If an alternative mask is utilized, having a mask exhaust valve 62 , {HEAD ~ the stimulus} is directed to the patient will provide a reminder for the patient to check whether the exhaust valve 62 is blocked against {TAIL ~ a pillow} or clothing 
If an alternative mask is utilized , having a mask exhaust valve 62 , { HEAD ~ the stimulus } is directed to the patient will provide a reminder for the patient to check whether the exhaust valve 62 is blocked against { TAIL ~ a pillow } or clothing
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH