Noninvasive Home Mechanical Ventilation for Stable Hypercapnic COPD: A Clinical Respiratory Review from Canadian Perspectives.

Acute short-term noninvasive ventilation (NIV) for hypercapnic respiratory failure in chronic obstructive pulmonary disease (COPD) has well-established benefits; however, the role of long-term home NIV remains controversial. In the past decade, studies utilizing aggressive NIV settings to maximally reduce carbon dioxide levels (PaCO2) have resulted in several positive clinical trials and led to updated guidelines on home NIV for stable hypercapnic COPD patients. This clinical respiratory review discusses the high-intensity NIV approach, summarizes recent key trials and guidelines pertaining to home NIV in COPD, and considers key clinical questions for future research and application in the Canadian context. With recent evidence and Canadian Thoracic Society (CTS) guidelines supporting the use of NIV in carefully selected COPD patients with persistent daytime hypercapnia, we believe it is time to reconsider our approach.

Factors Associated with Attrition in a Longitudinal Cohort of Older Adults in the Community.

Introduction: Retaining participants in longitudinal studies increases their power. We undertook this study in a population-based longitudinal cohort of adults with COPD to determine the factors associated with increased cohort attrition. Methods: In the longitudinal population-based Canadian Cohort of Obstructive Lung Disease (CanCOLD) study, 1561 adults > 40 years old were randomly recruited from 9 urban sites. Participants completed in-person visits at 18-month intervals and also were followed up every 3 months over the phone or by email. The cohort retention for the study and the reasons for attrition were analyzed. Hazard ratios and robust standard errors were calculated using Cox regression methods to explore the associations between participants who remained in the study and those who did not. Results: The median follow-up (years) of the study is 9.0 years. The overall mean retention was 77%. Reasons for attrition (23%) were: dropout by participant (39%), loss of contact (27%), investigator-initiated withdrawal (15%), deaths (9%), serious disease (9%), and relocation (2%). Factors independently associated with attrition were lower educational attainment, higher pack-year tobacco consumption, diagnosed cardiovascular disease, and a higher Hospital Anxiety and Depression Scale score: adjusted hazard ratios (95% confidence interval) were 1.43(1.11, 1.85); 1.01(1.00, 1.01); 1.44(1.13, 1.83); 1.06(1.02, 1.10) respectively. Conclusions: Identification and awareness of risk factors for attrition could direct targeted retention strategies in longitudinal studies. Moreover, the identification of patient characteristics associated with study dropout could address any potential bias introduced by differential dropouts.

The experience of family caregivers of ventilator-assisted individuals who participated in a pilot web-based peer support program: A qualitative study.

Introduction: Family caregivers play an important role supporting the day-to-day needs of ventilator-assisted individuals (VAIs) living at home. Peer-to-peer communication can help support these caregivers and help them sustain caregiving in the community. Online peer-support has been suggested as a way to help meet caregivers' support needs. Methods: A qualitative descriptive approach was used to elicit the perspectives of support received from caregivers who participated in a pilot web-based peer support program from October to December 2018. Data were collected through the transcripts of weekly online peer-to-peer group chats. Data were analyzed using an integration of thematic and framework analysis. Results: In total, eight caregivers and five peer mentors participated in the pilot. All five mentors and four of the caregivers participated in the weekly chats. We identified three themes, a) The experience of caregivers is characterized by unique challenges related to the complexity of VAI care including technology; b) Mentors and caregiver participants reciprocally share support; c) Despite hardships, there are things that make caregiving easier and joyful. Discussion: Our results add to the growing body of evidence pointing to the importance of online communities for supporting vulnerable caregivers. The reciprocal element of peer support, where trained mentors and untrained participants both benefit from support, can help sustain peer-support interventions. Despite the challenges of providing care to a VAI, there are facilitators that may help ease the caregiving experience and caregivers can benefit from ongoing support that is tailored to their needs along the caregiving trajectory.

Diaphragm pacing in spinal cord injury can significantly decrease mechanical ventilation in multicenter prospective evaluation.

