This work presents the development and testing of a system for evaluating the performance of critical care ventilators, after corrective maintenance, based on the NBR IEC 60601-2-12 standard and the use of GUM to estimate uncertainties. The system was developed with the help of LabView software (National Instruments) to use together with the gas analyzer VT60 from Fluke Biomedical. The lung test used was the PnewView3 from Michigan Instruments. For this study, 24 critical care ventilators from 4 different models, in use in the hospital, were tested. The equipaments were evaluated in the ventilation modes: volume control and pressure control inflation, for an adult lung, which corresponds to the first 8 tests presented in the standard. The tests carried out with the help of the developed system took only 1 hour per equipment. None of the 24 critical care ventilators tested passed all the standard's tests.