Protótipo para medição da pressão positiva expiratória nas vias aéreas humanas para aplicação na prática clínica

Abstract

Positive expiratory pressure (PEP) is a technique used in respiratory physiotherapy to treat diseases related to the respiratory system through spontaneous breathing. It consists of an oronasal mask and a T-connection with a unidirectional valve, PEP adjustable from 0 cmH2O to 20 cmH2O and a cephalic fixator. The aim of this study was to evaluate PEP valves from three different manufacturers and create a prototype with a pressure sensor to adjust the pressure in the equipment, developing a program to monitor patients in the treatment of diseases related to the respiratory system. To this end, three bench studies were carried out with valves from three manufacturers: Ventcare, Besmed and Headstar. In the first study, bench tests were carried out on the spring-loaded valves, using a U-tube pressure gauge. The second study created a prototype of the new equipment with a pressure sensor and a clinical monitoring program. In the third study, a mechanical ventilator was added to the valve and the lungs were tested with air volume, generating positive pressures (inspiratory pressure and pressure in the expiratory airway), a pressure sensor and the test lung to validate the PEP offers proposed by the valves. The values generated by the valves of the three manufacturers in the first study were higher than the baseline and there were significant differences between the manufacturers in the pressures generated at 2.5 cmH2O and 20 cmH2O. In the second study, the pressures were adjusted to the correct values on the scale proposed by the equipment and there were significant differences between the manufacturers in the pressures generated at 5 cmH2O, 10 cmH2O and 20 cmH2O. For the values of 2.5 cmH2O and 15 cmH2O, there was no significant difference between the manufacturers. In the third study, only the following measurements were taken: 0 cmH2O, 5 cmH2O and 10 cmH2O. For the pressures generated at 0 cmH2O and 5 cmH2O, there were no significant differences in relation to the baseline, but between the manufacturers Ventcare and Besmed there was a significant difference tested in relation to the baseline. For 10 cmH2O, there was no significant difference between the Ventcare and Headstar manufacturers tested in relation to the baseline, but the Besmed manufacturer had a significant difference tested in relation to the baseline. The results showed that the spring-loaded valves were not accurate in measuring pressure, so a re-evaluation will be necessary for greater quality, efficacy and accuracy in clinical application.