BACKGROUND: Cervical spinal cord injury (SCI) can lead to dependence on mechanical ventilation (MV) with significant morbidity and mortality. The diaphragm pacing system (DPS) was developed as an alternative to MV. METHODS: We conducted a prospective single-arm study of DPS in MV-dependent patients with high SCI and intact phrenic nerves. Following device acclimation, pacing effectiveness to provide ventilation was evaluated. The primary endpoint was the number who could use DPS to breathe for 4 continuous hours without MV. Secondary endpoints included the number of patients that could use DPS 24 h/day free of MV and the ability of DPS to maintain clinically acceptable tidal volume (Vt). In addition, we conducted a meta-analysis that included the prospective study along with data from four recently published studies to evaluate DPS hourly use. RESULTS: Fifty-three patients were implanted in the prospective study. Most were male (77.4%) with a median time from injury to treatment of 28.3 (IQR: 12.1, 83.3) months. Four- and 24-h use occurred in 96.2% (95% CI: 87.0%, 99.5%) and 58.5% (95% CI: 44.1%, 74.9%), respectively. Four and 24-h results in the meta-analysis cohort (n = 196) exhibited similar results 92.2% (95% CI: 82.6%, 96.7%) and 52.7% (95% CI: 36.2%, 68.6%) using DPS for 4 and 24 h, respectively. DPS use significantly exceeded the calculated basal tidal volume requirements by a mean of 48.4% (95% CI: 37.0, 59.9%; p < 0.001). CONCLUSIONS: This study demonstrates that in most ventilator-dependent patients, diaphragm pacing can effectively supplement or completely replace the need for MV and support basal metabolic requirements.

Incorporating remote patient monitoring in virtual pulmonary rehabilitation programs.

Most pulmonary rehabilitation (PR) programs have had to adapt due to the COVID-19 pandemic and associated restrictions. Current alternative home-based programs have limitations and require modification. In this paper, we outline a novel method to monitor home-based PR programs, which has the potential to improve PR safety and efficacy. This new method is based on a remote patient monitoring (RPM) system with connected smart devices that enables the Respiratory Therapist (RT) to have real-time access to patient data including heart rate and peripheral oxygen saturation during exercise. The RPM system also monitors daily physical activity, sedentary time, sleep quality, rescue inhaler use, and maintenance inhaler adherence, among other variables, which has the added advantage of predicting patterns consistent with symptoms that may require medical intervention. To increase privacy, data are anonymized at all levels and only the RT has access to patient information. RPM systems have the potential to give practitioners a holistic view of the participants' health status to better evaluate them during the entire PR program and to improve self-management. As this is not a formal research study, we cannot make definitive conclusions about the efficacy of the system, and further research is needed to examine safety and to compare our approach to other ways of conducting PR.

The Prevalence of Chronic Obstructive Pulmonary Disease (COPD) and the Heterogeneity of Risk Factors in the Canadian Population: Results from the Canadian Obstructive Lung Disease (COLD) Study.

PURPOSE: To determine the spirometric-based prevalence of COPD across different regions in Canada and to evaluate the site heterogeneity of risk factors. PATIENTS AND METHODS: In this cross-sectional, population-based study, random samples of non-institutionalized adults aged ≥40 years were generated by random digit dialling. Participants answered an interviewer-administered questionnaire and performed spirometry before and after bronchodilator administration. COPD was defined as post-bronchodilator FEV1/FVC <0.70 (fixed ratio, FR) and as FEV1/FVC <5th percentile (lower limits of normal, LLN). Separate logistic regression models were used to compute the risk (adjusted odds ratio, aOR) for COPD. I2 and Tau2 analyses were used to evaluate heterogeneity. RESULTS: Out of 5176 (95%) participants, 4893 (47% male with mean age 56.6 years (95% confidence interval, 56.0-57.2)) had spirometry that satisfied ATS criteria. The population prevalence of COPD was 16.2% (95% CI, 14.5-17.8) by FR and 11.2% (95% CI, 9.7-12.6) by LLN. Male predominance in prevalence was shown by FR but not by LLN criteria. Patient characteristics associated with an increased risk of COPD included: age (OR 1.56; 95% CI 1.33-1.84); history of physician-diagnosed asthma (OR 3.30; 95% CI 2.42-4.49); and childhood hospitalization for respiratory illness (OR 1.81; 95% CI 1.17-2.80). In terms of smoking-related risk factors, current smoking status had the highest odds ratio (OR 3.49; 95% CI 2.55-4.80). Variance in prevalence among sites was significantly reduced by adjusting for risk factors in Tau2 analyses. Higher odds of exposure for each risk factor was found in more severe COPD, suggesting that a higher risk could be linked to the development of severe disease. CONCLUSION: This study reports the population prevalence of COPD in nine urban cities which collectively represent the majority of the Canadian population and demonstrates that heterogeneity in prevalence among sites is substantially explained by variation in associated risk factors for COPD.

