Abstract: Embodiments of the invention relate to a mask assembly for use in treatment systems for treating obstructive sleep apnea using continuous positive air pressure (CPAP). The mask assembly comprises a mask or nasal interface for supplying gas to the nose of a wearer of the mask assembly. The mask assembly also comprises a strap or harness attached to the mask for securing the mask assembly to the wearer and sensors located on the mask assembly for measuring physiological signals of the wearer. These physiological signals are communicated to a monitoring unit which, in association with a CPAP device, serves to determine the efficacy of the CPAP treatment and to vary operational parameters of the treatment.

Abstract: Embodiments of the invention generally relate to needles having more than one electrode and which are particularly suited for use in electromyography. One embodiment relates to a tripolar needle having three concentric electrodes. The tripolar needle is formed by providing a needle blank having first and second concentric electrodes and forming a third concentric electrode around the needle blank. The tripolar needle has an outer diameter which is substantially constant along the shaft of the needle, except at the tip, where the needle is sharpened.