An elevated breathing reserve index at the lactate threshold is a predictor of mortality in patients with cystic fibrosis awaiting lung transplantation

Lung transplant referral considerations for individuals with cystic fibrosis

PURPOSE OF REVIEW

The cystic fibrosis (CF) Foundation issued guidelines to promote timely lung transplant referral for people with cystic fibrosis (pwCF) in 2019. Since then more has been published to help refine this complex decision. The goal of this review is to summarize the recent literature informing disease severity in CF, barriers to referral for pwCF and guide timely and appropriate lung transplant referrals.

RECENT FINDINGS

Existing guidelines utilize the degree of airflow limitation as the primary criteria to refer for lung transplant, yet this variable has some prognostic uncertainty. Novel prognostic tools may provide more reliable metrics for predicting who with CF is at greatest risk of dying from their lung disease and could be used as an indicator for when to refer. In addition, updated analyses of national registry data have highlighted the significance of hemoptysis, low body mass index, and extra-pulmonary organ failure, as important prognostic markers. PwCF with these complications have historically been under-referred for lung transplant despite data suggesting lung transplant can be safe for some in these populations. Early referral should be considered in the presence of these complications.

SUMMARY

This review builds on existing guidelines by incorporating novel data to better determine when lung transplant referral is most appropriate. Improved prognostic tools are still needed to decrease the chances of pwCF dying without consideration of lung transplant. It is still unclear how novel therapies for CF may change the need and timing for lung transplant referral.

Cardiopulmonary Exercise Testing Provides Prognostic Information in Advanced Cystic Fibrosis Lung Disease

Rationale: Cardiopulmonary exercise testing (CPET) provides prognostic information in cystic fibrosis (CF); however, its prognostic value for patients with advanced CF lung disease is unknown. Objectives: To determine the prognostic value of CPET on the risk of death or lung transplant (LTX) within 2 years. Methods: We retrospectively collected data from 20 CF centers in Asia, Australia, Europe, and North America on patients with a forced expiratory volume in 1 second (FEV1) ⩽ 40% predicted who performed a cycle ergometer CPET between January 2008 and December 2017. Time to death/LTX was analyzed using mixed Cox proportional hazards regression. Conditional inference trees were modeled to identify subgroups with increased risk of death/LTX. Results: In total, 174 patients (FEV1, 30.9% ± 5.8% predicted) were included. Forty-four patients (25.5%) died or underwent LTX. Cox regression analysis adjusted for age, sex, and FEV1 revealed percentage predicted peak oxygen uptake ([Formula: see text]o2peak) and peak work rate (Wpeak) as significant predictors of death/LTX: adjusted hazard ratios per each additional 10% predicted were 0.60 (95% confidence interval, 0.43-0.90; P = 0.008) and 0.60 (0.48-0.82; P < 0.001). Tree-structured regression models, including a set of 11 prognostic factors for survival, identified Wpeak to be most strongly associated with 2-year risk of death/LTX. Probability of death/LTX was 45.2% for those with a Wpeak ⩽ 49.2% predicted versus 10.9% for those with a Wpeak > 49.2% predicted (P < 0.001). Conclusions: CPET provides prognostic information in advanced CF lung disease, and Wpeak appears to be a promising marker for LTX referral and candidate selection.

Mechanisms of ventilatory limitation to maximum exercise in children and adolescents with chronic airway diseases

INTRODUCTION

Exercise intolerance is common in chronic airway diseases (CAD), but its mechanisms are still poorly understood. The aim of this study was to evaluate exercise capacity and its association with lung function, ventilatory limitation, and ventilatory efficiency in children and adolescents with cystic fibrosis (CF) and asthma when compared to healthy controls.

METHODS

Cross-sectional study including patients with mild-to-moderate asthma, CF and healthy children and adolescents. Anthropometric data, lung function (spirometry) and exercise capacity (cardiopulmonary exercise testing) were evaluated. Primary outcomes were peak oxygen consumption (VO2 peak), forced expiratory volume in 1 s (FEV1 ), breathing reserve (BR), ventilatory equivalent for oxygen consumption (VE /VO2 ) and for carbon dioxide production (VE /VCO2 ), both at the ventilatory threshold (VT1 ) and peak exercise.

