Three-minute step test to assess exercise capacity in children with cystic fibrosis with mild lung disease

Bibliometric Review of the Step Test: A Comprehensive Analysis of Research Trends and Development

BACKGROUND

The step test provides valuable information on cardiorespiratory parameters such as maximal oxygen uptake and heart rate. Cardiorespiratory capacity is critical to health-related fitness, with heart rate recovery after exercise serving as a predictor of mortality risk.

MAIN BODY

The primary objective of this review was to identify trends, key contributors, and emerging themes in the step test literature through 2023 using the Web of Science Core Collection. Bibliometric data extraction and analysis were performed using a dedicated bibliometric software (VOSviewer). The analysis showed continued interest through 2021. The research categories highlight the multidisciplinary nature of the step test, covering cardiovascular systems, respiratory systems, sports sciences, and medicine. It has gained global attention, with 31 countries involved, with Brazil and the United States leading the way. The diversity of contributing nations is increasing, reflecting a growing global interest. With 111 journals involved, such as Respiratory Care and Medicine and Science in Sports and Exercise, step test research is spread across the academic landscape. With 761 contributing researchers, there is a collaborative and diverse community. The top 10 institutions, including the University of Alabama System and Monash University, illustrate the variety of settings in which step test studies are conducted. Step test studies span multiple disciplines, underscoring their adaptability. The clusters identified in this bibliometric analysis of the step test literature guide future research, suggesting avenues for refining protocols, exploring health implications, optimizing tests for specific conditions such as chronic obstructive pulmonary disease, and adapting step tests in diverse populations.

CONCLUSIONS

Practical implications highlight the role of the step test in cardiovascular risk assessment, fitness monitoring, and rehabilitation. This broad review underscores the relevance of the step test in diverse settings, reflecting its adaptability and ease of application across occupational and clinical settings.

Feasibility of performing the 3-minute step test with remote supervision in children and adolescents with cystic fibrosis: A comparative study

Importance

The 3-min step test is a simple option to monitor submaximal exercise capacity, although its use via remote video monitoring has not been investigated in children with cystic fibrosis (CF).

Objective

This study aimed to assess the feasibility and reproducibility of performing the 3-min step test with remote supervision.

Methods

A cross-sectional study including CF patients (6-18 years) from two CF services were performed. Demographic, anthropometric, clinical, and lung function data were collected and two 3-min step tests were performed: (i) in-person supervision, and (ii) remotely supervised by video monitoring. Before and after the tests, heart rate (HR), oxygen saturation (SpO2), and the Borg score for dyspnea and lower limb fatigue were monitored.

Results

Twenty-three patients (10.7 ± 3.7 years) with a mean FEV1 of 89.5% ± 23.2% were included. There were no significant differences between tests, with mean differences (95% confidence intervals) in final HR of -3.3 (-8.9, 2.4), change in HR of -1.9 (-6.1, 2.1), final SpO2 of 0.3 (-0.4, 1.0), and final dyspnea of 0.1 (-0.8, 0.9). The intraclass correlation coefficient was 0.852 (final HR), 0.762 (final SpO2), and 0.775 (final lower limb fatigue). Significant and moderate correlations were found between tests for final HR (r = 0.75), change in HR (r = 0.61), and final SpO2 (r = 0.61). The Bland-Altman analysis showed a mean difference in final SpO2 between tests of 0.3% (limit of agreement -3.0%, 3.5%).

Interpretation

Physiological responses between tests were similar, indicating it was feasible to perform the 3-min step test with remote supervision in CF children.

Fixed-intensity exercise tests to measure exertional dyspnoea in chronic heart and lung populations: a systematic review

INTRODUCTION

Exertional dyspnoea is the primary diagnostic symptom for chronic cardiopulmonary disease populations. Whilst a number of exercise tests are used, there remains no gold standard clinical measure of exertional dyspnoea. The aim of this review was to comprehensively describe and evaluate all types of fixed-intensity exercise tests used to assess exertional dyspnoea in chronic cardiopulmonary populations and, where possible, report the reliability and responsiveness of the tests.

METHODS

A systematic search of five electronic databases identified papers that examined 1) fixed-intensity exercise tests and measured exertional dyspnoea, 2) chronic cardiopulmonary populations, 3) exertional dyspnoea reported at isotime or upon completion of fixed-duration exercise tests, and 4) published in English.

RESULTS

Searches identified 8785 papers. 123 papers were included, covering exercise tests using a variety of fixed-intensity protocols. Three modes were identified, as follows: 1) cycling (n=87), 2) walking (n=31) and 3) other (step test (n=8) and arm exercise (n=2)). Most studies (98%) were performed on chronic respiratory disease patients. Nearly all studies (88%) used an incremental exercise test. 34% of studies used a fixed duration for the exercise test, with the remaining 66% using an exhaustion protocol recording exertional dyspnoea at isotime. Exertional dyspnoea was measured using the Borg scale (89%). 7% of studies reported reliability. Most studies (72%) examined the change in exertional dyspnoea in response to different interventions.

