Early detection of lung disease and its association with the nutritional status, genetic background and life events in patients with cystic fibrosis

Inspiration for the Future: The Role of Inspiratory Muscle Training in Cystic Fibrosis

Cystic fibrosis (CF) is an inherited, multi-system, life-limiting disease characterized by a progressive decline in lung function, which accounts for the majority of CF-related morbidity and mortality. Inspiratory muscle training (IMT) has been proposed as a rehabilitative strategy to treat respiratory impairments associated with CF. However, despite evidence of therapeutic benefits in healthy and other clinical populations, the routine application of IMT in CF can neither be supported nor refuted due to the paucity of methodologically rigorous research. Specifically, the interpretation of available studies regarding the efficacy of IMT in CF is hampered by methodological threats to internal and external validity. As such, it is important to highlight the inherent risk of bias that differences in patient characteristics, IMT protocols, and outcome measurements present when synthesizing this literature prior to making final clinical judgments. Future studies are required to identify the characteristics of individuals who may respond to IMT and determine whether the controlled application of IMT can elicit meaningful improvements in physiological and patient-centered clinical outcomes. Given the equivocal evidence regarding its efficacy, IMT should be utilized on a case-by-case basis with sound clinical reasoning, rather than simply dismissed, until a rigorous evidence-based consensus has been reached.

High attainment of optimal nutritional and growth status observed among Greek pediatric cystic fibrosis patients: results from the GreeCF study

BACKGROUND

Pediatric cystic fibrosis (CF) patients suffer high rates of undernutrition, subject to several parameters. We aimed to assess growth and nutritional status of Greek children and adolescents with CF.

METHODS

Eighty-four patients (35 boys) formed the sample. Anthropometrics and FEV1 were measured, growth and weight status were assessed. Body mass index (BMI), arm circumference (MUAC), fat (MUAFA) and muscle (MUAMA) were calculated.

RESULTS

In the total sample, 6.0% of the patients were underweight, 4.8% stunted, 8.3% wasted and 17.9% in nutritional failure, whereas 59.5% attained the ideal BMI for CF. FEV1 positively associated with BMI (B=0.03, p≤0.003), weight (B=0.03, p≤0.003) and MUAMA z-scores (B=0.04, p≤0.005). Meconium ileus negatively associated with FEV1 (B=-14.17, p≤0.003) and stature (B=-0.65, p≤0.043). Pancreatic insufficiency negatively influenced MUAC and MUAFA z-scores (p≤0.05 for both).

CONCLUSIONS

The examined CF patients appear to be thriving. Unlike published research, the participants' sex, gene mutation and acquisition of pathogens did not affect growth.

Disease-modifying genes and monogenic disorders: experience in cystic fibrosis

The mechanisms responsible for the determination of phenotypes are still not well understood; however, it has become apparent that modifier genes must play a considerable role in the phenotypic heterogeneity of Mendelian disorders. Significant advances in genetic technologies and molecular medicine allow huge amounts of information to be generated from individual samples within a reasonable time frame. This review focuses on the role of modifier genes using the example of cystic fibrosis, the most common lethal autosomal recessive disorder in the white population, and discusses the advantages and limitations of candidate gene approaches versus genome-wide association studies. Moreover, the implications of modifier gene research for other monogenic disorders, as well as its significance for diagnostic, prognostic, and therapeutic approaches are summarized. Increasing insight into modifying mechanisms opens up new perspectives, dispelling the idea of genetic disorders being caused by one single gene.

Sex-specific embryonic origin of postnatal phenotypic variability

Preimplantation developmental plasticity has evolved in order to offer the best chances of survival under changing environments. Conversely, environmental conditions experienced in early life can dramatically influence neonatal and adult biology, which may result in detrimental long-term effects. Several studies have shown that small size at birth, which is associated with a greater risk of metabolic syndrome, is largely determined before the formation of the blastocysts because 70%–80% of variation in bodyweight at birth has neither a genetic nor environmental component. In addition, it has been reported that adult bodyweight is programmed by energy-dependent process during the pronuclear stage in the mouse. Although the early embryo has a high developmental plasticity and adapts and survives to adverse environmental conditions, this adaptation may have adverse consequences and there is strong evidence that in vitro culture can be a risk factor for abnormal fetal outcomes in animals systems, with growing data suggesting that a similar link may be apparent for humans. In this context, male and female preimplantation embryos display sex-specific transcriptional and epigenetic regulation, which, in the case of bovine blastocysts, expands to one-third of the transcripts detected through microarray analysis. This sex-specific bias may convert the otherwise buffered stochastic variability in developmental networks in a sex-determined response to the environmental hazard. It has been widely reported that environment can affect preimplantation development in a sex-specific manner, resulting in either a short-term sex ratio adjustment or in long-term sex-specific effects on adult health. The present article reviews current knowledge about the natural phenotypic variation caused by epigenetic mechanisms and the mechanisms modulating sex-specific changes in phenotype during early embryo development resulting in sex ratio adjustments or detrimental sex-specific consequences for adult health. Understanding the natural embryo sexual dimorphism for programming trajectories will help understand the early mechanisms of response to environmental insults.

