Pulmonary hypertension and cardiac function in adult cystic fibrosis: role of hypoxemia

Pulmonary Vascular Dysfunctions in Cystic Fibrosis

Cystic fibrosis (CF) is an inherited disorder caused by a deleterious mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Given that the CFTR protein is a chloride channel expressed on a variety of cells throughout the human body, mutations in this gene impact several organs, particularly the lungs. For this very reason, research regarding CF disease and CFTR function has historically focused on the lung airway epithelium. Nevertheless, it was discovered more than two decades ago that CFTR is also expressed and functional on endothelial cells. Despite the great strides that have been made in understanding the role of CFTR in the airway epithelium, the role of CFTR in the endothelium remains unclear. Considering that the airway epithelium and endothelium work in tandem to allow gas exchange, it becomes very crucial to understand how a defective CFTR protein can impact the pulmonary vasculature and overall lung function. Fortunately, more recent research has been dedicated to elucidating the role of CFTR in the endothelium. As a result, several vascular dysfunctions associated with CF disease have come to light. Here, we summarize the current knowledge on pulmonary vascular dysfunctions in CF and discuss applicable therapies.

What the future holds: cystic fibrosis and aging

Cystic fibrosis (CF) is one of the most common genetic diseases with around 70,000 affected patients worldwide. CF is a multisystem disease caused by a mutation in the CF transmembrane conductance regulator gene, which has led to a significant decrease in life expectancy and a marked impairment in the quality of life for people with CF (pwCF). In recent years, the use of highly effective CFTR modulator therapy (HEMT) has led to improved pulmonary function, fewer CF exacerbations, lower symptom burden, and increased weight. This has coincided with an increased life expectancy for pwCF, with mean age of survival being now in the 50s. This being a major breakthrough, which the CF population has hoped for, pwCF are now facing new challenges by growing old with a chronic respiratory disease. In this mini review, we are attempting to summarize the current knowledge of the aging process and its effect on CF disease and its manifestations including new developments, the current research gaps and potential future developments in the field to allow healthy aging for the CF community.

MRI evaluation of right heart functions in children with mild cystic fibrosis

BACKGROUND

This study aimed to assess the ventricular anatomy, function of the right ventricle, and the haemodynamic findings of pulmonary artery in children with cystic fibrosis using cardiac MRI.

PATIENTS

This prospective study consisted of 32 children with mild cystic fibrosis and 30 age-matched healthy control participants.

METHODS

Cardiac MRI was used to assess right ventricular volumes, anatomy, and function and to assessment of haemodynamic findings of pulmonary artery in the control and study groups. Haemodynamic findings of pulmonary arteries were determined using pulmonary arteries peak velocity (cm/s), and pulmonary arteries time-to-peak velocity (ms) and pulmonary artery systolic pressure. All data of children with mild cystic fibrosis were compared with those of 30 age-matched healthy control group participants.

RESULTS

Our patients and their age-matched controls were aged from 6 to 17 years and from 7 to 15 years, respectively. We found that ejection fraction (%), cardiac output (L/ml), cardiac output (L/ml/m2), and systolic volume (ml/m2) were significantly lower in children with cystic fibrosis (p < 0.01). Right ventricular anterior wall thickness (mm) was significantly higher in children with cystic fibrosis (p = 0.01). No significant difference was observed between the haemodynamic parameters of pulmonary artery in the patient group.

CONCLUSION

In our study, cardiac MRI was used to investigate whether the right ventricle was affected functionally and anatomically in children with mild cystic fibrosis. We detected a significant decrease in right ventricular systolic functions and notable alterations in the right ventricular geometry of children with mild cystic fibrosis. These alterations usually manifest themselves as hypertrophy of the right ventricle. Our study's results demonstrate no relationship between the development of pulmonary hypertension in mild cystic fibrosis children.

Effects of Elexacaftor/Tezacaftor/Ivacaftor on Cardiorespiratory Polygraphy Parameters and Respiratory Muscle Strength in Cystic Fibrosis Patients with Severe Lung Disease

BACKGROUND

Cystic fibrosis transmembrane conductance regulator (CFTR) modulators represent targeted therapies directly acting on the CFTR channel. The triple therapy Elexacaftor/Tezacaftor/Ivacaftor (ELX/TEZ/IVA) has been demonstrated to improve lung function and quality of life in cystic fibrosis (CF) patients. However, the effects of ELX/TEZ/IVA on sleep-disordered breathing (SDB) and respiratory muscle strength are poorly studied. The aim of this study was to assess the effects of ELX/TEZ/IVA in patients with CF and severe lung disease on cardiorespiratory polygraphy parameters, maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) measures.

METHODS

patients with CF aged ≥ 12 who started treatment in a compassionate use program were retrospectively studied through the evaluation of nocturnal cardiorespiratory polygraphy parameters, MIP and MEP; and six-minute walk test (6MWT) at baseline and at months 3, 6, and 12 of treatment.

RESULTS

Nine patients (mean age 30.3 ± 6.5 years) with severe CF (mean baseline ppFEV1 34.6 ± 5.1%) were evaluated. A significant improvement in nocturnal oxygenation measured by mean SpO2 (92.4 vs. 96.4%, p < 0.05), time spent with SpO2 ≤ 90% (-12.6, -14.6, -15.2 min from baseline at months 3, 6, and 12, respectively, p < 0.05), and respiratory rate (RR) was shown, at month 12 and across the time points compared with baseline, as well as in respiratory muscle strength, although only the change in MEP was significant.

CONCLUSIONS

We provide further evidence on the efficacy of the CFTR modulators ELX/TEZ/IVA, adding information about their effect on the respiratory muscles' performance and cardiorespiratory polygraphy parameters in CF patients with severe lung disease.

Obstructive sleep apnea and nocturnal hypoxemia in adult patients with cystic fibrosis

Background

Obstructive sleep apnea (OSA), nocturnal hypoxemia and excessive daytime sleepiness (EDS) are common comorbidities in people with cystic fibrosis (pwCF). Most of the data showing this originates from children and adolescents. The aim of this study was to collect data on sleep parameters, EDS and pulmonary function from a large cohort of adult pwCF.

Methods

Full overnight polysomnography (PSG) was performed. EDS was determined using the Epworth Sleepiness Scale (ESS). Demographic and clinical data (body mass index [BMI], pulmonary function, capillary blood gases) were collected.

Results

A total of 52 adult pwCF were included (mean age 30.7 ± 8.0 years, mean percent predicted forced expiratory volume in 1 s [ppFEV1] of 52.1 ± 14.8). Overall AHI was in the normal range (4.5 ± 4.0/h); 21/52 pwCF (40%) had an apnea-hypopnea index > 5/h. Nocturnal hypoxemia was found in 25% of participants and this was associated with ppFEV1 (p = 0.014), awake oxygen saturation (SpO2; p = 0.021) and awake partial pressure of oxygen (pO2; p = 0.003); there were no significant differences in age, lung function and BMI were found for pwCF with versus without OSA (all p > 0.05). Eight pwCF (15%) had an ESS score > 10 (indicating EDS). OSA was best predicted by awake pO2 (area under the curve [AUC] 0.66, p = 0.048), while nocturnal hypoxemia was best predicted by ppFEV1 (AUC 0.74, p = 0.009), awake pO2 (AUC 0.76, p = 0.006) and awake SpO2 (AUC 0.71; p = 0.025).

Conclusion

OSA, nocturnal hypoxemia and EDS were common in adult pwCF, but no strong predictors were identified. Therefore, we suggest regular PSG and ESS scoring in adult pwCF, regardless of disease severity.