CONCLUSION

Considerable methodological variety of fixed-intensity exercise tests exists to assess exertional dyspnoea and most test protocols require incremental exercise tests. There does not appear to be a simple, universal test for measuring exertional dyspnoea in the clinical setting.

Exercise and Airway Clearance Techniques in Cystic Fibrosis

Exercise and airway clearance techniques (ACTs) have been a cornerstone of treatment for people with cystic fibrosis (pwCF) for many decades. Exercise may confer both respiratory and nonrespiratory benefits for pwCF, with greater exercise capacity associated with improved survival. A wide variety of exercise interventions for pwCF have been investigated. ACTs may assist in reducing respiratory symptoms for pwCF and are currently recommended to be performed daily, with the types of ACTs used varying globally. While recommended components of care, both exercise and ACTs are time-intensive and maintaining adherence to the recommendations over the longer term can be challenging. It has been proposed that with advances in the therapeutic options for pwCF, a rationalization of the therapeutic regimen may be possible. We summarize the current evidence for the use of exercise and ACTs by pwCF, discuss the implications of the introduction of cystic fibrosis transmembrane conductance regulator modulators on both exercise and ACTs, and highlight areas for further research.

Aerobic exercise capacity, cough strength, posture, and depression in primary ciliary dyskinesia

INTRODUCTION

Assessment of exercise capacity is important for information about lung function and prognosis in primary ciliary dyskinesia (PCD). In addition, deterioration in the pulmonary system may affect cough efficiency, posture, and thoracoabdominal mobility. In turn, this deterioration may also disturb the psychological function of patients with PCD. Therefore, this study aimed to compare exercise capacity, cough strength, thoracoabdominal mobility, posture, and depression in children with PCD and healthy peers.

METHODS

Twenty-seven patients with PCD and 28 healthy peers were included. Aerobic exercise capacity (3-min step test), cough strength (peak expiratory flow meter), thoracoabdominal mobility (upper chest, lower chest, and abdomen), posture (Corbin postural assessment scale), and depression (Children's Depression Inventory) were evaluated.

RESULTS

Patients' number of steps completed, cough strength, and thoracoabdominal mobility were significantly decreased; total posture and depression scores were higher compared with healthy controls (p< 0.05). There was a significant relationship between cough strength and maximal expiratory strength (r = 0.541, p= 0.004) and total number of steps (r = 0.509, p= 0.007) in the patients.

CONCLUSION

Aerobic exercise capacity, cough strength, and thoracoabdominal mobility were impaired, posture was deteriorated, and depression perception elevated in children with PCD compared to healthy peers. Furthermore, aerobic exercise capacity and maximal expiratory strength are related to cough strength in these patients. Rehabilitation programs including aerobic and resistive exercise training, deep breathing and postural exercise, and nutrition counseling may improve these results and better be investigated. Trial registration: Clinicaltrials.gov: NCT03370029; December 12, 2017.

Quality of life and exercise tolerance tools in children/adolescents with cystic fibrosis: Systematic review

INTRODUCTION

This systematic review aims to analyze the validity and reliability of available tools to assess health-related quality of life (HRQoL) and exercise tolerance in children and adolescents with cystic fibrosis (CF).

MATERIALS AND METHODS

A review of observational studies studying the validity and reliability of the tools was conducted. The COSMIN (COnsesus-based Standards for the selection of health Measurements INstruments) guide was followed to analyze the quality of these tools.

RESULTS

A total of 18 studies were selected. Of the eight HRQoL tools, five generic and three specific, analyzed in 14 studies, the Cystic Fibrosis Questionnaire-Revised (CFQ-R) presents the best properties. Of the four tools analyzed to assess exercise tolerance, cycle ergometry and the modified shuttle test are the most valid and reliable.

CONCLUSIONS

The CFQ-R, cycloergometry and the modified shuttle test have the best properties for the assessment of children with CF, but more studies are needed.

Home-based or remote exercise testing in chronic respiratory disease, during the COVID-19 pandemic and beyond: A rapid review

Objectives:

To identify exercise tests that are suitable for home-based or remote administration in people with chronic lung disease.

Methods:

Rapid review of studies that reported home-based or remote administration of an exercise test in people with chronic lung disease, and studies reporting their clinimetric (measurement) properties.

Results:

84 studies were included. Tests used at home were the 6-minute walk test (6MWT, two studies), sit-to-stand tests (STS, five studies), Timed Up and Go (TUG, 4 studies) and step tests (two studies). Exercise tests administered remotely were the 6MWT (two studies) and step test (one study). Compared to centre-based testing the 6MWT distance was similar when performed outdoors but shorter when performed at home (two studies). The STS, TUG and step tests were feasible, reliable (intra-class correlation coefficients >0.80), valid (concurrent and known groups validity) and moderately responsive to pulmonary rehabilitation (medium effect sizes). These tests elicited less desaturation than the 6MWT, and validated methods to prescribe exercise were not reported.

