Effects of elexacaftor-tezacaftor-ivacaftor on daily treatment burden and airflow obstruction in adults with cystic fibrosis.

BACKGROUND: The drug combination elexacaftor-tezacaftor-ivacaftor (ETI) proved highly effective in the improvement of the respiratory symptoms, the percentage of predicted forced expiratory volume in 1 s (FEV1), and to reduce rates of pulmonary exacerbations in people with cystic fibrosis (CF) with at least one F508del mutation. The objectives of the study were to evaluate the impact of ETI on the daily treatment burden due to patient decision and the evolution of lung function parameters at 6 months of treatment in real life. METHODS: A single-center observational study was realized including adult patients starting ETI therapy from March 10, 2020 to April 5, 2022. Clinical characteristics were collected at initiation (T0) and at 6 months (T6) of treatment. Outcome measures included names and number of chronic daily medications, respectively lung function parameters: FEV1, forced vital capacity (FVC), FEV1/FVC ratio, peak expiratory flow (PEF), forced expiratory flow at 25-75% of FVC (FEF25-75), ß-angle and FEF50/PEF ratio. RESULTS: Sixty-five patients were included with a mean age of 29.4 ± 8.5 years old, 48% of them F508del homozygous previously treated by lumacaftor-ivacaftor. At T6, the median number of daily medications decreased from 13 [2-24] to 9 [1-19] (p < 0.001). All the studied functional respiratory parameters were improved: FEV1 +18%, FVC +14%, FEF25-75% + 18% (all p < 0.001), as well the airflow obstruction: FEV1/FVC +6%, FEF50/PEF by 0.1 ± 0.1 and ß-angle by 10° ± 13° (all p ≤ 0.007). CONCLUSION: ETI therapy can reduce the daily treatment burden in real-life at 6 months of treatment, increase a large number of lung function parameters and improve airflow obstruction.

Technical standards for respiratory oscillometry.

Oscillometry (also known as the forced oscillation technique) measures the mechanical properties of the respiratory system (upper and intrathoracic airways, lung tissue and chest wall) during quiet tidal breathing, by the application of an oscillating pressure signal (input or forcing signal), most commonly at the mouth. With increased clinical and research use, it is critical that all technical details of the hardware design, signal processing and analyses, and testing protocols are transparent and clearly reported to allow standardisation, comparison and replication of clinical and research studies. Because of this need, an update of the 2003 European Respiratory Society (ERS) technical standards document was produced by an ERS task force of experts who are active in clinical oscillometry research.The aim of the task force was to provide technical recommendations regarding oscillometry measurement including hardware, software, testing protocols and quality control.The main changes in this update, compared with the 2003 ERS task force document are 1) new quality control procedures which reflect use of "within-breath" analysis, and methods of handling artefacts; 2) recommendation to disclose signal processing, quality control, artefact handling and breathing protocols (e.g. number and duration of acquisitions) in reports and publications to allow comparability and replication between devices and laboratories; 3) a summary review of new data to support threshold values for bronchodilator and bronchial challenge tests; and 4) updated list of predicted impedance values in adults and children.

Breathing-related changes of respiratory resistance in vocal cord dysfunction.

Vocal cord dysfunction induced by exercise in children with uncontrolled asthma was identified by laryngoscopy. The paradoxical adduction of the vocal cords was also indicated by the breathing-related changes of the forced oscillation respiratory resistance showing prominent increase during inspiration and a large positive difference between inspiration and expiration. The breathing-related changes of respiratory resistance offer thus a useful first-line technique to diagnose vocal cord dysfunction.

Hypoventilation in patients with Prader-Willi syndrome across the pediatric age.

