Sleep-disordered breathing and nocturnal hypoxemia in chronic thromboembolic pulmonary disease

BACKGROUND AND AIMS

Sleep-disordered breathing (SDB) and nocturnal hypoxemia were known to be present in patients with chronic thromboembolic pulmonary hypertension (CTEPH), but the difference between SDB and nocturnal hypoxemia in patients who have chronic thromboembolic pulmonary disease (CTEPD) with or without pulmonary hypertension (PH) at rest remains unknown.

METHODS

Patients who had CTEPH (n = 80) or CTEPD without PH (n = 40) and who had undergone sleep studies from July 2020 to October 2022 at Shanghai Pulmonary Hospital were enrolled. Nocturnal mean SpO2 (Mean SpO2) <90% was defined as nocturnal hypoxemia, and the percentage of time with a saturation below 90% (T90%) exceeding 10% was used to evaluate the severity of nocturnal hypoxemia. Logistic and linear regression analyses were performed to investigate the difference and potential predictor of SDB or nocturnal hypoxemia between CTEPH and CTEPD without PH.

RESULTS

SDB was similarly prevalent in CTEPH and CTEPD without PH (P = 0.104), both characterised by obstructive sleep apnoea (OSA). Twenty-two patients with CTEPH were diagnosed with nocturnal hypoxemia, whereas only three were diagnosed with CTEPD without PH (P = 0.021). T90% was positively associated with mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance in patients with CTEPH and CTEPD without PH (P < 0.001); T90% was also negatively related to cardiac output in these patients. Single-breath carbon monoxide diffusing capacity, sex and mPAP were all correlated with nocturnal hypoxemia in CTEPH and CTEPD without PH (all P < 0.05).

CONCLUSION

Nocturnal hypoxemia was worse in CTEPD with PH; T90%, but not SDB, was independently correlated with the hemodynamics in CTEPD with or without PH.

Reduced exercise capacity occurs before intrinsic skeletal muscle dysfunction in experimental rat models of pulmonary hypertension

Reduced exercise capacity in pulmonary hypertension (PH) significantly impacts quality of life. However, the cause of reduced exercise capacity in PH remains unclear. The objective of this study was to investigate whether intrinsic skeletal muscle changes are causative in reduced exercise capacity in PH using preclinical PH rat models with different PH severity. PH was induced in adult Sprague-Dawley (SD) or Fischer (CDF) rats with one dose of SU5416 (20 mg/kg) injection, followed by 3 weeks of hypoxia and additional 0-4 weeks of normoxia exposure. Control s rats were injected with vehicle and housed in normoxia. Echocardiography was performed to assess cardiac function. Exercise capacity was assessed by VO2 max. Skeletal muscle structural changes (atrophy, fiber type switching, and capillary density), mitochondrial function, isometric force, and fatigue profile were assessed. In SD rats, right ventricular systolic dysfunction is associated with reduced exercise capacity in PH rats at 7-week timepoint in comparison to control rats, while no changes were observed in skeletal muscle structure, mitochondrial function, isometric force, or fatigue profile. CDF rats at 4-week timepoint developed a more severe PH and, in addition to right ventricular dysfunction, the reduced exercise capacity in these rats is associated with skeletal muscle atrophy; however, mitochondrial function, isometric force, and fatigue profile in skeletal muscle remain unchanged. Our data suggest that cardiopulmonary impairments in PH are the primary cause of reduced exercise capacity, which occurs before intrinsic skeletal muscle dysfunction.

Aerobically trained older adults show impaired resting, but preserved exercise-induced circulating progenitor cell count, which was not improved by sprint interval training

Older adults exhibit a reduced number and function of CD34 + circulating progenitor cells (CPC), a known risk factor for cardiovascular disease. Exercise promotes the mobilisation of CPCs from bone marrow, so whether ageing per se or physical inactivity in older age reduces CPCs is unknown. Thus, this study examined the effect of age on resting and exercise-induced changes in CPCs in aerobically trained adults and the effect of 8 weeks of sprint interval training (SIT) on resting and exercise-induced CPCs in older adults. Twelve young (22-34 years) and nine older (63-70 years) adults participated in the study. Blood was sampled pre and immediately post a graded exercise test to exhaustion in both groups. Older participants repeated the process after 8 weeks of SIT (3 × 20 s 'all-out' sprints, 2 × a week). Total CPCs (CD34⁺) and endothelial progenitor cells (EPCs: CD34⁺KDR⁺) were determined by flow cytometry. Older adults exhibited lower basal total CD34⁺ CPCs (828 ± 314 vs. 1186 ± 272 cells·mL^-1, p = 0.0149) and CD34⁺KDR⁺ EPCs (177 ± 128 vs. 335 ± 92 cells·mL^-1, p = 0.007) than younger adults. The maximal exercise test increased CPCs in young (CD34⁺: p = 0.004; CD34⁺KDR⁺: p = 0.017) and older adults (CD34⁺: p < 0.001; CD34⁺KDR⁺: p = 0.008), without difference between groups (p = 0.211). SIT did not alter resting or exercise-induced changes in CPCs in the older cohort (p > 0.232). This study suggests age per se does not impair exercise-induced CPC counts, but does lower resting CPC counts.

