Increased Virtual Visits to Physicians During the COVID-19 Pandemic and Estimated Impact on Physician Compensation: The Case of Lung and Colorectal Cancers, Chronic Obstructive Pulmonary Diseases, and Heart Failure in Alberta, Canada.

Introduction: The COVID-19 pandemic started in Alberta in March 2020 and significantly increased telehealth service use and provision reducing the risk of virus transmission. We examined the change in the number and proportion of virtual visits by physician specialty and condition (chronic obstructive pulmonary diseases [COPD], heart failure [HF], colorectal and lung cancers), as well as associated changes in physician compensation. Methods: A population-based design was used to analyze all processed physician claims comparing the number and proportion of virtual visits and associated physician billings relative to in-person between pre- (2019/2020) and intra-pandemic (2020/2021). Physician compensations were the claim amounts paid by the health insurance. Results: Pre-pandemic (intra-), there were 8,981 (8,897) lung cancer, 9,245 (9,029) colorectal, 37,558 (36,292) HF, and 68,270 (52,308) COPD patients. Each patient had totally 2.3-4.7 (of which 0.4-0.6% were virtual) general practitioner (GP) visits and 0.9-2.3 (0.2-0.7% were virtual) specialist visits per year pre-pandemic. The average number and proportion of per-patient virtual visits to GPs and specialists grew significantly pre- to intra-pandemic by 2,138-4,567%, and 2,201-7,104%, respectively. Given the lower fees of virtual compared with in-person visits, the reduction in physician compensation associated with the increased use of virtual care was estimated at $3.85 million, with $2.44 million attributed to specialist and $1.41 million to GP. Discussion: Utilization of telehealth increased significantly, while the physician billings per patient and physician compensation declined early in the pandemic in Alberta for the four chronic diseases considered. This study forms the basis for future study in understanding the impact of virtual care, now part of the fabric of health care delivery, on quality of care and patient safety, overall health service utilization (such as diagnostic imaging and other investigations), as well as economic impacts to patients, health care systems, and society.

Cardiopulmonary response to exercise in adults born very preterm.

This study aims to compare cardiopulmonary response to aerobic exercise between young adults born very preterm, including a subgroup with bronchopulmonary dysplasia (BPD), and term controls.Seventy-one adults (18-29 years) born <30 weeks' gestational age (24 with BPD) and 73 term controls were recruited. Assessment included cardiopulmonary exercise testing with impedance cardiography. We compared group differences in peak O2 consumption (peak VO2) and in ventilatory and cardiovascular responses to exercise using linear regression analyses.Preterm participants had reduced peak VO2 (mean difference -2.7; 95% CI -5.3, -0.1 mL·kg-1 lean body mass·min-1) versus controls. Those with BPD achieved lower peak work-rate compared to term controls (-21; 95% CI -38, -5 watts). There was no difference across groups in breathing reserve, ventilatory efficiency, peak heart rate and cardiac output. VO2 to work-rate relationship (ΔVO2/ΔWR) was reduced in preterm versus term. Peak systolic blood pressure and circulatory power (systolic blood pressure*VO2) were also lower in BPD versus term controls. In the preterm group, longer NICU stay and lower peak cardiac output were associated with lower peak VO2Results suggest limitations with peripheral O2 uptake in the muscle with reduced ΔVO2/ΔWR and peak circulatory power, but normal cardiac output. Investigations into skeletal muscle perfusion and O2 use during exercise are warranted to better understand mechanisms of exercise limitation.

Predicting family physician physical activity electronic medical record inputs.

OBJECTIVE: To compare characteristics of patients with and without physical activity noted in primary care electronic medical records. METHODS: We used pan-Canadian family physician electronic medical record data from the Canadian Primary Care Sentinel Surveillance Network (CPSSSN) to compare patient and provider characteristics on one visit per patient selected at random. Since patients were nested by providers, univariate statistics were explored then a multilevel model was constructed. RESULTS: The dataset included 769,185 patients, of whom 14,828 (1.9%) had physical activity information documented. Male patients, aged 25-34.9, no comorbidities prior to the random visit date, moderate or elevated blood pressure risk categories prior to the random visit date, the least materially deprived quintile, and with median body mass index in the normal category prior to the random visit date had the most physical activity mentions. Of the 879 family physicians in the sample, just over half (56.1%) documented physical activity at least once across their patients. More female physicians and physicians who practised in academic sites documented physical activity. In a two-level logistic model to predict physical activity documented in the randomly selected visit: older than mean patient age, having fewer comorbidities, younger than mean family physician age, academic teaching sites, and electronic medical record systems were statistically significant covariates. CONCLUSIONS: This work adds to existing literature by describing the frequency and the patient and family physician characteristics of physical activity documentation in the Canadian primary care context. Overall, patient physical activity was rarely documented in electronic medical records.