OBJECTIVES: Few data on alveolar hypoventilation in Prader-Willi syndrome (PWS) are available and the respiratory follow-up of these patients is not standardized. The objectives of this study were to evaluate the prevalence of alveolar hypoventilation in children with PWS and identify potential risk factors. STUDY DESIGN: This retrospective study included children with PWS recorded by polysomnography (PSG) with transcutaneous carbon dioxide pressure (PtcCO2) or end-tidal CO2 (ETCO2) measurements, between 2007 and 2021, in a tertiary hospital center. The primary outcome was the presence of alveolar hypoventilation defined as partial pressure of carbon dioxide (pCO2) ≥ 50 mmHg during ≥2% of total sleep time (TST) or more than five consecutive minutes. RESULTS: Among the 57 included children (38 boys, median age 4.8 years, range 0.1-15.6, 60% treated with growth hormone [GH], 37% obese), 19 (33%) had moderate-to-severe obstructive sleep apnea syndrome (defined as obstructive apnea-hypopnea index ≥5/h) and 20 (35%) had hypoventilation. The median (range) pCO2 max was 49 mmHg (38-69). Among the children with hypoventilation, 25% were asymptomatic. Median age and GH treatment were significantly higher in children with hypoventilation compared to those without. There was no significant difference in terms of sex, BMI, obstructive or central apnea-hypopnea index between both groups. CONCLUSION: The frequency of alveolar hypoventilation in children and adolescents with PWS is of concern and may increase with age and GH treatment. A regular screening by oximetry-capnography appears to be indicated whatever the sex, BMI, and rate of obstructive or central apneas.

Gas exchange parameters for the prediction of obstructive sleep apnea in infants.

STUDY OBJECTIVES: Sleep laboratory polysomnography is the gold standard for obstructive sleep apnea (OSA) diagnosis in infants, but its access remains limited. Oximetry-capnography is another simple and widely used tool that can provide information on the presence of desaturations and alveolar hypoventilation. However, its reliability is debated. This study aimed at examining its use in determining OSA severity in infants. METHODS: This retrospective study was conducted in a sleep unit in a tertiary hospital in infants < 4 months old with clinical signs of OSA or Pierre Robin sequence who underwent a 1-night polysomnography coupled with oximetry-capnography. RESULTS: Among the 78 infants included (median [interquartile range] age: 61 [45-89] days at polysomnography), 44 presented with Pierre Robin sequence and 34 presented with isolated airway obstruction. The clinical, sleep, and respiratory characteristics were not significantly different between the 2 subgroups. In the entire cohort, 63.5% had severe OSA. The median obstructive apnea-hypopnea index was 14.5 (7.4-5.9) events/h, peripheral oxygen saturation (SpO2) was 97.4% (96.5-98.1%), and transcutaneous carbon dioxide pressure (PtcCO2) was 41.1 mmHg (38.3-44.9). The optimal threshold to predict an obstructive apnea-hypopnea index > 10 events/h was 6 events/h for an oxygen desaturation index ≥ 3% (sensitivity, 95.7%; specificity, 51.9%) and 2 events/h for an oxygen desaturation index ≥ 4% (sensitivity, 95.7%; specificity, 48.1%). CONCLUSIONS: Whereas transcutaneous capnography does not appear to be sufficient in predicting severe OSA in infants < 4 months old with Pierre Robin sequence or clinical signs of OSA, oximetry may be a useful alternative for the screening of severe OSA in infants in the absence of polysomnography. CITATION: Gyapay R, Ioan I, Thieux M, et al. Gas exchange parameters for the prediction of obstructive sleep apnea in infants. J Clin Sleep Med. 2024;20(7):1059-1067.

Persistent and symptomatic periodic breathing beyond the neonatal period in full-term infants: A case series.

INTRODUCTION: Periodic breathing (PB) is considered physiological in the neonatal period and usually disappears in the first months of life. There are few data available on persistent PB after the neonatal period. The objective of this study was to characterize infants born at term with persistent PB after the age of 1 month through polysomnography (PSG) performed during symptoms. METHODS: This retrospective case series included infants born at term between 2012 and 2021, without an underlying disease, who presented with symptoms of persistent PB during a PSG. Persistent PB was defined as more than 1 % of total sleep time (TST) of PB after 1 month of life, and PB was defined as a succession of at least three episodes of central apnea lasting more than 3 s and separated by less than 20 s of normal breathing. RESULTS: A total of 10 infants born at term were included. They underwent PSG for brief resolved unexplained events, desaturation, pauses in breathing, cyanosis, and/or signs of respiratory distress. The percentage of TST spent with PB was 18.1 % before 3 months of age (n = 7), and 4.7 % between 3 and 6 months of age (n = 10). During the first PSG, ≥3 % of desaturation events were observed in 77-100 % of the PB episodes. At the first PSG, nine of the 10 infants had an obstructive apnea-hypopnea index of >10/h and five of 10 infants had a central apnea index of >5/h. Gastroesophageal reflux (GER) was suspected in eight infants. All infants showed improvement in the initial symptoms during the first year of life. CONCLUSION: This study presents cases of persistent and symptomatic PB after 1 month of life in infants born at term. The interesting finding was the presence of obstructive sleep apnea syndrome and/or central apnea syndrome in the majority of children, along with GER.

Non-invasive respiratory support in children and young adults with complex medical conditions in pediatric palliative care.

OBJECTIVE: Dyspnoea and sleep-disordered breathing (SDB) are common in children with life-limiting conditions but studies on treatment with non-invasive ventilation (NIV) or continuous positive airway pressure (CPAP) are scarce. The aim of the study was to describe children treated with long-term NIV/CPAP within a paediatric palliative care programme in France. METHODS: Cross-sectional survey on children and young adults with complex medical conditions treated within the French paediatric NIV network with long-term NIV/CPAP. Characteristics of the patients were analysed and patient-related outcome measures of NIV/CPAP benefit were reported. RESULTS: The data of 50 patients (68% boys), median age 12 (0.4-21) years were analysed. Twenty-three (46%) patients had a disorder of the central nervous system and 5 (10%) a chromosomal anomaly. Thirty-two (64%) patients were treated with NIV and 18 (36%) with CPAP. NIV/CPAP was initiated on an abnormal Apnoea-Hypopnoea Index in 18 (36%) of the patients, an abnormal nocturnal gas exchange alone in 28 (56%), and after an acute respiratory failure in 11 (22%) of the patients. Mean objective NIV/CPAP adherence was 9.3±3.7 hours/night. NIV/CPAP was associated with a decrease in dyspnoea in 60% of patients, an increase in sleep duration in 60% and in sleep quality in 74%, and an improvement in parents' sleep in 40%. CONCLUSIONS: In children with life-limiting conditions, long-term NIV/CPAP may be associated with relief of dyspnoea, an improvement of SDB and an improvement in parents' sleep.

Pediatric long-term noninvasive respiratory support in children with central nervous system disorders.

RATIONALE: The use of long-term noninvasive respiratory support is increasing in children along with an extension of indications, in particular in children with central nervous system (CNS) disorders. OBJECTIVE: The aim of this study was to describe the characteristics of children with CNS disorders treated with long-term noninvasive respiratory support in France. METHODS: Data were collected from 27 French pediatric university centers through an anonymous questionnaire filled for every child treated with noninvasive ventilatory support ≥3 months on 1st June 2019. MAIN RESULTS: The data of 182 patients (55% boys, median age: 10.2 [5.4;14.8] years old [range: 0.3-25]) were collected: 35 (19%) patients had nontumoral spinal cord injury, 22 (12%) CNS tumors, 63 (35%) multiple disabilities, 26 (14%) central alveolar hypoventilation and 36 (20%) other CNS disorders. Seventy five percent of the patients were treated with noninvasive ventilation (NIV) and 25% with continuous positive airway pressure (CPAP). The main investigations performed before CPAP/NIV initiation were nocturnal gas exchange recordings, alone or coupled with poly(somno)graphy (in 29% and 34% of the patients, respectively). CPAP/NIV was started in an acute setting in 10% of the patients. Median adherence was 8 [6;10] hours/night, with 12% of patients using treatment <4 h/day. Nasal mask was the most common interface (70%). Airway clearance techniques were used by 31% of patients. CONCLUSION: CPAP/NIV may be a therapeutic option in children with CNS disorders. Future studies should assess treatment efficacy and patient reported outcome measures.

Exercise-induced bronchoconstriction in school-age children born extremely preterm.

BACKGROUND: School children born preterm often show airway hyperresponsiveness to methacholine or histamine. Less attention has been paid to their airway response to exercise, an important point because of the role of exercise in the child's daily life. The aim of this study was to describe the characteristics of, and potential determinants to, the airway response to exercise in children born extremely preterm. METHODS: Forty-two nonasthmatic nonatopic children born before 32 wk gestation were compared with 27 healthy nonasthmatic nonatopic term children at age 7. Spirometry and respiratory impedance were measured at baseline and repeated after a single-step 6-min treadmill exercise in a climate-controlled room. RESULTS: The preterm group showed significant broncho-constriction induced by exercise. Prematurity, but not low baseline lung function, neonatal oxygen supplementation, mechanical ventilation, chronic lung disease, or maternal smoking, was a determinant of exercise-induced bronchoconstriction. CONCLUSION: Children born extremely preterm present significant exercise-induced airway obstruction at age 7. The response has different characteristics from that occurring in asthmatics and is likely to express airway noneosinophilic inflammation.

Unattended home sleep studies for the diagnosis of obstructive sleep apnea in a population of French children.

BACKGROUND: Ambulatory exams were preferred in children during the COVID-19 pandemic. Polysomnography (PSG), the gold standard for obstructive sleep apnea (OSA) diagnosis, requires several leads and sensors to be attached to the child's body. Children are more comfortable with respiratory polygraphic (RP) recording, which needs fewer sensors. OBJECTIVE: To compare respiratory parameters obtained by home RP with those obtained by home PSG with the device installed at the child's home by a trained sleep nurse from a national health care provider. METHODS: Data from home PSGs performed in children aged 2-19 years were retrospectively included. The obstructive apnea-hypopnea index (OAHI) was computed in PSG and then in RP after removing the sleep signals. The two indexes were compared using non-parametric paired Wilcoxon rank test, Bland-Altman analysis and sensitivity-specificity analysis. RESULTS: 44 PSGs of 44 children were included with only 34 (77%) PSGs interpretable. Median (min-max) OAHI was significantly underestimated in RP than in PSG (2.2 (0-25) vs 4.0 (0.4-28), p < 0.0001), confirmed also by the Bland-Altman diagram, the magnitude of the difference being mean ± standard deviation -1.7 ± 1.7. The sensitivity and specificity of OAHI in RP to identify an OAHI ≥2/h in PSG was 0.91 for both. CONCLUSION: Unattended ambulatory RP performed at child's house and installed under carefully controlled conditions is a useful exam for diagnosing OSA in children with or without comorbidities. However, RP must be installed in a supervised environment and interpreted with caution as it tends to underestimate OSA severity.

Real-Life Effectiveness of Benralizumab, Mepolizumab and Omalizumab in Severe Allergic Asthma Associated with Nasal Polyps.

Biological therapies are available for the treatment of the severe allergic asthma (SAA) with blood eosinophil count ≥ 0.3 × 109/L. Several of them also showed benefits on nasal polyps (NP), one of the most frequent comorbidities of the severe asthma, but comparative studies on their effectiveness in the association SAA-NP are currently lacking. The aim of this study is to compare the effectiveness of benralizumab, mepolizumab and omalizumab in patients with SAA-NP in real-life settings. A retrospective, observational, multicenter real-life study was realized including patients with SAA-NP treated by benralizumab, mepolizumab or omalizumab for 6 months. We analysed the nasal and respiratory symptoms, the number of asthma attacks and salbutamol use/week, acute sinusitis and severe exacerbation rates, the asthma control score, the lung function parameters, the NP endoscopic score, the sinus imaging and the blood eosinophil count 6 months before and after treatment. Seventy-two patients with SAA-NP were included: 16 treated by benralizumab, 21 by mepolizumab and 35 by omalizumab. After 6 months of treatment, almost all studied parameters were improved (except sinus imaging) with a greater effect of omalizumab on the nasal pruritus (p = 0.001) and more benefits of benralizumab on exacerbations rate, asthma attacks per week and lung function (all p < 0.05). Benralizumab and mepolizumab were more effective to improve the NP endoscopic score and the blood eosinophil count (both p < 0.001). All three biological therapies showed effectiveness by improving asthma and nasal outcomes in patients with SAA-NP. Several differences have been found that should be confirmed by larger comparative studies.

Evaluation of obesity and asthma as risk factors for moderate to severe obstructive sleep apnea in children.

STUDY OBJECTIVES: Asthma and obesity are risk factors for obstructive sleep apnea (OSA) in children but their link to OSA severity is uncertain. We aimed at determining whether asthma or obesity was associated with an increased risk of moderate/severe OSA. METHODS: Children undergoing a one-night polysomnography for suspicion of OSA were retrospectively included. Univariate and multivariate analyses were conducted to assess the clinical and demographic characteristics linked to moderate/severe OSA (obstructive apnea-hypopnea index ≥ 5 events/h of sleep) with odds ratio and 95% confidence interval reported. RESULTS: Four hundred ninety children (311 [64%] boys) were included with a median [25th; 75th percentile] age of 8.7 [5.4; 12.9] years, 164 (33%) nonasthmatics nonobese, 122 (25%) obese nonasthmatics, 125 (26%) asthmatics nonobese, 79 (16%) asthmatics and obese. Moderate/severe OSA was present in 157 (32%) children (75/157 [48%] obese and 52/157 [33%] asthmatics). Independent factors associated with increased or decreased risk of moderate/severe OSA were obesity and male sex (odds ratio 1.82 [1.16; 2.87], P = .01, and 1.55 [1.02; 2.36], P = .04, respectively), and current asthma, age > 6 years, or behavioral disorders (odds ratio 0.45 [0.29; 0.70], P < .001; 0.44 [0.27; 0.73], P < .001; and 0.55 [0.33; 0.92], P = .02, respectively). Abnormal resistance of the respiratory system (measured in 241 children), but not abnormal spirometry (measured in 213 children), increased the risk of moderate/severe OSA (odds ratio 2.95 [1.46-5.96], P = .003). CONCLUSIONS: In our cohort enriched in obese and asthmatic children, obesity was associated with higher risk of moderate/severe OSA whereas current asthma was not. CITATION: Ioan I, Mulier G, Taytard J, Césaire A, Beydon N. Evaluation of obesity and asthma as risk factors for moderate to severe obstructive sleep apnea in children. J Clin Sleep Med. 2022;18(6):1639-1648.

Asthma and obstructive sleep apnoea in adults and children - an up-to-date review.

Obstructive sleep apnoea (OSA) and asthma are two common respiratory disorders in children and adults. Apart from common risk factors, such as obesity, gastroesophageal reflux disease and allergic rhinitis, emerging evidence suggest that the two diseases may complicate the clinical course of each other. On one hand, OSA modifies asthmatic airway inflammation and is associated with poor asthma control. On the other hand, asthma and its medications increase the collapsibility of the upper airways contributing to the development and worsening of OSA. The overnight respiratory symptoms of OSA and asthma are often similar, and an inpatient polysomnography is often necessary for a proper diagnosis, especially in children. Continuous positive pressure, the gold standard treatment for OSA can improve asthma control in patients suffering from both diseases. However, there is limited evidence how anti-asthma medications act in the same patients. Nevertheless, adenotonsillectomy seems to be effective in children with concomitant asthma and OSA. This review summarises the evidence for the bidirectional link between asthma and OSA, focuses on diagnostic and therapeutic challenges and highlights the need for further research.

Pulse transit time as a diagnostic test for OSA in children with Down syndrome.