Skeletal muscle dysfunctions in pulmonary arterial hypertension: Effects of aerobic exercise training

Pulmonary arterial hypertension is associated with skeletal muscle myopathy and atrophy and impaired exercise tolerance. Aerobic exercise training has been recommended as a non-pharmacological therapy for deleterious effects imposed by pulmonary arterial hypertension. Aerobic physical training induces skeletal muscle adaptations via reduced inflammation, improved anabolic processes, decreased hypoxia and regulation of mitochondrial function. These benefits improve physical exertion tolerance and quality of life in patients with pulmonary arterial hypertension. However, the mechanisms underlying the therapeutic potential of aerobic exercise to skeletal muscle disfunctions in patients with pulmonary arterial hypertension are not well understood yet. This minireview highlights the pathways involved in skeletal muscle adaptations to aerobic exercise training in patients with pulmonary arterial hypertension.

Individually tailored home-based physiotherapy program makes sustainable improvement in exercise capacity and daily physical activity in patients with pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is a rare, chronic, progressive, and life-threatening cardiopulmonary disease. This study investigated the impact of an individually tailored 12 weeks home-based physiotherapy program in PAH patients, with the aim to evaluate change in exercise capacity and daily physical activity level.

METHODS

This was an analysis of secondary outcomes from a prospective, randomized, controlled intervention study. Twenty-one participants were recruited from the Latvian PH registry based on inclusion criteria and randomized in a training group (TG) and control group (CG). Both groups continued a medical target therapy, but for TG, the individually tailored home-based physiotherapy program was added including physical exercises, relaxation, self-control, education, and supervision with telehealth elements. Outcomes included a 6-min walk test (6MWT) (m) and daily physical activity based on accelerometry results assessed at baseline, after 12 weeks, and at follow-up 6 months after commencement of intervention.

RESULTS

6MWT distance significantly (p < 0.05) and clinically (>33 m) increased within TG after 12 weeks (51.8 m, 95% CI = 25.7-77.9 m, Cohen's d = 1.7) and at follow-up (75.5 m, 95% CI = 46.1-104.8 m, Cohen's d = 2.1). A significant difference in 6MWT results between the groups at 12 weeks and follow-up was approved. In TG, low-intensity activities significantly (p < 0.05) increased both after 12 weeks (Cohen's d = 1.6) and at follow-up (Cohen's d = 1.2), moderate-intensity activities significantly (p < 0.05) increased at follow-up (Cohen's d = 1.3), and no significant improvements were present in CG.

CONCLUSION

The individually tailored 12 weeks home-based physiotherapy program comprising comprehensive physical exercise training, relaxation, self-control skills training, and education, added to stable medical target therapy and supervised by physiotherapist through telehealth elements, is effective in improving exercise capacity and increasing daily time in low or moderate physical activities 6 months after commencement of the intervention in patients with PAH.

Skeletal muscle blood flow during exercise is reduced in a rat model of pulmonary hypertension

Pulmonary arterial hypertension (PAH) is characterized by exercise intolerance. Muscle blood flow may be reduced during exercise in PAH; however, this has not been directly measured. Therefore, we investigated blood flow during exercise in a rat model of monocrotaline (MCT)-induced pulmonary hypertension (PH). Male Sprague-Dawley rats (∼200 g) were injected with 60 mg/kg MCT (MCT, n = 23) and vehicle control (saline; CON, n = 16). Maximal rate of oxygen consumption (V̇o2max) and voluntary running were measured before PH induction. Right ventricle (RV) morphology and function were assessed via echocardiography and invasive hemodynamic measures. Treadmill running at 50% V̇o2max was performed by a subgroup of rats (MCT, n = 8; CON, n = 7). Injection of fluorescent microspheres determined muscle blood flow via photo spectroscopy. MCT demonstrated a severe phenotype via RV hypertrophy (Fulton index, 0.61 vs. 0.31; P < 0.001), high RV systolic pressure (51.5 vs. 22.4 mmHg; P < 0.001), and lower V̇o2max (53.2 vs. 71.8 mL·min-1·kg-1; P < 0.0001) compared with CON. Two-way ANOVA revealed exercising skeletal muscle blood flow relative to power output was reduced in MCT compared with CON (P < 0.001), and plasma lactate was increased in MCT (10.8 vs. 4.5 mmol/L; P = 0.002). Significant relationships between skeletal blood flow and blood lactate during exercise were observed for individual muscles (r = -0.58 to -0.74; P < 0.05). No differences in capillarization were identified. Skeletal muscle blood flow is significantly reduced in experimental PH. Reduced blood flow during exercise may be, at least in part, consequent to reduced exercise intensity in PH. This adds further evidence of peripheral muscle dysfunction and exercise intolerance in PAH.

Skeletal muscle deficits are associated with worse exercise performance in pediatric pulmonary hypertension

BACKGROUND

Skeletal muscle deficits are associated with worse exercise performance in adults with pulmonary hypertension (PH) but the impact is poorly understood in pediatric PH.

OBJECTIVE

To study muscle deficits, physical inactivity, and performance on cardiopulmonary exercise test (CPET) and exercise cardiac magnetic resonance (eCMR) in pediatric PH.

METHODS

Youth 8-18 years participated in a prospective, cross-sectional study including densitometry (DXA) for measurement of leg lean mass Z-score (LLMZ), handheld dynamometer with generation of dominant and non-dominant handgrip Z-scores, Physical Activity Questionnaire (PAQ), CPET, and optional eCMR. CPET parameters were expressed relative to published reference values. CMR protocol included ventricular volumes and indexed systemic flow at rest and just after supine ergometer exercise. Relationships between LLMZ, PAQ score, and exercise performance were assessed by Pearson correlation and multiple linear regression.

