Patient-ventilator asynchronies and periodic limb movement: a possible link?

Periodic limb movements (PLMs) during sleep are involuntary phenomena characterized by periodic episodes of repetitive, stereotypical movements of the limbs. PLMs are a common finding in sleep studies, but these movements are rarely perceived by the patient and do not typically cause specific symptoms. During sleep studies, an increase in respiratory flow can be observed for 1-2 breaths corresponding to the PLMs, as detected by nasal cannula or, more rarely, by thoraco-abdominal belts. It has been hypothesized that these brief increases in ventilation may cause difficulties in interpreting respiratory events, as they alter the breathing pattern. Non-invasive ventilation in spontaneous/assisted mode is commonly used during sleep in many chronic respiratory diseases characterized by hypercapnic respiratory failure. Patient-ventilator synchronization depends on the ventilator's algorithm and the patient's breathing pattern. We present some polysomnographic images that suggest a potential pathogenic role of PLMs in patient-ventilator asynchrony.