STUDY OBJECTIVES: Children with Down syndrome (DS) are at risk of obstructive sleep apnea (OSA), but the access to sleep lab polysomnography (PSG) is limited. Simplified techniques are needed, such as polygraphy coupled with pulse transit time (PTT-PG) that detects respiratory events and the total autonomic arousals index (PTTAI). Our objective was to assess the ability of PTT-PG compared with PSG to diagnose OSA in children with DS. METHODS: In this prospective multicenter study, patients with DS underwent a full-night PSG coupled with PTT. Sleep questionnaires (Sleep Disturbance Scale for Children and Pediatric Sleep Questionnaire) were filled by parents. PSG and PTT-PG results were compared to test their sensibility and specificity to diagnose OSA. RESULTS: A total of 53 patients with DS were included; their median age was 9.3 years. An obstructive apnea-hypopnea index (OAHI) by PSG > 1 event/h was found in 36 (68%) patients, OAHI was > 1 and < 5 events/h in 18 patients (34%), ≥ 5 and < 10 events/h in 11 patients (21%), and ≥ 10 events/h in 7 patients (13%). OAHI was larger on PSG than on PTT-PG (P = .0005). For OSA diagnosis, the sensitivity was excellent for OAHI by PTT-PG if the added total PTTAI was > 1 event/h (1.0) and the specificity was high for the Pediatric Sleep Questionnaire (0.88) and OAHI > 1 event/h on PTT-PG (1.0). CONCLUSIONS: More than two-thirds of children with DS referred for screening by a genetics specialist had OSA diagnosed by PSG. With its excellent sensitivity and specificity, PTT-PG could be a good and simplified alternative to PSG to diagnose OSA in children with DS. CITATION: Ioan I, Weick D, Sevin F, et al. Pulse transit time as a diagnostic test for OSA in children with Down syndrome. J Clin Sleep Med. 2022;18(1):119-128.

Real-world assessment of LCI following lumacaftor-ivacaftor initiation in adolescents and adults with cystic fibrosis.

Lung clearance index (LCI) is a biomarker of ventilation inhomogeneity. Data are scarce on its usefulness in daily practice for monitoring the effects of treatments in older children and adults with CF. In this French observational study of lumacaftor-ivacaftor, 63 of 845 patients (7.5%) had available LCI performed at baseline and at six (M6; n=34) or 12 months (M12; n=46) after lumacaftor-ivacaftor initiation. At inclusion, median [IQR] age was 16 years [13-17], ppFEV1 was 72.8 [59.6-80.7], and LCI was 12.3 [10.3-15.0]. At both M6 and M12, no statistically significant LCI increases of 0.13 units or 1.34% (95% CI: -4.85-7.53) and 0.6 units or 6.66% (95% CI: -0.03-13.5) were observed. Discordant results between LCI and ppFEV1 were observed in one-third of the patients. In daily practice, LCI monitoring in adolescents and young adults with moderate lung disease gives results that are more heterogenous than those reported in children with milder disease.

Neurocognitive evaluation of children with down syndrome and obstructive sleep apnea syndrome.

Obstructive sleep apnea syndrome (OSAS) treatment has been shown to improve cardiac behavioral and cognitive functions in typically developing children. Early OSAS diagnosis in children with Down syndrome (DS) would be important to prevent its complications, especially cognitive ones, but remains overlooked. The main objective of our study was to assess the cognitive function of children with DS, with and without OSAS. The second objective was to determine the impact of the therapeutic intervention on the cognitive function of children with OSAS. This study included 41 children with DS who underwent polysomnography for OSAS diagnosis and a cognitive evaluation. They were aged between 3.4 and 17.3 years and 24 (59%) were boys. Their median OAHI was 2.6 (0-31)/h of sleep, 30 (73%) were diagnosed with OSAS (15 had mild OSAS, and 15 had moderate/severe OSAS). Some scores of the Raven's colored progressive matrices were negatively correlated with the respiratory arousal index, OAHI tended to be positively correlated with Reiss behavioral problems. 24 (59%) patients received a treatment. Even if we were unable to demonstrate this formally due that only 16 children (39%) accepted a follow-up visit, some displayed improvement in their neuropsychological scores, especially those with moderate/severe OSAS after treatment. Children with DS have low intellectual abilities and more risk of developing OSAS compared to the general population, which may lead to further neurocognitive impairment. Early screening and management are important in this population to prevent any further neurocognitive delay in their development.

Clinical significance and applications of oscillometry.