The Pulmonary Vasculature.

The pulmonary circulation is a low-pressure, low-resistance circuit whose primary function is to deliver deoxygenated blood to, and oxygenated blood from, the pulmonary capillary bed enabling gas exchange. The distribution of pulmonary blood flow is regulated by several factors including effects of vascular branching structure, large-scale forces related to gravity, and finer scale factors related to local control. Hypoxic pulmonary vasoconstriction is one such important regulatory mechanism. In the face of local hypoxia, vascular smooth muscle constriction of precapillary arterioles increases local resistance by up to 250%. This has the effect of diverting blood toward better oxygenated regions of the lung and optimizing ventilation-perfusion matching. However, in the face of global hypoxia, the net effect is an increase in pulmonary arterial pressure and vascular resistance. Pulmonary vascular resistance describes the flow-resistive properties of the pulmonary circulation and arises from both precapillary and postcapillary resistances. The pulmonary circulation is also distensible in response to an increase in transmural pressure and this distention, in addition to recruitment, moderates pulmonary arterial pressure and vascular resistance. This article reviews the physiology of the pulmonary vasculature and briefly discusses how this physiology is altered by common circumstances.

Short-Term Health Outcomes of a Structured Pulmonary Rehabilitation Program Implemented Within Rural Canadian Sites Compared With an Established Urban Site: A Pre-Post Intervention Observational Study.

OBJECTIVES: To evaluate congruence in program delivery and short-term health outcomes of a structured pulmonary rehabilitation (S-PR) program implemented at 11 Canadian rural pulmonary rehabilitation (PR) sites compared with an urban reference site. DESIGN: Multi-center, pre- and post-intervention, comparative, observational study. SETTING: Eleven rural Canadian PR sites and 1 urban reference PR site. PARTICIPANTS: Adults with chronic respiratory diseases (CRDs) referred to PR. INTERVENTION: Clinicians at the reference site worked with local clinicians to implement the S-PR program in rural sites. A PR survey evaluated site congruence with the S-PR components, with congruence defined as delivering program components ≥80% in alignment with the S-PR program. Participants were enrolled in 16 sessions of group education and supervised exercise, offered twice or thrice a week. Health outcomes were tracked using a quality assurance database. OUTCOME MEASURES: Main outcomes were congruence in program delivery and changes in the 6-minute walk (6MW) distance and COPD Assessment Test (CAT). RESULTS: A total of 555 participants (rural n=204 and reference n=351) were included in the analyses. There was congruence in exercise and group education; however, individual education varied. Following the S-PR program, 6MW distance increased, with greater changes observed at rural sites (51±67 m at rural sites vs 30±46 m at the reference site). CAT score was reduced by -2.6±5.4 points with no difference between reference and rural sites. Changes in 6MW distance and CAT scores were similar for participants at sites that were congruent vs noncongruent with the individual education component, and similar for patients with COPD, asthma, bronchiectasis, and interstitial lung disease. CONCLUSION: The S-PR program components can be implemented with good congruence in Canadian rural settings, resulting in similar short-term health outcomes as in an established urban site and across CRDs.

Impaired Ventilatory Efficiency, Dyspnea, and Exercise Intolerance in Chronic Obstructive Pulmonary Disease: Results from the CanCOLD Study.

Rationale: Impaired exercise ventilatory efficiency (high ventilatory requirements for CO2 [[Formula: see text]e/[Formula: see text]co2]) provides an indication of pulmonary gas exchange abnormalities in chronic obstructive pulmonary disease (COPD). Objectives: To determine 1) the association between high [Formula: see text]e/[Formula: see text]co2 and clinical outcomes (dyspnea and exercise capacity) and its relationship to lung function and structural radiographic abnormalities; and 2) its prevalence in a large population-based cohort. Methods: Participants were recruited randomly from the population and underwent clinical evaluation, pulmonary function, cardiopulmonary exercise testing, and chest computed tomography. Impaired exercise ventilatory efficiency was defined by a nadir [Formula: see text]e/[Formula: see text]co2 above the upper limit of normal (ULN), using population-based normative values. Measurements and Main Results: Participants included 445 never-smokers, 381 ever-smokers without airflow obstruction, 224 with Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 COPD, and 200 with GOLD 2-4 COPD. Participants with [Formula: see text]e/[Formula: see text]co2 above the ULN were more likely to have activity-related dyspnea (Medical Research Council dyspnea scale ⩾ 2; odds ratio [5-95% confidence intervals], 1.77 [1.31 to 2.39]) and abnormally low peak [Formula: see text]o2 ([Formula: see text]o2peak below the lower limit of normal; odds ratio, 4.58 [3.06 to 6.86]). The Kco had a stronger correlation with nadir [Formula: see text]e/[Formula: see text]co2 (r = -0.38; P < 0.001) than other relevant lung function and computed tomography metrics. The prevalence of [Formula: see text]e/[Formula: see text]co2 above the ULN was 24% in COPD (similar in GOLD 1 and 2 through 4), which was greater than in never-smokers (13%) and ever-smokers (12%). Conclusions: [Formula: see text]e/[Formula: see text]co2 above the ULN was associated with greater dyspnea and low [Formula: see text]o2peak and was present in 24% of all participants with COPD, regardless of GOLD stage. The results show the importance of recognizing impaired exercise ventilatory efficiency as a potential contributor to dyspnea and exercise limitation, even in mild COPD.

Implementation and maintenance of an enhanced pulmonary rehabilitation program in a single centre: An implementation study.

BACKGROUND: Pulmonary rehabilitation (PR) has major benefits for patients with chronic obstructive pulmonary disease (COPD). An enhanced PR program was developed with a self-management education intervention. The objective of our study was to evaluate the implementation of the enhanced PR program into a single centre. METHODS: Pre-post implementation study consisted of two evaluation periods: immediately after implementation and 18 months later. Guided by the RE-AIM framework, outcomes included: Reach, Effectiveness, Adoption, Implementation and Maintenance. RESULTS: Reach: 70-75% of referred patients agreed to a PR program (n = 26). Effectiveness: Clinically important improvements occurred in some patients in functional exercise capacity (64% of the patients achieved clinical important difference in 6-min walk test in the first evaluation period and 44% in the second evaluation period), knowledge, functional status, and self-efficacy in both evaluation periods. Adoption: All healthcare professionals (HCPs) involved in PR (n = 8) participated. Implementation: Fidelity for the group education sessions ranged from 76 to 95% (first evaluation) and from 82 to 88% (second evaluation). Maintenance: The program was sustained over 18 months with minor changes. Patients and HCPs were highly satisfied with the program. CONCLUSIONS: The enhanced PR program was accepted by patients and HCPs and was implemented and maintained at a single expert center with good implementation fidelity.

Survival after inpatient or outpatient pulmonary rehabilitation in patients with fibrotic interstitial lung disease: a multicentre retrospective cohort study.

BACKGROUND: The impact of pulmonary rehabilitation (PR) on survival in patients with fibrotic interstitial lung disease (ILD) is unknown. Given the challenges conducting a large randomised controlled trial, we aimed to determine whether improvement in 6-minute walk distance (6MWD) was associated with better survival. METHODS: This retrospective, international cohort study included patients with fibrotic ILD participating in either inpatient or outpatient PR at 12 sites in 5 countries. Multivariable models were used to estimate the association between change in 6MWD and time to death or lung transplantation accounting for clustering by centre and other confounders. RESULTS: 701 participants (445 men and 256 women) with fibrotic ILD were included. The mean±SD ages of the 196 inpatients and 505 outpatients were 70±11 and 69±12 years, respectively. Baseline/changes in 6MWD were 262±128/55±83 m for inpatients and 358±125/34±65 m for outpatients. Improvement in 6MWD during PR was associated with lower hazard rates for death or lung transplant on adjusted analysis for both inpatient (HR per 10 m 0.94, 95% CI 0.91 to 0.97, p<0.001) and outpatient PR (HR 0.97, 95% CI 0.95 to 1.00, p=0.042). Participation in ≥80% of planned outpatient PR sessions was associated with a 33% lower risk of death (95% CI 0.49% to 0.92%). CONCLUSIONS: Patients with fibrotic ILD who improved physical performance during PR had better survival compared with those who did not improve performance. Confirmation of these hypothesis-generating findings in a randomised controlled trial would be required to definitely change clinical practice, and would further support efforts to improve availability of PR for patients with fibrotic ILD.