Evaluation of the Vibe Actigraph in Patients With Chronic Obstructive Pulmonary Disease: A Pilot Study.

STUDY OBJECTIVE: To validate the Vibe actigraph in assessing sleep-wake patterns compared to polysomnography (PSG) in patients with COPD. METHODS: Nine stable COPD patients wore actigraphs while undergoing PSG. The correlation between total sleep time (TST), total sleep period (TSP), sleep onset latency (SOL), wake after sleep onset (WASO), and sleep efficiency was determined for corresponding measurements from the actigraph and PSG. Sensitivity, specificity, and positive and negative predictive values were calculated for the actigraph, considering PSG the gold standard. Levels of agreement between the variables of PSG and the actigraph were estimated using Bland-Altman plots. RESULTS: A strong and statistically significant correlation was noted between PSG and the actigraph in detecting movement during sleep [mean activity score (counts)], TST and TSP (all rs = 0.83; p = 0.005). The median agreement of sleep and wake counts between PSG and the actigraph was 73% and the Cohen's Kappa value was 0.66. The medians of sensitivity and specificity of the actigraph for detecting sleep versus PSG were 84 and 66%, respectively. The median positive and negative predictive values of the actigraph were 74 and 72%, respectively. CONCLUSIONS: This study demonstrated that, under controlled laboratory conditions, the Vibe actigraph in its default settings is a promising tool for the detection of sleep-wake parameters in a small number of ambulatory patients with COPD. Clinical Impact: The actigraph used in this pilot study suggests that these devices could provide clinically relevant information in COPD to better understand the relationship between sleep and health in this population.

Scalene and sternocleidomastoid activation during normoxic and hypoxic incremental inspiratory loading.

The purpose of this study was to examine scalene (SA) and sternocleidomastoid (SM) activation during normoxic (norm-ITL; FIO2  = 21%) and hypoxic (hyp-ITL; FIO2  = 15%) incremental inspiratory threshold loading (ITL). Thirteen healthy participants (33 ± 4 years, 9 female) performed two ITL tests breathing randomly assigned gas mixtures through an inspiratory loading device where the load was increased every two minutes until task failure. SA and SM root mean square (RMS) electromyography (EMG) were calculated and expressed as a percentage of maximum (RMS%max ) to reflect muscle activation intensity. Myoelectric manifestations of fatigue were characterized as decreased SA or SM EMG median frequency during maximum inspiratory pressure maneuvers before and after ITL. Dyspnea was recorded at baseline and task failure. Ventilatory parameters and mouth pressure (Pm) were recorded throughout the ITL. SA,RMS%max and SM,RMS%max increased in association with ITL load (p ≤ .01 for both). SA,RMS%max was similar between norm-ITL and hyp-ITL (p = .17), whereas SM,RMS%max was greater during the latter (p = .001). Neither SA nor SM had a decrease in EMG median frequency after ITL (p = .75 and 0.69 respectively). Pm increased in association with ITL load (p < .001) and tended to be higher during hyp-ITL compared to norm-ITL (p = .05). Dyspnea was similar during both conditions (p > .05). There was a trend for higher tidal volumes during hyp-ITL compared to norm-ITL (p = .10). Minute ventilation was similar between both conditions (p = .23). RMS,%max of the SA and SM increased linearly with increasing ITL. The presence of hypoxia only increased SM activation. Neither SA nor SM presented myoelectric manifestations of fatigue during both conditions.

The effects of marijuana smoking on lung function in older people.