Discussion:

The STS, step and TUG tests can be performed at home, but do not accurately document desaturation with walking or allow exercise prescription. Patients at risk of desaturation should be prioritised for centre-based exercise testing when this is available.

Exercise testing for children with cystic fibrosis: A systematic review

BACKGROUND

Exercise testing is routinely used to measure exercise capacity in children with cystic fibrosis (CF). Various tests are available, however the psychometric properties of these measures have not been systematically reviewed for this population.

METHOD

A systematic search of electronic databases (PubMed, Web of Science, Medline, CINHAL, Cochrane, and PEDro) was performed to identify papers that: (a) reported original psychometric data, (b) examined a measure of exercise capacity, (c) examined children with CF aged eight to 18 years; and (d) were published in English after 1950. The level of psychometric evidence was evaluated using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist.

RESULTS

Searches identified 1025 papers. Forty-six papers were included, covering 15 tests: incremental cardiopulmonary exercise test using a cycle ergometer (CPET(cycle)) or treadmill (CPET(treadmill)), 6 minute walk test (6MWT), modified shuttle test (MST), 3-minute step test (3MST), 2 minute walk test (2MWT), Bratteby walk test, intermittent sprint test, speed ramp test, incremental step test, forward-backwards jump test (FBJT), astride jump test (AJT), motor quotient test, Munich fitness test, and Glittre ADL test.

CONCLUSION

There is a plethora of exercise tests available with varying psychometric robustness. The CPET, 6MWT, and MST have fair to good psychometric properties, but each with their clinical advantages and limitations. Thus, a Selection Guide was developed to assist clinicians and researchers in selecting the most appropriate exercise test for various situations.

Pulmonary function testing in children's interstitial lung disease

The use of pulmonary function tests (PFTs) has been widely described in airway diseases like asthma and cystic fibrosis, but for children's interstitial lung disease (chILD), which encompasses a broad spectrum of pathologies, the usefulness of PFTs is still undetermined, despite widespread use in adult interstitial lung disease. A literature review was initiated by the COST/Enter chILD working group aiming to describe published studies, to identify gaps in knowledge and to propose future research goals in regard to spirometry, whole-body plethysmography, infant and pre-school PFTs, measurement of diffusing capacity, multiple breath washout and cardiopulmonary exercise tests in chILD. The search revealed a limited number of papers published in the past three decades, of which the majority were descriptive and did not report pulmonary function as the main outcome.PFTs may be useful in different stages of management of children with suspected or confirmed chILD, but the chILD spectrum is diverse and includes a heterogeneous patient group in all ages. Research studies in well-defined patient cohorts are needed to establish which PFT and outcomes are most relevant for diagnosis, evaluation of disease severity and course, and monitoring individual conditions both for improvement in clinical care and as end-points in future randomised controlled trials.

Effects of aerobic interval training on glucose tolerance in children and adolescents with cystic fibrosis: a randomized trial protocol

BACKGROUND

Individuals with cystic fibrosis (CF) may develop CF-related diabetes (CFDR). This comorbidity is related to a poorer quality of life, microvascular complications, a decline in lung function, and an increase in exacerbations, as well as delayed growth and puberty. Evidence exists that physical exercise contributes to glycemic control in individuals with non-CF-related diabetes. This exercise is usually continuous with moderate intensity and long duration, which can cause muscle dyspnea and fatigue in CF individuals. Aerobic interval training (AIT) emerges as a safe and effective alternative for treating these individuals. The objective of this study is to evaluate the effects of AIT on glucose tolerance in children and adolescents with CF.

METHODS

This study will be a two-arm, prospectively registered, randomized controlled trial with blind assessors and twenty 6- to 18-year-old individuals with cystic fibrosis (CF) from two different Brazilian states. People with CF will be randomly allocated to either the experimental or control group using block randomization, stratified by puberty stage,. Participants from both groups will receive an educational intervention and will be asked to continue their usual daily treatment for the full duration of the study. Those in the experimental group will perform AIT on a cycle ergometer at home three times a week, for 8 consecutive weeks. The sample characterization will include an assessment of puberty stage, socioeconomic status, dyspnea, and anthropometry. The primary outcome will be the change in glucose tolerance, while the secondary outcomes will include lung function, exercise tolerance, respiratory muscle strength, quality of life, and CF exacerbations. All outcomes will be assessed at baseline, week 9, and week 17.

DISCUSSION

This is the first study to evaluate the effects of AIT on glucose tolerance in children and adolescents with CF. This study will serve as a basis for guiding clinical practice and decision-making in treating glucose intolerance and CF-related diabetes (CFRD) in children and adolescents with CF.

TRIAL REGISTRATION

ClinicalTrials.gov Protocol Registration System: NCT03653949. Registered on August 31, 2018.

PSYCHOMETRIC PROPERTIES OF FUNCTIONAL CAPACITY TESTS IN CHILDREN AND ADOLESCENTS: SYSTEMATIC REVIEW

OBJECTIVES

To identify studies that evaluated psychometric properties of functional capacity tests in children and adolescents, and to verify which of these have satisfactory properties of measurement.