Longitudinal assessment of lung function from infancy to childhood in patients with cystic fibrosis

RATIONALE

Infant pulmonary function testing (IPFT) has become an important clinical tool for the evaluation of lung function in infants with Cystic Fibrosis (CF); however, it is still unclear whether lung function in infancy is predictive of lung function later in life. We hypothesized that measures of airflow obstruction by IPFT would correlate strongly with lung function by conventional spirometry later in childhood.

STUDY DESIGN AND METHODOLOGY

A retrospective analysis was performed of all CF infants studied with IPFT at the University of Minnesota Children's Hospital between September 1994 and March 2003. A total of 41 patients underwent IPFT and had valid spirometry results available at age 6 or later. IPFT values, such as I:E ratio, respiratory rate, tidal volume, and T(ptef)/T(e), were calculated from tidal breathing loops. Passive respiratory system mechanics, which included C(rs), R(rs), and tau(rs), were measured by the single breath end-inspiratory occlusion technique. Forced expiratory flows, including V(max)FRC, FVC, FEF(50), and FEF(75), were obtained by rapid thoracic compression and included a full vital capacity maneuver by the multiple inflation method. FRC measurements were calculated from data obtained via nitrogen washout in a subset of patients. In addition, information on age at diagnosis and results of oropharyngeal (OP) cultures at diagnosis and on subsequent visits was recorded. Standard spirometry was performed in all patients starting at age 5. The first valid flow-volume loop after age six was selected for analysis.

RESULTS

Significant correlations were observed for the R(rs) and the FEF(50) by IPFT and the FEV(1) and the FEF(25-75) by standard spirometry (r > 0.4 and P < 0.03 for all correlations). These correlations were the strongest for those IPFT measurements obtained within 1 month of diagnosis and when R(rs) was expressed as sG(rs). The correlations observed were independent of the effects of age at diagnosis, gender and presence of Pseudomonas in oropharyngeal cultures at the time of diagnosis. Mean R(rs) declined from 0.050 to 0.027 cm H(2)O/ml/sec with treatment (P < 0.0001). There were no other significant associations found between other IPFT values measured and FEV(1) by spirometry.

CONCLUSIONS

Measures of airflow obstruction on IPFT, specifically R(rs), sG(rs), and FEF(50), were strongly correlated with future lung function. IPFT measurement of R(rs) in addition to forced expiratory flows may help select patients at the greatest risk of early lung function decline. This study supports the use of R(rs) as a surrogate variable to help assess the impact of early therapies in CF.

Correlation of chest radiograph pattern with genotype, age, and gender in adult cystic fibrosis: a single-center study

INTRODUCTION

Cystic fibrosis (CF) is a common lethal genetic disorder. The aim of this study was to determine the common chest radiograph (CXR) patterns in adult CF, and correlate disease distribution on CXRs with genotype, age, and gender.

METHODS

One hundred nine CF patients treated at Baylor Adult Cystic Fibrosis Center were identified. The intake CXR was reviewed and characterized as diffuse bilateral (DB), unilateral, upper lobe (UL), and lower lobe (LL) disease, or relatively normal. Lack of intake CXR, and/or genotype excluded 41 patients from analysis.

RESULTS

Of 68 patients, 38 were homozygous for DeltaF508 and 30 were heterozygous. Mean age of the population was 30 +/- 8 years (+/- SD) [range, 18 to 48 years]. The most common CXR pattern was DB; 62% had DB, 28% had UL, and 7% had LL predominance. This is in contrast to the UL-predominant CXR pattern commonly described in the pediatric population. In 18 DB patients, archived pediatric films were available, and the average patient age was 15.7 years. DB pattern was present in 16 of 18 CXRs that antedated adult intake CXRs by an average of 12.7 years. Homozygous DeltaF508 genotype was identified in 56% of patients and did not distinguish radiologic phenotypes. There was no association between radiograph pattern and identified infecting/colonizing organisms and percentage of predicted FEV(1).

CONCLUSIONS

CF has commonly been reported as an UL disease. However, in this study of adult patients, the common pattern observed was DB. A small subgroup analysis suggests that DB disease was not a pattern of disease evolution but may be present from disease onset.