BACKGROUND: Previous studies have associated marijuana exposure with increased respiratory symptoms and chronic bronchitis among long-term cannabis smokers. The long-term effects of smoked marijuana on lung function remain unclear. METHODS: We determined the association of marijuana smoking with the risk of spirometrically defined chronic obstructive pulmonary disease (COPD) (post-bronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity ratio <0.7) in 5291 population-based individuals and the rate of decline in FEV1 in a subset of 1285 males and females, aged ≥40 years, who self-reported use (or non-use) of marijuana and tobacco cigarettes and performed spirometry before and after inhaled bronchodilator on multiple occasions. Analysis for the decline in FEV1 was performed using random mixed effects regression models adjusted for age, sex and body mass index. Heavy tobacco smoking and marijunana smoking was defined as >20 pack-years and >20 joint-years, respectively. RESULTS: ∼20% of participants had been or were current marijuana smokers with most having smoked tobacco cigarettes in addition (83%). Among heavy marijuana users, the risk of COPD was significantly increased (adjusted OR 2.45, 95% CI 1.55-3.88). Compared to never-smokers of marijuana and tobacco, heavy marijuana smokers and heavy tobacco smokers experienced a faster decline in FEV1 by 29.5 mL·year-1 (p=0.0007) and 21.1 mL·year-1 (p<0.0001), respectively. Those who smoked both substances experienced a decline of 32.31 mL·year-1 (p<0.0001). INTERPRETATION: Heavy marijuana smoking increases the risk of COPD and accelerates FEV1 decline in concomitant tobacco smokers beyond that observed with tobacco alone.

Impaired Sleep Quality in COPD Is Associated With Exacerbations: The CanCOLD Cohort Study.

BACKGROUND: COPD increases susceptibility to sleep disturbances, which may in turn predispose to increased respiratory symptoms. The objective of this study was to evaluate, in a population-based sample, the relationship between subjective sleep quality and risk of COPD exacerbations. METHODS: Data were obtained from the Canadian Cohort Obstructive Lung Disease (CanCOLD) study. Participants with COPD who had completed 18 months of follow-up were included. Sleep quality was measured with the Pittsburgh Sleep Quality Index (PSQI) and a three-factor analysis. Symptom-based (dyspnea or sputum change ≥ 48 h) and event-based (symptoms plus medication or unscheduled health services use) exacerbations were assessed. Association of PSQI with exacerbation rate was assessed by using negative binomial regression. Exacerbation-free survival was also assessed. RESULTS: A total of 480 participants with COPD were studied, including 185 with one or more exacerbations during follow-up and 203 with poor baseline sleep quality (PSQI score > 5). Participants with subsequent symptom-based exacerbations had higher median baseline PSQI scores than those without (6.0 [interquartile range, 3.0-8.0] vs 5.0 [interquartile range, 2.0-7.0]; P = .01), and they were more likely to have baseline PSQI scores > 5 (50.3% vs 37.3%; P = .01). Higher PSQI scores were associated with increased symptom-based exacerbation risk (adjusted rate ratio, 1.09; 95% CI, 1.01-1.18; P = .02) and event-based exacerbation risk (adjusted rate ratio, 1.10; 95% CI, 1.00-1.21; P = .048). The association occurred mainly in those with undiagnosed COPD. Strongest associations were with Factor 3 (sleep disturbances and daytime dysfunction). Time to symptom-based exacerbation was shorter in participants with poor sleep quality (adjusted hazard ratio, 1.49; 95% CI, 1.09-2.03). CONCLUSIONS: Higher baseline PSQI scores were associated with increased risk of COPD exacerbation over 18 months' prospective follow-up.

Development of a Web-Based Peer Support Program for Family Caregivers of Ventilator-Assisted Individuals Living in the Community: Protocol for a Pilot Randomized Controlled Trial.

