Table 5

Indications for overnight sleep monitoring in children with neuromuscular weakness

IndicationNotes
Vital capacity <60% predictedChildren generally need to be over 6 years of age to produce reliable spirometry. In boys with DMD, a vital capacity of over 1.8 litres indicates that nocturnal hypoventilation is very unlikely to be present
Loss of ambulation because of progressive weakness, or children who never attain the ability to walkInability to walk is a measure of moderate to severe muscle weakness
Infants with weaknessInfantile onset is often associated with more severe weakness
Children with symptoms of obstructive sleep apnoea or hypoventilationSee section on clinical assessment
Children with diaphragmatic weaknessSleep-associated hypoventilation can occur even if general muscle strength is preserved
Children with rigid spine syndromeThese children are at particular risk of nocturnal hypoventilation despite relatively preservation of general muscle strength, ambulation and near normal vital capacity