The Efficacy of an N-Acetylcysteine-Antibiotic Combination Therapy on Achromobacter xylosoxidans in a Cystic Fibrosis Sputum/Lung Cell Model

Cystic fibrosis (CF) is a disorder causing dysfunctional ion transport resulting in the accumulation of viscous mucus. This environment fosters a chronic bacterial biofilm-associated infection in the airways. Achromobacter xylosoxidans, a gram-negative aerobic bacillus, has been increasingly associated with antibiotic resistance and chronic colonisation in CF. In this study, we aimed to create a reproducible model of CF infection using an artificial sputum medium (ASMDM-1) with bronchial (BEAS-2B) and macrophage (THP-1) cells to test A. xylosoxidans infection and treatment toxicity. This study was conducted in three distinct stages. First, the tolerance of BEAS-2B cell lines and two A. xylosoxidans strains against ASMDM-1 was optimised. Secondly, the cytotoxicity of combined therapy (CT) comprising N-acetylcysteine (NAC) and the antibiotics colistin or ciprofloxacin was tested on cells alone in the sputum model in both BEAS-2B and THP-1 cells. Third, the efficacy of CT was assessed in the context of a bacterial infection within the live cell/sputum model. We found that a model using 20% ASMDM-1 in both cell populations tolerated a colistin-NAC-based CT and could significantly reduce bacterial loads in vitro (~2 log10 CFU/mL compared to untreated controls). This pilot study provides the foundation to study other bacterial opportunists that infect the CF lung to observe infection and CT kinetics. This model also acts as a springboard for more complex co-culture models.

Pulmonary Complications in Cystic Fibrosis: Past, Present, and Future

Cystic fibrosis (CF) is an autosomal recessive genetic condition with multisystemic disease manifestations, the most prominent of which occur in the respiratory system. Despite significant developments in disease understanding and therapeutics, each contributing to improved lung function and survival in patients with CF, several pulmonary complications, including pneumothorax, massive hemoptysis, and respiratory failure, continue to occur. In this review, we briefly describe each of these complications and their management and discuss how they impact the care and disease trajectory of individuals in whom they occur. Finally, we discuss the evolving role that palliative care and CF transmembrane conductance regular modulator therapies play in the natural disease course and care of patients with CF.

Involvement of CFTR in the pathogenesis of pulmonary arterial hypertension

INTRODUCTION

A reduction in pulmonary artery (PA) relaxation is a key event in pulmonary arterial hypertension (PAH) pathogenesis. CFTR dysfunction in airway epithelial cells plays a central role in cystic fibrosis (CF); CFTR is also expressed in PAs and has been shown to control endothelium-independent relaxation.

AIM AND OBJECTIVES

We aimed to delineate the role of CFTR in PAH pathogenesis through observational and interventional experiments in human tissues and animal models.

METHODS AND RESULTS

RT-Q-PCR, confocal imaging and electron microscopy showed that CFTR expression was reduced in PAs from patients with idiopathic PAH (iPAH) and in rats with monocrotaline-induced pulmonary hypertension (PH). Moreover, using myograph on human, pig and rat PAs, we demonstrated that CFTR activation induces PAs relaxation. CFTR-mediated PA relaxation was reduced in PAs from iPAH patients and rats with monocrotaline- or chronic hypoxia-induced PH. Long-term in vivo CFTR inhibition in rats significantly increased right ventricular systolic pressure, which was related to exaggerated pulmonary vascular cell proliferation in situ and vessel neomuscularization. Pathologic assessment of lungs from patients with severe CF (F508del-CFTR) revealed severe PA remodeling with intimal fibrosis and medial hypertrophy. Lungs from homozygous F508delCftr rats exhibited pulmonary vessel neomuscularization. The elevations in right ventricular systolic pressure and end diastolic pressure in monocrotaline-exposed rats with chronic CFTR inhibition were more prominent than those in vehicle-exposed rats.

CONCLUSIONS

CFTR expression is strongly decreased in PA smooth muscle and endothelial cells in human and animal models of PH. CFTR inhibition increases vascular cell proliferation and strongly reduces PA relaxation.

Assessment of Right Heart Functions in Children with Mild Cystic Fibrosis

BACKGROUND

Cystic fibrosis (CF) is a multisystemic disease that prevalently involves the lungs. Hypoxemia occurs due to the existing of progressive damage to the pulmonary parenchyma and pulmonary vessels. The condition may cause systolic and diastolic dysfunction to the right ventricle due to the effects of high pulmonary artery systolic pressure (PASP). The study aimed to determine echocardiographic alterations in PASP, right ventricle (RV) anatomy, and functions in mild CF children.

MATERIALS AND METHODS

RV anatomy, systolic, and diastolic functions were evaluated with conventional echocardiographic measurements. Estimated PASP was used measured with new echocardiographic modalities, including pulmonary artery acceleration time (PAAT), right ventricular ejection time (RVET), and their ratio (PAAT/RVET). The obtained echocardiographic data were statistically compared between the patient group and the control group.

RESULTS

The study consisted of 30 pediatric patients with mild CF and 30 healthy children with similar demographics. In patient group, conventional parameters disclosed differences in RV anatomy, both systolic and diastolic functions of RV compared with the healthy group. We did not compare the patient group with published standard data because of the wide range variability. However, new echocardiographic parameters showed notable increase in pulmonary artery pressure compared with values of control group and published standard data (p<0.001).

CONCLUSION

Elevated PASP, RV failure, and Cor pulmonale usually begin early in children with mild CF. In addition to routine echocardiographic measurements to evaluate RV, we recommend the use of new echocardiographic modalities for routine examinations and in the follow up of children with mild CF.

A bird eye view on cystic fibrosis: An underestimated multifaceted chronic disorder

Cystic fibrosis (CF) is an autosomal recessive disease which involves the mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CF involves in the inflammatory processes and is considered as a multisystem disorder that is not confined to lungs, but it also affects other vital organs that leads to numerous co-morbidities. The respiratory disorder in the CF results in mortality and morbidity which is characterized by series of serious events involving mucus hypersecretion, microbial infections, airways obstruction, inflammation, destruction of epithelium, tissue remodeling and terminal lung diseases. Mucins are the high molecular weight glycoproteins important for the viscoelastic properties of the mucus, play a significant role in the disease mechanisms. Determining the functional association between the CFTR and mucins might help to identify the putative target for specific therapeutic approach. In fact, furin enzyme which helps in the entry of novel COVID-19 virus into the cell, is upregulated in CF and this can also serve as a potential target for CF treatment. Moreover, the use of nano-formulations for CF treatment is an area of research being widely studied as they have also demonstrated promising outcomes. The in-depth knowledge of non-coding RNAs like miRNAs and lncRNAs and their functional association with CFTR gene expression and mutation can provide a different range of opportunity to identify the promising therapeutic approaches for CF.

Sleep-disordered breathing and markers of morbidity in children and adolescents with cystic fibrosis

BACKGROUND

Studies have shown that sleep disorders occur in cystic fibrosis (CF) patients and may be present before daytime clinical manifestations.

OBJECTIVES

To evaluate the presence of sleep disorders among children and adolescents with CF, attempting to identify associations with pulmonary function, nutritional status, days in hospital, and days taking antibiotics.

METHODS

Individuals with a diagnosis of CF aged between 6 and 18 years were included. Information on sociodemographic, clinical profile, history of hospitalizations, and use of antibiotics in the last year were collected. Spirometry, bioimpedance, and polysomnography were performed. The presence of nocturnal hypoxemia and obstructive sleep apnea syndrome (OSAS) were evaluated and participants divided according to their presence.

RESULTS

Thirty-one patients were included. The prevalence of OSAS was 32.3% and nocturnal hypoxemia was 29.0%. Average nocturnal peripheral oxyhemoglobin saturation (SpO₂ ) correlated (P < .001) with forced vital capacity (r = .55) and forced expiratory volume in the first second (r = .62). The higher the percentage of total sleep time (TST) with SpO₂ less than 90%, the lower the pulmonary function. Individuals with OSAS and nocturnal hypoxemia had lower spirometric values compared to patients without these disorders, but the nocturnal hypoxemia group also had lower Shwachman-Kulczycki score, longer hospitalization time and antibiotic use. TST with SpO₂ less than 90% was associated with length of hospitalization (r²  = .53).

