Method for spectrophotometrically determining a blood oxygen parameter

A method for determining a blood oxygen parameter of a subject tissue, comprising the steps of:

• providing near-infrared spectroscopy (NIRS) system, which system includes at least one sensor assembly including a light source operable to emit light at one or more predetermined wavelengths, at least one light detector having an active area for detecting light emitted by the light source and passed through the biological tissue, and which detector is operable to produce signals representative of the detected light, and a subject contact layer disposed to cover one or both of the light detector and the light source, which subject contact layer has at least one optically transmissive portion, and which subject contact layer acts as a cushioning layer, and a processor;
• interrogating the subject tissue with light emitted from the sensor assembly;
• detecting light emitted by the light source, which light has passed through the biological tissue and has passed through a material of the subject contact layer, and producing signals representative of the detected light;
• and
• determining the blood oxygen parameter of the subject tissue using the processor and the signals representative of the detected light, which determination includes accounting for the optical transmissivity of the subject contact layer.