RESULTS

Mean age of 147 patients included was 11.8 ± 3.0 years. There were differences between asthmatics and CF children when compared to their healthy peers for anthropometric and lung function measurements. Asthmatics showed lower VO2 peak when compared to both healthy and CF subjects, although no differences were found between healthy and CF patients. A lower BR was found when CF patients were compared to both healthy and asthmatic. Both CF and asthmatic patients presented higher values for VE /VO2 and VE /VCO2 at VT1 when compared to healthy individuals. For both VE /VO2 and VE /VCO2 at peak exercise CF patients presented higher values when compared to their healthy peers.

CONCLUSION

Patients with CF achieved good exercise capacity despite low ventilatory efficiency, low BR, and reduced lung function. However, asthmatics reported reduced cardiorespiratory capacity and normal ventilatory efficiency at peak exercise. These results demonstrate differences in the mechanisms of ventilatory limitation to maximum exercise testing in children and adolescents with CAD.

Ventilatory efficiency and its clinical and prognostic value in adults with cystic fibrosis

Cystic fibrosis, due to the absence or abnormal function of the cystic fibrosis transmembrane conductance regulator, is the most common life-limiting autosomal recessive genetic disorder among the Caucasian population. The lungs are particularly affected due to thick and tenacious mucus causing parenchymal anomalies ranging from bronchiectasis, progressive airflow limitation, respiratory infections, lung destruction and ultimately respiratory failure. Despite the remarkable advances in treatment that have greatly improved survival, most patients experience progressive exercise curtailment, with the consequence that a growing number of patients with cystic fibrosis will be referred for exercise-based evaluations in the forthcoming years. Cardiopulmonary exercise testing, in particular, is a useful tool to assess the mechanisms of exercise intolerance in individual patients that may have treatment and prognostic implications. In this review, we will focus on ventilatory efficiency and its clinical and prognostic value in adults with cystic fibrosis.

Growing-rod Graduates With Idiopathic Early-onset Scoliosis Have Comparable Exercise Tolerance to Patients With Surgically Treated Adolescent Idiopathic Scoliosis

BACKGROUND

Growing-rod (GR) treatment is the current standard for progressive idiopathic early-onset scoliosis (I-EOS) in young children. Despite good radiographic outcomes, the impact of scoliosis treatment on pulmonary functions is not well-defined in this patient population. The aim of this study was to evaluate pulmonary functions and exercise tolerance in I-EOS patients graduated from GR treatment and to compare them with age-matched, surgically treated adolescent idiopathic scoliosis (AIS) patients and healthy controls.

METHODS

Eight GR graduates with I-EOS with pulmonary function tests and complete radiographic results were compared with a group of 9 thoracic AIS patients at least 2 years out from posterior fusion. Both groups were also compared with a set of 10 healthy individuals. All subjects underwent cardiopulmonary exercise testing and spirometry to evaluate pulmonary function.

RESULTS

Age, sex, height, arm span, weight, residual deformity, and level of instrumentation in GR and AIS patients were similar. In the GR group, forced vital capacity % and forced expiratory volume in 1 second % values were reduced compared with the healthy controls and AIS group (P<0.001, <0.001 and 0.036, 0.046, respectively). Breathing reserve index at lactate threshold (BRILT) was higher in GR and AIS patients (P=0.001 and 0.002, respectively), and was similar between GR and AIS patients (P=0.916). Heart rate at lactate threshold was higher in GR and AIS groups compared with controls (P<0.001 and 0.001, respectively).

CONCLUSIONS

AIS and GR patients demonstrated reduced pulmonary reserve and exercise tolerance compared with their peers with no spinal deformity. However, exercise tolerance of I-EOS patients treated with the GR method was similar to that of operated AIS patients. These results suggest a positive impact of GR treatment in children with I-EOS.

LEVEL OF EVIDENCE

Level III-cross-sectional comparative study.