RESULTS

There were 25 participants (13.7 ± 2.8 years, 56% female, 64% PH Group 1, 60% functional class I); 12 (48%) performed both CPET and eCMR. Mean LLMZ (-0.96 ± 1.14) was associated with PAQ score (r = 50, p = 0.01) and with peak oxygen consumption (VO₂) (r = 0.74, p = < 0.001), VO₂ at anaerobic threshold (r = 0.65, p < 0.001), and peak work rate (r = 0.64, p < 0.01). Higher handgrip Z-scores were associated with better CPET and eCMR performance. On regression analysis, LLMZ and PAQ score were positively associated with peak VO₂, while handgrip Z-score and PAQ score were positively associated with peak work rate.

CONCLUSION

Muscle mass and strength are positively associated with exercise performance in pediatric PH. Future studies should determine the effect of rehabilitation programs on muscle properties and exercise performance.

Prevalence of Micronutrient Deficiencies and Relationship with Clinical and Patient-Related Outcomes in Pulmonary Hypertension Types I and IV

Background: Pulmonary hypertension (PH) is a rare progressive and lethal disease affecting pulmonary arteries and heart function. The disease may compromise the nutritional status of the patient, which impairs their physical performance. This study aimed to determine the prevalence of micronutrient deficiencies in pulmonary arterial hypertension (PAH) and chronic thrombo-embolic pulmonary hypertension (CTEPH) patients. Methods: Eighty-one blood samples from a prospective observational cohort study were analyzed for concentrations of micronutrients and inflammation-related factors. The samples consisted of newly diagnosed (treatment-naive) PAH and CTEPH patients and patients treated for 1.5 years according to ERS/ESC guidelines. Results: In the newly diagnosed group, 42% of PAH patients and 21% of CTEPH patients were iron deficient compared to 29% of PAH patients and 20% of CTEPH patients in the treatment group. Vitamin D deficiency occurred in 42% of the newly diagnosed PAH patients, 71% of the newly diagnosed CTEPH patients, 68% of the treated PAH patients, and 70% of the treated CTEPH patients. Iron levels correlated with the 6 min walking distance (6MWD). Conclusions: Iron and vitamin D deficiencies are highly prevalent in PAH and CTEPH patients, underlining the need for monitoring their status. Studies evaluating the effects of supplementation strategies for iron and vitamin D are necessary.

Right ventricular contractility decreases during exercise in patients with non-advanced idiopathic pulmonary fibrosis

Early right ventricular dysfunction in patients with non-advanced idiopathic pulmonary fibrosis (IPF) has not been fully elucidated. Thus, we aimed to assess right ventricular functions in IPF patients and controls by speckle-tracking strain echocardiography at rest and peak exercise.We screened 116 IPF patients from February to August 2019 to include 20 patients with no history of oxygen therapy, peripheral saturation levels ≥92% at rest, Gender-Age-Physiology Index score ≤5, and modified Medical Research Council score ≤3. Additionally, we enrolled 10 matched controls. Transthoracic echocardiography images were acquired at rest and during a cardiopulmonary exercise test. We analyzed 2-dimensional echocardiographic parameters and right ventricular function using the global longitudinal strain assessed by the 2-dimensional speckle-tracking technique.In the control group, we found normal values of right ventricle longitudinal strain (RVLS) at rest and at peak exercise, the latter being much more negative (-23.6 ± 2.2% and -26.8 ± 3.1%, respectively; P < .001). By contrast, RVLS values in the IPF group increased from -21.1 ± 3.8% at rest to -17.0 ± 4.5% at peak exercise (P < .001). The exercise revealed a difference between the 2 groups as the mean RVLS values moved during peak exercise in opposite directions. Patients with IPF got worse, whereas control patients presented improved right ventricular contractility.Right ventricular dysfunction was unveiled by speckle-tracking echocardiography during exercise in non-advanced IPF patients. We suggest that this reflects an inadequate right ventricular-arterial coupling decreasing the right ventricular longitudinal contraction during exercise in these patients. This parameter may be useful as an early index of suspected pulmonary hypertension.

Exercise Program Improves Functional Capacity and Quality of Life in Uncorrected Atrial Septal Defect-Associated Pulmonary Arterial Hypertension: A Randomized-Control Pilot Study

OBJECTIVE

To assess the effect of combined hospital and home-based exercise programs on functional capacity and quality of life (QoL) among uncorrected atrial septal defect-associated pulmonary arterial hypertension (ASD-PAH) patients.

METHODS

This study was a randomized controlled trial with uncorrected ASD-PAH patients as the subjects. They were allocated randomly into control and exercise groups. Exercise group subjects performed hospital and home-based exercise programs, completing baseline 6-minute walking test (6MWT) and EQ-5D-3L QoL test (Utility Index and EQ-VAS scores), and were followed up for 12 weeks. The primary outcomes were 6MWT distance and EQ-5D-3L score at week 12. The N-terminal pro B-type natriuretic peptide (NT-proBNP) level was also assessed. A repeated-measure ANOVA was performed to detect endpoint differences over time.

RESULTS

The exercise group contained 20 subjects and control group contained 19. In total, 19 exercise group subjects and 16 control group subjects completed the protocol. The 6MWT distance, Utility Index score, and EQ-VAS score incrementally improved significantly in the exercise group from baseline until week 12, with mean differences of 76.7 m (p<0.001), 0.137 (p<0.001) and 15.5 (p<0.001), respectively. Compared with the control group, the exercise group had significantly increased 6MWT distance and utility index score at week 12. The EQ-VAS score increased in the exercise group at week 12. The NT-proBNP level decreased at week 12 in the exercise group.