CONCLUSION

Children and adolescents with CF have sleep disorders, including OSAS (32.3%) and nocturnal hypoxemia (29%). Individuals with nocturnal hypoxemia presented lower lung function, worse clinical score, and higher morbidity. TST with SpO₂ less than 90% was associated with length of hospitalization.

Pulmonary artery enlargement is associated with pulmonary hypertension and decreased survival in severe cystic fibrosis: A cohort study

BACKGROUND

Pulmonary artery (PA) enlargement, defined as pulmonary artery to ascending aorta diameter ratio (PA:A)>1 on computed tomography (CT), is a marker of pulmonary vascular disease in chronic lung diseases. PA enlargement is prevalent in cystic fibrosis (CF), but its relationship to hemodynamics and prognostic utility in severe CF are unknown. We hypothesized that the PA:A would have utility in identifying pulmonary hypertension (PH) in severe CF and that PA enlargement would be associated with reduced transplant-free survival.

METHODS

We conducted a retrospective study of adults with CF undergoing lung transplant evaluation at a single center between 2000 and 2015. CT, right heart catheterization (RHC), and clinical data were collected. The PA:A was measured from a single CT slice. We measured associations between PA:A and invasive hemodynamic parameters including PH defined as a mPAP ≥25mmHg using adjusted linear and logistic regression models. Kaplan-Meier and adjusted Cox regression models were used to measure associations between PA:A>1, RHC-defined PH, and transplant-free survival in severe CF.

RESULTS

We analyzed 78 adults with CF that had CT scans available for review, including 44 that also had RHC. RHC-defined PH defined as a mPAP ≥25mmHg was present in 36% of patients with CF undergoing transplant evaluation. The PA:A correlated with mPAP (r = 0.73; 95% CI 3.87-7.80; p<0.001) and PVR (r = 0.42, p = 0.005) and the PA:A>1 was an independent predictor of PH (aOR 4.50; 95% CI 1.05-19.2; p = 0.042). PA:A>1 was independently associated with increased hazards for death or transplant (aHR 2.69; 95% CI 1.41-5.14; P = 0.003). The presence of mPAP ≥25mmHg was independently associated with decreased survival in this cohort.

CONCLUSIONS

PA enlargement is associated with pulmonary hemodynamics and PH in severe CF. PA enlargement is an independent prognostic indicator of PH and decreased survival in this population.

Non-invasive Ventilation for Children With Chronic Lung Disease

Advances in medical care and supportive care options have contributed to the survival of children with complex disorders, including children with chronic lung disease. By delivering a positive pressure or a volume during the patient's inspiration, NIV is able to reverse nocturnal alveolar hypoventilation in patients who experience hypoventilation during sleep, such as patients with chronic lung disease. Bronchopulmonary dysplasia (BPD) is a common complication of prematurity, and despite significant advances in neonatal care over recent decades its incidence has not diminished. Most affected infants have mild disease and require a short period of oxygen supplementation or respiratory support. However, severely affected infants can become dependent on positive pressure support for a prolonged period. In case of established severe BPD, respiratory support with non-invasive or invasive positive pressure ventilation is required. Patients with cystic fibrosis (CF) and advanced lung disease develop hypoxaemia and hypercapnia during sleep and hypoventilation during sleep usually predates daytime hypercapnia. Hypoxaemia and hypercapnia indicates poor prognosis and prompts referral for lung transplantation. The prevention of respiratory failure during sleep in CF may prolong survival. Long-term oxygen therapy has not been shown to improve survival in people with CF. A Cochrane review on the use NIV in CF concluded that NIV in combination with oxygen therapy improves gas exchange during sleep to a greater extent than oxygen therapy alone in people with moderate to severe CF lung disease. Uncontrolled, non-randomized studies suggest survival benefit with NIV in addition to being an effective bridge to transplantation. Complications of NIV relate mainly to prolonged use of a face or nasal mask which can lead to skin trauma, and neurodevelopmental delay by acting as a physical barrier to social interaction. Another associated risk is pulmonary aspiration caused by vomiting whilst wearing a face mask. Adherence to NIV is one of the major barriers to treatment in children. This article will review the current evidence for indications, adverse effects and long term follow up including adherence to NIV in children with chronic lung disease.

Home Oxygen Therapy for Children. An Official American Thoracic Society Clinical Practice Guideline

Background: Home oxygen therapy is often required in children with chronic respiratory conditions. This document provides an evidence-based clinical practice guideline on the implementation, monitoring, and discontinuation of home oxygen therapy for the pediatric population.

Methods: A multidisciplinary panel identified pertinent questions regarding home oxygen therapy in children, conducted systematic reviews of the relevant literature, and applied the Grading of Recommendations, Assessment, Development, and Evaluation approach to rate the quality of evidence and strength of clinical recommendations.

Results: After considering the panel’s confidence in the estimated effects, the balance of desirable (benefits) and undesirable (harms and burdens) consequences of treatment, patient values and preferences, cost, and feasibility, recommendations were developed for or against home oxygen therapy specific to pediatric lung and pulmonary vascular diseases.

Conclusions: Although home oxygen therapy is commonly required in the care of children, there is a striking lack of empirical evidence regarding implementation, monitoring, and discontinuation of supplemental oxygen therapy. The panel formulated and provided the rationale for clinical recommendations for home oxygen therapy based on scant empirical evidence, expert opinion, and clinical experience to aid clinicians in the management of these complex pediatric patients and identified important areas for future research.

Biatrial Remodeling in Patients with Cystic Fibrosis Running Title: Atrial Function in Cystic Fibrosis

BACKGROUND

Previous studies have focused on left and right ventricular remodeling in cystic fibrosis (CF), whereas atrial function has not been assessed in detail so far. We sought to investigate left and right atrial (LA and RA) function in patients with CF.

METHODS

This retrospective investigation included 82 CF patients (64 survivors and 18 non-survivors) who were referred to CF department over the period of four years, as well as 32 control subjects matched by age and gender. All participants underwent an echocardiographic examination including a strain analysis, which was performed offline and blinded for groups.

RESULTS

LA and RA volume indexes were significantly higher in CF patients than in controls and were particularly high in CF non-survivors. LA conduit and reservoir functions were significantly worse in CF survivors and non-survivors, compared with control subjects. RA phasic function was not different between controls, CF survivors and non-survivors. The parameters of lung function (forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1)) and the LA and RA volume indexes were predictors of mortality in CF patients. However, in a multivariate analysis, only FVC was an independent predictor of mortality in CF patients.

CONCLUSIONS

Our results suggest that both atria are enlarged, but only LA function is impaired in CF patients. LA reservoir and conduit function is particularly deteriorated in CF patients. Though statistical significance was not reached due to our limited sample size, there was a trend of deterioration of LA and RA function from controls across CF survivors to CF non-survivors. LA and RA enlargement represented predictors of mortality in CF patients.

CT-measured pulmonary artery diameter as an independent predictor of pulmonary hypertension in cystic fibrosis

Purpose

The role of computed tomography (CT) scan, as a promising prognostic imaging modality in cystic fibrosis (CF), has been widely investigated, focusing on parenchymal abnormalities. The aim of the present study was to evaluate the diagnostic performance of thoracic vascular parameters on CT to detect pulmonary hypertension (PH).

Material and methods

CF patients who contemporaneously underwent CT and echocardiography were retrospectively enrolled. Baseline characteristics in addition to pulmonary artery diameter (PAD) and pulmonary to aortic (PA/A) ratio were compared between cohorts with and without PH, based on the results of echocardiography separately in paediatric patients (< 18) and adults (≥ 18).

