Add spaces: Combiningthemgivesanoverallseverityofsleepapneaincludingsleepdisruptionsanddesaturations(alowlevelofoxygenintheblood).Theapnea-hypopneaindex,liketheapneaindexandhypopneaindex,iscalculatedbydividingthenumberofapneasandhypopneasbythenumberofhoursofsleep.
Combining them gives an overall severity of sleep apnea including sleep disruptions and desaturations (a low level of oxygen in the blood). The apnea-hypopnea index, like the apnea index and hypopnea index, is calculated by dividing the number of apneas and hypopneas by the number of hours of sleep.