Reduced exercise ventilatory efficiency in adults with cystic fibrosis and normal to moderately impaired lung function

Despite being a hallmark and an independent prognostic factor in several cardiopulmonary diseases, ventilatory efficiency-i.e., minute ventilation/carbon dioxide output relationship (V̇e/V̇co₂)-has never been systematically explored in cystic fibrosis (CF). To provide a comprehensive frame of reference regarding measures of ventilatory efficiency in CF adults with normal to moderately impaired lung function and to confirm the hypothesis that V̇e/V̇co₂ is a sensitive marker of early lung disease. CF patients were divided into three groups, according to their spirometry: normal (G₁), mild impairment (G₂), and moderate impairment (G₃) in lung function. All participants underwent incremental cardiopulmonary exercise testing on a cycle ergometer. Lowest V̇e/V̇co₂ ratio (nadir) and the slope and the intercept of the linear region of the V̇e/V̇co₂ relationship were contrasted in a two-center retrospective analysis, involving 72 CF patients and 36 healthy controls (HC). Compared with HC, CF patients had significantly higher V̇e/V̇co₂ nadir, slope, and intercept (P < 0.001, P < 0.001, and P = 0.049, respectively). Subgroup analysis revealed significant differences in nadir (P = 0.001) and slope (P = 0.012) values even between HC and G₁. Dynamic hyperinflation related negatively with slope (P = 0.045) and positively with intercept (P = 0.001), while no impact on nadir was observed. Ventilatory inefficiency is a clear feature of adults with CF, even among patients with normal spirometry. V̇e/V̇co₂ nadir seems to be the most reliable metric to describe ventilatory efficiency in CF adults. Further prospective studies are needed to clarify whether V̇e/V̇co₂ could represent a useful marker in the evaluation of early lung disease in CF.NEW & NOTEWORTHY This is the first study to investigate ventilatory efficiency in a cohort of adult cystic fibrosis (CF) patients with nonsevere lung disease. The finding of impaired ventilatory efficiency in patients with normal lung function confirms the higher sensitivity of exercise testing in detecting early lung disease compared with spirometry. Dynamic hyperinflation plays a significant role in determining the behavior of V̇e/V̇co₂ slope and intercept values with increasing lung function impairment. Apparently free from interference from mechanical constraints, V̇e/V̇co₂ nadir seems the most reliable parameter to evaluate ventilatory efficiency in CF adults.

Lung transplant referral for individuals with cystic fibrosis: Cystic Fibrosis Foundation consensus guidelines

OBJECTIVE

Provide recommendations to the cystic fibrosis (CF) community to facilitate timely referral for lung transplantation for individuals with CF.

METHODS

The CF Foundation organized a multidisciplinary committee to develop CF Lung Transplant Referral Consensus Guidelines. Three workgroups were formed: timing for transplant referral; modifiable barriers to transplant; and transition to transplant care. A focus group of lung transplant recipients with CF and spouses of CF recipients informed guideline development.

RESULTS

The committee formulated 21 recommendation statements based on literature review, committee member practices, focus group insights, and in response to public comment. Critical approaches to optimizing access to lung transplant include early discussion of this treatment option, assessment for modifiable barriers to transplant, and open communication between the CF and lung transplant centers.

CONCLUSIONS

These guidelines will help CF providers counsel their patients and may reduce the number of individuals with CF who die without consideration for lung transplant.

Cardiopulmonary exercise testing with supramaximal verification produces a safe and valid assessment of V̇o2max in people with cystic fibrosis: a retrospective analysis

The validity and safety of using supramaximal verification (S_max) to confirm a maximal effort during cardiopulmonary exercise testing (CPET) in people with cystic fibrosis (CF) and/or those with severe disease has been questioned. Therefore, this study aimed to investigate these concerns in children, adolescents, and adults with mild-to-severe CF lung disease. Retrospective analysis of 17 pediatric and 28 adult participants with CF [age range: 9.2-62.9 y; forced expiratory volume in 1 s: 66.7% (range: 29.9%-102.3%); 30 men] who completed a routine ramp-incremental cycling test to determine peak oxygen uptake (V̇o_2peak) was studied. Maximal oxygen uptake (V̇o_2max) was subsequently confirmed by S_max at 110% of peak power output. All participants satisfied the criteria to verify a maximal effort during CPET. However, S_max-V̇o_2peak exceeded ramp-V̇o_2peak in 3/14 (21.4%) of pediatric and 6/28 (21.4%) adult exercise tests. A valid measurement of V̇o_2max was attained in 85.7% of pediatric and 96.4% of adult exercise tests, as S_max-V̇o_2peak did not exceed ramp-V̇o_2peak by >9%. Adults ( n = 9) experienced a ≥5% reduction in arterial O₂ saturation during CPET, 4 during both the ramp and S_max, 3 during only the ramp, and 2 during only S_max. S_max did not significantly worsen perceived breathing effort, chest tightness, throat narrowing, or exertion compared with ramp-incremental testing. Given the clinical importance of aerobic fitness in people with CF, incorporating S_max is recommended to provide a safe and valid measure of V̇o_2max in children, adolescents, and adults who span the spectrum of CF disease severity. NEW & NOTEWORTHY Incorporating supramaximal verification into cardiopulmonary exercise testing protocols did not increase the frequency of adverse events or perceived discomfort versus a single-phase incremental exercise test in people with mild-to-severe cystic fibrosis. Furthermore, a valid measure of maximal oxygen uptake (V̇o_2max) was obtained from 85.7% of pediatric and 96.4% of adult exercise tests, whereas peak oxygen uptake underestimated aerobic fitness in comparison with V̇o_2max in 21.4% of cases (by up to 24.4%).