BACKGROUND: Across Europe, Canada, Australia, and the United States, the prevalence of home mechanical ventilation (HMV) prevalence is 6.6-12.9 per 100,000. At-home ventilator-assisted individuals (VAIs) are often vulnerable and highly comorbid, requiring complex care. In Canada, most VAI care is provided by family, leading to poor health-related quality of life and increased caregiver burden. No supportive interventions or peer support programs are tailored to VAI caregivers. Owing to the financial, geographic, and time limitations, Web-based support delivery may especially meet VAI family caregiver needs. We have developed a peer mentor training and Web-based peer support program for VAI caregivers including information-sharing, peer-to-peer communication, and peer mentorship. OBJECTIVE: Study Stage 1 aims to (1) evaluate the face and content validity of the peer mentor training program and (2) investigate participant satisfaction. Study Stage 2 aims to evaluate (1) the feasibility of participant recruitment and Web-based program delivery; (2) acceptability, usability, and satisfactoriness; (3) experiences of caregivers and peer mentors with the Web-based peer support program; and (4) effect of the Web-based peer support program on caregiver health outcomes. METHODS: Study Stage 1: We will train 7 caregivers to act as peer mentors for the Web-based peer support program trial; they will complete questionnaires rating the utility of individual training sessions and the training program overall. Study Stage 2: We will recruit 30 caregiver peers for a pilot randomized controlled trial of the 12-week Web-based peer support program using a waitlist control; the program includes private chat, a public discussion forum, and weekly moderated chats. Caregiver peers will be randomized to the intervention or waitlist control group using a 1:1 ratio using Randomize.net. Both groups will complete pre- and postintervention health outcome questionnaires (ie, caregiving impact, mastery, coping, personal gain, positive affect, and depression). Caregiver peers in the intervention arm will only complete a program evaluation and will be invited to participate in an interview to provide insight into their experience. Peer mentors will be invited to participate in a Web-based focus group to provide insight into their experience as mentors. We will judge the feasibility per the number of recruitment and program delivery goals met, use analysis of covariance to compare health outcomes between intervention and control groups, and analyze qualitative data thematically. RESULTS: Peer mentor training was completed with 5 caregivers in July 2018. To date, 2 caregivers have beta-tested the website, and the Web-based peer support program trial will commence in September 2018. Results are expected by early 2019. CONCLUSIONS: This study will result in the production and initial evaluation of a rigorously developed, evidence- and stakeholder-informed Web-based peer training and peer support program for caregivers of VAIs residing at home. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/11827.

Manipulation of mechanical ventilatory constraint during moderate intensity exercise does not influence dyspnoea in healthy older men and women.

KEY POINTS: The perceived intensity of exertional breathlessness (i.e. dyspnoea) is higher in older women than in older men, possibly as a result of sex-differences in respiratory system morphology. During exercise at a given absolute intensity or minute ventilation, older women have a greater degree of mechanical ventilatory constraint (i.e. work of breathing and expiratory flow limitation) than their male counterparts, which may lead to a greater perceived intensity of dyspnoea. Using a single-blind randomized study design, we experimentally manipulated the magnitude of mechanical ventilatory constraint during moderate-intensity exercise at ventilatory threshold in healthy older men and women. We found that changes in the magnitude of mechanical ventilatory constraint within the physiological range had no effect on dyspnoea in healthy older adults. When older men and women perform moderate intensity exercise, mechanical ventilatory constraint does not contribute significantly to the sensation of dyspnoea. ABSTRACT: We aimed to determine the effect of manipulating mechanical ventilatory constraint during submaximal exercise on dyspnoea in older men and women. Eighteen healthy subjects (aged 60-80 years; nine men and nine women) completed two days of testing. On day 1, subjects were assessed for pulmonary function and performed a maximal incremental cycle exercise test. On day 2, subjects performed three 6-min bouts of cycling at ventilatory threshold, in a single-blind randomized manner, while breathing: (i) normoxic helium-oxygen (HEL) to reduce the work of breathing (Wb ) and alleviate expiratory flow limitation (EFL); (ii) through an inspiratory resistance (RES) of ∼5 cmH2 O L-1  s-1 to increase Wb ; and (iii) ambient air as a control (CON). Oesophageal pressure, diaphragm electromyography, and sensory responses (category-ratio 10 Borg scale) were monitored throughout exercise. During the HEL condition, there was a significant decrease in Wb (men: -21 ± 6%, women: -17 ± 10%) relative to CON (both P < 0.01). Moreover, if EFL was present during CON (four men and five women), it was alleviated during HEL. Conversely, during the RES condition, Wb (men: 42 ± 19%, women: 50 ± 16%) significantly increased relative to CON (both P < 0.01). There was no main effect of sex on Wb (P = 0.59). Across conditions, women reported significantly higher dyspnoea intensity than men (2.9 ± 0.9 vs. 1.9 ± 0.8 Borg scale units, P < 0.05). Despite significant differences in the degree of mechanical ventilatory constraint between conditions, the intensity of dyspnoea was unaffected, independent of sex (P = 0.46). When older men and women perform moderate intensity exercise, mechanical ventilatory constraint does not contribute significantly to the sensation of dyspnoea.

Monitoring Cough Effectiveness and Use of Airway Clearance Strategies: A Canadian and UK Survey.