Nutrition and Lung Disease in Cystic Fibrosis

Among patients who have cystic fibrosis (CF), lung disease is a significant contributor to morbidity. From a clinical perspective, the link between malnutrition and lung dysfunction in CF is well established; however, the causal relationship remains unclear. Nutritional intervention for CF patients is predicated on the hypothesis that improved nutritional status improves pulmonary function. Which interventions will be of most value and have sustained gains is not completely clear from the available data. Taking into account that several factors condition the deficits that lead to malnutrition in CF, multidisciplinary interventions are likely to give the best results. More research is needed to better dissect the nutritional factors involved in lung disease and to identify effective and safe interventions through systematic controlled trials.

Long-Term Benefits of Inhaled Tobramycin in Children with Cystic Fibrosis: First Clinical Observations from Poland

BACKGROUND

Respiratory disease is the major cause of mortality in cystic fibrosis (CF) patients and inhaled antibiotic therapy may contribute to the stabilization of lung function.

OBJECTIVES

This is a small, open, uncontrolled, observational study of clinical experience obtained with 2 years of maintenance treatment with inhaled tobramycin in 12 children and adolescents with CF.

METHODS

Twelve subjects aged 6-18 years infected by Pseudomonas aeruginosa were qualified for treatment with inhaled tobramycin. Pulmonary function, weight and height, clinical status, and chest X-ray were continually monitored. After an active 2-year treatment period, results of all measured parameters in our patients were compared with their previous results (2-year period before treatment with tobramycin).

RESULTS

During 2 years before treatment with tobramycin solution for inhalation (TOBI), pulmonary function decline was observed, the median value of FEV(1) change was -7.6% (lower quartile -13.1, upper quartile -5.9). After 2 years of treatment, FEV(1) percent predicted value declined by 1.5% (lower quartile -11.1, upper quartile 3.7) from baseline; 2 years of TOBI therapy significantly reduced lung function decline (p = 0.049). There were no significant changes in thoracic gas volume and specific airway resistance before and after treatment. Two years of TOBI therapy significantly improved body mass index (p = 0.02). TOBI treatment significantly delayed progression of pulmonary X-ray changes assessed by Brasfield score (p = 0.02).

CONCLUSIONS

We found that patients with CF can gain substantial benefits from long-term TOBI treatment, including reduced pulmonary function decline, delayed progression of pulmonary X-ray changes and improved weight gain in growing children and adolescents.

Developmental paradigm for early features of cystic fibrosis

Cystic fibrosis (CF) is a progressive disease in which the lung is perceived to be normal at birth and is injured by recurrent infection. However, there is increasing evidence that the lung is functionally and structurally abnormal prior to the appearance of clinical infection. The cystic fibrosis transmembrane regulator (CFTR) is highly expressed in fetal tissues, and this review examines the role of CFTR in regulatory cascades during lung development. Early changes in the CF lung are examined from a perspective of disrupted fetal development, explaining a number of paradoxes seen with the disease.

Growth in prepubertal children with cystic fibrosis, homozygous for the Delta F508 mutation

BACKGROUND AND METHODS

In cystic fibrosis, growth and lung function have been identified as prognostic markers of both severity of pulmonary disease and survival. Cross-sectional studies in patients with cystic fibrosis (CF) including all genotypes have shown that in prepubertal patients with lifetime continuous care within a specialised CF centre, growth can normalise. No corresponding improvement in lung function has been found. We used a longitudinal design to determine whether normalisation of growth could be found in the genetic subgroup of prepubertal children with CF with the homozygous Delta F508 mutation, which is one of the known severe mutations.

METHODS

Data of all children born after 1980 with the homozygous Delta F508 mutation, diagnosed in early childhood at the specialised centre of the Children's Hospital of Berne were systematically assessed up to the age of 11 years and retrospectively analysed. Follow-up data of height, weight and BMI were compared to the Swiss reference population using z-scores. The correlations between lung function parameters (FEV1, MEF50, VC) and age, as well as lung function parameters and growth indices, were calculated. Additionally, the same correlations were examined in a cohort with the same mutation born 10 years earlier.

RESULTS

In the study, cohort growth (height, weight and BMI) was significantly below that of the normal Swiss population. A significant decline of lung function with age was also found, however, no association between lung function and growth could be seen. Compared to an earlier cohort, an improved growth over the last decade could be shown but no improvement on lung function could be detected. Lung function varied widely in both groups.

