk of falls and balance were determined using the Berg Balance Scale (BBS), Timed Up and Go Test (TUG) and the Activity-Specific Balance Confidence (ABC) Scale. Exercise tolerance was determined from the Six-Minute Walk Test and functional limitation attributable to dyspnea from the Medical Research Council (MRC) dyspnea scale. RESULTS Of the 39 COPD subjects (FEV(1)=41.5+/-17.0% predicted; age: 71.1+/-6.8 years) who completed the study, 46% (n=18) reported at least one fall in the preceding year. Significant differences between fallers and non-fallers were found for the ABC (65.8+/-18.2 vs. 81.7+/-11.1; p=0.002), TUG (17.0+/-4.9 vs. 14.0+/-3.1s; p=0.024), BBS (45.2+/-5.4 vs. 48.8+/-5.0; p=0.042), use of supplemental oxygen (72% vs. 24%; p=0.002), and MRC dyspnea scale (median 4, range 3 vs. median 3, range 4; p=0.046). CONCLUSIONS Patients with COPD fall frequently. Standard clinical balance measures discriminate self-reported fallers from non-fallers. These observations draw attention to an important secondary impairment in COPD.