Is early noninvasive mechanical ventilation of first choice in stable restrictive patients with chronic respiratory failure?

Abstract

Noninvasive long-term ventilation is consensually advocated when daytime hypercapnia > 6 kPa at steady state in chronic restrictive pulmonary syndromes. Several mechanisms can cause the occurrence of hypercapnia in these diseases. They may involve impairment of lung mechanics or airway function and cough, ventilation-perfusion mismatching, blunted central ventilatory drive or respiratory muscle fatigue. These abnormalities may occur while awake or during sleep. From a practical point of view, imperative ventilation, a palliative technique that aims to supply respiratory muscle weakness, and preventive ventilation, aimed at delaying respiratory handicap, should be distinguished between. The latter is offered to patients who do not fulfil any criteria for mechanical ventilation. Otherwise, the underlying disease markedly influences both pathophysiology and outcome. This implies that the available modes of ventilatory support should be assessed in each disease. Several findings have been published about Duchenne's muscular dystrophy. Mechanical ventilation, usually using noninvasive methods, is offered to patients with either hypercapnia or a forced vital capacity < 20% of the predicted value. Nevertheless, based on our experience, deterioration of the restrictive syndrome should be followed by a tracheostomy. By contrast, early ventilation, offered to patients free of symptoms and whose forced vital capacity are within 20-50% pred and with normal arterial blood gas levels, achieves no benefit.