COVID-19 hospitalization is associated with pulmonary/diffusion abnormalities but not post-acute sequelae of COVID-19 severity.

Coronavirus disease-19 (COVID-19) has resulted in much acute morbidity and mortality worldwide. There is now a growing recognition of the post-acute sequela of COVID-19, termed long COVID. However, the risk factors contributing to this condition remain unclear. Here, we address the growing controversy in the literature of whether hospitalization is a risk factor for long COVID. We found that hospitalization is associated with worse pulmonary restriction and reduction in diffusion capacity at 3 months post-infection. However, the impact on mental health, functional and quality of life is equally severe in those who have and have not been hospitalized during the acute infection. These findings suggest that hospitalization is a risk factor for pulmonary complications of long COVID but not the overall severity of long COVID.

A single breath of nitric oxide does not alter pulmonary perfusion pressure.

NEW FINDINGS: What is the central question of this study? Is the amount of inhaled nitric oxide (NO) used during a diffusing capacity for inhaled NO manoeuvre sufficient to reduce pulmonary artery systolic pressure (PASP)? What is the main finding and its importance? These findings suggest that a single breath of inhaled NO does not change PASP, and combined with previous correlational work, further validates the use of the diffusing capacity for NO manoeuvre as a technique to determine pulmonary capillary blood volume and membrane diffusing capacity. ABSTRACT: The measurement of diffusing capacity is an important pulmonary function test to evaluate gas exchange. Using both carbon monoxide and nitric oxide (NO), the diffusing capacity for nitric oxide (DL,NO ) technique allows for the partitioning of capillary blood volume and membrane diffusing capacity. However, inhaled NO is known to dilate pulmonary arterioles in both health and disease and therefore could alter the outcomes that the DL,NO technique aims to quantify. The purpose of the study was to determine if a DL,NO manoeuvre alters pulmonary perfusion pressure. Nine participants completed 12 simulated 10-s breath-hold DL,NO manoeuvres (n = 6 placebo inhalations and n = 6 with 40 ppm NO; order randomized) during which tricuspid regurgitant jet velocity was recorded continuously using Doppler ultrasound to estimate pulmonary artery systolic pressure (PASP) as a surrogate for pulmonary perfusion pressure. The PASP was not different between the placebo and NO conditions (P = 0.742). These data indicate that a single DL,NO manoeuvre does not alter PASP and therefore would not be expected to acutely alter pulmonary capillary blood volume or membrane diffusing capacity.

Physical Activity in Renal Disease and the Effect on Hypertension: A Randomized Controlled Trial.

INTRODUCTION: Exercise is an effective strategy for blood pressure (BP) reduction in the general population, but its efficacy for the management of hypertension in chronic kidney disease (CKD) is not known. We evaluated the difference in 24-h ambulatory systolic BP (SBP) with exercise training in people with moderate to severe CKD. METHODS: Participants with an estimated glomerular filtration rate (eGFR) of 15-44 mL/min per 1.73 m2 and SBP >120 mm Hg were randomized to receive thrice-weekly moderate-intensity aerobic-based exercise over 24 weeks, or usual care. Phase 1 included supervised in-center and home-based sessions for 8 weeks. Phase 2 was 16 weeks of home-based sessions. BP, arterial stiffness, cardiorespiratory fitness, and markers of cardiovascular (CV) risk were analyzed using mixed linear regression. RESULTS: We randomized 44 people; 36% were female, the median age was 69 years, 55% had diabetes, and the median eGFR was 28 mL/min per 1.73 m2. Compared with usual care, there was no significant change in 24-ambulatory SBP at 8 weeks (2.96 mm Hg; 95% confidence interval (CI): -2.56, 8.49) or 24 weeks. Peak oxygen uptake improved by 1.9 mL/kg/min in the exercise group (95% CI: 0.03, 3.79) at 8 weeks with a trend toward higher body mass index 1.84 kg/m2 (95% CI: -0.10, 3.78) and fat free mass, but this was not sustained at 24 weeks. Markers of CV risk were unchanged. CONCLUSIONS: Despite an improvement in peak aerobic capacity and body composition, we did not detect a change in 24-h ambulatory SBP in people with moderate-to-severe CKD.

