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.

Respiratory management of spinal muscular atrophy type 1 patients treated with Nusinersen

INTRODUCTION

The recent development of disease-modifying treatments in spinal muscular atrophy (SMA) type 1 shifted these patients' management from palliative to proactive. The aim of this study was to assess patients' nocturnal gas exchanges before noninvasive ventilation (NIV) initiation and their clinical evolution to determine if capnia is a good criterion to decide when to introduce respiratory support.

PATIENTS AND METHODS

This multicentric retrospective study reports the respiratory management and evolution of 17 SMA type 1 children (10 females) for whom treatment with Nusinersen was initiated between 2016 and 2018.

RESULTS

Median [interquartile range-IQR] age at diagnosis and at first Nusinersen injection was of 4 [3;8] and 4 [3;9] months, respectively. Patients were followed during 38 [24;44] months. Thirteen (76%) patients were started on NIV at a median [IQR] age of 12 [9;18] months. Repeated hospitalizations and intensive care unit admissions were needed for 11 of them. Blood gas and nocturnal gas exchange recordings performed before NIV initiation were always normal. 9/13 X-ray performed before NIV showed atelectasis and/or acute lower respiratory tract infections. There was a significant decrease in the total number of hospital admissions between the first and second year of treatment (p = 0.04).

CONCLUSION

This study shows that patients do not present with nocturnal hypoventilation before respiratory decompensations and NIV initiation, and suggests that a delay in NIV initiation might result in respiratory complications. There is a need for disease-centered guidelines for the respiratory management of these patients, including NIV indications.

Heterozygous frameshift variants in HNRNPA2B1 cause early-onset oculopharyngeal muscular dystrophy

Missense variants in RNA-binding proteins (RBPs) underlie a spectrum of disease phenotypes, including amyotrophic lateral sclerosis, frontotemporal dementia, and inclusion body myopathy. Here, we present ten independent families with a severe, progressive muscular dystrophy, reminiscent of oculopharyngeal muscular dystrophy (OPMD) but of much earlier onset, caused by heterozygous frameshift variants in the RBP hnRNPA2/B1. All disease-causing frameshift mutations abolish the native stop codon and extend the reading frame, creating novel transcripts that escape nonsense-mediated decay and are translated to produce hnRNPA2/B1 protein with the same neomorphic C-terminal sequence. In contrast to previously reported disease-causing missense variants in HNRNPA2B1, these frameshift variants do not increase the propensity of hnRNPA2 protein to fibrillize. Rather, the frameshift variants have reduced affinity for the nuclear import receptor karyopherin β2, resulting in cytoplasmic accumulation of hnRNPA2 protein in cells and in animal models that recapitulate the human pathology. Thus, we expand the phenotypes associated with HNRNPA2B1 to include an early-onset form of OPMD caused by frameshift variants that alter its nucleocytoplasmic transport dynamics.

Missense variants in RNA-binding proteins underlie many diseases. Here the authors report an oculopharyngeal muscular dystrophy caused by heterozygous frameshift mutations in HNRNPA2B1 that alter its nucleocytoplasmic transport dynamics and result in cytoplasmic accumulation of hnRNPA2 protein.

Paediatric long term continuous positive airway pressure and noninvasive ventilation in France: A cross-sectional study

OBJECTIVE

To describe the characteristics of children treated with long term continuous positive airway pressure (CPAP) or noninvasive ventilation (NIV) in France.

DESIGN

Cross-sectional national survey.

SETTING

Paediatric CPAP/NIV teams of 28 tertiary university hospitals in France.

PATIENTS

Children aged <20 years treated with CPAP/NIV since at least 3 months on June 1st, 2019.

INTERVENTION

An anonymous questionnaire was filled in for every patient.

RESULTS

The data of 1447 patients (60% boys), mean age 9.8 ± 5.8 years were analysed. The most frequent underlying disorders were: upper airway obstruction (46%), neuromuscular disease (28%), disorder of the central nervous system (13%), cardiorespiratory disorder (7%), and congenital bone disease (4%). Forty-five percent of the patients were treated with CPAP and 55% with NIV. Treatment was initiated electively for 92% of children, while 8% started during an acute illness. A poly(somno)graphy (P(S)G) was performed prior to treatment initiation in 26%, 36% had a P(S)G with transcutaneous carbon dioxide monitoring (PtcCO₂), while 23% had only a pulse oximetry (SpO₂) with PtcCO₂ recording. The decision of CPAP/NIV initiation during an elective setting was based on the apnea-hypopnea index (AHI) in 41% of patients, SpO₂ and PtcCO₂ in 25% of patients, and AHI with PtcCO₂ in 25% of patients. Objective adherence was excellent with a mean use of 7.6 ± 3.2 h/night. Duration of CPAP/NIV was 2.7 ± 2.9 years at the time of the survey.

CONCLUSION

This survey shows the large number of children treated with long term CPAP/NIV in France with numerous children having disorders other than neuromuscular diseases.

Expanding the clinical spectrum of hereditary fibrosing poikiloderma with tendon contractures, myopathy and pulmonary fibrosis due to FAM111B mutations

Background

Hereditary Fibrosing Poikiloderma (HFP) with tendon contractures, myopathy and pulmonary fibrosis (POIKTMP [MIM 615704]) is a very recently described entity of syndromic inherited poikiloderma. Previously by using whole exome sequencing in five families, we identified the causative gene, FAM111B (NM_198947.3), the function of which is still unknown. Our objective in this study was to better define the specific features of POIKTMP through a larger series of patients.

Methods

Clinical and molecular data of two families and eight independent sporadic cases, including six new cases, were collected.