CONCLUSION

Combined hospital and home-based exercise program added to PAH-targeted therapy, improving functional capacity and QoL in uncorrected ASD-PAH patients.

Treatment Targets for Right Ventricular Dysfunction in Pulmonary Arterial Hypertension

Right ventricle (RV) dysfunction is the strongest predictor of mortality in pulmonary arterial hypertension (PAH), but, at present, there are no therapies directly targeting the failing RV. Although there are shared molecular mechanisms in both RV and left ventricle (LV) dysfunction, there are important differences between the 2 ventricles that may allow for the development of RV-enhancing or RV-directed therapies. In this review, we discuss the current understandings of the dysregulated pathways that promote RV dysfunction, highlight RV-enriched or RV-specific pathways that may be of particular therapeutic value, and summarize recent and ongoing clinical trials that are investigating RV function in PAH. It is hoped that development of RV-targeted therapies will improve quality of life and enhance survival for this deadly disease.

Clinical utility of ventilatory and gas exchange evaluation during low-intensity exercise for risk stratification and prognostication in pulmonary arterial hypertension

BACKGROUND AND OBJECTIVE

Peak oxygen consumption (pVO₂ ), determined from CPET, provides a valuable indication of PAH severity and patient prognosis. However, CPET is often contraindicated in severe PAH and frequently terminated prior to achievement of a sufficient exercise effort. We sought to determine whether in PAH low-intensity [i.e. freewheeling exercise (FW)] exercise reveals abnormal V_E /VCO₂ and P_ET CO₂ responses that are associated with pVO₂ and serve as indices of PAH risk stratification and mortality.

METHODS

Retrospective analysis of CPET from 97 PAH patients and 20 age-matched controls was undertaken. FW V_E /VCO₂ and P_ET CO₂ were correlated with pVO₂ % age-predicted. Prognostication analysis was conducted using pVO₂  > 65% age-predicted, as known to represent a low mortality risk. Primary outcome was mortality from any cause.

RESULTS

FW P_ET CO₂ was correlated with pVO₂ (P < 0.0001; r = 0.52), while FW V_E /VCO₂ was not (P = 0.13; r = -0.16). ROC curve analyses showed that FW P_ET CO₂ (AUC = 0.659), but not FW V_E /VCO₂ (AUC = 0.587), provided predictive information identifying pVO₂  > 65% age-predicted (best cut-off value of 28 mm Hg). By Cox analysis, FW P_ET CO₂  < 28 mm Hg remained a predictor of mortality after adjusting for age and PAH aetiology (HR: 2.360, 95% CI: 1.144-4.866, P = 0.020).

CONCLUSION

Low P_ET CO₂ during FW is associated with reduced pVO₂ in PAH and provides predictive information for PAH risk stratification and prognostication.

Exercise intolerance establishment in pulmonary hypertension: Preventive effect of aerobic exercise training

AIMS

1) Characterize the progression of exercise intolerance in monocrotaline-induced pulmonary hypertension (PH) in mice and 2) evaluate the therapeutic effect of aerobic exercise training (AET) on counteracting skeletal and cardiac dysfunction in PH.

MAIN METHODS

Wild type C57BL6/J mice were studied in two different time points: 2 months and 4 months. Exercise tolerance was evaluated by graded treadmill exercise test. The AET was performed in the last month of treatment of 4 months' time point. Cardiac function was evaluated by echocardiography. Skeletal muscle cross-sectional area was assessed by immunofluorescence. The diameter of cardiomyocytes and pulmonary edema were quantified by staining with hematoxylin-eosin. The variables were compared among the groups by two-way ANOVA or non-paired Student's t-test. Significance level was set at p < 0.05.

KEY FINDINGS

After 2 months of MCT treatment, mice presented pulmonary edema, right cardiac dysfunction and left ventricle hypertrophy. After 4 months of MCT treatment, mice showed pulmonary edema, right and left cardiac dysfunction and remodeling associated with exercise intolerance and skeletal muscle atrophy. AET was able to reverse cardiac left ventricle dysfunction and remodeling, prevent exercise intolerance and skeletal muscle dysfunction. Thus, our data provide evidence of skeletal muscle abnormalities on advanced PH. AET was efficient in inducing an anti-cardiac remodeling effect besides preventing exercise intolerance.

SIGNIFICANCE

Our study provides a robust model of PH in mice, as well as highlights the importance of AET as a preventive strategy for exercise intolerance and, skeletal and cardiac muscle abnormalities in PH.

Inspiratory Muscle Training Improves Inspiratory Muscle Strength and Functional Exercise Capacity in Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension: A Pilot Randomised Controlled Study

BACKGROUND

Exercise intolerance is present even in the early stages of pulmonary arterial hypertension (PAH) and is associated with poorer prognosis. Respiratory muscle dysfunction is common and may contribute to exercise limitation. We sought to investigate the effects of inspiratory muscle training (IMT) to improve exercise capacity in PAH.

METHODS

Adults with PAH were prospectively recruited and randomly assigned to either IMT or a control group. At baseline and after 8 weeks, assessment of respiratory muscle function, pulmonary function, neurohormonal activation, 6-minute walk distance and cardiopulmonary exercise testing variables were conducted. Inspiratory muscle strength was assessed by maximal static inspiratory pressure (PImax). The IMT group performed two cycles of 30 breaths at 30-40% of their PImax 5 days a week for 8 weeks.

