Bench evaluation of flow limitation detection by automated continuous positive airway pressure devices.
OBJECTIVE
Automatic continuous positive airway pressure (CPAP) devices that adjust the pressure delivered to the patient are now available to treat sleep-disordered breathing. Sophisticated auto-CPAP devices can detect and correct flattened inspiratory flow contours (FIFCs) associated with subtle upper airway obstruction. However, evaluations of their performance are made difficult by differences across patients and devices. We performed a bench study of five commercially available auto-CPAP devices using a breath waveform simulator to evaluate sensitivity for detecting flattened inspiratory flow.


METHODS
Five degrees of FIFC were simulated. In addition, normal and abnormal flow contours from patients published in the literature were evaluated.


RESULTS
One device showed autotriggering leading to CPAP increases, and another device varied the CPAP level independently from the presence of an FIFC. The three remaining devices differed regarding the detection of FIFCs and the means used to increase CPAP.


CONCLUSIONS
Based on the characteristics of each patient, physicians must choose among devices with different thresholds of FIFC detection and different pressure responses to detection. Therefore, physicians need details on the algorithms used in auto-CPAP devices. Manufacturers should supply detailed algorithms.
Lofaso
Frédéric
F
National Institute for Health and Medical Research (Institut National de la Santé et de la Recherche Médicale), Unit 651, Henri Mondor Teaching Hospital, Créteil, France. f.lofaso@rpc.ap-hop-paris.fr
Desmarais
Gilbert
G
Leroux
Karl
K
Zalc
Vincent
V
Fodil
Redouane
R
Isabey
Daniel
D
Louis
Bruno
B
D045422:Continuous Positive Airway Pressure / Q000295:instrumentation* / Q000592:standards; D004867:Equipment Design; D006801:Humans; D012015:Reference Standards; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D012891:Sleep Apnea Syndromes / Q000628:therapy