Pediatric Exercise Testing: Value and Implications of Peak Oxygen Uptake

Peak oxygen uptake (peakV˙O2) measured by clinical exercise testing is the benchmark for aerobic fitness. Aerobic fitness, estimated from maximal treadmill exercise, is a predictor of mortality in adults. PeakV˙O2 was shown to predict longevity in patients aged 7–35 years with cystic fibrosis over 25 years ago. A surge of exercise studies in young adults with congenital heart disease over the past decade has revealed significant prognostic information. Three years ago, the first clinical trial in children with pulmonary arterial hypertension used peakV˙O2 as an endpoint that likewise delivered clinically relevant data. Cardiopulmonary exercise testing provides clinicians with biomarkers and clinical outcomes, and researchers with novel insights into fundamental biological mechanisms reflecting an integrated physiological response hidden at rest. Momentum from these pioneering observations in multiple disease states should impel clinicians to employ similar methods in other patient populations; e.g., sickle cell disease. Advances in pediatric exercise science will elucidate new pathways that may identify novel biomarkers. Our initial aim of this essay is to highlight the clinical relevance of exercise testing to determine peakV˙O2, and thereby convince clinicians of its merit, stimulating future clinical investigators to broaden the application of exercise testing in pediatrics.

Mortality Risk and Pulmonary Function in Adults With Cystic Fibrosis at Time of Wait Listing for Lung Transplantation

BACKGROUND

Lung transplantation (LTx) benefit for survival in cystic fibrosis (CF) patients placed on the wait list is not well studied.

METHODS

To predict the relationship between initial forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) and the hazard ratio (HR) associated with LTx in CF patients, the United Network for Organ Sharing database was queried from 2005 to 2006 for adult patients with CF. Survival was assessed from wait list entry time until death on wait list, death after LTx, or censoring. Multivariate Cox proportional hazards models were used to assess the effect of LTx. The first model estimated the HR of LTx with adjustment for FEV1 or FVC and other covariates, and the second model estimated the HR of LTx conditional on FEV1 or FVC at listing.

RESULTS

Two hundred seventy-eight patients with CF were included in the cohort, and 277 were used for survival analysis. Lung transplantation reduced the risk for death controlling for FEV1 (HR, 0.601; 95% confidence interval, 0.375 to 0.964; p = 0.035) or controlling for FVC (HR, 0.547; 95% confidence interval, 0.336 to 0.889; p = 0.015). Interaction models found that the HR of LTx varied significantly across initial FEV1 and FVC, with the predicted LTx HR and 95% confidence interval being protective (HR < 1) at FEV1 of 25% or less and FVC of 40% or less, respectively.

CONCLUSIONS

The benefit of LTx in adults with CF was significant at a lower baseline FEV1 than expected. A threshold for baseline FVC was established below which LTx was protective.

Putting lung function and physiology into perspective: cystic fibrosis in adults

Adult cystic fibrosis (CF) is notable for the wide heterogeneity in severity of disease expression, both between patients and within the lungs of individuals. Although CF airways disease appears to start in the small airways, in adults there is typically widespread bronchiectasis, increased airway secretions, and extensive obstruction and inflammation of the small airways. The complexity and heterogeneity of airways disease in CF means that although there are many different methods of assessing and describing lung 'function', none of these single-dimensional tests is able to provide a comprehensive assessment of lung physiology across the spectrum seen in adult CF. The most widely described measure, the forced expiratory volume in 1 s, remains a useful and simple clinical tool, but is insensitive to early changes and may be dissociated from other more detailed assessments of disease severity such as computed tomography. In this review, we also discuss the use of more sensitive novel assessments such as multiple breath washout tests and impulse oscillometry, as well as the role of cardiopulmonary exercise testing. In the future, hyperpolarized gas magnetic resonance imaging techniques that combine regional structural and functional information may help us to better understand these measures, their applications and limitations.

