Normal range of values for contractility and relaxation parameters of inspiratory muscles in healthy children: An exploratory study

OBJECTIVES

To estimate normal range of values for the contractility and relaxation parameters of inspiratory muscles and compare them by sex, age, nutritional status and level of physical activity in healthy children.

WORKING HYPOTHESIS

We hypothesized that healthy children present similar range of values for the contractility and relaxation parameters of inspiratory muscles.

STUDY DESIGN

Exploratory study conducted between 2017 and 2018.

PATIENT-SUBJECT SELECTION

Healthy children aged 6 to 11 years without history of respiratory, cardiac, cerebrovascular or neuromuscular disease as well as no nasal congestion, influenza or known septum deviation were included.

METHODOLOGY

Anthropometric, spirometry and respiratory muscle strength data were assessed. Maximum rate of pressure development (MRPD), maximum relaxation rate (MRR), time constant of decay curve (τ), contraction time (CT) and half-relaxation time (½ RT) were calculated from the nasal inspiratory pressure curve.

RESULTS

The sample was composed of 110 children (55 boys) with 1.045 as mean z-BMI-score. MRPD range of values was 8.09% to 10.86% rise/10 ms, MRR range of values was 8.09% to 10.86% fall/10 ms, τ range of values was 36.41 to 49.88 ms, CT range of values was 200 to 276 ms, ½ RT range of values was 117.5 to 148 ms and MRPD/MRR range of values was 0.71 to 1.04. The contractility and relaxation parameters did not present significant differences among children when compared by sex, age, nutritional status, or level of physical activity groups (P > .05).

CONCLUSIONS

The contractility and relaxation parameters present similar values among children and they are not influenced by age, sex, nutritional status or physical activity level.

Montelukast reverses airway remodeling in actively sensitized young mice

Asthma is characterized by airway hyperresponsiveness (AHR) and inflammation leading to airway remodeling (AR). In children, AR may occur very early prior to the age of 6 years. Treatments to prevent or reverse AR are unknown.

AIM

We sought to determine (i) whether short allergenic sensitization at a young age in a mouse model may induce enhanced AR and inflammation compared to adults; (ii) the effect of Montelukast on such AR.

METHODS

Immature and adult Balb/c mice were sensitized and challenged with ovalbumin. AHR and AR were measured using cultured precision-cut lung slices and inflammation by bronchoalveolar lavage. Experiments were repeated after administration of Montelukast.

RESULTS

OVA-challenged mice developed AHR to methacholine regardless of age of first exposure to OVA. Young mice developed greater thickened basement membrane, increased smooth muscle mass, and increased area of bronchovascular fibrosis compared with adult mice. Cellular infiltrates in BAL differed depending upon animal age at first exposure with higher eosinophilia measured in younger animals. Montelukast decreased ASM mass, BAL cellularity.

CONCLUSION

We provide thus evidence for a greater degree of AR after allergenic sensitization and challenge in younger mice versus adults. This study provides proof of concept that airway remodeling can be prevented and reversed in this case by anti-asthmatic drug Montelukast in this model.

Respiratory muscle training improves respiratory muscle endurance but not exercise tolerance in children with cystic fibrosis

BACKGROUND

Respiratory muscle endurance (RME) training has been shown to increase exercise endurance and lung function in adults with cystic fibrosis (CF). We conducted an interventional study to investigate the effectiveness of RME training on CF-related health outcomes in children.

METHODS

In a crossover trial, 22 children, aged 9-18 years, with CF performed 8 weeks of RME training and standard chest physiotherapy in a randomized sequence separated by a 1 week washout period. All children underwent training sessions using the RME training device before beginning the study. The primary outcomes were RME (in minutes) and exercise endurance (in minutes). Data were analyzed according to the intention-to-treat principle.

RESULTS

Sixteen of 22 children (73%) completed the study. Study dropouts tended to be older with more advanced lung disease. After RME training, respiratory muscle endurance significantly increased by 7.03 ± 8.15 min (mean ± standard deviation, P < 0.001), whereas exercise endurance was unchanged by RME training (0.80 ± 2.58 min, P = 0.169). No significant improvement in secondary outcomes (lung function, CF quality of life, and CF clinical score) were observed. The small sample size and short intervention time have to be acknowledged as limitations of our study.

