K. Behbehani et al., AUTOMATIC-CONTROL OF AIRWAY PRESSURE FOR TREATMENT OF OBSTRUCTIVE SLEEP-APNEA, IEEE transactions on biomedical engineering, 42(10), 1995, pp. 1007-1016
Obstructive sleep apnea (OSA) occurs when airflow ceases because of ph
aryngeal wall collapse in sleep, Repeated apneic events results in the
development of a pathological condition called OSA syndrome, We descr
ibe the methodology and design of a prosthetic device, named automatic
positive airway pressure (APAP), for treatment of this syndrome, APAP
applies a stream of air via a nasal mask at an initial pressure selec
ted by the patient. By sensing specific pressure characteristics of ai
r flow immediately preceding pharyngeal wall collapse, the APAP device
automatically raises the applied pressure to maintain a patent upper
airway and thus prevent apnea, Conversely, when such conditions are ab
sent, pressure is lowered step wise until a preselected minimum pressu
re is reached, Performance evaluation of the APAP system in five OSA p
atients and five normal (asymptomatic for sleep apnea) subjects reveal
ed that it effectively treated OSA syndrome, It lowered the apnea-hypo
pnea index without disturbing sleep and resulted in a lower mean airwa
y pressure compared to the traditional continuous positive airway pres
sure (CPAP) therapy, The results also show that the pressure needed to
prevent OSA varied significantly throughout the night, For OSA syndro
me patients, this pressure ranged from 3 to 18 cm H2O, The mean airway
pressure for these patients had a sample average of 6.80 cm H2O and a
standard deviation of 3.17 cm H2O, In normal subjects, the device did
not raise pressure except in response to Pharyngeal Wall Vibration ev
ents.