CONCLUSION

In contrast to sequential cross-sectional studies of children with CF, the present longitudinal study of children with homozygous for the Delta F508 mutation failed to confirm normalisation of growth over time. However, compared to the data of children born in the previous decade, improved growth was observed.

What is the role of tests of lung function in the management of infants with lung disease?

This review considers whether there is a role for lung function tests in the clinical management of infants with lung disease. The purpose of testing lung function in older subjects, the tests available for infants, and the practical problems of testing lung function in infants are considered. After reviewing all the facts, we suggest that there are four situations in which lung function testing should be recommended for infants, as follows: (1) the infant who presents with unexplained tachypnea, hypoxia, cough, or respiratory distress in whom a definitive diagnosis is not apparent from physical examination and other, less difficult investigations; (2) the infant with severe, continuous, chronic obstructive lung disease who does not respond to an adequate clinical trial of combined corticosteroid and bronchodilator therapy; (3) the infant with known respiratory disease of uncertain severity in whom there is need to justify management decisions; and (4) research and development. A review of 62 recent publications to determine how lung function tests are being used at the present time showed that they are being used overwhelmingly for research. The role of lung function testing in the clinical management of infants has not been established, and research is needed to clarify this situation. We suggest that such studies should explore the role of lung function tests in infants with specific symptoms, signs, or diagnoses, taking into account information from other types of investigation and the cost/benefit/risk ratios.

Growth and nutritional indexes in early life predict pulmonary function in cystic fibrosis

OBJECTIVE

To determine the relation of growth and nutritional status to pulmonary function in young children with cystic fibrosis (CF).

STUDY DESIGN

The relation of weight-for-age (WFA), height-for-age (HFA), percent ideal body weight (%IBW), and signs of lung disease at age 3 years with pulmonary function at age 6 years was assessed in 931 patients with CF. Associations of changes in WFA from age 3 to 6 on pulmonary function were also assessed.

RESULTS

WFA, HFA, and %IBW were poorly associated with lung disease at age 3 years, but all were strongly associated with pulmonary function at age 6 years. Those with WFA below the 5th percentile at age 3 had lower pulmonary function at age 6 compared with those above the 75th percentile (FEV(1): 86 +/- 20 [SD] versus 102 +/- 18 % predicted, respectively). Pulmonary function was highest in those whose WFA remained >10th percentile from age 3 to 6 (FEV(1): 100 +/- 19 % predicted) and lowest in those who remained <10th percentile (84 +/- 21 % predicted). Patients with signs and symptoms of lung disease at age 3 years had lower pulmonary function at age 6 years.

CONCLUSIONS

Aggressive intervention early in life aimed at growth and nutrition and/or lung disease may affect pulmonary function.

Comparison of subjective and objective measures in recurrently wheezy infants

OBJECTIVES

The aim of this study was to compare subjective measures (overall health assessment both by the study physician and the child's mother) with objective measurements of forced expiratory volumes (FEV(t)) and maximal flow at functional residual capacity V(max)FRC) in recurrently wheezy infants.

METHODS

Sixteen wheezy infants (12 boys) aged 8-26 months were studied. A clinical assessment at visit 1 was followed by the run-in period during which day- and nighttime asthma symptom scores were obtained. The actual study period consisted of 2 visits when patient's lung function was assessed. The first of which was during an acute exacerbation (visit 2), while the second was when the infant was asymptomatic (visit 3). FEV(t) were obtained by the raised volume rapid thoracic compression technique (RVRTC) and V(max)FRC by the tidal volume rapid thoracic compression technique (TVRTC).

RESULTS

Mean FEV(t) but not mean V(max)FRC were significantly lower at visit 2 compared to visit 3 (FEV(0.5): p = 0.005, and FEV(0.75): p = 0.002; V(max)FRC: p = 0.15) and correlated well with overall health assessment by the study physician (FEV(0.5): r = 0.82, and FEV(0.75): r = 0.84), but not with the overall health assessment by the mother.

CONCLUSIONS

We have shown in the present study that objective measurements of FEV(t) from a raised lung volume correlate well with the overall health assessment by the study physician; this was in contrast to measurements of V(max)FRC in the tidal volume range. We therefore conclude that the RVRTC technique is a feasible method to assess and monitor obstructive lung disease in infancy.

Clinical applications of infant lung function testing: does it contribute to clinical decision making?

Infant lung function testing is important in clinical research and recent standardisation efforts have enabled measurements to be made in infants in different laboratories throughout the world. Thus, the theoretical conditions are now fulfilled for use of these techniques in clinical practice. This review discusses the usefulness of various infant lung function techniques in a clinical setting and their potential present or future clinical application. It will focus on the role of infant lung function in the clinical management of infants with respiratory disease.