RESULTS

Twelve (12) PAH patients (60±14 years, 10 females) were recruited and randomised (six in the IMT group and six in the control group). After 8 weeks, the IMT group improved PImax by 31 cmH₂O compared with 10 cmH₂O in controls, p=0.02. Following IMT, 6-minute walk distance improved by 24.5 m in the IMT group and declined by 12 m in the controls (mean difference 36.5 m, 95% CI 3.5-69.5, p=0.03). There was no difference in peak oxygen uptake between-groups (mean difference 0.4 mL/kg/min, 95% CI -2.6 to 3.4, p=0.77). There was no difference in the mean change between-groups in neurohormonal activation or pulmonary function.

CONCLUSION

In this pilot randomised controlled study, IMT improved PImax and 6-minute walk distance in PAH patients.

Beyond the genome: challenges and potential for epigenetics-driven therapeutic approaches in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a devastating disease of the cardiopulmonary system caused by the narrowing of the pulmonary arteries, leading to increased vascular resistance and pressure. This leads to right ventricle remodeling, dysfunction, and eventually, death. While conventional therapies have largely focused on targeting vasodilation, other pathological features of PAH including aberrant inflammation, mitochondrial dynamics, cell proliferation, and migration have not been well explored. Thus, despite some recent improvements in PAH treatment, the life expectancy and quality of life for patients with PAH remains poor. Showing many similarities to cancers, PAH is characterized by increased pulmonary arterial smooth muscle cell proliferation, decreased apoptotic signaling pathways, and changes in metabolism. The recent successes of therapies targeting epigenetic modifiers for the treatment of cancer has prompted epigenetic research in PAH, revealing many new potential therapeutic targets. In this minireview we discuss the emergence of epigenetic dysregulation in PAH and highlight epigenetic-targeting compounds that may be effective for the treatment of PAH.

Supervised pulmonary hypertension exercise rehabilitation (SPHERe): study protocol for a multi-centre randomised controlled trial

Background

Supervised cardio-pulmonary rehabilitation may be safe and beneficial for people with pulmonary hypertension (PH) in groups 1 (pulmonary arterial hypertension) and 4 (chronic thromboembolic disease), particularly as a hospital in-patient. It has not been tested in the most common PH groups; 2 (left heart disease), 3 (lung disease), or 5 (other disorders). Further it has not been evaluated in the UK National Health Service (NHS) out-patient setting, or with long-term follow-up. The aim of this randomised controlled trial (RCT) is to test the clinical and cost-effectiveness of a supervised exercise rehabilitation intervention with psychosocial support compared to best practice usual care for people with PH in the community/outpatient setting.

Methods

This multi-centre, pragmatic, two-arm RCT with embedded process evaluation aims to recruit 352 clinically stable adults with PH (groups 1–5) and WHO functional class II-IV. Participants will be randomised to either the Supervised Pulmonary Hypertension Exercise Rehabilitation (SPHERe) intervention or control. The SPHERe intervention consists of 1) individual assessment and familiarisation sessions; 2) 8-week, twice-weekly, supervised out-patient exercise training; 3) psychosocial/motivational support and education; 4) guided home exercise plan. The control intervention consists of best practice usual care with a single one-to-one practitioner appointment, and general advice on physical activity. Outcomes will be measured at baseline, 4 months (post-intervention) and 12 months by researchers blinded to treatment allocation. The primary outcome is the incremental shuttle walk test at 4 months. Secondary outcomes include health-related quality of life (HRQoL), time to clinical worsening and health and social care use. A purposive sample of participants (n = 20 intervention and n = 20 control) and practitioners (n = 20) will be interviewed to explore experiences of the trial, outcomes and interventions.

Discussion

The SPHERe study is the first multi-centre clinical RCT to assess the clinical and cost effectiveness of a supervised exercise rehabilitation intervention compared to usual care, delivered in the UK NHS, for people in all PH groups. Results will inform clinicians and commissioners as to whether or not supervised exercise rehabilitation is effective and should be routinely provided for people with PH.

Trial registration

ISRCTN no. 10608766, prospectively registered on 18th March 2019.

Reliability and responsiveness of incremental shuttle walk test to estimate exercise capacity in patients with pulmonary arterial hypertension

The purpose of the present study was to evaluate the reliability and responsiveness of the incremental shuttle walk test (ISWT) to estimate exercise capacity in patients with pulmonary arterial hypertension (PAH). This was a cross-sectional longitudinal study performed on stable PAH patients (n=30, mean age ± standard deviation, 60±13.6 years) with World Health Organization functional class II & III. Reliability was assessed by comparing the distance covered between ISWT-1 (initial) and ISWT-2 (retest). Responsiveness was determined by comparing the distance covered in the ISWT-3 post pulmonary rehabilitation (PR) to the ISWT-1. The distance covered between ISWT-1 (177±87.85 m) and ISWT-2 (191.67±96.39 m) was not statistically significant. The result of the relative reliability has shown to be excellent with an intraclass correlation coefficient (ICC2,1= 0.98, 95%CI = 0.95-0.99). Absolute reliability was evaluated through the standard error of the measurement and minimal detectable change at a 95% confidence interval (MDC95) were 12.29 and 33.9 m, respectively. Bland Altman plot showed good agreement between the two ISWTs. Following PR, the effect size (ES=0.78) and standardised response mean (SRM=1.50) were moderate and large respectively. ISWT is considered to be a reliable and responsive measure to estimate exercise capacity in patients with PAH. The ISWT may be considered a suitable alternative tool over a 6-min walk test and in the absence of equipment availability or expertise for conducting cardiopulmonary exercise test for the assessment of exercise capacity in these patients.

