Usinas concentradoras de oxigênio: evolu??o da fra??o inspirada de oxigênio e repercuss?es no paciente anestesiado em sistema com absorvedor de CO2. Estudo piloto

摘要

BACKGROUND AND OBJECTIVES: Resolution 1355/92 of the Conselho Federal de Medicina approved minimal standards for the installation and operation of oxygen concentrators (PSA) and recommended University Hospitals to undertake a prospective analysis in order to improve the system. It motivated this pilot study whose objective was to determine the clinical viability of using PSA oxygen by analyzing the variation in oxygen concentration in the fresh gas flow (FGF) outlet and in the inspired concentration of oxygen. METHODS: An observational study with 30 patients, ASA I, undergoing upper abdominal surgeries using a CO2 absorber system and fresh gas flow (FGF) O293 at 500 mL.min-1. Weight, age, type and duration of the surgery, inspired and expired fraction of CO2 (FiCO2, PETCO2); inspired fraction of O2 (FiO2); and O2 concentration (O2ent) in the FGF. The following parameters were measured after intubation and every 10 minutes until the end of the procedure: PETCO2, FiO2, and O2. Results underwent statistical analysis and p < 0.05 was considered significant. RESULTS: The inspired fraction of carbon dioxide was equal to zero in all patients and moments of the study, but there was a significant reduction in PETCO2 with time. The variables O2ent and FiO2 had similar tendencies with time (p = 0.1283), but the variable O2ent presented higher means (p < 0.001); evolution of mean O2ent and FiO2 was observed (p < 0.05). CONCLUSIONS: This study demonstrated that the use of PSA oxygen, within the conditions proposed for the experiment, is safe and induced a progressive increase in O293 in the FGF and of FiO2.