Results

Of a total 119 CF patients, 39 (32.8%) had PH (paediatric: 23/78, 29.5%, adult: 16/41, 39%). In paediatric CF patients, mean age, HCo₃, PCo₂, and pulmonary artery diameter (PAD) were significantly higher in the PH group compared to the non-PH group. Mean pulmo however, only PAD remained as the independent predictor of PH based on multivariate analysis (overall: 22.86 mm [±3.86] vs. 18.43 mm [±4.72], p = 0.005, paediatric patients: 22.63 mm [±4.4] vs. 17.10 mm [±4.64], p = 0.03). Using a cut off of 19.25 mm, the diagnostic performance of PAD to detect PH was found to be as follows: sensitivity = 82%, specificity = 70%, and accuracy = 73.1%. No significant difference was demonstrated in PAD between PH and non-PH groups in adults with CF (23.19 [±3.60] vs. 21.34 [±3.49], p = 0.7).

Conclusions

In CF patients, PAD revealed an age-dependent performance to detect PH. PAD can be applied to predict pulmonary hypertension in paediatric CF patients and may be recommended to be routinely measured on follow-up chest CT scan in childhood CF.

Comparative Effectiveness Research in Pediatric Respiratory Disease: Promise and Pitfalls

Comparative effectiveness research (CER) has become increasing central to clinical research in medicine. CER seeks to conduct clinical trials that compare different commonly used interventions in real-world settings (pragmatic clinical trials) and use a multitude of sources of evidence (including registries and cohort studies) to inform clinical decision making. CER also ensures that stakeholders (patients, families, care providers, insurers) have a voice in the research process by integrating formal stakeholder engagement as part of the research. This innovative approach to clinical research has distinct benefits and pitfalls. This review first defines what CER is and then describes some of its benefits and then pitfalls. The focus is on the role of CER in pediatrics.

Prognostic significance of pulmonary hypertension in patients with cystic fibrosis: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Pulmonary hypertension (PH) is frequently found in advanced parenchymal lung diseases like cystic fibrosis (CF), but the role played by PH in the clinical outcome of CF patients remains unclear. The aim of this study is to determine the influence of PH on survival in the CF population by meta-analysis.

METHODS

Publications addressing the associations between PH and overall survival (OS) or other clinical characteristics in CF patients were selected from electronic databases. Odds ratios (ORs) or mean differences (MDs) were used to estimate the association between PH and the clinical characteristics. The hazard ratios (HRs) with 95% confidence interval (CI) were abstracted or calculated to evaluate the association between PH and CF survival outcome. Subgroup analyses were also conducted.

RESULTS

Seven studies including 2141 CF patients who met the inclusion criteria were included in our meta-analysis. With respect to clinical features, PH was significantly associated with lower PaO2 (P < .001), higher PaCO2 (P = .02), lower forced expiratory volume in 1 second percent (P < .001) and lower forced vital capacity percent (P < .001). However, PH had no significant impact on CF patients' OS (HR = 1.29, 95% CI 0.81 to 2.06, P = .283). Furthermore, subgroup analyses also showed no evidence of prognostic role of PH in CF patients (all P values >.05).

CONCLUSIONS

Our findings suggest that the presence of PH was strongly correlated with worse blood-gas parameters and worse lung function, but surprisingly had no significant prognostic value on survival among CF patients. Further large-scale and prospective studies are needed to confirm these findings.

Current and emerging comorbidities in cystic fibrosis

Cystic fibrosis transmembrane conductance regulator (CFTR) is expressed ubiquitously throughout the body. Thus, while respiratory manifestations dominate much of cystic fibrosis (CF) care, there are prominent multi-organ manifestations and comorbidities. In the general population, the number of comorbidities increases with aging. Few illnesses have experienced such a dramatic improvement in survival as CF, which has been transformed from an illness of childhood death to one of adult survival. Hence, as longevity increases in CF, it is paralleled by an increasing number of patients with multicomplex comorbidities availing of care from adult CF multi-disciplinary teams. This review gives an overview of the traditional CF associated comorbidities and those emerging in an aging adult cohort. While historically the treatment of CF focused on the consequences of CFTR dysfunction, the recent advent of CFTR modulators with the potential to enhance CFTR function represents an opportunity to potentially reverse or delay the development of some of the comorbidities associated with CF. Where evidence is available for the impact of CFTR modulatory therapy, namely ivacaftor on comorbidities in CF, this is highlighted.

Common clinical features of CF (respiratory disease and exocrine pancreatic insufficiency)

First described as a disease of the pancreas, cystic fibrosis is a genetically inherited progressive disease affecting multiple organ systems. Pulmonary and pancreatic involvement is common in individuals with cystic fibrosis, and the former is attributable to most of the mortality that occurs with the condition. This chapter provides an overview of a clinical approach to the pulmonary and pancreatic manifestations of cystic fibrosis.

Technological advances shed light on left ventricular cardiac disturbances in cystic fibrosis

Cystic fibrosis (CF), the most common autosomal recessive lethal disease in Caucasians, causes chronic pulmonary disease and can lead to cor pulmonale with right ventricular dysfunction. The presence of the cystic fibrosis transmembrane conductance regulator (CFTR) in cardiac myocardia has prompted debate regarding possible defective ion channel-induced cardiomyopathy. Clinical heart disease in CF is considered rare and is restricted to case reports. It has been unclear if this is due to the lack of physiological importance of CFTR in the heart, the relatively short lifespan of those with CF, or a technical inability to detect subclinical disease. Extensive echocardiographic investigations have yielded contradictory results, leading to the dogma that left ventricular defects in CF occur secondary to lung disease. In this review, we consider why studies examining heart function in CF have not provided clarity on this topic. We then focus on data from new echocardiographic and magnetic resonance imaging technology, which are providing greater insight into cardiac function in CF and demonstrating that, in addition to secondary effects from pulmonary disease, there may be an intrinsic primary defect in the CF heart. With advancing lifespans and activity levels, understanding the risk of cardiac disease is vital to minimizing morbidity in adults with CF.

Anesthesia for Patients with Concomitant Hepatic and Pulmonary Dysfunction

Hepatic function and pulmonary function are interrelated with failure of one organ system affecting the other. With improved therapies, patients with concomitant hepatic and pulmonary failure increasingly enjoy a good quality of life and life expectancy. Therefore, the prevalence of such patients is increasing with more presenting for both emergent and elective surgical procedures. Hypoxemia requires a thorough evaluation in patients with end-stage liver disease. The most common etiologies respond to appropriate therapy. Portopulmonary hypertension and hepatopulmonary syndrome are associated with increased perioperative morbidity and mortality. It is incumbent on the anesthesiologist to understand the physiology of liver failure and its early effect on pulmonary function to ensure a successful outcome.

Pulmonary hypertension as estimated by Doppler echocardiography in adolescent and adult patients with cystic fibrosis and their relationship with clinical, lung function and sleep findings

BACKGROUND

In cystic fibrosis (CF) patients, end stage of pulmonary disease is characterized by pulmonary hypertension (PH), hypoxemia, decrease in exercise tolerance, and sleep quality.

OBJECTIVE

To evaluate the association between clinical, lung function, sleep quality, and polysomnographic variables with PH in CF patients aged 16 years or older.

METHODS

In a cross-sectional study, 51 clinically stable CF patients underwent a clinical evaluation, an overnight polysomnography and answered sleep questionnaires (Pittsburgh Sleep Quality Index and Epworth sleepiness scale). Also, CF patients had their pulmonary function, 6-minute walk test (6MWT) and echocardiography assessed.