DATA SOURCES

Searches on MEDical Literature Analysis and Retrieval System Online (MEDLINE), Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Scientific Electronic Library Online (SciELO) databases without limiting period or language. Two investigators independently selected articles based on the following inclusion criteria: children and/or adolescent population (healthy or with cardiorespiratory diseases); and assessment of psychometric properties of functional capacity tests. Studies with (I) adult samples, (II) sample with neurological diseases, and (III) on reference values or prediction equations only were excluded.

DATA SYNTHESIS

From the total of 677 articles identified, 11 were selected. These evaluated the psychometric properties of the following tests: 6-minute walk test (6MWT) (n=7); 6MWT and the 3-minute step test (3MST) (n=1); and Incremental Shuttle Walk Test (ISWT) (n=3). Reproducibility and reliability were good for 6MWT and ISWT, and moderate for 3MST. The ISWT showed high validity measures for both healthy children and children with chronic respiratory disease. The validity of 6MWT varied across studies, and should be analyzed according to the health conditions of test takers. The validity of 3MST is unclear, and further studies in pediatric population are required.

CONCLUSIONS

Most studies investigated 6MWT measurement properties. Validity of 6MWT varied according to different pediatric populations. The use of 6MWT, ISWT and 3MST tests to measure clinically important changes in children and adolescents with cardiorespiratory diseases is still unclear.

Three-Minute Step Test for Predicting Acute Mountain Sickness: A Post Hoc Analysis of Rhodiola Crenulata Extract for Prevention of Acute Mountain Sickness, a Randomized, Double-Blind, Placebo-Controlled, Crossover Trial

Background

Acute mountain sickness (AMS) often occurs in individuals who rapidly travel above 2,500 m. As the convenience of traveling and the development of mountain sports increase, AMS will become an increasingly important public health problem. However, no method to effectively predict AMS before it occurs is currently available.

Methods

This post hoc study investigated whether the 3-Minute Step Test (3MST), which evaluates physical fitness, is predictive of AMS development. The data collected in "Rhodiola crenulata extract for prevention of AMS: a randomized, double-blind, placebo-controlled, crossover trial" was used in the analysis. This study collected 204 observations of 102 participants who made two ascents of Hehuan Mountain (3,100 m) by bus within a 3-month period. Participants completed the 3MST at 250 m (before ascent) and 3,100 m (on Hehuan Mountain). The presence of AMS was accessed using the Lake Louise scoring system.

Results

AMS was identified in 124 observations (60.78%). In the univariate analysis, the pre-departure 3MST score (at 250 m) was not significantly associated with AMS (p = 0.498), but the 3MST score measured at 3,100 m, ascent number, pulse rate at 3,100 m, and saturation of peripheral oxygen (SpO₂) measured at 3,100 m were significantly correlated with the occurrence of AMS (p = 0.002, 0.039, 0.005, < 0.001, respectively). In a further multivariate analysis, only SpO₂ measured at 3,100 m had a significant association with AMS (p = 0.016 and 0.006, respectively). The trend analysis showed that for every 1-point increase in the 3MST score at 3,100 m, the AMS decreased by 4% (adjusted odds ratio [AOR] = 0.96, 95% confidence interval [CI] = 0.92-1.01).

Conclusion

The 3MST score cannot be a predictor of AMS, but it may have a potential role in predicting ascent safety in high-altitude areas.

Physiological Responses of the Modified Shuttle Test in Adults With Cystic Fibrosis

PURPOSE

The modified shuttle test (MST) is increasingly used in clinical practice to assess functional capacity in patients with cystic fibrosis (CF). The purpose of this study was to evaluate the physiological responses of the MST in adults with CF as compared with the gold standard cardiopulmonary exercise test (CPET).

METHODS

Participants performed an MST and a CPET on a cycle ergometer in random order. Oxygen (O2) uptake ((Equation is included in full-text article.)O2), carbon dioxide (CO2) retention (end-tidal PCO2; PETCO2), minute ventilation, heart rate, and peripheral O2 saturation (SpO2) were continuously monitored. Whole blood lactate, dyspnea, and leg discomfort were recorded immediately after both exercises.

RESULTS

Twenty patients with CF (aged 33 ± 8 years; forced expiratory volume in 1 second = 48% ± 17%) completed both tests. Peak values for (Equation is included in full-text article.)O2 (27 ± 7 vs 24 ± 6 mL/kg/min), heart rate (169 ± 19 vs 163 ± 16 bpm), end PETCO2 (42 ± 7 vs 39 ± 8 mm Hg), and O2 desaturation (end SpO2, 86% ± 7% vs 90% ± 6%) were significantly higher during the MST than during the CPET (all Ps < .05). Leg discomfort and whole blood lactate were significantly higher after the CPET (both Ps < .05). Thirty-five percent and 40% of patients showed significant O2 desaturation and CO2 retention, respectively, during the MST, which was not detected during the CPET. A strong relationship was found between MST peak (Equation is included in full-text article.)O2 and body weight walking distance product (r = 0.90; P < .01).