Inhaled nitric oxide does not improve maximal oxygen consumption in endurance trained and untrained healthy individuals.

PURPOSE: Previous work suggests that endurance-trained athletes have superior pulmonary vasculature function as compared to untrained individuals, which may contribute to their greater maximal oxygen uptake ([Formula: see text]O2max). Inhaled nitric oxide (iNO) reduces pulmonary vascular resistance in healthy individuals, which could translate into greater cardiac output and improved [Formula: see text]O2max, particularly in untrained individuals. The purpose of the study was to examine whether iNO improved [Formula: see text]O2max in endurance trained and untrained individuals. METHODS: Sixteen endurance-trained and sixteen untrained individuals with normal lung function completed this randomized double-blind cross-over study over four sessions. Experimental cardiopulmonary exercise tests were completed while breathing either normoxia (placebo) or 40 ppm of iNO, on separate days (order randomized). On an additional day, echocardiography was used to determine pulmonary artery systolic pressure at rest and during sub-maximal exercise (60 Watts) while participants breathed normoxia or iNO. RESULTS: Right ventricular systolic pressure was significantly reduced by iNO during exercise (Placebo: 34 ± 7 vs. iNO: 32 ± 7; p = 0.04). [Formula: see text]O2max was greater in the endurance trained group (Untrained: 3.1 ± 0.7 vs. Endurance: 4.3 ± 0.9 L min-1; p < 0.01), however, there was no effect of condition (p = 0.79) and no group by condition interaction (p = 0.68). Peak cardiac output was also unchanged by iNO in either group. CONCLUSION: Despite a reduction in right ventricular systolic pressure, the lack of change in [Formula: see text]O2max with iNO suggests that the pulmonary vasculature does not limit [Formula: see text]O2max in young healthy individuals, regardless of fitness level.

Effectiveness of home-based pulmonary rehabilitation programs for patients with chronic obstructive pulmonary disease (COPD): systematic review.

BACKGROUND: Although pulmonary rehabilitation (PR) is considered a key component in managing chronic obstructive pulmonary disease (COPD) patients, uptake remains suboptimal. This systematic review aimed to determine the effectiveness of home-based PR (HBPR) programs for COPD patients. METHODS: A systematic review of scholarly literature published within the last 10 years from the conception of this project was conducted using internationally recognized guidelines. Search strategies were applied to electronic databases and clinical trial registries through March 2020 and updated in November 2021 to identify studies comparing HBPR with 'usual care' or outpatient pulmonary rehabilitation (OPR). To critically appraise randomized studies, the Cochrane Collaboration risk of bias tool (ROB) was used. The quality of non-randomized studies was evaluated using the ACROBAT-NRSI tool. The quality of evidence relating to key outcomes was assessed using Grading of Recommendations, Assessment, Development and Evaluations (GRADE) on health-related quality of life (HRQoL), exacerbation frequencies, COPD-related hospital admissions, and program adherence. Three independent reviewers assessed methodologic quality and reviewed the studies. RESULTS: Twelve randomized controlled trials (RCTs) and 2 comparative observational studies were included. While considerable evidence relating to the effectiveness of HBPR programs for COPD patients exist, overall quality is low. There were no differences between HBPR and OPR in terms of safety, HRQoL, functional exercise capacity and health care resource utilization. Compared to usual care, functional exercise capacity seemed to significantly improve after HBPR. While patient compliance with HBPR is good, two factors appeared to increase the 'risk' of non-compliance: expectations of patients to 1) complete daily diaries/activity logs and 2) engage in solely unsupervised exercise sessions. CONCLUSION: The overall quality for most outcomes was low to very low; however, HBPR seems to offer comparable short-term benefits to OPR.

Effectiveness of remote home monitoring for patients with Chronic Obstructive Pulmonary Disease (COPD): systematic review.

