Bench testing of auto-adjusting positive airway pressure devices

Abstract

Continuous positive airway pressure devices are routinely used to treat sleep breathing disorders. Automated devices that adjust the therapeutic pressure have recently been proposed. The utility of such devices is still controversial, as rigorous clinical comparisons are difficult to perform as a result of patient and device differences.The current authors studied automated devices in a respiratory model that was able to mimic upper airway mechanics and to interact with pressure adjustment in a closed loop. Five auto-adjusted devices were submitted to this model, in order to determine their ability to detect respiratory events and adjust pressure accordingly.All apnoeas were suppressed, whilst the reaction to repetitive hypopnoeas was dependent on the airflow shape. In some devices, repetitive hypopnoeas were changed to flow limitation. Artificial snoring caused a pressure increase in four devices, and constant mask leak was not systematically compensated. Only one device did not raise pressure in response to central apnoeas with opened upper airways. These findings show that, in some devices, event classification failed and normal airflow was not fully restored, resulting in elevated residual event indices.In conclusion, this model is useful in order to reproducibly compare diagnostic and therapeutic capacities of commercial devices as a first step, before costly clinical studies.

Residual sleep-disordered breathing during autotitrating continuous positive airway pressure therapy

“…Bench studies have indicated that autoCPAP devices variably respond to certain types of simulated hypopnoeas and demonstrate delays when responding to apnoeas [12,13,[17][18][19]. Numerous clinical studies have reported high proportions (17-29%) of under-treated patients on autoCPAP and fixedpressure CPAP therapy [8,9,20,21].…”

Pressure-Relief Features of Fixed and Autotitrating Continuous Positive Airway Pressure May Impair Their Efficacy: Evaluation with a Respiratory Bench Model

“…Bench studies have been proposed to evaluate the responses of APAP devices in different conditions, such as the presence of predefined sleep disordered breathing (SDB) patterns and air leak, [18][19][20][21][22][23][24][25] whereas no such study to date has focused on pressure-relief CPAPs and APAPs. We investigated seven pressure-relief features developed by three CPAP device manufacturers with a previously reported bench model.…”

Bench Test Evaluation of Adaptive Servoventilation Devices for Sleep Apnea Treatment

“…A similar system to that described by Abdenbi et al 9 was set in the bench. In short, a cylindrical transparent chamber (200 mm long, 60 mm external diameter) containing a compliant rubber tube was connected to 2 pumps (KMP830KNDC, KNF Neuberger GmbH, Freiburg, Germany), which supplied continuous positive and negative pressures and controlled the pressure surrounding the tube inside the chamber (P ch ).…”

“…9 A pneumotachograph (PN279331, Hamilton Medical, Bonaduz, Switzerland) was connected downstream to the mask, and the airflow was measured by a differential pressure transducer (Honeywell DC001NDC4). In addition, another 2 pressure sensors (Honeywell DC030NDC4) were placed in the circuit to record the mask pressure (P m ) and the tracheal pressure (P tr ).…”

“…[4][5][6][7] It is noteworthy that bench testing of these devices has predicted these detection and response limitations under simulated obstructive events. [8][9][10][11] More recently, some manufacturers have developed new devices based on adaptive servoventilation (ASV) to treat patients with mixed events of alternating central and obstructive mechanisms as observed in heart failure 12 or so-called complex sleep apnea (CompSA). 13 These ASV devices apply a closed-loop mechanical ventilation, pressure preset, and volume or airfl ow cycled.…”