Determinants of exercise capacity in cystic fibrosis patients with mild-to-moderate lung disease

Background

Adult patients with cystic fibrosis (CF) frequently have reduced exercise tolerance, which is multifactorial but mainly due to bronchial obstruction. The aim of this retrospective analysis was to determine the mechanisms responsible for exercise intolerance in patients with mild-to-moderate or severe disease.

Methods

Cardiopulmonary exercise testing with blood gas analysis at peak exercise was performed in 102 patients aged 28 ± 11 years: 48 patients had severe lung disease (FEV₁ < 50%, group 1) and 54 had mild-to-moderate lung disease (FEV₁ ≥ 50%, group 2). VO₂ peak was measured and correlated with clinical, biological, and functional parameters.

Results

VO₂ peak for all patients was 25 ± 9 mL/kg/min (65 ± 21% of the predicted value) and was < 84% of predicted in 82% of patients (100% of group 1, 65% of group 2). VO₂ peak was correlated with body mass index, C-reactive protein, FEV₁, FVC, RV, DLCO, V_E/VCO₂ peak, V_D/V_T, PaO₂, PaCO₂, P(A-a)O₂, and breathing reserve. In multivariate analysis, FEV₁ and overall hyperventilation during exercise were independent determinants of exercise capacity (R² = 0.67). FEV₁ was the major significant predictor of VO₂ peak impairment in group 1, accounting for 31% of VO₂ peak alteration, whereas excessive overall hyperventilation (reduced or absent breathing reserve and V_E/VCO₂) accounted for 41% of VO₂ alteration in group 2.

Conclusion

Exercise limitation in adult patients with CF is largely dependent on FEV₁ in patients with severe lung disease and on the magnitude of the ventilatory response to exercise in patients with mild-to-moderate lung disease.

Practical guidelines: lung transplantation in patients with cystic fibrosis

There are no European recommendations on issues specifically related to lung transplantation (LTX) in cystic fibrosis (CF). The main goal of this paper is to provide CF care team members with clinically relevant CF-specific information on all aspects of LTX, highlighting areas of consensus and controversy throughout Europe. Bilateral lung transplantation has been shown to be an important therapeutic option for end-stage CF pulmonary disease. Transplant function and patient survival after transplantation are better than in most other indications for this procedure. Attention though has to be paid to pretransplant morbidity, time for referral, evaluation, indication, and contraindication in children and in adults. This review makes extensive use of specific evidence in the field of lung transplantation in CF patients and addresses all issues of practical importance. The requirements of pre-, peri-, and postoperative management are discussed in detail including bridging to transplant and postoperative complications, immune suppression, chronic allograft dysfunction, infection, and malignancies being the most important. Among the contributors to this guiding information are 19 members of the ECORN-CF project and other experts. The document is endorsed by the European Cystic Fibrosis Society and sponsored by the Christiane Herzog Foundation.

Exercise testing in pediatric lung transplant candidates with cystic fibrosis

Exercise testing is considered an important prognostic tool for the selection of pediatric lung transplant candidates with end-stage CF lung disease. To better understand the current practice as it pertains to exercise testing, a self-administered questionnaire was distributed to 25 pediatric lung transplant centers within the IPLTC across Australia, Europe, and North America. All centers perform standardized exercise tests. Fifteen centers perform one single-field test (6MWT/12MWT), while seven perform a six-min walk plus an additional test: SWT (N = 1), 3MST (N = 1), and CPET (N = 5). Frequency of testing is markedly different among centers. Two centers conduct exercise testing once, all others at multiple time points. Equipment availability and cost were no limitations, but lack of time (20%) and personnel (16%), and paucity of prognostic evidence (16%) and reference values (12%) were stated. Exercise testing is considered important and extensively used in the evaluation of pediatric lung transplant candidates with CF; methods of exercise test and the frequency of testing vary widely. We propose a prospective multicenter study to evaluate the efficacy of exercise testing and its prognostic value using a standardized protocol.

