Continuous positive airway pressure (CPAP) masks have become very widely used at home medical device. Many companies specialize in cleaning and reprocessing these masks.
We would recommend Tergazyme® Enzyme-Active Powdered Detergent. It is an anionic, widely available and potent emulsifier of organic and oily residue, along with protease enzymes for removal of persistent bio residues.
Use a warm (< 130°F/55°C) bath with a 1-2% solution for 10-20 minutes. This ensures the enzymes are not degraded or reduce activitym which occurs at elevated temperatures. Please also use within eight hours of formulation to ensure avoidance of enzyme autocatalysis. After all, protein enzymes are made of protein.
Thorough rinsing ensures a residue-free surface.