CONCLUSIONS

The MST may provide a strong indicator of exercise tolerance in adults with CF as indicated by high peak (Equation is included in full-text article.)O2 values. In clinical practice, body weight walking distance should be considered as the primary outcome. This test is also better than cycle ergometry CPET for detecting O2 desaturation and CO2 retention, further emphasizing its clinical interest.

How does heart rate recovery after sub-maximal exercise correlate with maximal exercise testing in children with CF?

BACKGROUND

Disease progression in cystic fibrosis (CF) is marked by worsening exercise tolerance. Further, maximal exercise capacity (VO2 peak) correlates with survival in CF, but maximal tests are uncomfortable and resource-intensive. A three-minute step test (STEP) has been validated in CF. Heart rate (HR) recovery after exercise correlates with all-cause mortality in adult non-CF populations. We compared HR recovery after the three-minute step test with VO2 peak in children with CF.

METHODS

Twenty-four children with CF performed STEP and a maximal exercise test. Correlation between the tests was assessed.

RESULTS

Maximum HR on STEP was lower than on the maximal test (140 vs. 190, p<0.01). Peak HR during STEP correlated inversely with VO2 peak. In subjects with mild lung disease, faster HR recovery after STEP correlated with higher VO2 peak.

CONCLUSIONS

The three-minute step test is a feasible submaximal test in this patient population. HR during and after a three-minute step test may reflect VO2 peak in children with CF.

Expiratory flow limitation and breathing strategies in overweight adolescents during submaximal exercise

OBJECTIVE

To investigate whether ventilatory factors limit exercise in overweight and obese children during a 6-min step test and to compare ventilatory responses during this test with those of healthy weight children.

DESIGN

Cross-sectional, prospective comparative study.

SUBJECTS

Twenty-six overweight/obese subjects and 25 healthy weight subjects with no known respiratory illness.

MEASUREMENTS

Various fatness and fat distribution parameters (using air displacement plethysmography and anthropometry), pulmonary function tests, breath-by-breath gas analysis during exercise, perceived exertion.

RESULTS

Young people who are overweight or obese are more likely to experience expiratory flow limitation (expFL) during submaximal exercise compared with their healthy weight peers [OR 7.2 (1.4, 37.3), P=0.019]. Subjects who had lower lung volumes at rest were even more likely to experience exercise-induced expFLs [OR 8.35 (1.4-49.3)]. Both groups displayed similar breathing strategies during submaximal exercise.

CONCLUSION

Young people who are overweight/obese are more likely to display expFL during submaximal exercise compared with children of healthy weight . Use of compensatory breathing strategies appeared to enable overweight children to avoid the experience of breathlessness at this intensity of exercise.

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.

Recommendations for long-term home oxygen therapy in children and adolescents

OBJECTIVE

To advise pediatricians, neonatologists, pulmonologists, pediatric pulmonologists, and other professionals in the area on the main indications and characteristics of long-term home oxygen therapy in children and adolescents.

DATA SOURCE

A literature search was carried out in the MEDLINE/PubMed database (1990 to 2011). Additionally, references from selected studies were included. As consistent scientific evidence does not exist for many aspects, some of the recommendations were based on clinical experience.

DATA SYNTHESIS

Long-term home oxygen therapy has been a growing practice in pediatric patients and is indicated in bronchopulmonary dysplasia, cystic fibrosis, bronchiolitis obliterans, interstitial lung diseases, and pulmonary hypertension, among others. The benefits are: decrease in hospitalizations, optimization of physical growth and neurological development, improvement of exercise tolerance and quality of sleep, and prevention of pulmonary hypertension/cor pulmonale. The levels of oxygen saturation indicative for oxygen therapy differ from those established for adults with chronic obstructive pulmonary disease, and vary according to age and disease. Pulse oximetry is used to evaluate oxygen saturation; arterial blood gas is unnecessary. There are three available sources of oxygen: gas cylinders, liquid oxygen, and oxygen concentrators. The flows used are usually smaller, as are the number of hours/day needed when compared to the use in adults. Some diseases show improvement and oxygen therapy discontinuation is possible.

CONCLUSIONS

Long-term home oxygen therapy is increasingly common in pediatrics and has many indications. There are relevant particularities when compared to its use in adults, regarding indications, directions for use, and monitoring.

Exercise as part of a cystic fibrosis therapeutic routine

The role of exercise in cystic fibrosis (CF) is well established, and over the last three decades it has become an important component in the management of all individuals with CF. The role of exercise as a prognostic indicator or therapeutic tool is an important area of research interest in CF care internationally. This article summarizes the currently available evidence regarding exercise capacity in CF, the potential effects of exercise on health outcomes in CF and the challenges faced when trying to incorporate exercise into a CF therapeutic routine, and highlights some methods to facilitate the incorporation of exercise into CF therapeutic routines.

