RESUMO
OBJECTIVE: To investigate the effects of the reinstitution of continuous mechanical ventilator support of >21 days in 370 prolonged mechanical ventilation (PMV) patients, all free from ventilator support for ≥5 days. METHODS: Four groups were formed based on the time and number of PMV reinstitutions and compared (group A: reinstitutions within 28 days, n = 51; group B: a single reinstitution after 28 days, n = 53; group C: multiple reinstitutions after 28 days, n = 52; and group D: no known reinstitutions, n = 214). RESULTS: Of the 370 patients, 156 (42%) required PMV reinstitutions. Most reinstitutions occurred within 7 months: 51 (33%) of the 156 patients within 28 days and 49 (31%) within the next 6 months. Group comparisons revealed a progression of outcomes from group A, the worst, to group D, the best, with groups B and C having intermediate but significantly different values. Decannulation was associated with an 88% decreased risk of PMV reinstitution and a 43% lower risk of death (all P < .001). CONCLUSION: Prolonged mechanical ventilation reinstitution rates were high, with most occurring within 7 months of freedom from MV. In general, the longer the period of ventilator freedom, the less the likelihood of a PMV reinstitution. The identification of 4 distinct PMV groups of patients by time and number of reinstitutions added useful prognostic information. Since PMV reinstitutions within 28 days lead to permanent MV support, >28 days of ventilator freedom provided an optimal cut point for assessing the likelihood of again requiring PMV.