LONGITUDINAL ASSESSMENT OF HYPERCAPNIC VENTILATORY DRIVE AFTER TRACHEOTOMY IN A PATIENT WITH THE PRADER-WILLI-SYNDROME

The clinical course and changes in hypercapnic ventilatory drive over time were serially assessed before and after tracheostomy placement in a 14 year old, morbidly obese female patient with Prader-Willi syndro me, severe obstructive sleep apnoea, and obesity-hypoventilation syndr ome. A tracheostomy became necessary after supplemental oxygen and con tinuous positive airway pressure (CPAP) had failed to improve the seve rity of nocturnal hypoventilation. Continued improvement in the slope to rebreathing hyperoxic hypercapnia occurred from 2-10 weeks after tr acheotomy in conjunction with night-time bilevel pressure ventilation, and remained unchanged thereafter. In contrast, increases in mean res ting minute ventilation at an end-tidal carbon dioxide tension (PET,CO 2) of 8 kPa (60 mmHg) were documented even after 30 weeks. This case s tudy illustrates the time-frame of dynamic ventilatory changes occurri ng after removal of upper ah-way resistance and normalization of noctu rnal alveolar ventilation.