The largest occlusion time in maximum inspiratory pressure measurements in patients under mechanical ventilation can determine higher values to those calculated by the predictive formula: croos sectional study?

Introduction: The occlusion time to obtain the MIP (maximal inspiratory pressure) is still not consensus in the studies. Objective: To compare initial and final MIP values in neurological patients undergoing ventilatory weaning (VW), with 40 seconds (G40) and 20 seconds (G20) occlusion in unidirectional valve, with values predicted by the MIP predicted formula. Method: Prospective study performed with neurological patients in spontauneous mode in mechanical ventilation. The MIP was measured daily during the VW with a digital manovacuometer calibrated and coupled to the unidirectional valve. Values measured with 20 and 40 seconds of oclusion time were compared with the MIP values predicted by the formula of Costa et al., 2010. Results: 37 patients were selected, 15 excluded; 22 patients were included, 10 intubated and 12 tracheostomized. For both occlusion times, there was a significant difference between the initial to final MIP compared to that predicted: G20 (p=0.03; p=0.01) and G40 (p=0.01; p=0.03). The comparison between initial and final inter-group MIP did not show a statistically significant difference, however, there was a greater tendency in the final MIP values to be significant (p=0.19; p=0.05). Conclusion: The occlusion time of 40 seconds determined larger values compared to the values obtained with 20 seconds occlusion and were closer to those predicted by the formula in neurological patients.