BACKGROUND: Regular monitoring combined with early and appropriate use of airway clearance can reduce unplanned hospital admissions for patients with neuromuscular disease (NMD) and spinal cord injury (SCI). We aimed to describe and compare knowledge of guidelines, monitoring of cough effectiveness, clinician prescription/provision of airway clearance strategies, and service provision constraints in the United Kingdom and Canada. METHODS: This was a cross-sectional survey of clinicians affiliated with NMD and SCI clinics in Canada, 2016 attendees at the Home Mechanical Ventilation Conference in the United Kingdom, and United Kingdom physiotherapist networks. RESULTS: We received 155 surveys (92 from Canada; 63 from the United Kingdom). More UK respondents (76%) were aware of airway clearance guidelines than Canadian (56%) respondents (P = .02). Routine assessment of cough effectiveness was reported by more UK respondents (59%) than Canadian (42%) respondents (P = .044). Cough peak flow (CPF) was the most common method used in both countries, although it was more commonly used in the UK (96%) than in Canada (81%, P = .02). Fewer Canadian respondents reported using CPF before initiation of airway clearance (81% vs 94%, P = .046), and fewer Canadian respondents showed results to patients for technique feedback (76% vs 97%, P = .007). Similar participant numbers reported using CPF after initiation to ensure adequate technique (73% vs 72%, P = .92). Mechanical insufflation-exsufflation (MI-E) + lung volume recruitment (LVR) + manually assisted cough when CPF ≤ 270 L/min was most routinely recommended (41% overall). Monotherapy was infrequent (LVR 15%, manually assisted cough 7%, and MI-E 4%). More Canadians identified constraints on service provision, specifically insufficient public funding for equipment (68% vs 39%, P = .002) and inadequate community workers' knowledge (56% vs 34%, P = .002). Funding for community support was a common constraint in both countries (49% vs 42%). CONCLUSIONS: The somewhat variable cough effectiveness monitoring and airway clearance practices identified in this survey confirm the need for further work on knowledge translation related to guideline recommendations and the need to address common constraints to optimal service delivery.

Effects of Age and Sex on Inspiratory Muscle Activation Patterns during Exercise.

PURPOSE: To characterize the effects of age, sex, and their interaction on inspiratory muscle activation patterns during exercise. METHODS: Twenty younger (20-30 yr, n = 10 women) and 20 older (60-80 yr, n = 10 women) subjects performed an incremental cycle exercise test. Electromyography (EMG) of the scalene (EMGsca) and EMG of the sternocleidomastoid (EMGscm) muscles were measured using skin surface electrodes, whereas diaphragm EMG (EMGdi) and esophageal and transdiaphragmatic pressures were measured using an esophageal catheter. Electromyography data were transformed into root mean square with a 100-ms time constant. Esophageal and diaphragmatic pressure-time products were used as indices of total inspiratory muscle pressure production and diaphragmatic pressure production, respectively. RESULTS: At absolute minute ventilations (V˙E), women and older subjects had greater EMGdi than men and younger subjects, respectively (all P < 0.05), but no differences were noted when V˙E was expressed in relative terms (all P > 0.05). Women had greater EMGsca activity than men at absolute and relative levels of V˙E (all P < 0.05). Older subjects had greater EMGsca than younger subjects when V˙E was expressed in relative (all P < 0.05) but not absolute terms (all P > 0.05). At absolute and relative levels of V˙E, women and older subjects had greater EMGscm than men and younger subjects, respectively (all P < 0.05). Women and older subjects had a greater esophageal and diaphragmatic pressure-time products at a V˙E of 70 L·min than men and younger subjects, respectively (both P < 0.05), but no differences were noted when V˙E was expressed in relative terms (all P > 0.05). No significant interactions between age and sex were noted (all P > 0.05). CONCLUSIONS: Age and sex significantly affect inspiratory muscle activation patterns during exercise; however, the extent of the effects depends on whether comparisons are made at absolute or relative V˙E.

The effects of age and sex on mechanical ventilatory constraint and dyspnea during exercise in healthy humans.