RESULTS

Fifty-one CF patients participated in the study; 47% were female. The mean age was 25.1 ± 8.8 years. Pulmonary artery systolic pressure (PASP) was greater than 35 mm Hg in 11 (27.5%) patients. Variables associated with PASP>35 mm Hg in univariate analysis were Shwachman-Kulczycki clinical score, forced expiratory volume in 1 second % of predicted, Pseudomonas aeruginosa in sputum culture, at-rest peripheral capillary oxygen saturation (SpO₂ ), SpO₂ at end of 6MWT and time of oxygen desaturation <90% during sleep. These variables were included in the binary logistic regression. The independent variable associated with the PASP > 35 mm Hg was at-rest SpO₂ (OR = 10.8, CI 95% 1.7-67.3, P = .011). The cuttoff SpO₂ < 94% had the sensitivity = 7/11 = 64%, specificity = 40/40 = 100%, positive predicted values = 7/7 = 100% and negative predicted values = 40/44 = 91% to the diagnosis of PH.

CONCLUSION

the present study showed a high rate of PH in adolescent and adult CF patients. At-rest SpO₂ was associated with PH.

Hypoxia and sterile inflammation in cystic fibrosis airways: mechanisms and potential therapies

Cystic fibrosis is one of the most common autosomal recessive genetic diseases in Caucasian populations. Diagnosisvianewborn screening and targeted nutritional and antibiotic therapy have improved outcomes, however respiratory failure remains the key cause of morbidity and mortality. Progressive respiratory disease in cystic fibrosis is characterised by chronic neutrophilic airway inflammation associated with structural airway damage leading to bronchiectasis and decreased lung function. Mucus obstruction is a characteristic early abnormality in the cystic fibrosis airway, associated with neutrophilic inflammation often in the absence of detectable infection. Recent studies have suggested a link between hypoxic cell death and sterile neutrophilic inflammation in cystic fibrosis and other diseasesviathe IL-1 signalling pathway. In this review, we consider recent evidence regarding the cellular responses to respiratory hypoxia as a potential driver of sterile neutrophilic inflammation in the lung, current knowledge on hypoxia as a pathogenic mechanism in cystic fibrosis and the potential for current and future therapies to alleviate hypoxia-driven sterile inflammation.

Pulmonary vascular collagen content, not cross-linking, contributes to right ventricular pulsatile afterload and overload in early pulmonary hypertension

Hypoxic pulmonary hypertension (HPH) is associated with pulmonary artery (PA) remodeling and right ventricular (RV) overload. We have previously uncovered collagen-mediated mechanisms of proximal PA stiffening in early HPH by manipulating collagen degradation and cross-linking using a transgenic mouse strain and a potent collagen cross-link inhibitor, β-aminopropionitrile (BAPN). However, the roles of collagen in distal PA remodeling, overall RV afterload, and RV hypertrophy in HPH remain unknown. Here, we used the same experimental strategy to investigate the effect of pulmonary vascular collagen content and cross-linking on steady and pulsatile RV afterload and on RV hypertrophy in early HPH. Collagenase-resistant mice (Col1a1^R/R) and their littermate controls (Col1a1^+/+) were exposed to normobaric hypoxia for 10 days with or without BAPN treatment. In vivo pulmonary vascular impedance, a comprehensive measure of RV afterload, was measured via simultaneous RV catheterization and echocardiography. Morphology and collagen accumulation were examined using histological techniques and ELISA in lungs and RVs. In both mouse strains, BAPN did not limit increases in pulmonary arterial pressure or pulmonary vascular resistance, indicating a negligible effect of either collagen content or cross-linking on steady RV afterload. However, BAPN prevented the increase in pulse pressure and RV hypertrophy in Col1a1^+/+ mice and these effects were absent in Col1a1^R/R mice, suggesting a role for PA collagen content, not cross-linking, in the pulsatile RV afterload. Moreover, we found a significant correlation between pulse pressure and RV hypertrophy, indicating an important role for pulsatile RV afterload in RV overload in early HPH.

NEW & NOTEWORTHY

The present study found an important role for collagen content, but not collagen cross-linking, in the pulsatile right ventricular (RV) afterload, which is correlated with RV hypertrophy. These results uncover a new collagen-mediated mechanical mechanism of RV dysfunction in early pulmonary hypertension progression. Furthermore, our results suggest that measures and metrics of pulsatile hemodynamics such as pulse pressure and pulse wave velocity are potentially important to cardiovascular mortality in patients with pulmonary hypertension.

Heart involvement in cystic fibrosis: A specific cystic fibrosis-related myocardial changes?

Cystic fibrosis is a complex multi-systemic chronic disease characterized by progressive organ dysfunction with development of fibrosis, possibly affecting the heart. Over the last four decades pathological, experimental, and clinical evidence points towards the existence of a specific myocardial involvement in cystic fibrosis. Multi-modality cardiac imaging, especially recent echocardiographic techniques, evidenced diastolic and/or systolic ventricular dysfunction in cystic fibrosis leading to the concept of a cystic fibrosis-related cardiomyopathy. Hypoxemia and inflammation are among the most important factors for heart involvement in cystic fibrosis. Cystic Fibrosis Transmembrane Regulator was found to be involved in the regulation of cardiomyocyte contraction and may also account for cystic fibrosis-related myocardial dysfunction. This review, mainly focused on echocardiographic studies, seeks to synthesize the existing literature for and against the existence of heart involvement in cystic fibrosis, its mechanisms and prognostic implications. Careful investigation of the heart function may be helpful for risk stratification and therapeutic decisions in patients with cystic fibrosis.

Pulmonary artery enlargement and cystic fibrosis pulmonary exacerbations: a cohort study

Background

Acute pulmonary exacerbations are associated with progressive lung function decline and increased mortality in cystic fibrosis (CF). The role of pulmonary vascular disease in pulmonary exacerbations is unknown. We investigated the association between pulmonary artery enlargement (PA:A>1), a marker of pulmonary vascular disease, and exacerbations.

Methods

We analyzed clinical, computed tomography (CT), and prospective exacerbation data in a derivation cohort of 74 adult CF patients, measuring the PA:A at the level of the PA bifurcation. We then replicated our findings in a validation cohort of 190 adult CF patients. Patients were separated into groups based on the presence or absence of a PA:A>1 and were followed for 1-year in the derivation cohort and 2-years in the validation cohort. The primary endpoint was developing ≥1 acute pulmonary exacerbation during follow-up. Linear and logistic regression models were used to determine associations between clinical factors, the PA:A ratio, and pulmonary exacerbations. We used Cox regression to determine time to first exacerbation in the validation cohort.

Findings

We found that PA:A>1 was present in n=37/74 (50%) of the derivation and n=89/190 (47%) of the validation cohort. In the derivation cohort, n=50/74 (68%) had ≥1 exacerbation at 1 year and n=133/190 (70%) in the validation cohort had ≥1 exacerbation after 2 years. PA:A>1 was associated with younger age in both cohorts and with elevated sweat chloride (100.5±10.9 versus 90.4±19.9mmol/L, difference between groups 10.1mmol/L [95%CI 2.5–17.7], P=0.017) in the derivation group. PA:A>1 was associated with exacerbations in the derivation (OR 3.49, 95%CI 1.18–10.3, P=0.023) and validation (OR 2.41, 95%CI 1.06–5.52, P=0.037) cohorts when adjusted for confounders. Time to first exacerbation was shorter in PA:A>1 versus PA:A<1 [HR 1.66 (95%CI 1.18–2.34), P=0.004] in unadjusted analysis, but not when adjusted for sex, BMI, prior exacerbation, positive Pseudomonas status, and FEV1/FVC [HR 1.14 (95%CI 0.80–1.62), P=0.82]).

Interpretation

PA enlargement is prevalent in adult CF patients and is associated with acute pulmonary exacerbation risk in two well-characterized cohorts. PA:A may be a predictive marker in CF.

Hemodynamic predictors of long term survival in end stage cystic fibrosis

BACKGROUND

Pulmonary hypertension (PH) is often found in cystic fibrosis (CF) patients affected by end-stage lung disease but its impact on outcome remains unclear. Pulmonary arterial compliance (PAC) is an important determinant of right ventricle (RV) workload and it is a strong predictor of survival in other forms of PH. The aim of this study is to investigate whether PAC is a predictor of long-term prognosis in a population of CF patients affected by advanced lung disease.