BACKGROUND: Although remote home monitoring (RHM) has the capacity to prevent exacerbations in patients with chronic obstructive pulmonary disease (COPD), evidence regarding its effectiveness remains unclear. The objective of this study was to determine the effectiveness of RHM in patients with COPD. METHODS: A systematic review of the scholarly literature published within the last 10 years was conducted using internationally recognized guidelines. Search strategies were applied to several electronic databases and clinical trial registries through March 2020 to identify studies comparing RHM to 'no remote home monitoring' (no RHM) or comparing RHM with provider's feedback to RHM without feedback. To critically appraise the included randomized studies, the Cochrane Collaboration risk of bias tool (ROB) was used. The quality of included non-randomized interventional and comparative observational studies was evaluated using the ACROBAT-NRSI tool from the Cochrane Collaboration. The quality of evidence relating to key outcomes was assessed using Grading of Recommendations, Assessment, Development and Evaluations (GRADE) on the following: health-related quality of life (HRQoL), patient experience and number of exacerbations, number of emergency room (ER) visits, COPD-related hospital admissions, and adherence as the proportion of patients who completed the study. Three independent reviewers assessed methodologic quality and reviewed the studies. RESULTS: Seventeen randomized controlled trials (RCTs) and two comparative observational studies were included in the review. The primary finding of this systematic review is that a considerable amount of evidence relating to the efficacy/effectiveness of RHM exists, but its quality is low. Although RHM is safe, it does not appear to improve HRQoL (regardless of the type of RHM), lung function or self-efficacy, or to reduce depression, anxiety, or healthcare resource utilization. The inclusion of regular feedback from providers may reduce COPD-related hospital admissions. Though adherence RHM remains unclear, both patient and provider satisfaction were high with the intervention. CONCLUSIONS: Although a considerable amount of evidence to the effectiveness of RHM exists, due to heterogeneity of care settings and the low-quality evidence, they should be interpreted with caution.

Inhaled nitric oxide improves ventilatory efficiency and exercise capacity in patients with mild COPD: A randomized-control cross-over trial.

KEY POINTS: Patients with mild chronic obstructive pulmonary disease (COPD) have an elevated ventilatory equivalent to CO2 production ( V̇E / V̇CO2 ) during exercise, secondary to increased dead space ventilation. The reason for the increased dead space is unclear, although pulmonary microvascular dysfunction and the corresponding capillary hypoperfusion is a potential mechanism. Despite emerging evidence that mild COPD is associated with pulmonary microvascular dysfunction, limited research has focused on experimentally modulating the pulmonary microvasculature during exercise in mild COPD. The present study sought to examine the effect of inhaled nitric oxide (iNO), a selective pulmonary vasodilator, on V̇E / V̇CO2 , dyspnoea and exercise capacity in patients with mild COPD. Experimental iNO increased peak oxygen uptake in mild COPD, secondary to reduced V̇E / V̇CO2 and dyspnoea. This is the first study to demonstrate that experimental manipulation of the pulmonary circulation alone, can positively impact dyspnoea and exercise capacity in mild COPD. ABSTRACT: Patients with mild chronic obstructive pulmonary disease (COPD) have an exaggerated ventilatory response to exercise, contributing to dyspnoea and exercise intolerance. Previous research in mild COPD has demonstrated an elevated ventilatory equivalent to CO2 production ( V̇E / V̇CO2 ) during exercise, secondary to increased dead space ventilation. The reason for the increased dead space is unclear, although pulmonary microvascular dysfunction and the corresponding capillary hypoperfusion is a potential mechanism. The present study tested the hypothesis that inhaled nitric oxide (iNO), a selective pulmonary vasodilator, would lower V̇E / V̇CO2 and dyspnoea, and improve exercise capacity in patients with mild COPD. In this multigroup randomized-control cross-over study, 15 patients with mild COPD (FEV1  =  89 ± 11% predicted) and 15 healthy controls completed symptom-limited cardiopulmonary exercise tests while breathing normoxic gas or 40 ppm iNO. Compared with placebo, iNO significantly increased peak oxygen uptake (1.80 ± 0.14 vs. 1.53 ± 0.10 L·min-1 , P < 0.001) in COPD, whereas no effect was observed in controls. At an equivalent work rate of 60 W, iNO reduced V̇E / V̇CO2 by 3.8 ± 4.2 units (P = 0.002) and dyspnoea by 1.1 ± 1.2 Borg units (P < 0.001) in COPD, whereas no effect was observed in controls. Operating lung volumes and oxygen saturation were unaffected by iNO in both groups. iNO increased peak oxygen uptake in COPD, secondary to reduced V̇E / V̇CO2 and dyspnoea. These data suggest that mild COPD patients demonstrate pulmonary microvascular dysfunction that contributes to increased V̇E / V̇CO2 , dyspnoea and exercise intolerance. This is the first study to demonstrate that experimental manipulation of the pulmonary circulation alone, can positively impact dyspnoea and exercise capacity in mild COPD.

