Optimizing expiratory flows during mechanical cough in a pediatric neuromuscular lung model

Area of Science:

• Pediatric Pulmonology
• Biomedical Engineering
• Respiratory Therapy

Background:

• Mechanical insufflation-exsufflation (MI-E) is crucial for managing weak cough in individuals with neuromuscular disorders (NMDs).
• Optimal MI-E settings for young children with NMDs remain poorly understood, necessitating research into safe and effective parameters.
• This study addresses the knowledge gap concerning MI-E titration in pediatric populations.

Purpose of the Study:

• To determine Mechanical Insufflation-Exsufflation (MI-E) settings that maximize expiratory airflow while maintaining safe inspiratory volumes in young children with NMDs.
• To identify the pressure and time limits beyond which increasing MI-E settings yield diminishing returns in expiratory airflow.
• To establish a baseline for titrating MI-E in pediatric NMD patients.

Main Methods:

• Utilized an MI-E device with a lung model simulating a 1-year-old child with NMD.
• Investigated 120 combinations of MI-E pressure and time settings.
• Measured maximal expiratory airflow and inspiratory volume for each setting combination.

Main Results:

• High expiratory airflows were achieved, with exsufflation pressure having the most significant impact, followed by insufflation pressure and time.
• The benefit of increasing settings for expiratory airflow plateaued for insufflation pressure and time, but not for exsufflation pressure.
• Safe inspiratory volumes were maintained at insufflation pressures up to 35 cmH2O with specific exsufflation pressures and longer insufflation times.

Conclusions:

• Expiratory pressure is a more critical factor than inspiratory pressure and time for enhancing expiratory airflow in MI-E.
• Recommended MI-E settings for young children with NMDs include inspiratory pressure of 20-30 cmH2O, expiratory pressure of -40 cmH2O, and inspiratory time >1 second.
• Further validation through clinical trials is essential to confirm these findings in practice.