Mechanical cardiopulmonary interactions during exercise in health and disease

The heart and lungs are anatomically coupled through the pulmonary circulation and coexist within the sealed thoracic cavity, making the function of these systems highly interdependent. Understanding of the complex mechanical interactions between cardiac and pulmonary systems has evolved over the last century to appreciate that changes in respiratory mechanics significantly impact pulmonary hemodynamics and ventricular filling and ejection. Furthermore, given that the left and right heart share a common septum and are surrounded by the nondistensible pericardium, direct ventricular interaction is an important mediator of both diastolic and systolic performance. Although it is generally considered that cardiopulmonary interaction in healthy individuals at rest minimally affects hemodynamics, the significance during exercise is less clear. Adverse heart-lung interaction in respiratory disease is of growing interest as it may contribute to the pathogenesis of comorbid cardiovascular dysfunction and exercise intolerance in these patients. Similarly, heart failure represents a pathological uncoupling of the cardiovascular and pulmonary systems, whereby cardiac function may be impaired by the normal ventilatory response to exercise. Despite significant research contributions to this complex area, the mechanisms of cardiopulmonary interaction in the intact human and the clinical consequences of adverse interactions in common respiratory and cardiovascular diseases, particularly during exercise, remain incompletely understood. The purpose of this review is to present the key physiological principles of cardiopulmonary interaction as they pertain to resting and exercising hemodynamics in healthy humans and the clinical implications of adverse cardiopulmonary interaction during exercise in chronic obstructive pulmonary disease (COPD), pulmonary hypertension, and heart failure.

Gremlin-1 is a key regulator of endothelial-to-mesenchymal transition in human pulmonary artery endothelial cells

BACKGROUND

Endothelial-to-mesenchymal transition (EndMT) has been implicated in initiation and progression of pulmonary arterial hypertension (PAH). Gremlin-1 promotes vascular remodeling of PAH and mediates epithelial-mesenchymal transition, which is similar to EndMT. In the present study we investigated the potential role of gremlin-1 plays in EndMT of pulmonary artery endothelial cells (PAECs).

METHODS

Immunofluorescence staining was performed to detect the expression of alpha smooth muscle actin (α-SMA) and von Willebrand factor (VWF). Migration and angiogenic responses of PAECs were determined by transwell assay and tube formation assay, respectively. Protein expression levels were determined by western blotting.

RESULTS

Gremlin-1 induced EndMT of PAECs in a phospho-smad2/3-dependent manner. This was characterized by the loss of platelet endothelial cell adhesion molecule 1 and an increase in protein levels of a-SMA, nerve-cadherin, and matrix metalloproteinase 2. It was also determined that gremlin-1 facilitated the migration and angiogenic responses of PAECs in a dose-dependent manner. Bone morphogenetic protein 7 (BMP-7) was found to attenuate gremlin-1-mediated EndMT, migration and angiogenesis of PAECs by inducing phosphorylation of Smad1/5/8 and suppressing phosphorylation of Smad2/3.

CONCLUSION

Gremlin-1 mediates EndMT in PAECs, and BMP-7 reverses gremlin-1-induced EndMT by an induction of p-Smad1/5/8 and suppression of p-Smad2/3.

Predictors for plication performance following diaphragmatic paralysis in children

INTRODUCTION AND OBJECTIVES

Diaphragmatic paralysis (DP) in children can result from various etiologies. Guidelines for patient selection for diaphragmatic plication (DPL) are lacking. Our objectives were to describe the etiologies of DP and to determine the risk factors and predictors for DPL in the pediatric population.

METHODS

Retrospective data were retrieved from departmental databases on patients with DP from the pediatric, cardiac, and neonatal intensive care departments of Safra Children's Hospital from 2010 to 2017.

RESULTS

DP was diagnosed in 88 patients, 29 with noncardiac surgery-related etiologies, for example, congenital, surgery, trauma, and shock and 59 with cardiac surgery-related etiologies. In total, 27 (31%) patients underwent DPL, and they had significant comorbidities involving respiratory, central nervous, and cardiovascular systems, higher lung injury scores, and lower weight compared with the patients who did not undergo DPL (P = .002, P = .002, P < .001, P = .012, and P = .013, respectively). A multivariate regression model revealed significant independent predictors for DPL, including morbidities of central nervous (odds ratio [OR = 9.651, P = .005), respiratory (OR = 4.875, P = .039), and cardiovascular systems (OR = 23.938, P = .001).

CONCLUSIONS

Etiologies of DP are very diverse in the pediatric population. Comorbidities of respiratory, central nervous, and cardiovascular systems are risk factors for plication requirement in respiratory support-dependent pediatric patients with DP. Early DPL should be considered in these patients.

Effects of neuromuscular electrical stimulation in patients with pulmonary arterial hypertension: a randomized controlled pilot study

BACKGROUND

Patients with pulmonary arterial hypertension (PAH) present impairments in muscle strength and exercise capacity. There is growing evidence about the benefits of neuromuscular electrical stimulation (NMES) in patients with respiratory diseases, except in patients with PAH. The aim of this study was to investigate the effects of NMES on muscle strength, and other physical and psychosocial variables in patients with PAH.

METHODS

Patients with PAH were randomly divided into two groups as NMES and control. The NMES was applied to the bilateral deltoid and quadriceps femoris muscles with 50 Hz for 3 days/week, 8 weeks for the NMES group. Muscle strength, muscle cross-sectional area and thickness, arterial stiffness, exercise capacity, functional mobility and balance, balance confidence, fatigue, physical activity, and quality of life were assessed at baseline and after 8 weeks by blinded assessors.