Exertional intolerance and dyspnea with preserved lung function: an emerging long COVID phenotype?

The COVID-19 pandemic has resulted in significant acute morbidity and mortality worldwide. There is now a growing recognition of the longer-term sequelae of this infection, termed "long COVID". However, little is known about this condition. Here, we describe a distinct phenotype seen in a subset of patients with long COVID who have reduced exercise tolerance as measured by the 6 min walk test. They are associated with significant exertional dyspnea, reduced health-related quality of life and poor functional status. However, surprisingly, they do not appear to have any major pulmonary function abnormalities or increased burden of neurologic, musculoskeletal or fatigue symptoms.

Blunted sympathetic neurovascular transduction is associated to the severity of obstructive sleep apnea.

PURPOSE: Obstructive sleep apnea (OSA) is a common disorder (~ 4%) that augments sympathetic nerve activity (SNA) and elevates blood pressure. The relationship between sympathetic vasomotor outflow and vascular responsiveness, termed sympathetic neurovascular transduction (sNVT), has been sparsely characterized in patients with OSA. Therefore, we sought to quantify spontaneous sympathetic bursts and related changes in diastolic pressure. METHODS: Twelve participants with variable severities of OSA were recruited. We collected muscle sympathetic nerve activity (MSNA) (microneurography) and beat-by-beat diastolic pressure (finger photoplethysmography) during normoxia (FiO2 = 0.21) and hyperoxia (FiO2 = 1.0) to decrease MSNA burst frequency. MSNA burst sequences (i.e. singlets, doublets, triplets and quadruplets) were identified and coupled to changes in diastolic pressure over 15 cardiac cycles as an index of sNVT. sNVT slope for each individual was calculated from the slope of the relationship between peak responses in outcome plotted against normalized burst amplitude. RESULTS: sNVT slope was unchanged during hyperoxia compared to normoxia (normoxia 0.0024 ± 0.0011 Δ mmHg total activity [a.u.]-1 vs. hyperoxia 0.0029 ± 0.00098 Δ mmHg total activity [a.u.]-1; p = 0.14). sNVT slope was inversely associated with burst frequency during hyperoxia (r = -0.58; p = 0.04), but not normoxia (r = -0.11; p = 0.71). sNVT slope was inversely associated with the apnea-hypopnea index (AHI) (r = -0.62; p = 0.030), but not after age was considered. CONCLUSIONS: We have demonstrated that the prevailing MSNA frequency is unmatched to the level of sNVT, and this can be altered by acute hyperoxia.

Cardiac rehabilitation in the paediatric Fontan population: development of a home-based high-intensity interval training programme.

INTRODUCTION: We evaluated the safety and feasibility of high-intensity interval training via a novel telemedicine ergometer (MedBIKE™) in children with Fontan physiology. METHODS: The MedBIKE™ is a custom telemedicine ergometer, incorporating a video game platform and live feed of patient video/audio, electrocardiography, pulse oximetry, and power output, for remote medical supervision and modulation of work. There were three study phases: (I) exercise workload comparison between the MedBIKE™ and a standard cardiopulmonary exercise ergometer in 10 healthy adults. (II) In-hospital safety, feasibility, and user experience (via questionnaire) assessment of a MedBIKE™ high-intensity interval training protocol in children with Fontan physiology. (III) Eight-week home-based high-intensity interval trial programme in two participants with Fontan physiology. RESULTS: There was good agreement in oxygen consumption during graded exercise at matched work rates between the cardiopulmonary exercise ergometer and MedBIKE™ (1.1 ± 0.5 L/minute versus 1.1 ± 0.5 L/minute, p = 0.44). Ten youth with Fontan physiology (11.5 ± 1.8 years old) completed a MedBIKE™ high-intensity interval training session with no adverse events. The participants found the MedBIKE™ to be enjoyable and easy to navigate. In two participants, the 8-week home-based protocol was tolerated well with completion of 23/24 (96%) and 24/24 (100%) of sessions, respectively, and no adverse events across the 47 sessions in total. CONCLUSION: The MedBIKE™ resulted in similar physiological responses as compared to a cardiopulmonary exercise test ergometer and the high-intensity interval training protocol was safe, feasible, and enjoyable in youth with Fontan physiology. A randomised-controlled trial of a home-based high-intensity interval training exercise intervention using the MedBIKE™ will next be undertaken.

