Dados do Trabalho

Título

A physical simulator for bench tests of therapeutic devices for respiratory sleep disorders

Introdução

The most used respiratory therapies for obstructive sleep apnea syndrome (OSAS) are the Continuous Positive Airway Pressure (CPAP) and BiPAP (Bilevel). Some of these devices perform automatic titration of the pressure, devised to lessen typical respiratory events of OSAS. The literature presents evidence that devices of different brands disagree as to the titrated pressures. Thus, standardized and reproducible bench tests of new devices seem to be recommended.

Objetivo

To evaluate MecLung, a commercial simulator of respiratory system (RS) mechanics, as a single component of a bench test for automatic CPAP devices.

Métodos

MecLung simulates the compliance (C) and resistance (R) of the RS, as well as the respiratory muscular effort. All parameters can be varied in real time with a web app either manually or from a user-defined table. By combining different R and respiratory efforts it would be possible to generate patterns resembling apneas, hypopneas, and Cheyne-Stokes with obstructive or central events characterized without the need of the commonly used Starling resistor.
For the evaluation, we used a CPAP of 10 cmH2O (BMC GII) and set up MecLung to simulate, in sequence, a moderate obstruction (R=20 cmH2O/L/s) and average compliance (C=50 ml/cmH2O) at peak inspiratory muscular pressures (Pmusc,peak) of -8, -10, -12 and -14 cmH2O. Also, at Pmusc,peak=-8 cmH2O and the combinations of C=20, 50, 80 ml/cmH2O with R=5, 20, 80 cmH2O/L/s. Pressure and flow were continuously recorded and breath cycles were detected from flow. Volume was calculated by integration of flow within each cycle. The simulated respiratory effort was then estimated as Pmusc = Pressure - R•Flow - Volume/C, and compared with the set curve.

Resultados

The median (range) of Pmusc,peak for three repetitions of the single RS test was -8.0 (0.04), -10.1 (0.1), -12.0 (0.2), -14.1 (0.5) cmH2O. For the multiple RS test Pmusc,peak for a total of 27 cycles was -8.1 (1.6) cmH2O.

Conclusões

By reproducing RS mechanics and respiratory efforts compatible with OSAS, a bench test using MecLung may allow for comparing different devices under various specific patient needs.

Acknowledgments: This work was partially funded by the Instituto de Ciência, Tecnologia e Inovação de Maricá (ICTIM), the Fundação de Amparo à Pesquisa do Rio de Janeiro (FAPERJ) and the Universidade Federal do Rio de Janeiro.

Palavras -chave

Bench testing, respiratory system mechanics, obstructive sleep apnea