PURPOSE: Morquio's Syndrome (MS) is an inherited metabolic disorder caused by a deficiency of a specific lysosomal enzyme. Patients develop respiratory failure secondary to reduced chest wall compliance, reversible and irreversible airway obstruction, chronic obstructive lung disease and obstructive sleep apnea. Formal respiratory function tests are difficult to perform and to interpret owing to the small size of these patients and to poor patient cooperation. The advent of infant pulmonary function testing (IOS) may identify MS children with significant pulmonary limitations. The aim of this study is to evaluate this hypothesis.
METHODS: We retrospectively reviewed pulmonary function tests from patients with MS who had performed an IOS study with the Jaeger system. The patients were breathing spontaneously during wakefulness. The following parameters were studied: SaO2, end-tidal CO2, minute ventilation (MV), rib cage contribution to tidal volume excursions (RC%), phase angle (Ph°), and the impulse oscillation parameters: Rrs5–35, Xrs5–35, resonant frequency and their frequency-dependency. Clinical history was reviewed for pertinent respiratory features including sleep study results and the use of supplementary oxygen or/and continuous positive airway pressure (CPAP).
RESULTS: Patients ages ranged from 7 to 20 years old and heights from 95 –129 cm. Decreased reactance at low-frequency and increased airway resistance even independent of oscillation frequency were observed. There was a positive correlation between reactance and RC% (r=0.9). Overall, 75% had a diagnosis of abnormal sleep study.
CONCLUSION: IOS appears to be a reliable tool to evaluate MS patients with pulmonary dysfunction. Findings support clinically reported large airway and restrictive pulmonary defects.
CLINICAL IMPLICATIONS: Because the infiltration of pulmonary structures with mucopolysaccharides, the early recognition and treatment of airway disease may improve the quality of life and enhance survival of individuals with Morquio's Syndrome.
DISCLOSURE: M Rodriguez, No Financial Disclosure Information; No Product/Research Disclosure Information