Comparison of effects of 3 and 7% hypertonic saline nebulization on lung function in children with cystic fibrosis: a double-blind randomized, controlled trial

BACKGROUND

Beneficial effects of hypertonic saline on lung function in cystic fibrosis patients are well documented. However, the effects of various concentrations of hypertonic saline are not well studied. We, therefore, compared the effects of 3 and 7% hypertonic saline administered by nebulization on lung function in children with cystic fibrosis.

METHOD

In a double-blind randomized controlled trial, 31 children with cystic fibrosis were randomized to receive either 3% saline or 7% saline nebulization twice daily for 28 days. Spirometry was performed and functional status was measured on Day 14 and 28.

RESULTS

Of 31 children enrolled in the study, 30 completed the 28 days follow up (15 in each group). Percentage change in Forced Expiratory Volume during first second (FEV(1)) from baseline to Day 14 and on Day 28 was significantly higher in the group receiving 3% saline as compared with those receiving 7% saline inhalation. There was some decrease in FEV(1) (percentage predicted) immediately after 7% saline inhalation unlike 3% saline. The functional status remained comparable between the two groups.

CONCLUSION

The results suggest that 3% hypertonic saline nebulization was better than 7% saline inhalation. There is a need for studies with larger sample size and longer duration to confirm our results.

The use of step tests for the assessment of exercise capacity in healthy subjects and in patients with chronic lung disease

Step tests are typically used to assess exercise capacity. Given the diversity of step tests, the aim of this review was to describe the protocols that have been used in healthy subjects and in patients with chronic lung disease. Step tests for use in healthy subjects have undergone a number of modifications over the years. In most step tests, the duration is variable (90 s-10 min), but the step height (23.0-50.8 cm) and stepping rate (22.5-35.0 steps/min) remain constant throughout the test. However, the use of a fixed step height and constant stepping rate might not provide adequate work intensity for subjects with different levels of fitness, the workload therefore being above or below individual capacity. Consequently, step test protocols have been modified by introducing changes in step heights and stepping rates during the test. Step tests have been used in patients with chronic lung diseases since the late 1970s. The protocols are quite varied, with adjustments in step height (15-30 cm), pacing (self-paced or externally paced), and test duration (90 s-10 min). However, the diversity of step test protocols and the variety of outcomes studied preclude the determination of the best protocol for use in individuals with chronic lung disease. Shorter protocols with a high stepping rate would seem to be more appropriate for assessing exercise-related oxygen desaturation in chronic lung disease. Symptom-limited testing would be more appropriate for evaluating exercise tolerance. There is a need for studies comparing different step test protocols, in terms of their reliability, validity, and ability to quantify responses to interventions, especially in individuals with lung disease.

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.

Oxygen therapy for cystic fibrosis

BACKGROUND

The most serious complications of cystic fibrosis (CF) relate to respiratory insufficiency. Oxygen supplementation therapy has been a standard of care for individuals with chronic lung diseases associated with hypoxemia for decades. 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 STRATEGY

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.Most recent search of Group's Trials Register: November 2008.

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 study quality and extracted data.

MAIN RESULTS

Eleven published studies (172 participants) are included in this review, of which 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 took less time to fall asleep 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.

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.

Dyspnoea in children. Does development alter the perception of breathlessness?

Dyspnoea, the perception of an unpleasant and/or uncomfortable sensation of breathlessness, offers several physiological, anatomical and teleological analogies with pain. Pain perception has been shown to exist in the newborn, suggesting that dyspnoea may also occur from birth onwards. The perception of breathlessness will be subservient to developmental changes in the behaviour of sensors and lung and muscular receptors implicated in dyspnoea, some of which are known to be active at time of birth. For example, perinatal resetting of the arterial chemoreceptor could lead to transient depression of the dyspnoeic response to hypoxia. However, though early evoked ventilatory responses and peripheral receptor maturation do exist, dyspnoea will only occur if the corresponding central neural circuitry undergoes parallel maturation. Our knowledge of dyspnoea in later childhood is based on a small number of clinical or psychophysical studies, predominantly dealing with asthma and exercise. There is a thus a clear need for systematic assessment of the existence and severity of dyspnoea sensing in younger children that takes into account its role as an alarm mechanism for triggering adaptive and/or protective responses.

[3-min step test: feasibility study for children with bone marrow transplantation]

INTRODUCTION

Bronchiolitis obliterans following a bone marrow transplantation needs an early diagnosis for a better evolution. First signs are exercise dyspnea and hypoxemia. A walking test evaluating the tolerance for effort could have an interest in detecting such symptoms. We report a preliminary study of feasibility of the 3-minute step-test in children with a bone marrow transplantation.

METHODS

Ten patients (5 boys, median 11.7 years, range 5.1-15.5 years) were included within at least 3 months away from a bone marrow transplantation. After clinical examination and realisation of pulmonary function tests, the test was to step up and down a single step which is 15 cm high, rhythmically (30 per minute) during 3 minutes. Heart rate and pulsed oxygen saturation were registered, dyspnea being assessed before and after the test by means of a visual analogue score and the fifteen-count breathlessness score.