RESULTS

There was no significant difference in the demographic and clinical characteristics between the patient groups (p > 0.05). The improvements in muscle strength, muscle cross-sectional area and thickness, pulse wave velocity, exercise capacity, functional mobility and balance, balance confidence, fatigue, physical activity, and quality of life were significantly higher in the NMES group compared to the control group (p < 0.05).

CONCLUSIONS

This study suggests that NMES intervention is safe and effective for patients with PAH.

Pertinent clinical outcomes in pediatric survivors of pediatric acute respiratory distress syndrome (PARDS): a narrative review

The objectives of this review are to describe the limitations of commonly used clinical outcomes [e.g., mortality, ventilation parameters, need for extracorporeal membrane oxygenation (ECMO), pediatric intensive care unit (PICU) and hospital length of stay (LOS)] in pediatric acute respiratory distress syndrome (PARDS) studies; and to explore other pertinent clinical outcomes that pediatric critical care practitioners should consider in future clinical practice and research studies. These include long-term pulmonary function, risk of pulmonary hypertension (PHT), nutrition status and growth, PICU-acquired weakness, neurological outcomes and neurocognitive development, functional status, health-related quality of life (HRQOL)], health-care costs, caregiver and family stress. PubMed was searched using the following keywords or medical subject headings (MESH): "acute lung injury (ALI)", "acute respiratory distress syndrome (ARDS)", "pediatric acute respiratory distress syndrome (PARDS)", "acute hypoxemia respiratory failure", "outcomes", "pediatric intensive care unit (PICU)", "lung function", "pulmonary hypertension", "growth", "nutrition', "steroid", "PICU-acquired weakness", "functional status scale", "neurocognitive", "psychology", "health-care expenditure", and "HRQOL". The concept of contemporary measure outcomes was adapted from adult ARDS long-term outcome studies. Articles were initially searched from existing PARDS articles pool. If the relevant measure outcomes were not found, where appropriate, we considered studies from non-ARDS patients within the PICU in whom these outcomes were studied. Long-term outcomes in survivors of PARDS were not follow-up in majority of pediatric studies regardless of whether the new or old definitions of ARDS in children were used. Relevant studies were scarce, and the number of participants was small. As such, available studies were not able to provide conclusive answers to most of our clinical queries. There remains a paucity of data on contemporary clinical outcomes in PARDS studies. In addition to the current commonly used outcomes, clinical researchers and investigators should consider examining these contemporary outcome measures in PARDS studies in the future.

Diaphragm function does not independently predict exercise intolerance in patients with precapillary pulmonary hypertension after adjustment for right ventricular function

Background: Several determinants of exercise intolerance in patients with precapillary pulmonary hypertension (PH) due to pulmonary arterial hypertension and/or chronic thromboembolic PH (CTEPH) have been suggested, including diaphragm dysfunction. However, these have rarely been evaluated in a multimodal manner. Methods: Forty-three patients with PH (age 58 ± 17 years, 30% male) and 43 age- and gender-matched controls (age 54 ± 13 years, 30% male) underwent diaphragm function (excursion and thickening) assessment by ultrasound, standard spirometry, arterial blood gas analysis, echocardiographic assessment of pulmonary artery pressure (PAP), assay of amino-terminal pro-brain natriuretic peptide (NT-proBNP) levels, and cardiac magnetic resonance (CMR) imaging to evaluate right ventricular systolic ejection fraction (RVEF). Exercise capacity was determined using the 6-min walk distance (6MWD). Results: Excursion velocity during a sniff maneuver (SniffV, 4.5 ± 1.7 vs. 6.8 ± 2.3 cm/s, P<0.01) and diaphragm thickening ratio (DTR, 1.7 ± 0.5 vs. 2.8 ± 0.8, P<0.01) were significantly lower in PH patients versus controls. PH patients with worse exercise tolerance (6MWD <377 vs. ≥377 m) were characterized by worse SniffV, worse DTR, and higher NT-pro-BNP levels as well as by lower arterial carbon dioxide levels and RVEF, which were all univariate predictors of exercise limitation. On multivariate analysis, the only independent predictors of exercise limitation were RVEF (r = 0.47, P=0.001) and NT-proBNP (r = −0.27, P=0.047). Conclusion: Patients with PH showed diaphragm dysfunction, especially as exercise intolerance progressed. However, diaphragm dysfunction does not independently contribute to exercise intolerance, beyond what can be explained from right heart failure.

Dynamic right ventricular-pulmonary arterial uncoupling during maximum incremental exercise in exercise pulmonary hypertension and pulmonary arterial hypertension

Despite recent advances, the prognosis of pulmonary hypertension (PH) remains poor. While the initial insult in PH implicates the pulmonary vasculature, the functional state, exercise capacity, and survival of such patients are closely linked to right ventricular (RV) function. In the current study, we sought to investigate the effects of maximum incremental exercise on the matching of RV contractility and afterload (i.e. right ventricular-pulmonary arterial [RV-PA] coupling) in patients with exercise PH (ePH) and pulmonary arterial hypertension (PAH). End-systolic elastance (Ees), pulmonary arterial elastance (Ea), and RV-PA coupling (Ees/Ea) were determined using single-beat pressure-volume loop analysis in 40 patients that underwent maximum invasive cardiopulmonary exercise testing. Eleven patients had ePH, nine had PAH, and 20 were age-matched controls. During exercise, the impaired exertional contractile reserve in PAH was associated with blunted stroke volume index (SVI) augmentation and reduced peak oxygen consumption (peak VO₂ %predicted). Compared to PAH, ePH demonstrated increased RV contractility in response to increasing RV afterload during exercise; however, this was insufficient and resulted in reduced peak RV-PA coupling. The dynamic RV-PA uncoupling in ePH was associated with similarly blunted SVI augmentation and peak VO₂ as PAH. In conclusion, dynamic rest-to-peak exercise RV-PA uncoupling during maximum exercise blunts SV increase and reduces exercise capacity in exercise PH and PAH. In ePH, the insufficient increase in RV contractility to compensate for increasing RV afterload during maximum exercise leads to deterioration of RV-PA coupling. These data provide evidence that even in the early stages of PH, RV function is compromised.

