Is two better than one? Targeted treatment of obstructive sleep apnoea using combination therapy to attack endotypes

The heterogeneity of obstructive sleep apnoea (OSA) is becoming increasingly appreciated [1]. Subclassification based on physiological endotypes may have the potential to facilitate targeted therapy for OSA patients. Four main physiological endotypes have been described, each with different possible management approaches (figure 1). Endotypes might not act in isolation, and modification of one may affect another [2]. Respiratory system gain (loop gain) has been extensively studied in the context of sleep apnoea [3, 4]. Increased loop gain is associated with ventilatory instability, and may predispose patients to OSA; treatment modalities that can lower loop gain might stabilise ventilation and improve OSA [3].