[Prognostic value of clinical exercise testing in adult patients with cystic fibrosis]

BACKGROUND

Current guidelines for referring cystic fibrosis (CF) patients for lung transplantation, based on resting parameters, are insufficient to predict 3-year mortality. The aim of this study was to determine the prognostic value of cardiopulmonary exercise testing (CPET) in adult CF patients.

METHODS

A multicenter retrospective study on 3-year outcomes was made on 51 adult CF patients who underwent CPET with blood gas analysis. Demographic data, resting pulmonary function and CPET parameters were collected to perform a univariate survival analysis by Kaplan-Meier curves and log-rank tests. To estimate prognosis, a multivariate logistic regression analysis was performed.

RESULTS

The survival log-rank analysis indicated that lower FEV(1), lower body mass index (BMI), diabetes mellitus, lower work rate and higher alveolar-arterial gradient for oxygen (P[A-a]O(2)) at peak exercise were associated with a significantly higher risk of death. The logistic regression analysis showed that BMI (<19.8) and P(A-a)O(2) peak (>43 mmHg) were independently associated with a lower chance of survival.

CONCLUSION

CPET with blood gas analysis may have a prognostic value in adult CF patients. Further larger prospective clinical studies are warranted to confirm these preliminary results.

Exercise testing in children with lung diseases

Exercise is an important aspect of health and development in children. By placing the pulmonary system under stress, exercise testing may reveal subtle dynamic abnormalities that are not apparent on conventional static pulmonary function tests. Furthermore, exercise testing assesses the functional impact of respiratory disease on children. Exercise testing has been used in children with a variety of respiratory diseases such as exercise induced bronchoconstriction, asthma, cystic fibrosis and bronchopulmonary dysplasia to assess the severity of disease as well as response to various interventions. Furthermore, there is good evidence that exercise testing is a useful tool to help determine prognosis in patients with cystic fibrosis. In addition to the clinical utility, exercise testing is also becoming an increasingly important outcome measure in research studies.

Substrate utilization during and after exercise in mild cystic fibrosis

PURPOSE

To determine substrate utilization and energy expenditure during maximal and submaximal exercise and recovery in adolescents with cystic fibrosis (CF) and healthy age-matched controls (C).

METHODS

Ten clinically stable CF patients (four girls, six boys; age = 10-22 yr) were matched by body mass index, age, gender, and Tanner stage to healthy controls. Subjects completed VO(2peak) testing and submaximal exercise (20 min) on a cycle ergometer at a relative intensity of 50% VO2(peak) and at an absolute power output (PO). Metabolic parameters were assessed during exercise and recovery (20 min).

RESULTS

Similar respiratory quotient (RQ) values occurred in both groups during maximal exercise and recovery, despite differences in the maximal PO [CF = 114 (60-180) W and C = 171 (105-280) W, P = 0.006], the total work completed [CF = 27 (9.0-54.3) kJ and C = 55 (25.3-126.5) kJ, P = 0.008], or the VO(2peak) value attained [CF = 30.6 (8.5-45.2) mL kg(-1) min(-1) and C = 40.6 (29-64.5) mL kg(-1) min(-1), P = 0.027]. Submaximal exercise at the same absolute PO resulted in similar RQ values during exercise and recovery despite higher heart rates and average VO2 [CF = 18.8 (9.3-28.7) mL kg(-1) min(-1) and C = 15.2 (6.5-20.1) mL kg(-1)min(-1), P = 0.031] values in CF adolescents, and submaximal exercise at the same relative intensity also resulted in similar RQ values despite significantly greater average PO in the C group [CF = 38.7 (12.3-80) W and C = 67.8 (25.5-140) W, P = 0.039]. Excess postexercise oxygen consumption (EPOC) was greater in CF [2.79 (1.14-5.24) L O2] than C [1.46 (0.56-2.80) L O2] after submaximal exercise at a fixed PO (P = 0.036) but not after the relative exercise bout.

CONCLUSIONS

Habitual physical activity participation does not warrant adjustment of macronutrient intake ratios in adolescents with mild to moderate CF, but total caloric intake may need to be increased based on the level of EPOC and upon the intensity and the duration of the habitual activity.