RESULTS

All the children realised the 3-minute step-test successfully and with excellent tolerance. Only 1 child made an effort judged maximum. No hypoxemia caused by the effort was highlighted.

CONCLUSION

The 3-minute step-test is easy to achieve in a population of paediatric patients who have undergone a bone marrow transplantation. It could be a valuable tool in the respiratory follow up of these children.

Factors that correlate with sleep oxygenation in children with cystic fibrosis

OBJECTIVE

Cystic fibrosis (CF) patients may develop hypoxemia during sleep. Limited information is available on nocturnal oxygen saturation in CF children with less severe lung disease. The aim of this study was to investigate the degree of nocturnal oxygen desaturation and factors that correlate with nocturnal oxygenation in CF children with normal pulmonary function tests (PFTs) or mild to moderate lung disease.

METHOD

Awake resting and post-exercise SpO2 were measured by pulse oximetry. Each patient had overnight oximetry monitorization at home. Six minutes walk test (6MWT), Shwachman-Kulczycki (S-K), Brasfield and computed tomography (CT) scores, blood gas analysis and nutritional status of patients were evaluated.

RESULTS

Twenty-four patients with a median age of 9.5 years were included. Nocturnal mean SpO2 did not differ according to the severity of lung disease based on PFT. However, lowest SpO2 obtained was lower in children with both mild and moderate lung disease compared to normals (87.4% vs. 91.7%, respectively, p = 0.009). 95.8% of CF children with normal PFT or mild to moderate lung disease had desaturation events during sleep. Nocturnal mean SpO2 correlated with S-K (Spearman's rho = 0.64, p < 0.0001), Brasfield (Spearman's rho = 0.31, p = 0.007) and CT scores (Spearman's rho = -0.67, p < 0.0001) as well as PaO2 (Spearman's rho = 0.28, p = 0.021), SaO2 (Spearman's rho = 0.28, p = 0.023), z-score of weight (Spearman's rho = 0.23, p = 0.20) and height (Spearman's rho = 0.20, p = 0.30), there was no correlation with 6MWT.

CONCLUSIONS

In CF children with normal PFT or mild-to-moderate lung disease, nocturnal oxygenation may correlate with S-K, Brasfield and CT scores as well as PaO2, SaO2, z-score of weight and height.

Inhalation of Moli1901 in patients with cystic fibrosis

BACKGROUND

In cystic fibrosis (CF) patients, the absence or dysfunction of the chloride channel CF transmembrane conductance regulator (CFTR) results in reduced chloride ion transport in respiratory epithelial cells. Moli1901 stimulates an alternative chloride channel and may thus compensate for the CFTR deficiency in the airway epithelium of CF patients.

METHODS

A phase II, placebo-controlled, double-blinded, single-center, multiple (5 consecutive days), rising-dose (daily dose, 0.5, 1.5, or 2.5 mg of Moli1901) study was conducted to investigate the safety and tolerability of multiple doses of aerosolized inhaled Moli1901 in 24 patients with CF and stable lung disease.

RESULTS

Moli1901 was well tolerated in all but one CF patient, in whom a transient significant decrease in FEV(1) developed following inhalation, which resolved spontaneously, and in a second patient in whom transient throat numbness developed during drug inhalation. A significant improvement of FEV(1) was observed in the group receiving treatment with 2.5 mg/d Moli1901 compared to the group receiving placebo (p = 0.01 [Wilcoxon test]). Moli1901 was not detected in the plasma of the highest dose group.

CONCLUSIONS

The inhalation of Moli1901 up to a total cumulative dose of 12.5 mg appears to be safe in adult patients with CF. In addition, Moli1901 had a sustained beneficial effect on pulmonary function, which supports further studies of its efficacy in CF patients.

Análise comparativa e reprodutibilidade do teste de caminhada com carga progressiva (modificado) em crianças normais e em portadoras de fibrose cística

OBJETIVO: Realizar uma análise comparativa do teste de caminhada com carga progressiva e respectivo re-teste em crianças com fibrose cística (FC), em relação a crianças normais. MÉTODOS: As crianças foram divididas em dois grupos: grupo FC, com diagnóstico confirmado pelo teste de suor, e grupo controle, de crianças normais, sem relatos de doenças pulmonares e com prova de função pulmonar sem alterações. As crianças foram submetidas a pelo menos dois testes consecutivos, com intervalo de 30 min entre eles. Os parâmetros avaliados foram: distância caminhada, sobrecarga cardíaca, saturação periférica de oxigênio (SpO2) e percepção subjetiva do esforço (escala de dispnéia em repouso, e de Borg). RESULTADOS: Foram avaliadas 28 crianças entre 7 e 15 anos de idade (11,57 ± 2,50 e 11,28 ± 1,85 anos para os grupos FC e controle, respectivamente). Os escores da escala de Borg foram significativamente maiores nos controles (p = 0,007). Não foram encontradas diferenças quanto à sobrecarga cardíaca e SpO2. Em relação ao re-teste intergrupos, no segundo teste o grupo controle apresentou aumento significativo tanto da distância caminhada quanto da dispnéia em repouso (p = 0,014 e p = 0,036, respectivamente). O grupo FC apresentou aumento significativo apenas da escala de dispnéia em repouso (p = 0,168 e p = 0,042, respectivamente). CONCLUSÃO: A sobrecarga cardíaca imposta pelo teste não diferiu entre os grupos. O maior cansaço inicial no segundo teste sugere que o intervalo de 30 min entre os testes não foi suficiente para o descanso das crianças.