Coping Versus Mastery Modeling Intervention to Enhance Self-efficacy for Exercise in Patients with COPD.

The literature suggests self-efficacy is a determinant of physical activity and management of Chronic Obstructive Pulmonary Disease (COPD). The purpose of this study was to (1) test the effects of two vicarious experience interventions, coping versus mastery modeling, on self-efficacy in COPD patients performing a cardiopulmonary exercise test (CPET), and (2) determine the type of self-efficacy most strongly related to physical activity in COPD patients. After a baseline assessment of self-efficacy (task, coping for exercise, coping for breathing, scheduling, and walking) and potential moderators, 120 COPD patients watched a mastery model or coping model CPET video, or received usual care verbal instructions. Then, self-efficacy was assessed, followed by a CPET, and another assessment of self-efficacy. Fitbits tracked participants' step count the week following contact. Repeated measures MANOVAs assessed the intervention effects and multiple regressions assessed the contribution of self-efficacy subtypes to step count. All self-efficacy subtypes improved in the mastery and coping conditions, although greater improvement of self-efficacy for coping with exercise barriers was observed in the coping condition. Self-efficacy did not improve in the control condition and no moderators were identified. Self-efficacy for coping with exercise barriers was the self-efficacy subtype most strongly related to step count. This research suggests modeling is a useful intervention technique to enhance self-efficacy in COPD patients, although coping models may be more beneficial than mastery models for enhancing capability beliefs during complex tasks. Future interventions in COPD patients should target self-efficacy for coping with exercise barriers.

Precapillary pulmonary gas exchange is similar for oxygen and inert gases.

KEY POINTS: Precapillary gas exchange for oxygen has been documented in both humans and animals. It has been suggested that, if precapillary gas exchange occurs to a greater extent for inert gases than for oxygen, shunt and its effects on arterial oxygenation may be underestimated by the multiple inert gas elimination technique (MIGET). We evaluated fractional precapillary gas exchange in canines for O2 and two inert gases, sulphur hexafluoride and ethane, by measuring these gases in the proximal pulmonary artery, distal pulmonary artery (1 cm proximal to the wedge position) and systemic artery. Some 12-19% of pulmonary gas exchange occurred within small (1.7 mm in diameter or larger) pulmonary arteries and this was quantitatively similar for oxygen, sulphur hexafluoride and ethane. Under these experimental conditions, this suggests only minor effects of precapillary gas exchange on the magnitude of calculated shunt and the associated effect on pulmonary gas exchange estimated by MIGET. ABSTRACT: Some pulmonary gas exchange is known to occur proximal to the pulmonary capillary, although the magnitude of this gas exchange is uncertain, and it is unclear whether oxygen and inert gases are similarly affected. This has implications for measuring shunt and associated gas exchange consequences. By measuring respiratory and inert gas levels in the proximal pulmonary artery (P), a distal pulmonary artery 1 cm proximal to the wedge position (using a 5-F catheter) (D) and a systemic artery (A), we evaluated precapillary gas exchange in 27 paired samples from seven anaesthetized, ventilated canines. Fractional precapillary gas exchange (F) was quantified for each gas as F = (P - D)/(P - A). The lowest solubility inert gases, sulphur hexafluoride (SF6 ) and ethane were used because, with higher solubility gases, the P-A difference is sufficiently small that experimental error prevents accurate assessment of F. Distal samples (n = 12) with oxygen (O2 ) saturation values that were (within experimental error) equal to or above systemic arterial values, suggestive of retrograde capillary blood aspiration, were discarded, leaving 15 for analysis. D was significantly lower than P for SF6 (D/P = 88.6 ± 18.1%; P = 0.03) and ethane (D/P = 90.6 ± 16.0%; P = 0.04), indicating partial excretion of inert gas across small pulmonary arteries. Distal pulmonary arterial O2 saturation was significantly higher than proximal (74.1 ± 6.8% vs. 69.0 ± 4.9%; P = 0.03). Fractional precapillary gas exchange was similar for SF6 , ethane and O2 (0.12 ± 0.19, 0.12 ± 0.20 and 0.19 ± 0.26, respectively; P = 0.54). Under these experimental conditions, 12-19% of pulmonary gas exchange occurs within the small pulmonary arteries and the extent is similar between oxygen and inert gases.