Neuromuscular diseases (NMD) in children are severe, possibly life-threatening orphan conditions. The children are vulnerable and often subject to rapid deterioration of pulmonary function due to impaired ability to clear airway secretions. The use of mechanical cough augmentation with insufflation-exsufflation (MIE) is a strategy to treat and prevent. Possible major benefits are described, but optimal settings for best efficacy and comfort in children are not established. The project aim to improve the quality of the treatment with MIE in children with NMD and weak cough. On the basis of a bench study a clinical trial aims to examine the most effective MIE settings when used in stable state and when respiratory tract infections are present.

On the basis of a prevalence study and a bench study different settings will be studied in children with NMD and weak cough to examine if settings derived from the lung model, are optimal to increase the peak cough flow (PCF) and comfort measured by visual analogue scale (VAS) in children with NMD and weak cough.

Inclusion Criteria:

• Diagnosed neuromuscular disease < 18 years

• Established use (> 3mnd) of MI-E.

• Reduced PCF

  • PCF < 270 l/min (when > 12 years)
  • < 5th percentiles for PCF 16 (when 4 - 12 years)

• Clinical indication (difficulty to clear secretions, audible weak cough, history of pneumonia or frequent or prolonged respiratory tract infections).

Exclusion Criteria:

• age < 6 mnd
• obstructive lung disease (hyperinflation or emphysema on x-ray.

Participant, care provider, investigator and outcomes assessor are blinded from the order of the settings tested. Only a technician change settings and know the order.