Modified shuttle test performance in hospitalized children and adolescents with cystic fibrosis

BACKGROUND

The Modified Shuttle Test (MST) is a valid and sensitive measure of exercise capacity in adult CF patients. Recently, its validity in children has been demonstrated. The aim of this study was to demonstrate the utility of the MST as a measure of responsiveness to hospitalisation for i.v. antibiotic and supportive therapy in children and adolescents with CF.

METHODS

28 children and adolescents (40 admissions) performed a MST and lung function within 48 h of admission and discharge to hospital for administration of intravenous antibiotics. Mean age was 12.7 years and antibiotic therapy length was 14.7 days.

RESULTS

Upon admission, the mean (S.D.) FEV(1) was 63 (19)% predicted, FVC was 80 (18)% predicted, FEF(25-75) 43 (29)% predicted and MST distance 718 (232) m. FEV(1) increased by 15% (p<or=0.001), FVC by 13% (p<or=0.001), FEF(25-75) by 39% (p<or=0.001) and MST distance by 102 m (p<or=0.001). The percentage improvement in MST distance at 18% (p<or=0.001) was similar to that for FEV(1), but could not be predicted by the change in FEV(1).

CONCLUSION

This study demonstrated the utility of the MST to assess the effect of hospitalisation for i.v. antibiotic and supportive therapy in children and adolescents with CF.

Tests de marche : une avancée dans l'évaluation fonctionnelle cardiorespiratoire

Exercise testing provides information on physical capacity during exercise in addition to spirometric measures of lung function or assessment on treadmills or ergonomic cycle. The "gold standard" assessment of exercise tolerance is measured in the laboratory using treadmills or ergonomic cycle but the necessary equipment is expensive and may not be readily accessible; such tests require people used to work with children. Walking tests are field tests providing a valid and easily accessible method of measuring function-limited exercise tolerance in patients with respiratory or cardiac chronic diseases. These walking tests are non-threatening, inexpensive, easy to perform and to understand for children. Walking tests performed in daily practice are the following: "time-based" tests (2-, 6- or 12-min walking test), 3-min step test (on a step) and the shuttle walking test. It may be a useful measure to assess therapeutic intervention and provide information on the prognosis. They are simple and safe methods to evaluate quality of life in these patients.

Assessment of hypoxia in children with cystic fibrosis

Hypoxia during sleep and exercise may occur in an important number of patients with cystic fibrosis (CF). Despite its recognition, no clear definition for hypoxia in CF exists, and nor do guidelines for commencing oxygen therapy. CF patients with hypoxia may have increased pulmonary artery pressure, reduced exercise ability, and skeletal muscle strength, and most importantly of all worse sleep quality, and a worse quality of life. Laboratory and rodent evidence exists to suggest that hypoxia may contribute to the decline in lung function in CF by upregulating lung inflammation, and encouraging growth of Pseudomonas aeruginosa, the most important pathogen associated with CF lung disease. The effects of hypoxia in childhood CF need to be fully studied, and a potential expanded role for oxygen as therapy in CF may be worthy of exploration.

Oxygen therapy for cystic fibrosis

BACKGROUND

The most serious complications of cystic fibrosis (CF) relate to respiratory insufficiency. Oxygen supplementation therapy has been a standard of care for individuals with chronic lung diseases associated with hypoxemia for decades. It is common for physicians to 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 STRATEGY

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. Most recent search of Group's Trials Register: April 2005.

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

Two authors independently assessed study quality and extracted data.

MAIN RESULTS

Nine published studies (149 participants) are included in this review, of which only one examined long-term oxygen therapy (28 participants). There was no statistically significant improvement in survival, lung, or cardiac health. Four studies examined the effect of oxygen supplementation during sleep by polysomnography. Although oxygenation improved, there were no demonstrable improvements in qualitative sleep parameters and modest hypoventilation was noted. In three studies, oxygen supplementation was evaluated during exercise. Hypoxemia was prevented, but mild hypercapnia resulted. Work performance was not improved, as measured in one study, but was improved in a second study. Furthermore, in two studies, exercise duration was enhanced by oxygen supplementation. In the study examining the impact of oxygen supplementation after exercise, recovery time was enhanced.

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. During exercise, there are improvements in exercise duration and peak performance. 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.