Clinical exercise testing in children and adolescents with cystic fibrosis

PURPOSE

To review the most common field and laboratory exercise tests available for children and adolescents with cystic fibrosis (CF).

METHODS

Relevant studies for this review were identified by electronic search of Medline and PubMed databases between the years 1958 and 2008. The bibliographies of all accessed publications were also searched. Key descriptors were cystic fibrosis, exercise testing, aerobic fitness, children, and adolescents.

RESULTS

Five field tests were selected for presentation, including discussion of their strengths and weaknesses. Laboratory tests measuring aerobic and anaerobic responses to exercise in children with CF were also selected for presentation and discussed along with a summary of safety considerations for exercise testing of children with CF.

CONCLUSION

Exercise testing is regarded an important prognostic tool in CF care. However, despite its beneficial effects, clinical exercise testing seems underused. Clinicians and their staff should encourage patients with CF to be physically active and recommend exercise testing annually.

Lung transplantation for cystic fibrosis: Current concepts and one center's experience

BACKGROUND

Although new approaches to the treatment of patients with cystic fibrosis (CF) are significantly prolonging their lives, most patients will eventually develop respiratory failure due to progressive bronchiectasis caused by chronic lung infection and inflammation and die from to respiratory failure. We examined our center's (University of Wisconsin Hospital and Clinics) experience with lung transplantation for patients with CF and reviewed the literature to examine current and evolving approaches to transplantation for this indication.

METHODS

We reviewed all published literature pertaining to lung transplantation for CF through 2006, and we reviewed all aspects of transplantation for patients with CF at our institution from 1994 to 2005.

RESULTS

Major complications following lung transplantation include acute rejection, bacterial infection, and bronchiolitis obliterans. Five-year survival at UWHC (Kaplan-Meier) is 67%, and survival was not adversely affected by transplanting patients receiving mechanical ventilation. The major cause of death for transplant recipients was bronchiolitis obliterans syndrome (BOS).

CONCLUSIONS

Lung transplantation for CF is associated with acceptable survival rates and can improve quality of life. Lung transplant should be offered to all patients with advanced CF lung disease if they meet currently accepted inclusion and exclusion criteria.

Mucoviscidose : du bon usage des explorations fonctionnelles respiratoires

INTRODUCTION

Neonatal screening for cystic fibrosis (CF) leads to early dedicated specialist care for all patients.

BACKGROUND

Pulmonary function tests (PFT) are mandatory for routine monitoring of CF patients. The aim of this article is to review the current guidelines for PFTs in CF, particularly the type of test, the age and the clinical status of the patient.

VIEWPOINT

The regular use of spirometry is generally accepted. Many other tests are used but their clinical value in the routine follow-up of CF patients remains to be established.

CONCLUSION

Further efforts should be made to evaluate the value of PFTs in CF, particularly in very young children.

Lung transplantation for cystic fibrosis

PURPOSE OF REVIEW

To examine recent publications on lung transplantation for cystic fibrosis for changes in surgical techniques, selection criteria of patients, and impact on quality of life.

RECENT FINDINGS

Recent evidence focuses on cystic fibrosis patient subsets enabling better decisions about listing for lung transplantation as a therapeutic option. There is information about Burkholderia cepacia infection, ventilator dependence, young age, and arthropathy. In the US, the United Network for Organ Sharing has addressed perceived inequities in organ distribution by allocating organs by illness severity rather than time on the waiting list. A Lung Allocation Score ranks severity for patients 12 years of age and older for transplantation based on variables including lung function, oxygen and ventilatory needs, diabetes, weight and physical performance. Some recently studied important variables that influence survival in cystic fibrosis and after lung transplantation, including airway infections, pancreatic exocrine function and acute exacerbations, are not included in the Lung Allocation Score. Few publications have examined quality of life after transplantation, and a definitive work has yet to appear.

SUMMARY

New information has refined decision-making about lung transplantation for patients with cystic fibrosis. We examine recent findings and make recommendations for patients, families and medical providers.