Novel insights into the molecular mechanisms underlying the beneficial effects of exercise training on pulmonary arterial hypertension

BACKGROUND

Recent animal and clinical studies report that exercise training exerts positive influences in pulmonary arterial hypertension (PAH); however, the underlying mechanisms are largely unknown. To give insight into the molecular mechanisms of the improvement effects, we performed gene expression analysis.

METHODS

Three Gene Expression Omnibus (GEO) datasets were analyzed, including peripheral blood mononuclear (PBMC) gene expression profiles of exercise training in men and patients with PAH. Differentially expressed genes (DEGs) in each dataset were identified, and then, the common DEGs positively regulated by PAH and negatively regulated by exercise training, or the opposite, were further identified. Subsequently, biological processes and pathways were analyzed.

RESULTS

A total of 7229 DEGs with logFC>0.3 and P<0.05 were identified in exercise, whereas 749 and 2207 DEGs were identified in PAH from the two datasets. After overlapping the whole DEGs from all three datasets, total 16 common DEGs were identified, including BCLAF1, SATB1 and ZFP36L2. Seven of them were up-regulated in exercise training and down-regulated in PAH, and the others were opposite. In addition, these common DEGs were mainly enriched in negative regulation of cellular process, negative regulation of biological process and negative regulation of cellular macromolecule biosynthetic process.

CONCLUSIONS

Some genes have been implicated in the improvement of pulmonary vascular remodeling and PAH. These findings could not only improve the knowledge about the molecular mechanisms underlying the beneficial effects of exercise training on PAH, but also provide clues for further clinical and animal studies.

Exercise rehabilitation programmes for pulmonary hypertension: a systematic review of intervention components and reporting quality

Objectives

To identify the components, and assess the reporting quality, of exercise training interventions for people living with pulmonary hypertension.

Design

Systematic review with analysis of intervention reporting quality using the Consensus on Exercise Reporting Template (CERT).

Data sources

Eligible studies in the Cochrane Systematic Review of exercise-based rehabilitation for pulmonary hypertension, updated with a new search of relevant databases from 1 August 2016 to 15 January 2018.

Eligibility criteria

Peer-reviewed journal articles of randomised and non-randomised controlled trials, and non-controlled prospective observational studies, investigating dynamic exercise training interventions in adult humans with diagnosed pulmonary hypertension, reporting on at least one physiological and/or psychosocial outcome.

Results

Interventions typically involved cycle ergometry and walking. They were delivered as 3-week inpatient, or outpatient and/or home-based programmes, lasting for 4–15 weeks. Components relating specifically to exercise prescription were described satisfactorily and in more detail than motivational/behavioural change strategies, adherence and fidelity. Mean CERT score was 13.1 (range 8–17) out of a possible maximum score of 19. No studies fully reported every aspect of an exercise intervention to the standard recommended by CERT.

Summary/conclusion

Considerable variability was evident in the components and reporting quality of interventions for exercise rehabilitation studies in pulmonary hypertension. Interventional studies using exercise training should pay greater attention to describing motivational/behavioural change strategies, adherence and fidelity. Detailed description of these parameters is essential for the safe and effective replication of exercise rehabilitation interventions for pulmonary hypertension in clinical practice.

Trial registration number

CRD42018085558.

Increasing quality of life in pulmonary arterial hypertension: is there a role for nutrition?

Pulmonary arterial hypertension (PAH) is a progressive disease primarily affecting the pulmonary vasculature and heart. PAH patients suffer from exercise intolerance and fatigue, negatively affecting their quality of life. This review summarizes current insights in the pathophysiological mechanisms underlying PAH. It zooms in on the potential involvement of nutritional status and micronutrient deficiencies on PAH exercise intolerance and fatigue, also summarizing the potential benefits of exercise and nutritional interventions. Pubmed/Medline, Scopus, and Web of Science were searched for publications on pathophysiological mechanisms of PAH negatively affecting physical activity potential and nutritional status, and for potential effects of interventions involving exercise or nutritional measures known to improve exercise intolerance. Pathophysiological processes that contribute to exercise intolerance and impaired quality of life of PAH patients include right ventricular dysfunction, inflammation, skeletal muscle alterations, and dysfunctional energy metabolism. PAH-related nutritional deficiencies and metabolic alterations have been linked to fatigue, exercise intolerance, and endothelial dysfunction. Available evidence suggests that exercise interventions can be effective in PAH patients to improve exercise tolerance and decrease fatigue. By contrast, knowledge on the prevalence of micronutrient deficiencies and the possible effects of nutritional interventions in PAH patients is limited. Although data on nutritional status and micronutrient deficiencies in PAH are scarce, the available knowledge, including that from adjacent fields, suggests that nutritional intervention to correct deficiencies and metabolic alterations may contribute to a reduction of disease burden.