METHODS

Between 2000 and 2014, 178 patients with CF have been evaluated for lung transplantation in our CF Center. Right heart catheterization (RHC) and follow up data were retrievable and analyzed in 141 of them. PAC was defined as the ratio between stroke volume (SV) and pulse pressure (PP) at heart catheterization. The association of PAC with survival was tested at 4 years and compared to other hemodynamic parameters.

RESULTS

PH prevalence was 56.4%. Most patients had mild elevation of pulmonary artery pressure (PAP). No difference in mortality was observed in patients with PH compared to patients with normal PAP (HR 0.95: 95% CI 0.49-1.89, p=0.89). At receiver operating characteristic curve (ROC) analysis, the optimal prognostic cut-off point of PAC was 1.95 ml/mmHg. An impaired PAC (≤1.95 ml/mmHg) was a strong independent predictor of long-term mortality (HR 3.44: 95% CI 1.51-7.85: p=0.003).

CONCLUSIONS

Impaired PAC is associated with poor prognosis in CF patients awaiting lung transplantation. Other traditional hemodynamic parameters add no prognostic information.

Pulmonary hypertension is associated with increased post-lung transplant mortality risk in patients with chronic obstructive pulmonary disease

BACKGROUND

Pulmonary hypertension associated with lung disease (PHLD) has been shown to be a predictor of disease severity and survival in patients awaiting lung transplantation. Little is known about the relationship of PHLD and survival after lung transplantation or how this may vary by disease. This study evaluated the effect of PHLD on 1-year survival after lung transplantation for patients with the 3 most common indications for transplantation: chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and cystic fibrosis (CF).

METHODS

Organ Procurement and Transplantation Network data were obtained for all lung transplant recipients who received an allograft between May 2005 and June 2010. The relationship between PHLD and 1-year survival after lung transplantation for each diagnostic group was examined with Kaplan-Meier estimates and Cox regression. Covariates included in the model were those defined in the current Lung Allocation Score system post-transplant survival model, including age, serum creatinine, percentage predicted forced vital capacity, functional status, and mechanical ventilation use at time of transplant. The estimated relative risk was calculated using Poisson regression with robust error variance and adjustment for covariates.

RESULTS

Sample sizes for COPD, IPF, and CF patients were 2,025, 2,304, and 866, respectively. The 1-year post-transplant survival for COPD patients with PHLD was 76.9% vs 86.2% for COPD patients without PHLD (p = 0.001). In multivariate Cox regression analysis COPD patients with PHLD had a 1.74 (95% confidence interval, 1.3-2.3) times higher risk of 1-year post-transplant mortality (p = 0.001). Similar analyses for IPF and CF diagnostic groups showed no significant difference in survival between patients with and without PHLD.

CONCLUSIONS

COPD patients with PHLD have increased post-transplant 1-year mortality. No significant difference was seen in patients with IPF or CF. Further studies to evaluate the potential mechanisms for this difference between diagnoses are needed.

Inflammation, oxidative stress, and cardiovascular disease risk factors in adults with cystic fibrosis

Cystic fibrosis (CF) represents one of a number of localized lung and non-lung diseases with an intense chronic inflammatory component associated with evidence of systemic oxidative stress. Many of these chronic inflammatory diseases are accompanied by an array of atherosclerotic processes and cardiovascular disease (CVD), another condition strongly related to inflammation and oxidative stress. As a consequence of a dramatic increase in long-lived patients with CF in recent decades, the specter of CVD must be considered in these patients who are now reaching middle age and beyond. Buttressed by recent data documenting that CF patients exhibit evidence of endothelial dysfunction, a recognized precursor of atherosclerosis and CVD, the spectrum of risk factors for CVD in CF is reviewed here. Epidemiological data further characterizing the presence and extent of atherogenic processes in CF patients would seem important to obtain. Such studies should further inform and offer mechanistic insights into how other chronic inflammatory diseases potentiate the processes leading to CVDs.

Nocturnal hypoxemia in children and adolescents with cystic fibrosis

OBJECTIVE:

To determine the prevalence of nocturnal hypoxemia and its association with pulmonary function, nutritional status, sleep macrostructure, and obstructive respiratory events during sleep in a population of clinically stable children and adolescents with cystic fibrosis (CF).

METHODS:

This was a cross-sectional study involving 67 children and adolescents with CF between 2 and 14 years of age. All of the participants underwent polysomnography, and SpO₂ was measured by pulse oximetry. We also evaluated the Shwachman-Kulczycki (S-K) scores, spirometry findings, and nutritional status of the patients.

RESULTS:

The study involved 67 patients. The mean age of the patients was 8 years. The S-K scores differed significantly between the patients with and without nocturnal hypoxemia, which was defined as an SpO₂ < 90% for more than 5% of the total sleep time (73.75 ± 6.29 vs. 86.38 ± 8.70; p < 0.01). Nocturnal hypoxemia correlated with the severity of lung disease, FEV₁ (r_s = −0.42; p = 0.01), FVC (r_s = −0.46; p = 0.01), microarousal index (r_s = 0.32; p = 0.01), and apnea-hypopnea index (r_s = 0.56; p = 0.01).

CONCLUSIONS:

In this sample of patients with CF and mild-to-moderate lung disease, nocturnal oxygenation correlated with the S-K score, spirometry variables, sleep macrostructure variables, and the apnea-hypopnea index.

Impact of increased hematocrit on right ventricular afterload in response to chronic hypoxia

Chronic hypoxia causes chronic mountain sickness through hypoxia-induced pulmonary hypertension (HPH) and increased hematocrit. Here, we investigated the impact of increased hematocrit and HPH on right ventricular (RV) afterload via pulmonary vascular impedance. Mice were exposed to chronic normobaric hypoxia (10% oxygen) for 10 (10H) or 21 days (21H). After baseline hemodynamic measurements, ∼500 μl of blood were extracted and replaced with an equal volume of hydroxyethylstarch to normalize hematocrit and all hemodynamic measurements were repeated. In addition, ∼500 μl of blood were extracted and replaced in control mice with an equal volume of 90% hematocrit blood. Chronic hypoxia increased input resistance (Z0 increased 82% in 10H and 138% in 21H vs. CTL; P < 0.05) and characteristic impedance (ZC increased 76% in 10H and 109% in 21H vs. CTL; P < 0.05). Hematocrit normalization did not decrease mean pulmonary artery pressure but did increase cardiac output such that both Z0 and ZC decreased toward control levels. Increased hematocrit in control mice did not increase pressure but did decrease cardiac output such that Z0 increased. The paradoxical decrease in ZC with an acute drop in hematocrit and no change in pressure are likely due to inertial effects secondary to the increase in cardiac output. A novel finding of this study is that an increase in hematocrit affects the pulsatile RV afterload in addition to the steady RV afterload (Z0). Furthermore, our results highlight that the conventional interpretation of ZC as a measure of proximal artery stiffness is not valid in all physiological and pathological states.

Pulmonary hypertension survival effects and treatment options in cystic fibrosis

PURPOSE OF REVIEW

This review discusses the current impact of pulmonary hypertension on the outcome and treatment of cystic fibrosis (CF).

RECENT FINDINGS

Pulmonary hypertension is commonly encountered in advanced lung diseases such as CF. The prevalence of pulmonary hypertension in CF patients varies based on disease severity and methodology used for diagnosis. Chronic alveolar hypoxia is the most likely cause. The majority of recent studies have shown worse survival in CF patients who develop pulmonary hypertension. The impact of pulmonary hypertension-specific therapies on symptomatology and outcomes in CF patients has not been well studied.

SUMMARY

Pulmonary hypertension is common in patients with CF and it occurs largely because of hypoxemia. The presence of pulmonary hypertension in patients with CF is likely associated with worse outcome; however, it remains unknown whether treatment with pulmonary hypertension-specific therapies would be beneficial.