CONCLUSIONS

RME training led to a significant increase in respiratory muscle endurance in children with CF. However, RME training did not improve exercise endurance or other CF-related health outcomes. Thus, our results do not support the routine use of RME training in the care of children with CF. Future studies in larger populations and with prolonged intervention time may overcome the limitations of our study. Pediatr Pulmonol. 2017;52:331-336. © 2017 Wiley Periodicals, Inc.

Apparent life-threatening events could be a wake-up call for sleep disordered breathing

INTRODUCTION

Polysomnographic recordings of children with an apparent life-threatening event (ALTE) have often displayed signs of partial or complete obstruction during sleep. Various studies have focused on facial dysmorphia in infants with ALTE and tried to establish a correlation between ALTE and obstructive sleep apnoea. Our study evaluates the phenotypic characteristics and the presence of sleep disorders in pre-school children who had at least one ALTE in the first year of life.

MATERIALS AND METHODS

We analyzed a group of pre-school children (mean age 5.21 ± 0.90 years) who were referred for an ALTE between 2008 and 2010. Children with no history of ALTEs were recruited as a control group. A detailed personal and family history was obtained for all the participants. Moreover, all the children underwent a general clinical examination and an ear, nose, and throat and orthodontic assessment. A clinical score was calculated according to the previously validated Sleep Clinical Record (SCR).

RESULTS

In the ALTE group (n = 107), snoring (25.2% vs. 6.1%), apnoeas (19.6% vs. 4.3%), restless sleep (31.7% vs. 6.1%), and habitual mouth breathing (35.5% vs. 12.2%, P < 0.05) were significantly more common (P < 0.05) than in the control group (n = 115). The ALTE group also displayed a higher frequency of Angle class II (27.1% vs. 15.7%, P < 0.05), narrow palate (72.9% vs. 51.3%, P < 0.05), and Friedman palate position (grades III-IV) (31.7% vs. 16.6%, P < 0.05) than the control group. Moreover, 38/107 (35.5%) children in the ALTE group had a positive SCR score compared with 14/115 controls (12.2%) (P < 0.05).

CONCLUSIONS

Pre-school age children with previous ALTE had a higher frequency of sleep disordered breathing and malocclusion phenotypes. The occurrence of ALTEs may be predictive of the development of sleep disordered breathing and highlight the importance of a long-term follow-up. Pediatr Pulmonol. 2016;51:1403-1408. © 2016 Wiley Periodicals, Inc.

Prevalence and characteristics of tracheal cobblestoning in children

BACKGROUND

Tracheal follicular pattern or so-called tracheal cobblestoning is a poorly described entity in the literature and is depicted as a nodular or lumpy appearance of the tracheal wall mucosa suggesting tracheal irritation from factors like gastro-esophageal reflux (GERD) or pulmonary infection. The aim of the present study was to investigate the prevalence and characteristics of tracheal cobblestones in a large pediatric population.

METHODS

A large database of rigid tracheoscopies recorded in children (0-6 years of age) undergoing general anesthesia with planned tracheal intubation for elective surgical procedures was retrospectively analyzed. Tracheoscopy records were reviewed by five pediatric airway experts (authors 3-7). Data were compared using the Mann-Whitney test, chi-square or Fisher exact test as appropriate (P < 0.05).

RESULTS

A total of 971 rigid tracheoscopy records were analyzed. The median age of the patients was 3.3 years (range 0.4-6.0 yrs). Cobblestones were present in 377 out of 971 patients (38.8%) with a male to female prevalence of 254 (40.6%)/123 (35.5%). None of the children under four months of age showed the presence of cobblestones. The prevalence of cobblestones was significantly less in patients under 3 years of age compared to over 3 years (P < 0.01). There was no association between prevalence of cobblestones and GERD, current or recent respiratory infection or concomitant enlarged tonsils.

CONCLUSION

The prevalence of tracheal cobblestones in otherwise healthy children is high and is not associated with GERD or respiratory infection. The gender and age related differences are novel interesting findings that require further investigations.