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