Flow-volume curves and sleep-disordered breathing: Therapeutic implications

To assess the relationship of abnormal flow-volume curves during awake periods to the clinical severity of sleep-disordered breathing and the need for surgical treatment of obstructive sleep apnoea, flow-volume curves were measured in 72 adults with obstructive apnoea. Patients in whom surgery was recommended for standard clinical indications had significantly lower inspiratory flow rates (p < 0.01) and a higher incidence of flow-volume curves indicating extrathoracic airway obstruction (p < 0.01) than did non-surgical patients. These abnormal flowvolume curves correlated with an increased severity of nocturnal oxygen desaturation (p < 0.01).Furthermore, increases in inspiratory flow rates measured serially in 22 patients were related to improvement in their polysomnography (p < 0.05), suggesting that alterations of airway function during awake periods correlate with changes in the severity of sleep apnoea.