We examined the effects of age, sex, and their interaction on mechanical ventilatory constraint and dyspnea during exercise in 22 older (age = 68 ± 1 yr; n = 12 women) and 22 younger (age = 25 ± 1 y, n = 11 women) subjects. During submaximal exercise, older subjects had higher end-inspiratory (EILV) and end-expiratory (EELV) lung volumes than younger subjects (both P < 0.05). During maximal exercise, older subjects had similar EILV ( P > 0.05) but higher EELV than younger subjects ( P < 0.05). No sex differences in EILV or EELV were observed. We noted that women had a higher work of breathing (Wb) for a given minute ventilation (V̇e) ≥65 l/min than men ( P < 0.05) and older subjects had a higher Wb for a given V̇e ≥60 l/min ( P < 0.05). No sex or age differences in Wb were present at any submaximal relative V̇e. At absolute exercise intensities, older women experienced expiratory flow limitation (EFL) more frequently than older men ( P < 0.05), and older subjects were more likely to experience EFL than younger subjects ( P < 0.05). At relative exercise intensities, women and older individuals experienced EFL more frequently than men and younger individuals, respectively (both P < 0.05). There were significant effects of age, sex, and their interaction on dyspnea intensity during exercise at absolute, but not relative, intensities (all P < 0.05). Across subjects, dyspnea at 80 W was significantly correlated with indexes of mechanical ventilatory constraint (all P < 0.05). Collectively, our findings suggest age and sex have significant impacts on Wb, operating lung volumes, EFL, and dyspnea during exercise. Moreover, it appears that mechanical ventilatory constraint may partially explain sex differences in exertional dyspnea in older individuals. NEW & NOTEWORTHY We found that age and sex have a significant effect on mechanical ventilatory constraint and the perception of dyspnea during exercise. We also observed that the perception of exertional dyspnea is associated with indexes of mechanical ventilatory constraint. Collectively, our results suggest that the combined influences of age and biological sex on mechanical ventilatory constraint during exercise contributes, in part, to the increased perception of dyspnea during exercise in older women.

Healthcare utilisation and costs of home mechanical ventilation.

BACKGROUND: Individuals using home mechanical ventilation (HMV) frequently choose to live at home for quality of life, despite financial burden. Previous studies of healthcare utilisation and costs do not consider public and private expenditures, including caregiver time. OBJECTIVES: To determine public and private healthcare utilisation and costs for HMV users living at home in two Canadian provinces, and examine factors associated with higher costs. METHODS: Longitudinal, prospective observational cost analysis study (April 2012 to August 2015) collecting data on public and private (out-of-pocket, third-party insurance, caregiving) costs every 2 weeks for 6 months using the Ambulatory and Home Care Record. Functional Independence Measure (FIM) was used at baseline and study completion. Regression models examined variables associated with total monthly costs selected a priori using Andersen and Newman's framework for healthcare utilisation, relevant literature, and clinical expertise. Data are reported in 2015 Canadian dollars ($C1=US$0.78=£0.51=€0.71). RESULTS: We enrolled 134 HMV users; 95 with family caregivers. Overall median (IQR) monthly healthcare cost was $5275 ($2291-$10 181) with $2410 (58%) publicly funded; $1609 (39%) family caregiving; and $141 (3%) out-of-pocket (<1% third-party insurance). Median healthcare costs were $8733 ($5868-$15 274) for those invasively ventilated and $3925 ($1212-$7390) for non-invasive ventilation. Variables associated with highest monthly costs were amyotrophic lateral sclerosis (1.88, 95% CI 1.09 to 3.26, P<0.03) and lower FIM quintiles (higher dependency) (up to 6.98, 95% CI 3.88 to 12.55, P<0.0001) adjusting for age, sex, tracheostomy and ventilation duration. CONCLUSIONS: For HMV users, most healthcare costs were publicly supported or associated with family caregiving. Highest costs were incurred by the most dependent users. Understanding healthcare costs for HMV users will inform policy decisions to optimise resource allocation, helping individuals live at home while minimising caregiver burden.

A Comparison of Pain, Fatigue, Dyspnea and their Impact on Quality of Life in Pulmonary Rehabilitation Participants with Chronic Obstructive Pulmonary Disease.

