2004 OPEN FORUM Abstracts
MORQUIO SYNDROME PRESENTING AS ACUTE RESPIRATORY FAILURE.
Carolyn Pelley, BS, RRT; Jean Kwo, MD; Dean R. Hess, PhD, RRT, FAARC. Massachusetts General Hospital and Harvard Medical School, Boston, MA.
Introduction: Morquio Syndrome is an autosomal recessive mucopolysaccharidoses (MPS) affecting about 1 in 300,000 to 500,000 births. With Morquio Syndrome Type A there is a deficiency of galactosamine-6-sulfate sulfatase, precipitating the build up of keratan sulfate in lysosomes. This causes defects in the formation of muscles, bones and connective tissues. Patients present with coarse facial features, macrocephaly, bell-shaped chest with flared ribs, short trunk, kyphoscoliosis, and hypermobile joints. Unlike other MPS, neurological function is preserved. Patients often have irregularly shaped vocal cords and trachea, making mechanical ventilation difficult due to airway collapse. Complications include spinal cord compression, cardiac anomalies, and respiratory failure. Diagnosis can be made either prenatally by testing enzyme activity of the amniotic fluid or after birth by radiographs, urine chemistry, or skin fibroblast culture. Treatment is supportive and symptom-based. Enzyme replacement therapy has been attempted, but fails due to inability to provide adequate repletion.
Case Summary: This 29 yr-old female presented to the emergency department with severe wheezing and tachycardia. One month prior to admission, she underwent elective spinal stabilization which resulted in fixed head flexion. The surgery was complicated by paraplegia and long-term mechanical ventilation by tracheostomy tube (#6 Bivona TTS custom-made). She required heavy sedation to adequately ventilate on pressure controlled ventilation (initial arterial blood gas pH 7.24, PCO2 71 mm Hg), and was later transferred to the medical ICU. The next day, ventilation became very difficult. Bronchoscopy revealed severe tracheomalacia and the tracheostomy tube was changed to a #6 Bivona adjustable with the flange secured 10 cm from distal. A persistent cuff leak was noted and the following day the tracheostomy tube was again changed to a #7 Bivona adjustable with the flange at 9 cm. Subsequently, the patient’s sedation was decreased and she was transferred to our Respiratory Acute Care Unit for further ventilator weaning. Over the next 20 days, she was weaned with spontaneous breathing trials and pressure support ventilation. Three times during this period, she was noted to have labored breathing with dramatically decreased tidal volumes. On each occasion, bronchoscopy revealed almost complete occlusion of the distal end of the tracheostomy tube by the posterior tracheal membrane (Figure). Each time, the tracheostomy tube was advanced past the obstruction and ventilation became much easier. After 1 month, she became febrile, severely hypoxemic, and was transferred to the medical ICU. She was placed on pressure controlled ventilation and in the setting of sepsis and severe hypoxemia, required an inspiratory pressures of 25 cm H2O and positive end-expiratory pressure of 22 cm H2O due to high airways resistance and markedly elevated intra-abdominal pressure. Over the next few days, her condition worsened and her family decided to withdraw care.
Discussion: Morquio Syndrome is a rare disease and unexpected complications during treatment may occur. Close attention must be given to the patient’s abnormal airways and malformed chest cage, as illustrated by the management issues in this patient. Mechanical ventilation may be difficult due to upper airway obstruction or low compliance imposed by the restrictive chest. Complete tracheal collapse can occur in these patients, especially during fixed head flexion, as shown in this case.