Earlier decline in sniff nasal inspiratory pressure than peak expiratory flow in children with Duchenne muscular dystrophy

Can Sniff Nasal Inspiratory Pressure be a guide in detecting of sleep-disordered breathing in children with Duchenne Muscular Dystrophy?

PURPOSE

Duchenne muscular dystrophy (DMD) is a severe, progressive condition characterized by muscle degeneration and weakness, significantly affecting respiratory function. This study aimed to evaluate the presence of sleep-disordered breathing (SDB) in children with DMD and investigate the relationships between sleep and respiratory function using spirometry, sniff nasal inspiratory pressure (SNIP), and polysomnography (PSG) along with capnography.

RESEARCH QUESTION

Can low SNIP be a guide for detecting respiratory muscle involvement early and determining the right time to perform early PSG and capnography in DMD?

STUDY DESIGN

Prospective, observational, cross-sectional study.

METHODS

This study included DMD patients aged <18 years. Pulmonary function tests were conducted using spirometry and SNIP, and maximum inspiratory and expiratory pressure were measured. PSG and capnography were performed within two weeks after the pulmonary function tests, and their relationships with each other were investigated.

RESULTS

The study included 44 children. Obstructive sleep apnea syndrome (OSAS) was present in 70.5 % of patients, while nocturnal hypoventilation was observed in 4.5 %. SNIP values were significantly lower in patients with moderate-to-severe OSAS than in those without OSAS. An SNIP value below 40 cm H2O was associated with a 92.8 % prevalence of OSAS.

CONCLUSION

SNIP is a valuable, noninvasive marker for the early detection of respiratory muscle involvement and SDB in patients with DMD. This study highlights the need for early and regular respiratory monitoring in children with DMD to enhance care and quality of life.

Non-Invasive Respiratory Assessment in Duchenne Muscular Dystrophy: From Clinical Research to Outcome Measures

Ventilatory failure, due to the progressive wasting of respiratory muscles, is the main cause of death in patients with Duchenne muscular dystrophy (DMD). Reliable measures of lung function and respiratory muscle action are important to monitor disease progression, to identify early signs of ventilatory insufficiency and to plan individual respiratory management. Moreover, the current development of novel gene-modifying and pharmacological therapies highlighted the urgent need of respiratory outcomes to quantify the effects of these therapies. Pulmonary function tests represent the standard of care for lung function evaluation in DMD, but provide a global evaluation of respiratory involvement, which results from the interaction between different respiratory muscles. Currently, research studies have focused on finding novel outcome measures able to describe the behavior of individual respiratory muscles. This review overviews the measures currently identified in clinical research to follow the progressive respiratory decline in patients with DMD, from a global assessment to an individual structure–function muscle characterization. We aim to discuss their strengths and limitations, in relation to their current development and suitability as outcome measures for use in a clinical setting and as in upcoming drug trials in DMD.

The assessment of sniff nasal inspiratory pressure in patients with Duchenne muscular dystrophy in China

OBJECTIVE

Progressive weakness of respiratory muscles remains one of the leading causes of death among patients with Duchenne muscular dystrophy (DMD). Currently, there are few pulmonary function data among Chinese DMD patients. This study was carried out to evaluate the sniff nasal inspiratory pressure (SNIP) change among a group of Chinese DMD patients, and compare it with the SNIP value of patients with neuromuscular disorders in other countries.

METHODS

SNIP data were collected in three research groups that consists of 581 subjects: 125 DMD boys who have taken steroid (Age 5.0-13.3, DMD-steroid group), 145 DMD steroid-naive boys (Age 5.0-13.9, DMD-nonsteroid group), and 311 healthy controls (Age 5.0-14.0, Control group).

RESULTS

The SNIP for DMD-nonsteroid group, DMD-steroid group and Control group were: 56.5 (±14.3) cm H₂O,66.4 (±15.5) cm H₂O and 78.9 (±21.5) respectively. The SNIP in the DMD-nonsteroid group became significantly different from that of the healthy controls since age 7.0-8.9. The significant difference of SNIP between DMD-steroid group and DMD-nonsteroid group at age 7.0-10.9. The peak value of SNIP in the DMD-nonsteroid group appeared at age 8.7, and decreased dramatically thereafter, while in DMD-steroid group and the Control group peaked at 10.2 years and 12.2 years respectively. There was a bit difference between SNIP in this group and that in previous researches which may be due to geographical distribution and ethnic backgrounds.

CONCLUSION

This study strengthens the previous findings that SNIP can be used to evaluate respiratory dysfunction during the early stage of young patients with neuromuscular disorders, and demonstrates that steroid is effective in slowing the decrease of SNIP in this group of Chinese DMD boys.

Chronotropic incompetence can limit exercise tolerance in COPD patients with lung hyperinflation

Purpose

Metabolic-chronotropic relationship is the only concept that assesses the entire chronotropic function during exercise, as it takes into account individual fitness. To better understand interrelationships between chronotropic incompetence (CI), dynamic hyperinflation (DH) and exercise limitation among Global initiative for chronic Obstructive Lung Disease (GOLD) stages of chronic obstructive pulmonary disease (COPD) disease severity, we evaluated cardiopulmonary responses to symptom-limited cycle exercise in stable patients.

Patients and methods

We prospectively studied 47 COPD patients classified by GOLD stage severity. Pulmonary function tests and cardiopulmonary responses to symptom-limited incremental exercise were studied. CI was defined by regression line between percent heart rate (HR) reserve and percent oxygen uptake (V’O₂) reserve, ie, chronotropic-metabolic index (CMI). DH was defined from the knot resulting from the nonlinear regressions of inspiratory capacity changes from rest to peak (dynamic inspiratory capacity (IC_dyn)) with percentage of maximal HR and CMI.

Results

Aerobic capacity (median interquartile ranges) peak V’O₂, 24.3 (23.6; 25.2), 18.5 (15.5; 21.8), 17.5 (15.4; 19.1) mL·kg⁻¹·min⁻¹ and CMI worsened according to GOLD severity. The optimal knot of IC_dyn was equal to −0.34 L. The multivariate logistic regression showed a strong relationship between CI (outcome) and DH (odds ratio [confidence interval 95]) 25 (3.5; 191.6).

Conclusion

COPD patients with DH have a poor cardiovascular response to exercise, which may be attributed to CI.