In addition to dyspnea and fatigue, pain is a prevalent symptom in chronic obstructive pulmonary disease (COPD). Understanding the relative prevalence, magnitude, and interference with aspects of daily living of these symptoms can improve COPD management. Therefore, the purposes of this study were to: (1) compare the prevalence and magnitude of dyspnea, fatigue, and pain and how each limits aspects of daily living; (2) determine the association between pain and the other two symptoms; and (3) assess the impact of these symptoms on quality of life in COPD. Participants were recruited from pulmonary rehabilitation programs. Pain, dyspnea, and fatigue were measured using the Brief Pain Inventory (BPI), Brief Fatigue Inventory (BFI), and Dyspnea Inventory (DI), respectively. Quality of life was measured using the Clinical COPD Questionnaire (CCQ). The prevalence of dyspnea, fatigue, and pain were 93%, 77%, and 74%, respectively. Individuals with COPD reported similar severity scores of the three symptoms. Dyspnea interfered with general activity more than pain (F1.7,79.9 = 3.1, p < 0.05), whilst pain interfered with mood (F1.8, 82.7 = 3.6, p < 0.05) and sleep (F1,46 = 7.4, p < 0.01) more than dyspnea and fatigue. These three symptoms were moderately-to-highly correlated with each other (ρ = 0.49-0.78, p < 0.01) and all individually impacted quality of life. In summary, pain is a common symptom in addition to dyspnea and fatigue in COPD; all three interfere similarly among aspects of daily living with some exceptions. Accordingly, management of COPD should include a multifaceted approach that addresses pain as well as dyspnea and fatigue.

Framing of mobility items: a source of poor agreement between preference-based health-related quality of life instruments in a population of individuals receiving assisted ventilation.

PURPOSE: To explore the influence of descriptive differences in items evaluating mobility on index scores generated from two generic preference-based health-related quality of life (HRQoL) instruments. METHODS: The study examined cross-sectional data from a postal survey of individuals receiving assisted ventilation in two state/province-wide home mechanical ventilation services, one in British Columbia, Canada and the other in Victoria, Australia. The Assessment of Quality of Life 8-dimension (AQoL-8D) and the EQ-5D-5L were included in the data collection. Graphical illustrations, descriptive statistics, and measures of agreement [intraclass correlation coefficients (ICCs) and Bland-Altman plots] were examined using index scores derived from both instruments. Analyses were performed on the full sample as well as subgroups defined according to respondents' self-reported ability to walk. RESULTS: Of 868 individuals receiving assisted ventilation, 481 (55.4%) completed the questionnaire. Mean index scores were 0.581 (AQoL-8D) and 0.566 (EQ-5D-5L) with 'moderate' agreement demonstrated between the two instruments (ICC = 0.642). One hundred fifty-nine (33.1%) reported level 5 ('I am unable to walk about') on the EQ-5D-5L Mobility item. The walking status of respondents had a marked influence on the comparability of index scores, with a larger mean difference (0.206) and 'slight' agreement (ICC = 0.386) observed when the non-ambulant subgroup was evaluated separately. CONCLUSIONS: This study provides further evidence that between-measure discrepancies between preference-based HRQoL instruments are related in part to the framing of mobility-related items. Longitudinal studies are necessary to determine the responsiveness of preference-based HRQoL instruments in cohorts that include non-ambulant individuals.

Lung volume recruitment acutely increases respiratory system compliance in individuals with severe respiratory muscle weakness.

The aim of the present study was to determine whether lung volume recruitment (LVR) acutely increases respiratory system compliance (Crs) in individuals with severe respiratory muscle weakness (RMW). Individuals with RMW resulting from neuromuscular disease or quadriplegia (n=12) and healthy controls (n=12) underwent pulmonary function testing and the measurement of Crs at baseline, immediately after, 1 h after and 2 h after a single standardised session of LVR. The LVR session involved 10 consecutive supramaximal lung inflations with a manual resuscitation bag to the highest tolerable mouth pressure or a maximum of 50 cmH2O. Each LVR inflation was followed by brief breath-hold and a maximal expiration to residual volume. At baseline, individuals with RMW had lower Crs than controls (37±5 cmH2O versus 109±10 mL·cmH2O-1, p<0.001). Immediately after LVR, Crs increased by 39.5±9.8% to 50±7 mL·cmH2O-1 in individuals with RMW (p<0.05), while no significant change occurred in controls (p=0.23). At 1 h and 2 h post-treatment, there were no within-group differences in Crs compared to baseline (all p>0.05). LVR had no significant effect on measures of pulmonary function at any time point in either group (all p>0.05). During inflations, mean arterial pressure decreased significantly relative to baseline by 10.4±2.8 mmHg and 17.3±3.0 mmHg in individuals with RMW and controls, respectively (both p<0.05). LVR acutely increases Crs in individuals with RMW. However, the high airway pressures during inflations cause reductions in mean arterial pressure that should be considered when applying this technique.