Spontaneous Breathing Pattern as Respiratory Functional Outcome in Children with Spinal Muscular Atrophy (SMA).
BACKGROUND
SMA is characterised by progressive motor and respiratory muscle weakness. We aimed to verify if in SMA children 1)each form is characterized by specific ventilatory and thoraco-abdominal pattern(VTAp) during quiet breathing(QB); 2)VTAp is affected by salbutamol therapy, currently suggested as standard treatment, or by the natural history(NH) of SMA; 3)the severity of global motor impairment linearly correlates with VTAp.


METHODS
VTAp was analysed on 32 SMA type I (SMA1,the most severe form), 51 type II (SMA2,the moderate), 8 type III (SMA3,the mildest) and 20 healthy (HC) using opto-electronic plethysmography. Spirometry, cough and motor function were measured in a subgroup of patients.


RESULTS
In SMA1, a normal ventilation is obtained in supine position by rapid and shallow breathing with paradoxical ribcage motion. In SMA2, ventilation is within a normal range in seated position due to an increased respiratory rate(p<0.05) with reduced tidal volume(p<0.05) secondary to a poor contribution of pulmonary ribcage(%ΔVRC,P, p<0.001). Salbutamol therapy had no effect on VTAp during QB(p>0.05) while tachypnea occurred in type I NH. A linear correlation(p<0.001) was found between motor function scales and VTAp.


CONCLUSIONS
A negative or reduced %ΔVRC,P, indicative of ribcage muscle weakness, is a distinctive feature of SMA1 and SMA2 since infancy. Its quantitative assessment represents a non-invasive, non-volitional index that can be obtained in all children, even uncollaborative, and provides useful information on the action of ribcage muscles that are known to be affected by the disease.Low values of motor function scales indicate impairment of motor but also of respiratory function.
Dipartimento di Elettronica, Informazione e Bioingegneria; Politecnico di Milano, Italy.
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LoMauro
Dipartimento di Elettronica, Informazione e Bioingegneria; Politecnico di Milano, Italy.
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Aliverti
S.A.PRE., Ospedale Policlinico Maggiore Mangiagalli, and Regina Elena Foundation, Milan, Italy.
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Mastella
Developmental Neurology Unit, Carlo Besta Neurological Research Institute Foundation, Milan, Italy.
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Arnoldi
Pulmonary Rehabilitation Fondazione Don Carlo Gnocchi, Milan, Italy.
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Banfi
Developmental Neurology Unit, Carlo Besta Neurological Research Institute Foundation, Milan, Italy.
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Baranello
D002648:Child; D002675:Child, Preschool; D003371:Cough / Q000503:physiopathology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D008168:Lung / Q000503:physiopathology; D008297:Male; D009134:Muscular Atrophy, Spinal / Q000503:physiopathology*; D010991:Plethysmography / Q000379:methods; D011446:Prospective Studies; D012119:Respiration; D015656:Respiratory Mechanics / Q000502:physiology*; D012132:Respiratory Muscles / Q000503:physiopathology*; D013147:Spirometry / Q000379:methods; D016683:Supine Position / Q000502:physiology; D035441:Thoracic Wall / Q000503:physiopathology; D013990:Tidal Volume / Q000502:physiology