Results

Key features consist of: (i) early-onset poikiloderma, hypotrichosis and hypohidrosis; (ii) multiple contractures, in particular triceps surae muscle contractures; (iii) diffuse progressive muscular weakness; (iv) pulmonary fibrosis in adulthood and (v) other features including exocrine pancreatic insufficiency, liver impairment and growth retardation. Muscle magnetic resonance imaging was informative and showed muscle atrophy and fatty infiltration. Histological examination of skeletal muscle revealed extensive fibroadipose tissue infiltration. Microscopy of the skin showed a scleroderma-like aspect with fibrosis and alterations of the elastic network. FAM111B gene analysis identified five different missense variants (two recurrent mutations were found respectively in three and four independent families). All the mutations were predicted to localize in the trypsin-like cysteine/serine peptidase domain of the protein. We suggest gain-of-function or dominant-negative mutations resulting in FAM111B enzymatic activity changes.

Conclusions

HFP with tendon contractures, myopathy and pulmonary fibrosis, is a multisystemic disorder due to autosomal dominant FAM111B mutations. Future functional studies will help in understanding the specific pathological process of this fibrosing disorder.

[Update on the management of acute viral bronchiolitis: proposed guidelines of Grand Ouest University Hospitals]

BACKGROUND AND OBJECTIVES

While our European and North American colleagues have recently updated their recommendations, the 2000 Consensus Conference remains the main guideline on management of acute viral bronchiolitis in France. We aimed to establish an updated inter-regional protocol on management of acute viral bronchiolitis in infants.

METHOD

Pediatricians, pediatric pulmonologists, and emergency physicians of the Grand Ouest University Hospitals (France) gathered to analyze the recent data from the literature.

RESULTS

Criteria to distinguish childhood asthma from acute viral bronchiolitis were established, then prescriptions of diagnostic tests, antibiotics, and chest physiotherapy were defined and reserved for very limited situations. Similarly, the modalities of oxygen therapy prescription and nutritional support were proposed. Finally, other therapeutics such as nebulized hypertonic saline seem promising, but their place in the treatment of acute bronchiolitis in infants remains unclear.

CONCLUSION

This work has provided new proposals for management of acute viral bronchiolitis and helped standardize practices within the Grand Ouest University Hospitals. This local organization could lay the keystone for working toward guidelines initiated by learned societies at the national level.

Leukocytosis is a risk factor for lung function deterioration in children with sickle cell disease

BACKGROUND

The decline in lung volumes associated with sickle cell disease (SCD) may begin in childhood. Risk factors for early restrictive lung disease may include SCD severity markers such as leukocytosis.

OBJECTIVE

We examined the relationship between early alteration of lung function and extra-pulmonary markers of SCD severity.

METHODS

We analyzed pulmonary function test results for 184 SCD children (mean age 12.6 y) enrolled in a pediatric cohort.

MAIN RESULTS

Total lung capacity (TLC) and vital capacity (VC) were not associated with a history of acute chest syndrome. Lower TLC values were significantly associated with three independent factors: older age, previous acute episodes of anemia <6 g/dl, and higher baseline white blood cell counts. Only the baseline WBC count and age were independent risk factors for lower VC. Relative risks to have a TLC or a VC lower than the mediane value in our population were significantly associated to the baseline leukocytosis (per 10(9) G/L), after adjustment on age, sex, genotype, baseline Hb, and treatment (RR (95% CI) =1.16 (1.04-1.29) p<0.009, and 1.17 (1.06-1.29) p<0.002, respectively). The obstructive pattern, defined by FEV1/FVC ratio, was not significantly associated to biological parameters.

CONCLUSIONS

Hemolysis and leukocytosis were independent risk factors for an early decline in lung volumes in this pediatric SCD cohort.

Comparative Efficacy of Intratracheal Adeno-Associated Virus Administration to Newborn Rats

Transient local overexpression of genes that promote lung defense or repair may help to protect or promote alveolar development in premature neonates. We showed that the use of adenoviral vectors in neonates was limited by the induction of lung growth disorders. In the present work we compare the efficiency of gene transfer to the neonatal lung by three adeno-associated viral vectors: rAAV1, rAAV2, and rAAV5. Transduction efficiency was first measured in vitro, by infecting A549 immortalized human lung epithelial cells, and primary epithelial and mesenchymal cells isolated from human fetal lung. AAV vectors yielded similar low levels of luciferase gene expression in the different cell types. In vivo transduction efficiency was evaluated in newborn rats, with AAV-LacZ vectors being intratracheally instilled at 3 days of age. Both rAAV5 and rAAV1, but not rAAV2, induced significant lung beta-galactosidase expression, which persisted on day 35. Highest beta- galactosidase levels were measured with rAAV5, but remained far lower than those obtained with adenoviral vectors. A transient increase in alveolar macrophages was observed on day 6, but not on day 8, after rAAV5-LacZ instillation. Morphometric evaluation of lung structures was performed on day 21, and showed no altered lung growth. We conclude that rAAV1 or rAAV5 was more efficient at mediating gene transfer in the neonatal lung than was rAAV2, without adversely affecting lung development. However, in vivo transgene expression was relatively low, and needs to be improved for future therapeutic use of these adeno-associated vectors.

[Inhaled antiasthmatics in children. How to choose?]

An optimal combination of anti-asthmatic drugs and delivery devices produces the best short- and long-term control in asthmatic children. Various inhalation devices can be used: nebulizer, metered dose inhaler with or without spacer devices, dry powder inhaler. Their use will depend on age, asthma severity, acute or long-term treatment and the child's preference. Explanation and control of inhalation techniques are essential for a good compliance.