Pediatric lung transplantation

Lung transplantation in children has been performed since the early 1990s. The indications are cystic fibrosis, pulmonary vascular disease, and a variety of other pulmonary problems leading to death in small children. These other diseases include abnormalities in the metabolism of surfactant producing severe respiratory insufficiency in newborn infants. Many problems accompany these patients before transplantation and many problems are produced both by the transplant itself and immunosuppressant drugs which these children are obliged to take following transplantation. Nonetheless, lung transplantation offers the only real hope of survival in many instances. The long-term results have been somewhat discouraging with a 5-year survival of approximately 50%. The major causes of mortality late following lung transplantation are bronchiolitis obliterans, infections, and malignancy. The development of newer immunosuppressant drugs may offer hope for better results in the future.

Lung transplantation for cystic fibrosis: 6-year follow-up

Lung transplantation is currently the most effective means of improving survival and quality of life in patients with end-stage cystic fibrosis. In reviewing our 6-year experience we sought to evaluate complications and survival after sequential bilateral lung transplantation. Between October 1996 and October 2002, 114 patients with cystic fibrosis were referred to us from 15 Italian regional centers and 2 support centers for cystic fibrosis as possible candidates for lung transplantation. Of these 114 patients, 99 were included in the waiting list and 15 were refused. The mean time spent on the waiting list was 6.8+/-5.2 months (range 1 day-21 months) for those patients receiving lung transplantation, and 5.4+/-4.5 months (range 10 days-18 months) for those 35 patients who died while on the waiting list. A total 55 patients (6 children and 49 adults), mean age 25.6+/-6.6 years (range 9-52 years), 29 males, underwent bilateral sequential lung transplantation. One patient had a second transplantation 14 months after the first. The most frequent medical non-infective complications after transplantation were chronic renal failure (n=27 patients), diabetes (n=31), osteoporosis (n=17), arterial hypertension (n=14), seizures (n=4), transient cerebral ischaemia (n=1), and transient bilateral blindness (n=1). Bacterial lower airways respiratory infections with the organisms that colonized patients' airways before lung transplantation developed in 42 patients; cytomegalovirus (CMV) infection in 41; and opportunistic infections of the lung with Pneumocystis carinii in 3 patients. Cultures of sputum or bronchoalveolar lavage fluid grew Aspergillus fumigatus in nine patients; aspergillosis of right bronchial anastomosis developed in one patient and a lung infection in another. Another patient had a pulmonary infection secondary to Aspergillus niger. An average of 1.3 episodes of acute rejection developed per patient in the first 6 months after lung transplantation. Freedom from bronchiolitis obliterans syndrome was 95% at 1 year, 82.5% at 2 years, 70% at 3 years, and 65% at 4, 5 and 6 years. Actuarial survival rates were 80% at 1 month, 79% at 1 year, 74% at 2 years, 70% at 3 years and 58% at 4, 5 and 6 years. Ten patients (17.8%) died in the early postoperative period (1-30 days) for the following reasons: primary graft failure (n=4), multiorgan failure (n=3), Burkholderia cepacia sepsis (n=1), myocardial infarction (n=1), and pulmonary embolism (n=1). Mortality was accounted for by 9 patients (16%) who died from 9 to 43 months after lung transplantation, for the following reasons: P. carinii infection (n=2), bronchiolitis obliterans syndrome (n=4), A. fumigatus pulmonary infection (n=1), unknown cause (n=1) and suicide (n=1). In conclusion, the leading causes of morbidity after lung transplantation for cystic fibrosis are pulmonary bacterial infection and opportunistic infections. Bronchiolitis obliterans develops in more than half of lung transplant recipients who survive for more than 3 years and is an important cause of death in the late post transplantation period.

Lung Transplantation

The timing of the referral and listing of patients for lung transplantation remains a difficult decision. Life expectancy and quality of life with and without transplantation are the pivotal issues that need to be considered by physicians and presented to prospective transplant candidates. The recognition of recent advances in the understanding of the various primary diseases, other potential therapies, and the latest posttransplant statistics are essential for a balanced discussion or decision about lung transplantation. This article provides a review of these and other pertinent issues for patients with various forms of advanced lung disease.

Recipient selection

Since international recommendations for lung transplant recipients were made in 1998, newer tools for predicting mortality in patients who have end-stage lung disease have been investigated. This article reviews studies for predicting mortality in obstructive, restrictive, pulmonary vascular, and suppurative/bronchiectatic lung disease. Newer considerations for alternative treatments, postoperative risks, and contraindications are also examined. The article aims to provide more accurate data for selecting patients who will benefit from lung transplantation.