Recently, "Technical standards for respiratory oscillometry" was published, which reviewed the physiological basis of oscillometric measures and detailed the technical factors related to equipment and test performance, quality assurance and reporting of results. Here we present a review of the clinical significance and applications of oscillometry. We briefly review the physiological principles of oscillometry and the basics of oscillometry interpretation, and then describe what is currently known about oscillometry in its role as a sensitive measure of airway resistance, bronchodilator responsiveness and bronchial challenge testing, and response to medical therapy, particularly in asthma and COPD. The technique may have unique advantages in situations where spirometry and other lung function tests are not suitable, such as in infants, neuromuscular disease, sleep apnoea and critical care. Other potential applications include detection of bronchiolitis obliterans, vocal cord dysfunction and the effects of environmental exposures. However, despite great promise as a useful clinical tool, we identify a number of areas in which more evidence of clinical utility is needed before oscillometry becomes routinely used for diagnosing or monitoring respiratory disease.

Long term noninvasive ventilation and continuous positive airway pressure in children with neuromuscular diseases in France.

The aim of the study was to describe the characteristics of children with neuromuscular diseases treated with long term noninvasive ventilation or continuous positive airway pressure in France. On June 1st 2019, 387 patients (63% boys, mean age 11.2 ± 5.5 years) were treated with long term noninvasive ventilation/continuous positive airway pressure. Thirty three percent of patients had spinal muscular atrophy, 30% congenital myopathy/dystrophy, 20% Duchenne muscular dystrophy, 7% Steinert myotonic dystrophy, and 9% other neuromuscular diseases. Ninety-four percent of patients were treated with long term noninvasive ventilation and 6% with continuous positive airway pressure. Treatment was initiated electively for 85% of patients, mainly on an abnormal overnight gas exchange recording (38% of patients). Noninvasive ventilation/continuous positive airway pressure was initiated during a respiratory exacerbation in 15% of patients. Mean duration of noninvasive ventilation/continuous positive airway pressure was 3.3 ± 3.1 years. Mean objective long term noninvasive ventilation/continuous positive airway pressure use was 8.0 ± 3.1 h/24. Spinal muscular atrophy, congenital myopathy/dystrophy, and Duchenne muscular dystrophy represented 83% of children with neuromuscular diseases treated with long term noninvasive ventilation in France. Screening for nocturnal hypoventilation was satisfactory as noninvasive ventilation /continuous positive airway pressure was predominantly initiated electively.

Comparative analysis between available challenge tests in the hyperventilation syndrome.

BACKGROUND: The hyperventilation syndrome (HVS) is characterized by somatic/ psychological symptoms due to sustained hypocapnia and respiratory alkalosis without any organic disease. OBJECTIVE: The purpose of this study was to compare ventilatory parameters and symptoms reproducibility during the hyperventilation provocation test (HVPT) and cardiopulmonary exercise test (CPET) as diagnostic tools in patients with HVS, and to identify the most frequent etiologies of the HVS by a systematic assessment. METHODS: After exclusion of organic causes, 59 patients with HVS according to Nijmegen's questionnaire (NQ) score ≥23 with associated hypocapnia (PaCO2/PETCO2<35 mm Hg) were studied. RESULTS: The most frequent comorbidities of HVS were anxiety and asthma (respectively 95% and 73% of patients). All patients described ≥3 symptoms of NQ during the HVPT vs 14% of patients during the CPET (p<0.01). For similar maximal ventilation (61 L/min during HVPT vs 60 L/min during CPET), the median level of PETCO2 decreased from 30 mmHg at baseline to 15 mmHg during hyperventilation and increased from 31 mmHg at baseline to 34 mmHg at peak exercise (all p<0.01). No significant difference for the ventilatory parameters was found between patients with HVS (n = 16) and patients with HVS + asthma (n = 43). CONCLUSIONS: In term of symptoms reproducibility, HVPT is a better diagnostic tool than CPET for HVS. An important proportion of patients with HVS has an atypical asthma previously misdiagnosed. The exercise-induced hyperventilation did not induce abnormal reduction in PETCO2, suggesting that the exercise could be a therapeutic tool in HVS.