Impact of pulmonary hypertension on survival in patients with cystic fibrosis undergoing lung transplantation: an analysis of the UNOS registry

BACKGROUND

Pulmonary hypertension (PH) is a comorbidity reported in patients with cystic fibrosis (CF) with research limited to single-center studies.

METHODS

To assess the impact of PH in patients with CF who received a lung transplant (LTx), the United Network for Organ Sharing was queried from 1987 to 2012, restricting analysis to transplant patients 6-55 years old between 1/1/2005 and 7/6/2011.

RESULTS

Of 23,951 lung transplants, 1177 met inclusion criteria with 831 having mean pulmonary artery pressure (mPAP) data available. For the entire cohort, mean age was 30.3 (SD=9.2, range 12-55), and mean mPAP was 26.5 (SD = 7.8, range 5-66) mmHg. A total of 470 (57%) had PH defined as mPAP ≥ 25 mmHg. Comparing PH to non-PH groups, mean forced expiratory volume in one second (FEV1) was 24.4 (SD = 13.8) vs. 26 (SD=13.9) % of predicted, mean supplemental oxygen requirement at rest was 4.5 (SD = 4.1) vs. 3.7 (SD = 3.0) liters per minute, and mean lung allocation score was 49 (SD = 16) vs. 43 (SD = 12), respectively. For the PH group, median survival was 84.4 months compared to 67.1 months for the non-PH group (log-rank p-value = 0.326). The adjusted hazard ratio for PH vs. non-PH was 0.862 (95% CI: 0.653-1.138; p = 0.293), thus indicating no statistically significant effect of PH on survival.

CONCLUSIONS

A high prevalence of PH was found in CF patients prior to LTx. Based on our models despite PH being prevalent, there is no strong evidence suggesting that it significantly alters the risk of death in CF patients after LTx.

Gas exchange in disease: asthma, chronic obstructive pulmonary disease, cystic fibrosis, and interstitial lung disease

Ventilation-perfusion (VA/Q) inequality is the underlying abnormality determining hypoxemia and hypercapnia in lung diseases. Hypoxemia in asthma is characterized by the presence of low VA/Q units, which persist despite improvement in airway function after an attack. This hypoxemia is generally attenuated by compensatory redistribution of blood flow mediated by hypoxic vasoconstriction and changes in cardiac output, however, mediator release and bronchodilator therapy may cause deterioration. Patients with chronic obstructive pulmonary disease have more complex patterns of VA/Q inequality, which appear more fixed, and changes in blood flow and ventilation have less benefit in improving gas exchange efficiency. The inability of ventilation to match increasing cardiac output limits exercise capacity as the disease progresses. Deteriorating hypoxemia during exacerbations reflects the falling mixed venous oxygen tension from increased respiratory muscle activity, which is not compensated by any redistribution of VA/Q ratios. Shunt is not a feature of any of these diseases. Patients with cystic fibrosis (CF) have no substantial shunt when managed according to modern treatment regimens. Interstitial lung diseases demonstrate impaired oxygen diffusion across the alveolar-capillary barrier, particularly during exercise, although VA/Q inequality still accounts for most of the gas exchange abnormality. Hypoxemia may limit exercise capacity in these diseases and in CF. Persistent hypercapnic respiratory failure is a feature of advancing chronic obstructive pulmonary disease and CF, closely associated with sleep disordered breathing, which is not a prominent feature of the other diseases. Better understanding of the mechanisms of hypercapnic respiratory failure, and of the detailed mechanisms controlling the distribution of ventilation and blood flow in the lung, are high priorities for future research.

Genotype-specific alterations in vascular smooth muscle cell function in cystic fibrosis piglets

BACKGROUND

The most common CF-causing mutations interfere with CFTR trafficking from the endoplasmic reticulum (CFTR-F508del) or prematurely terminate transcription (CFTR-null). We suspected that genotype-specific patterns of CFTR expression would have differential effects on smooth muscle cell calcium signaling and hence vascular tone. We hypothesized that compared to wild-type or CFTR-null aorta, aorta from CFTR-F508del (dF) piglets will have reduced endoplasmic reticulum calcium mobilization and decreased vasoconstriction.

METHODS

Aortic reactivity was assessed by myography, and ratiometric calcium imaging was performed in isolated vascular smooth muscle cells.

RESULTS

Aorta from dF piglets had reduced myogenic tone (P<0.001) and decreased constriction to KCl (P<0.05). Combined inhibition of ryanodine and IP3 receptors decreased wild-type and CFTR-null responses to levels seen in dF aorta. Compared to wild-type cells, dF-expressing smooth muscle cells had reduced calcium transients, while CFTR-null cells had decreased baseline intracellular calcium concentrations.

CONCLUSIONS

Expression of CFTR-F508del interferes with smooth muscle cell calcium handling and decreases aortic responsiveness.

Aortopulmonary collateral flow in cystic fibrosis assessed with phase-contrast MRI

BACKGROUND

Cystic fibrosis (CF) is a common genetic disease in Caucasians. Chronic pulmonary disease with progressive destruction of the pulmonary parenchyma is two of the major morbidities, but the relationship between clinical severity of CF and aortopulmonary collateral blood flow has not been assessed.

OBJECTIVE

The purpose of this study is to measure changes in aortopulmonary collateral blood flow by phase-contrast magnetic resonance imaging (MRI) in children with CF across the spectrum of disease severity as measured by the forced expiratory volume in one second as percent predicted value (FEV1% predicted).

MATERIALS AND METHODS

Sixteen patients with CF were prospectively evaluated. Eight were classified as having mild CF lung disease (FEV1 ≥80% predicted) and eight were classified as having moderate to severe CF lung disease (FEV1 <80% predicted). Seventeen age- and gender-matched non-CF subjects without cardiac or lung disease served as controls. Phase-contrast flow was measured at the ascending aorta, main pulmonary artery and both pulmonary arteries. Aortopulmonary collateral blood flow was calculated for each subject. The relationship between collateral flow and FEV1% predicted was modeled using nonparametric regression. Group differences were assessed by analysis of variance.

RESULTS

Aortopulmonary collateral blood flow began to increase as FEV1% predicted in subjects with CF fell below 101.5% with significant further increase in the aortopulmonary collateral blood flow in the subjects with CF with moderate to severe lung disease compared to controls (0.89 vs. 0.20 L/min, P < 0.0001). Aortopulmonary collateral blood flow correlated negatively with FEV1% predicted (r=0.70, P = 0.0050) confirming its relationship to this established marker of disease severity. There was no statistically significant difference in results obtained from two independent observers.

CONCLUSION

These preliminary findings suggest that phase-contrast MRI can be performed reliably with consistent results and without interobserver variability. While the aortopulmonary collateral blood flow is within the normal range in subjects with mild CF disease, it begins to increase even when lung function is still in the normal range. A significant increase in the aortopulmonary collateral blood flow compared to controls is measured in patients with moderate to severe CF lung disease. The studies support the notion that aortopulmonary collateral blood flow may serve as a novel and sensitive biomarker of early pulmonary disease in cystic fibrosis.

Oxygen therapy for cystic fibrosis

BACKGROUND

The most serious complications of cystic fibrosis (CF) relate to respiratory insufficiency. Oxygen supplementation therapy has long been a standard of care for individuals with chronic lung diseases associated with hypoxemia. Physicians commonly prescribe oxygen therapy for people with CF when hypoxemia occurs. However, it is unclear if empiric evidence is available to provide indications for this therapy with its financial costs and often profound impact on lifestyle.

OBJECTIVES

To assess whether oxygen therapy improves the longevity or quality of life of individuals with CF.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Latest search of Group's Trials Register: 15 May 2013.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials comparing oxygen, administered at any concentration, by any route, in people with documented CF for any time period.

DATA COLLECTION AND ANALYSIS

Authors independently assessed the risk of bias for included studies and extracted data.

MAIN RESULTS

This review includes 11 published studies (172 participants); only one examined long-term oxygen therapy (28 participants). There was no statistically significant improvement in survival, lung, or cardiac health. There was an improvement in regular attendance at school or work in those receiving oxygen therapy at 6 and 12 months. Four studies examined the effect of oxygen supplementation during sleep by polysomnography. Although oxygenation improved, mild hypercapnia was noted. Participants fell asleep quicker and spent a reduced percentage of total sleep time in rapid eye movement sleep, but there were no demonstrable improvements in qualitative sleep parameters. Six studies evaluated oxygen supplementation during exercise. Again, oxygenation improved, but mild hypercapnia resulted. Participants receiving oxygen therapy were able to exercise for a significantly longer duration during exercise. Other exercise parameters were not altered by the use of oxygen.

AUTHORS' CONCLUSIONS

There are no published data to guide the prescription of chronic oxygen supplementation to people with advanced lung disease due to CF. Short-term oxygen therapy during sleep and exercise improves oxygenation but is associated with modest and probably clinically inconsequential hypercapnia. There are improvements in exercise duration, time to fall asleep and regular attendance at school or work. There is a need for larger, well-designed clinical trials to assess the benefits of long-term oxygen therapy in people with CF administered continuously or during exercise or sleep or both. However, we do not expect any new research to be undertaken in this area any time soon and do not plan to update this review again until any new evidence does become available.

Pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic and progressive disease leading to right heart failure and ultimately death if untreated. The first classification of PH was proposed in 1973. In 2008, the fourth World Symposium on PH held in Dana Point (California, USA) revised previous classifications. Currently, PH is devided into five subgroups. Group 1 includes patients suffering from idiopathic or familial PAH with or without germline mutations. Patients with a diagnosis of PAH should systematically been screened regarding to underlying mutations of BMPR2 gene (bone morphogenetic protein receptor type 2) or more rarely of ACVRL1 (activine receptor-like kinase type 1), ENG (endogline) or Smad8 genes. Pulmonary veno occusive disease and pulmonary capillary hemagiomatosis are individualized and designated as clinical group 1'. Group 2 'Pulmonary hypertension due to left heart diseases' is divided into three sub-groups: systolic dysfonction, diastolic dysfonction and valvular dysfonction. Group 3 'Pulmonary hypertension due to respiratory diseases' includes a heterogenous subgroup of respiratory diseases like PH due to pulmonary fibrosis, COPD, lung emphysema or interstitial lung disease for exemple. Group 4 includes chronic thromboembolic pulmonary hypertension without any distinction of proximal or distal forms. Group 5 regroup PH patients with unclear multifactorial mechanisms. Invasive hemodynamic assessment with right heart catheterization is requested to confirm the definite diagnosis of PH showing a resting mean pulmonary artery pressure (mPAP) of ≥ 25 mmHg and a normal pulmonary capillary wedge pressure (PCWP) of ≤ 15 mmHg. The assessment of PCWP may allow the distinction between pre-capillary and post-capillary PH (PCWP > 15 mmHg). Echocardiography is an important tool in the management of patients with underlying suspicion of PH. The European Society of Cardiology and the European Respiratory Society (ESC-ERS) guidelines specify its role, essentially in the screening proposing criteria for estimating the presence of PH mainly based on tricuspid regurgitation peak velocity and systolic artery pressure (sPAP). The therapy of PAH consists of non-specific drugs including oral anticoagulation and diuretics as well as PAH specific therapy. Diuretics are one of the most important treatment in the setting of PH because right heart failure leads to fluid retention, hepatic congestion, ascites and peripheral edema. Current recommendations propose oral anticoagulation aiming for targeting an International Normalized Ratio (INR) between 1.5-2.5. Target INR for patients displaying chronic thromboembolic PH is between 2–3. Better understanding in pathophysiological mechanisms of PH over the past quarter of a century has led to the development of medical therapeutics, even though no cure for PAH exists. Several specific therapeutic agents were developed for the medical management of PAH including prostanoids (epoprostenol, trepoprostenil, iloprost), endothelin receptor antagonists (bosentan, ambrisentan) and phosphodiesterase type 5 inhibitors (sildenafil, tadalafil). This review discusses the current state of art regarding to epidemiologic aspects of PH, diagnostic approaches and the current classification of PH. In addition, currently available specific PAH therapy is discussed as well as future treatments.

Pulmonary hypertension is a mild comorbidity in end-stage cystic fibrosis patients

BACKGROUND

This study investigated the prevalence of pulmonary hypertension (PH) in cystic fibrosis (CF) patients awaiting lung transplantation (LTx) and its influence on survival. We also explored the feasibility of using echocardiography as a first assessment for diagnosing PH.

METHODS

The study included 93 CF patients (46 women [50%]) evaluated for LTx between 2001 and 2010. Median age was 29 years. PH was defined as a mean pulmonary artery pressure (mPAP) measured by right heart catheterization (mPAP(cath)) of ≥ 25 mm Hg with a wedge pressure of ≤ 15 mm Hg. Echocardiographic results were divided into 3 categories based on current guidelines as "unlikely," "possible," or "likely" to have PH.

RESULTS

In 23 patients (25%) the mPAP(cath) was between 25 and 35 mm Hg, and 1 (1%) had severe PH (mPAP(cath) of ≥ 35 mm Hg). PH did not influence survival after enlistment (p = 0.7) and after LTx (p = 0.8). For 62 patients (67%), the sPAP(echo) could be measured, and PH was unlikely in 24 (39%). In another 19 patients (20%), PH was unlikely based on the absence of tricuspid regurgitation. The negative-predictive value (NPV) of measuring PH by echocardiography was 88% in whom PH was estimated to be unlikely (n = 43); whereas in 24 patients with a measurable low sPAP(echo), the NPV was 96%.

CONCLUSIONS

PH exists in 26% of end-stage CF patients and has no effect on survival on the waiting list for LTx or after LTx. Echocardiography might be used as the first tool to rule out PH, showing a NPV of 88%.

Effects of collagen deposition on passive and active mechanical properties of large pulmonary arteries in hypoxic pulmonary hypertension

Proximal pulmonary artery (PA) stiffening is a strong predictor of mortality in pulmonary hypertension. Collagen accumulation is mainly responsible for PA stiffening in hypoxia-induced pulmonary hypertension (HPH) in mouse models. We hypothesized that collagen cross-linking and the type I isoform are the main determinants of large PA mechanical changes during HPH, which we tested by exposing mice that resist type I collagen degradation (Col1a1[Formula: see text] and littermate controls (Col1a1[Formula: see text] to hypoxia for 10 days with or without [Formula: see text]-aminopropionitrile (BAPN) treatment to prevent cross-link formation. Static and dynamic mechanical tests were performed on isolated PAs with smooth muscle cells (SMC) in passive and active states. Percentages of type I and III collagen were quantified by histology; total collagen content and cross-linking were measured biochemically. In the SMC passive state, for both genotypes, hypoxia tended to increase PA stiffness and damping capacity, and BAPN treatment limited these increases. These changes were correlated with collagen cross-linking ([Formula: see text]). In the SMC active state, hypoxia increased PA dynamic stiffness and BAPN had no effect in Col1a1[Formula: see text] mice ([Formula: see text]). PA stiffness did not change in Col1a1[Formula: see text] mice. Similarly, damping capacity did not change for either genotype. Type I collagen accumulated more in Col1a1[Formula: see text] mice, whereas type III collagen increased more in Col1a1[Formula: see text] mice during HPH. In summary, PA passive mechanical properties (both static and dynamic) are related to collagen cross-linking. Type I collagen turnover is critical to large PA remodeling during HPH when collagen metabolism is not mutated and type III collagen may serve as a reserve.